Anthropomorphic Test Devices; THOR 50th Percentile Adult Male Test Dummy; Incorporation by Reference, 61896-61949 [2023-19008]
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Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 / Proposed Rules
DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety
Administration
49 CFR Part 572
[Docket No. NHTSA–2023–0031]
RIN 2127–AM20
Anthropomorphic Test Devices; THOR
50th Percentile Adult Male Test
Dummy; Incorporation by Reference
National Highway Traffic
Safety Administration (NHTSA),
Department of Transportation (DOT).
ACTION: Notice of proposed rulemaking
(NPRM).
AGENCY:
This document proposes to
amend NHTSA’s regulations to include
an advanced crash test dummy, the Test
Device for Human Occupant Restraint
(THOR) 50th percentile adult male
(THOR–50M). The dummy represents
an adult male of roughly average height
and weight and is designed for use in
frontal crash tests. NHTSA plans to
issue a separate NPRM to amend
Federal Motor Vehicle Safety Standard
(FMVSS) No. 208, ‘‘Occupant crash
protection,’’ to specify the THOR–50M
as an alternative (at the vehicle
manufacturer’s option) to the 50th
percentile adult male dummy currently
specified in FMVSS No. 208 for use in
frontal crash compliance tests.
DATES: You should submit your
comments early enough to be received
not later than November 6, 2023.
Proposed Effective Date: Since this
rulemaking action would not impose
requirements on anyone, we are
proposing that the final rule would be
effective on publication in the Federal
Register.
ADDRESSES: You may submit comments
electronically to the docket identified in
the heading of this document by visiting
the Federal eRulemaking Portal at
https://www.regulations.gov. Follow the
online instructions for submitting
comments.
Alternatively, you can file comments
using the following methods:
• Mail: Docket Management Facility:
U.S. Department of Transportation, 1200
New Jersey Avenue SE, West Building
Ground Floor, Room W12–140,
Washington, DC 20590–0001.
• Hand Delivery or Courier: West
Building Ground Floor, Room W12–140,
1200 New Jersey Avenue SE, between 9
a.m. and 5 p.m. ET, Monday through
Friday, except Federal holidays. To be
sure someone is there to help you,
please call (202) 366–9826 before
coming.
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SUMMARY:
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• Fax: (202) 493–2251.
Instructions: All submissions must
include the agency name and docket
number or Regulatory Information
Number (RIN) for this rulemaking. For
detailed instructions on submitting
comments and additional information
on the rulemaking process, see the
Public Participation heading of the
Supplementary Information section of
this document. Note that all comments
received will be posted without change
to https://www.regulations.gov, including
any personal information provided.
Please see the Privacy Act heading
below.
Docket: For access to the docket to
read background documents or
comments received, go to https://
www.regulations.gov. You may also
access the docket at 1200 New Jersey
Avenue SE, West Building, Room W12–
140, Washington, DC 20590, between 9
a.m. and 5 p.m., Monday through
Friday, except Federal Holidays.
Telephone: 202–366–9826.
Confidential Business Information: If
you claim that any of the information in
your comment (including any additional
documents or attachments) constitutes
confidential business information
within the meaning of 5 U.S.C. 552(b)(4)
or is protected from disclosure pursuant
to 18 U.S.C. 1905, please see the
detailed instructions given under the
Public Participation heading of the
Supplementary Information section of
this document.
Privacy Act: Please see the Privacy
Act heading under the Regulatory
Analyses section of this document.
FOR FURTHER INFORMATION CONTACT: For
non-legal issues, you may contact Mr.
Garry Brock, Office of Crashworthiness
Standards, Telephone: (202) 366–1740;
Email: Garry.Brock@dot.gov; Facsimile:
(202) 493–2739. For legal issues, you
may contact Mr. John Piazza, Office of
Chief Counsel, Telephone: (202) 366–
2992; Email: John.Piazza@dot.gov;
Facsimile: (202) 366–3820. The address
of these officials is: the National
Highway Traffic Safety Administration,
1200 New Jersey Avenue SE,
Washington, DC 20590.
SUPPLEMENTARY INFORMATION:
Table of Contents
I. Executive Summary
II. Background
III. Design, Construction, and
Instrumentation
A. Anthropometry
B. Technical Data Package
C. Head and Face
D. Neck
E. Chest
1. Design
2. Instrumentation
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F. Shoulder
1. Alternate Shoulder Specification
2. Shoulder Slip
G. Hands
H. Spine
I. Abdomen
J. Pelvis
K. Upper Leg
L. Knee
M. Lower Leg
N. Data Acquisition System
IV. Biofidelity
V. Qualification Tests
A. Head Impact
B. Face Impact
C. Neck
D. Upper Thorax
E. Lower Thorax
F. Abdomen
G. Upper Leg
H. Knee and Lower Leg
VI. Repeatability and Reproducibility
A. Qualification Tests
B. Sled Tests
1. Methodology
2. Thoracic Injury Criteria Development
Sled Tests
3. Low-Speed Belted Sled Tests
4. Low-Speed Unbelted Sled Tests
VII. Overall Usability and Performance
A. Assembly and Qualification
B. Durability and Maintenance
1. Elevated Energy Qualification Test
Series
2. Oblique OMDB Test Series
3. FMVSS No. 208 Unbelted Vehicle Crash
Tests
C. Sensitivity to Restraint System
Performance
VIII. Intellectual Property
IX. Consideration of Alternatives
X. Lead Time
XI. Incorporation by Reference
XII. Regulatory Analyses
XIII. Public Participation
Proposed Regulatory Text
I. Executive Summary
This document proposes to amend
NHTSA’s regulation on
anthropomorphic test devices—or, more
colloquially, crash test dummies—to
include an advanced crash test dummy,
the Test Device for Human Occupant
Restraint (THOR) 50th percentile adult
male (THOR–50M). The dummy
represents an adult male of roughly
average height and weight and is
designed for use in frontal crash tests.
Crash test dummies are complex
instruments that simulate the response
of a human occupant in a crash. Each
type of test dummy is designed for use
in specific types of crashes (for instance,
frontal or side) and is instrumented with
sensors to measure the forces that would
have been experienced by a human
occupant in a similar crash in the real
world. These measurements are then
used to assess the potential for injury.
Crash test dummies are used by
NHTSA and by the broader vehicle
safety community in a variety of ways.
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NHTSA uses crash test dummies to test
vehicles for compliance with Federal
Motor Vehicle Safety Standards
(FMVSSs) and to determine vehicle
crashworthiness ratings for the New Car
Assessment Program’s (NCAP) 5-Star
Safety Ratings, as well as to conduct
vehicle safety research. Crash test
dummies are also used by regulatory
authorities in other countries and
regions, third-party vehicle rating
programs, motor vehicle and equipment
manufacturers, and others to evaluate
vehicle safety and design safer vehicles
and equipment.
The dummies NHTSA currently uses
in FMVSS compliance testing and
NCAP are documented in 49 CFR part
572, Anthropomorphic Test Devices.
Part 572 sets out detailed design
information, including engineering
drawings and procedures for assembly
and inspection. These are intended to
describe the dummy with sufficient
detail so that it is an objective
measuring tool that produces consistent
responses. NHTSA has codified
numerous dummies that range in sex,
size, age, and measurement capability.
This includes dummies representing
midsize adult males, small-stature adult
females, infants, toddlers, and older
children.1 These dummies are meant to
provide a range of body types in order
to maximize data and test results that
can assess injury and fatality risks in a
range of crash outcomes. The 50th
percentile male dummy currently
defined in Part 572 for frontal impacts
is the Hybrid III–50M, which NHTSA
uses to test for compliance with the
frontal crash test requirements in
FMVSS No. 208, ‘‘Occupant crash
protection’’ and to rate vehicles for
NCAP. NHTSA added the HIII–50M to
Part 572 in 1986.
NHTSA is continually researching
and improving its test dummies and has
been researching advanced test
dummies since the implementation of
the HIII–50M. An initial THOR–50M
design was published in 2001. There are
currently two different THOR dummies,
the THOR–50M, and one under
development that represents a smallstatured adult female, the THOR 5th
percentile adult female (THOR–05F).
Although this proposal is limited to the
THOR–50M, we anticipate publishing a
rulemaking proposal in the near future
to add the THOR–05F to Part 572.
1 This reflects a ‘‘bookend’’ approach to testing
vehicles for crashworthiness, in which a range of
occupant types, bookended by an average male and
a small-stature female, is tested. NHTSA is
currently supporting research to assess the possible
benefits of developing new crash test dummies,
such as a 50th percentile female crash test dummy.
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The THOR–50M improves on the
HIII–50M in a number of ways. It
responds more like a human occupant
in a crash and its advanced
instrumentation enables it to more
accurately measure the forces acting on
the dummy. As a result, it is better able
to predict the risk of injury to a human
occupant. This should help vehicle
designers develop and test improved
occupant restraint systems (e.g.,
advanced seat belts and air bags) as well
as the types of novel vehicle seating
configurations likely to be used in
highly automated vehicles.
NHTSA has tentatively concluded
that the THOR–50M is sufficiently
biofidelic, exhibits repeatable and
reproducible performance, and is
sufficiently durable. As such, we believe
that it would be suitable for use in
regulatory compliance testing and is
therefore suitable for incorporation into
Part 572. NHTSA and others have
already taken advantage of the THOR–
50M’s advanced capabilities. NHTSA,
vehicle and restraint manufacturers, and
vehicle safety researchers have used the
THOR–50M to evaluate vehicle
crashworthiness and develop occupant
protection countermeasures for frontal
and oblique crashes. The European New
Car Assessment Programme (Euro
NCAP) has officially adopted the
THOR–50M and is currently rating
vehicles using the dummy. Moreover,
the Economic Commission for Europe is
considering adopting the THOR–50M
for use in frontal crash testing under its
vehicle safety regulations.
NHTSA expects a variety of benefits
from incorporating the THOR–50M into
Part 572. The definition of the THOR–
50M in Part 572 will enable its use in
regulatory and consumer information
programs, both within NHTSA and
externally. NHTSA believes that the
THOR–50M’s enhancements will lead to
more effective restraint system designs
and more informative comparisons of
the safety of different vehicles. Because
of this—as well as the fact that
manufacturers are already using the
dummy—we believe vehicle
manufacturers would choose to certify
vehicles to FMVSS No. 208 using the
THOR–50M if given the option. This
would enable manufacturers to
streamline testing by using the same
dummy for research and development
and to verify compliance. NHTSA
anticipates issuing a proposal in the
near future to amend FMVSS No. 208 to
specify the THOR–50M as an alternative
(at the vehicle manufacturer’s option) to
the HIII–50M test dummy for use in
frontal crash compliance tests. There
would be other benefits as well. For
instance, NHTSA’s test dummies are
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used in a range of applications beyond
FMVSS compliance testing—such as
NCAP testing, standards and regulations
in other transportation modes, and
research. Including the dummy design
in Part 572 will help provide a suitable,
standardized, and objective test tool for
the safety community.
II. Background
This document proposes to amend 49
CFR part 572, Anthropomorphic Test
Devices, to include an advanced test
dummy representing a 50th percentile
adult male, the Test Device for Human
Occupant Restraint (THOR–50M).2 The
THOR–50M is a test dummy designed
for use in frontal crash tests. It has
several advanced capabilities and
advantages over the Hybrid III 50th
percentile male test dummy (HIII–50M)
that is currently specified in Part 572
and used in frontal crash testing under
FMVSS No. 208, ‘‘Occupant crash
protection,’’ and the U.S. New Car
Assessment Program (NCAP).3 NHTSA
plans to issue a proposal in the near
future to amend FMVSS No. 208 to
specify the THOR–50M as an alternative
to the HIII–50M for use in frontal crash
tests.4
This document proposes
incorporating by reference in Part 572 a
parts list, design drawings, qualification
procedures, and procedures for
assembly, disassembly, and inspection,
to ensure that THOR–50M dummies are
uniform in design, construction, and
response. This section provides
background on NHTSA’s crash test
dummies, the development of the
THOR–50M, and its use in other
jurisdictions, among other topics.
Overview of Use of Vehicle Crash Test
Dummies
Anthropomorphic Test Devices
(ATDs)—or crash test dummies—are
complex instruments that serve as
human surrogates in vehicle crash tests
(among other types of tests 5). Test
dummies simulate the response of a
human occupant in a crash and measure
2 NHTSA has registered the term ‘‘THOR’’ as a
trademark (U.S. Registration No. 5,104,395).
3 The HIII–50M is also specified for use in FMVSS
No. 202a, Head Restraints, in an optional rear
impact dynamic test.
4 FMVSS No. 208 THOR–50M Compliance Option
(RIN 2127–AM21), Spring 2023 Unified Agenda of
Regulatory and Deregulatory Actions; Department
of Transportation, available at https://
www.reginfo.gov/public/do/eAgendaViewRule?
pubId=202304&RIN=2127-AM21.
5 NHTSA also uses ATDs in sled tests (which
simulate a vehicle crash by using a simplified test
buck to represent a vehicle), and out-of-position air
bag tests. ATDs are also used outside the vehicle
safety context to measure human responses in a
variety of other areas, such as aviation and
aeronautics.
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the effects of the crash forces on the
occupant. They are used to estimate the
severity of the injuries that would have
been experienced by a human occupant
in a similar crash in the real world. Each
type of test dummy is designed for use
in specific types of crashes (frontal,
side, etc.), and is instrumented with a
wide array of sensors to measure the
forces that would be relevant in the type
of crash for which it is designed and to
assess the potential for injury. The more
closely a dummy represents how an
actual human would respond, the more
biofidelic the dummy is considered to
be.
NHTSA and the vehicle safety
community use crash test dummies in a
variety of ways. NHTSA uses crash test
dummies for vehicle compliance testing,
safety ratings, and safety research.
NHTSA’s Federal Motor Vehicle Safety
Standards establish mandatory
minimum safety performance
requirements for motor vehicles and
motor vehicle equipment. Vehicles and
equipment manufactured for sale in the
United States must be certified to
comply with all applicable FMVSSs. A
number of the FMVSSs specify crash
tests, using specified dummies, that the
vehicle must be certified as passing.6
NHTSA’s vehicle safety compliance
program selects vehicles (and
equipment) for compliance testing every
year; this includes crash testing vehicles
to ensure that they comply with the
performance requirements that are
evaluated by means of crash tests.
NHTSA’s NCAP also evaluates vehicle
performance in crash tests using
dummies as part of its 5-Star Safety
Ratings. Finally, NHTSA’s vehicle safety
research program uses crash test
dummies to evaluate new vehicle safety
countermeasures and develop new
vehicle crash testing protocols.
Dummies are also used outside of
NHTSA by regulatory authorities in
other countries and regions, for thirdparty ratings (such as Insurance Institute
for Highway Safety ratings), and by
industry and the vehicle safety
community to measure performance and
design safer vehicles.
6 The FMVSS specify the procedures NHTSA will
use in compliance testing, including what dummies
it will use for testing. Part 572 specifies the
dummies. While manufacturers must exercise
reasonable care in certifying that their products
meet applicable standards, they are not required to
follow the compliance test procedures set forth in
a standard or use the dummy specified in Part 572.
See, e.g., 38 FR 12934, 12935 (May 17, 1973)
(‘‘Manufacturers should understand that they are
not required to test their products in any particular
manner, as long as they exercise due care that their
products will meet the requirements when tested by
the NHTSA under the procedures specified in the
standard.’’).
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The dummies NHTSA currently uses
in FMVSS compliance testing and in
NCAP are documented in 49 CFR part
572, Anthropomorphic Test Devices.
Part 572 sets out detailed design
information, including engineering
drawings and procedures for assembly
and inspection. These are all intended
to describe the dummy with sufficient
detail so that it produces consistent
responses when it is tested under
similar conditions in repeated tests at
the same laboratory (repeatability) or
between multiple dummies
manufactured to the same specification
used at different test laboratories
(reproducibility).
FMVSS No. 208 Frontal Crash Tests
Using a 50th Percentile Male Dummy
FMVSS No. 208, ‘‘Occupant crash
protection,’’ specifies a variety of
different requirements using crash test
dummies. This includes frontal crash
tests in which the vehicle is moving and
tests that are performed with a
stationary vehicle and are intended to
help ensure that air bags do not harm
small-stature occupants and children.
The test dummies used in FMVSS No.
208 were designed to evaluate vehicle
performance in frontal crashes and are
fitted with a variety of instruments to
measure the forces typically
experienced by an occupant in a frontal
crash.7 The 50th percentile male
dummy that is currently specified for
use in FMVSS No. 208 is the Hybrid III–
50M.8 The HIII–50M has been specified
in FMVSS No. 208 since 1986,9 and
replaced an even earlier dummy, the
Hybrid II. FMVSS No. 208 also specifies
tests using dummies representing a 5th
percentile female, a 6-year-old, a 3-yearold, and an infant.10
FMVSS No. 208 specifies two tests
(both of which are crash tests) using the
HIII–50M: a crash test in which the
dummy is belted and the test vehicle,
traveling up to 35 mph, impacts a rigid
barrier at a ninety-degree angle or
7 Other FMVSS specify different types of crash or
sled tests that use different dummies. For example,
FMVSS No. 214, Side Impact Protection, specifies
two crash tests (simulating a side impact with a
vehicle and a pole impact). This test uses two
different side impact dummies.
8 Part 572, Subpart E.
9 51 FR 26688 (July 25, 1986) (final rule adding
HIII–50M). The Hybrid III–50M was developed by
General Motors and added to Part 572 and for use
in FMVSS No. 208 in response to a petition for
rulemaking from GM.
10 This reflects a ‘‘bookend’’ approach to testing
vehicles for crashworthiness, in which a range of
occupant types, bookended by an average male and
a small-stature female, is tested. NHTSA is
currently supporting research to assess the possible
benefits of developing new crash test dummies,
such as a 50th percentile female crash test dummy.
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perpendicular; 11 and a crash test in
which the dummy is unbelted and the
test vehicle, traveling 20–25 mph,
impacts a rigid barrier at an angle
ranging from ± 30 degrees oblique from
perpendicular.12 NCAP also evaluates
vehicle performance in a frontal crash
test at 35 mph using a belted HIII–50M
dummy.
FMVSS No. 208 regulates vehicle
performance in these crash tests by
specifying injury criteria and associated
injury assessment reference values
(IARVs). Injury criteria and their
respective risk functions relate
instrumentation measurements to a
predicted risk of human injury. Each
IARV is a maximum value or threshold
for a specific injury criterion that may
not be exceeded when the vehicle is
tested with the specified dummy under
the specified test conditions and
procedures. For example, FMVSS No.
208 specifies a head injury criterion,
HIC15, with an IARV of 700. Thus, if
NHTSA runs a compliance frontal crash
test and the calculated HIC15 value
exceeds 700, this would be considered
an apparent noncompliance. FMVSS
No. 208 specifies the following injury
criteria for the HIII–50M: a head injury
criterion (HIC15); 13 a thoracic
acceleration criterion; 14 a chest
deflection criterion; 15 a criterion based
on the maximum force transmitted
axially through the upper leg (femur); 16
and three neck injury criteria.17
Development of the THOR ATDs
NHTSA has continually conducted
research into advancements in crash
safety, including the development of
advanced dummies.18 The goal of this
research has been to create ATDs that
represent the responses of human
occupants in modern vehicle
environments with advanced restraint
systems. This research has led to the
development of the two Test Device for
Human Occupant Restraint (THOR)
ATDs, designed primarily for use in
frontal and frontal oblique motor
vehicle crash environments. There are
currently two main implementations of
the THOR design, both representing
seated motor vehicle occupants: one
representing a 50th percentile male and
11 S5.1.1(b)(2),
12 S5.1.2(b),
S14.5.1(b).
S14.5.2.
13 S6.2(b).
14 S6.3.
15 S6.4.
16 S6.5.
17 S6.6.
18 Haffner, M., Rangarajan, N., Artis, M., Beach,
D., Eppinger, R., Shams, T., ‘‘Foundations and
Elements of the NHTSA THOR Alpha ATD Design,’’
The 17th International Technical Conference for the
Enhanced Safety of Vehicles, Paper No. 458, 2001.
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one representing a 5th percentile
female.
Development of THOR–50M
The initial design version of the
THOR–50M, introduced in 2001, was
the THOR Alpha.19 The THOR Alpha,
which integrated some components
from the earlier prototype demonstrator
known as the Trauma Assessment
Device, introduced some of the features
that exist in the current version of
THOR–50M, including the multidirection neck, human-like ribcage
geometry and impact response, multipoint thorax and abdomen deflection
measurement system, and instrumented
lower extremities. NHTSA refined the
THOR Alpha design and reintroduced it
in 2005 as the THOR–NT,20 which
included updates to anthropometry,
durability, usability, biofidelity, and fit
and finish. In 2011, NHTSA, in
coordination with the SAE International
(SAE) THOR Evaluation Task Group,
introduced a modification package (Mod
Kit) intended to enhance the biofidelity,
repeatability, durability, and usability of
the THOR–NT.21 After the introduction
of the THOR Mod Kit, an upgrade to the
Chalmers shoulder assembly that was
developed through the European
Union’s THORAX project was integrated
into the THOR–50M design.22 The
THOR–50M drawing package was then
converted from the traditional
measurement system to the metric
system through soft conversion (where
any non-metric measurements are
mathematically converted to metric
equivalents without changes to the
physical dimensions). All fasteners were
also replaced with the nearest metric
equivalents. NHTSA made this
integrated drawing package (with
incremental improvements and
corrections) publicly available online in
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19 Id.
20 Shams, T., Rangarajan, N., McDonald, J., Wang,
Y., Platten, G., Spade, C., Pope, P., Haffner, M.,
‘‘Development of THOR NT: Enhancement of THOR
Alpha—the NHTSA Advanced Frontal Dummy,’’
The 19th International Technical Conference for the
Enhanced Safety of Vehicles, Paper No. 05–0455,
2005.
21 Ridella, S., Parent, D., ‘‘Modifications to
Improve the Durability, Usability, and Biofidelity of
the THOR–NT Dummy,’’ The 22nd International
Technical Conference for the Enhanced Safety of
Vehicles, Paper No. 11–0312, 2011.
22 Lemmen, P., Been, B., Carroll, J., Hynd, D.,
Davidsson, J., Song, E., Lecuyer, E., ‘‘Development
of an advanced frontal dummy thorax
demonstrator,’’ Proceedings of the 2012 IRCOBI
Conference, 2012.
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2015,23 2016,24 2020,25 and 2023.26 The
version published in 2023 is referred to
as the 2023 drawing package, which
consists of two-dimensional drawings
and a Parts list; this, together with the
Procedures for Assembly, Disassembly,
and Inspection (PADI), and qualification
procedures, is referred to as the 2023
technical data package. (The version
published in 2020 is referred to as the
‘‘2018 drawing package’’ or the ‘‘2018
technical data package.’’) The version of
THOR that is being proposed is the
version defined in the 2023 technical
data package. In 2019, NHTSA began
publishing THOR–50M documentation
in a new docket titled, ‘‘NHTSA
Crashworthiness Research—THOR–50M
Documentation.’’ 27 In addition to the
documents that make up the 2018 and
2023 technical data packages, the docket
folder includes the following: durability
report; seating procedure; injury criteria;
biofidelity report; Oblique Moving
Deformable Barrier (OMDB)
Repeatability and Reproducibility
(R&R); and Qualification test R&R. This
documentation is discussed further in
Section III.B and in the relevant sections
of this preamble.28 NHTSA has
tentatively concluded that the THOR–
50M is sufficiently biofidelic, exhibits
repeatable and reproducible
performance, and is sufficiently durable.
23 National Highway Traffic Safety
Administration (2015). Parts List and Drawings,
THOR–M Advanced Frontal Crash Test Dummy,
September 2015. Regulations.gov Docket ID
NHTSA–2015–0119–0005, available at: https://
www.regulations.gov/document/NHTSA-2015-01190005 (NCAP docket).
24 National Highway Traffic Safety
Administration (2016). Parts List and Drawings,
THOR–50M Advanced Frontal Crash Test Dummy,
August 2016, available at: https://www.nhtsa.gov/
es/document/thor-50m-drawing-package-august2016.pdf.
25 National Highway Traffic Safety
Administration. Parts List and Drawings, THOR–
50M Advanced Frontal Crash Test Dummy, August
2018. Regulations.gov Docket ID NHTSA–2019–
0106–0002, available at: https://
www.regulations.gov/document/NHTSA-2019-01060002.
26 National Highway Traffic Safety
Administration. THOR 50th Percentile Male with
Alternate Shoulders Frontal Crash Test Dummy
Drawings, External Dimensions, and Mass
Properties, THOR–50M Advanced Frontal Crash
Test Dummy, August 2018. Regulations.gov Docket
ID NHTSA–2019–0106–0013, available at: https://
www.regulations.gov/document/NHTSA-2019-01060013.
27 Docket NHTSA–2019–0106.
28 These documents are located in the research
docket, Docket No. NHTSA–2019–0106. NHTSA is
not placing copies of these documents in the docket
for this rulemaking action in order to avoid
potential confusion from having identical
documents docketed at different times in different
dockets. Nevertheless, NHTSA intends these to be
included as part of the rulemaking record for this
rulemaking action. A memorandum explaining this
is also being placed in the docket for this
rulemaking.
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As such, we believe that it would be
suitable for use in regulatory
compliance testing and is therefore
suitable for incorporation into Part 572.
A more detailed discussion of the
technical data package is provided in
Section III.B.
Development of THOR–05F
NHTSA understands that the risk of
injury in a crash can depend on the
occupant’s physical characteristics (e.g.,
height, weight, bone density) and how
they interact with the restraint system
and vehicle environment. To that end,
NHTSA has developed comprehensive
research plans to address differences in
crashworthiness safety testing and
outcomes, including differences in
injury risk. Human body modeling
research efforts are underway to
consider female and male occupants
and vulnerable road users of various
ages, shapes, and sizes. This includes
continuing and accelerating research
efforts to address differences in motor
vehicle safety based on physical
characteristics, including sex, and
making data-driven decisions supported
by the research outcomes. A series of
efforts is specifically focused on female
occupant crash safety, spanning field
data analysis, tool development,
demonstration, and application.29
As part of these efforts, NHTSA has
been developing the THOR 5th
percentile adult female frontal crash test
dummy (THOR–05F). The THOR–05F
represents a small adult female and has
a seated height of 81.3 cm (32.0 in),
approximate standing height of 151 cm
(59.4 in), and weight of 49 kg (108.0
lbs). The THOR–05F has improved
measurement capabilities over the
Hybrid III–5F, which is specified in
FMVSS No. 208 and documented in Part
572. The THOR–05F’s instrumentation
is similar to that of the THOR–50M.
Improved designs resulting from the
development of the THOR–50M related
to the head, neck, thorax, and lower
extremities have also been incorporated
into the design of the THOR–05F.
Currently, NHTSA is evaluating the
THOR–05F’s biofidelity and durability,
developing design updates, injury
criteria, and documentation, and
assessing its utility in full-scale crash
testing.
NHTSA anticipates completing the
research and testing necessary to
support a rulemaking for the THOR–05F
29 See National Highway Traffic Safety
Administration (2022). NHTSA Female Crash Safety
Research Plan, November 2022. Regulations.gov
Docket ID NHTSA–2022–0091–0002, available at:
https://www.regulations.gov/document/NHTSA2022-0091-0002.
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in 2023.30 Possible test modes in which
THOR–05F may be used include
FMVSS No. 208 testing and NCAP
frontal crash tests. NHTSA has placed
documentation and research for the
THOR–05F in an online docket and will
continue adding additional research and
information to this docket as it becomes
available.31
Innovative Features of the THOR–50M
Frontal crashes are the leading cause
of injuries and fatalities in occupants of
motor vehicle crashes on U.S. public
roadways. The vehicle front is the initial
point of impact in a majority of crashes
in the U.S. In 2021, 15,570 occupants of
passenger cars or light trucks died, and
1,144,169 were injured, in frontal
crashes.32 This suggests that even
though occupant protection systems
have improved over the years and saved
many lives,33 improvements to
occupant protection in frontal crashes
still need to be made.
The THOR–50M is designed to better
evaluate the effectiveness of modern
vehicle restraint systems and address
the types of injuries that continue to
occur. These improvements include the
following:
Improved biofidelity. Biofidelity is a
measure of how well a dummy
replicates the response of a human. The
THOR–50M was designed with
advanced features that enable it to have
improved biofidelity compared to the
HIII–50M. The dummy’s head includes
a deformable facial insert that emulates
human response to impact. The
components in the neck representing
bone and ligament structure are separate
from those representing muscular
structure, improving both kinematic
response and injury prediction. The
thorax simulates the shape and impact
response of the human rib cage. The
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30 Part
572 THOR 5th Female Crash Test Dummy
(RIN 2127–AM56), Spring 2023 Unified Agenda of
Regulatory and Deregulatory Actions; Department
of Transportation, available at https://
www.reginfo.gov/public/do/eAgendaViewRule?
pubId=202304&RIN=2127-AM56. This rulemaking
would amend 49 CFR part 572 by adding design
and performance specifications for a new test
dummy known as the THOR–05F.
31 See Docket No. NHTSA–2019–0107, available
at regulations.gov.
32 Data Sources: Fatality Analysis Reporting
System (FARS): 2017–2020 Final File and 2021
Annual Report File (ARF); Report Generated:
Wednesday, June 28, 2023 (12:48:52 p.m.);
VERSION 5.6, RELEASED MAY 19, 2023
33 Charles J. Kahane, Lives Saved by Vehicle
Safety Technologies and Associated Federal Motor
Vehicle Safety Standards, 1960 to 2012—Passenger
Cars and LTVs—With Reviews of 26 FMVSS and
the Effectiveness of Their Associated Safety
Technologies in Reducing Fatalities, Injuries, and
Crashes. 89 DOT HS 812 069 at 89, Department of
Transportation, National Highway Traffic Safety
Administration (2015).
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spine incorporates flexible joints in the
thoracic and lumbar spine, allowing
dynamic spine flexion as well as static
adjustment in the neck and lumbar
spine to accommodate seating in various
postures. The upper leg has a
compressive element in the femur and
the lower leg has a compressive element
in the tibia and an Achilles tendon load
path to achieve human-like impact
response. The biofidelity of the THOR–
50M has been assessed in a wide array
of both component and full-body test
conditions for which human response is
known and was found to be both
qualitatively and quantitatively
congruent with human response
corridors.
Improved instrumentation. The
THOR–50M has both improved and
additional instrumentation compared to
the HIII–50M. The thorax
instrumentation measures the threedimensional deformation of the rib cage
at four locations. The abdomen is also
designed with a multi-point
measurement system that monitors
three-dimensional deformation of the
abdomen at two locations. The upper
leg includes an acetabulum load cell in
the pelvis to measure load transfer from
the femur to the hip. The lower leg has
extensive instrumentation to support
injury risk calculation.
Improved injury prediction. The
biofidelity of the THOR–50M, combined
with its extensive instrumentation,
provides an enhanced capability to
measure expected human response and
predict injury. Injury criteria and injury
risk functions, which relate
instrumentation measurements to a
predicted risk of human injury, have
been developed for the head, neck,
chest, abdomen, pelvis, upper leg, and
lower leg of the THOR–50M.34 These
include injury criteria analogous to
those currently specified for the HIII–
50M in FMVSS No. 208 as well as injury
criteria that are not currently specified
for the HIII–50M in FMVSS No. 208. We
believe this enhanced injury prediction
capability will translate into restraint
system designs that have the potential to
enhance occupant protection. NHTSA
and others, including vehicle
manufacturers, have already taken
advantage of these capabilities in the
research arena.
Improved evaluation of vehicle
performance. These enhancements
allow the THOR–50M to better
differentiate the performance of
34 Craig, M., Parent, D., Lee, E., Rudd, R.,
Takhounts, E., Hasija, V. (2020). Injury Criteria for
the THOR 50th Male ATD. Regulations.gov Docket
ID NHTSA–2019–0106–0008, available at: https://
www.regulations.gov/document/NHTSA-2019-01060008.
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different vehicles and restraint systems.
The more sophisticated measurement
capabilities of an advanced ATD are
better suited to develop and test more
sophisticated and highly tunable
contemporary restraint systems with
features such as multi-stage air bags and
force-limiting/pretensioning seat belts.
Motor vehicle manufacturers and
restraint suppliers have already used the
THOR–50M to evaluate vehicle
crashworthiness and develop occupant
protection countermeasures. Numerous
conference and journal articles
describing the use of the THOR–50M
have been published. For example, in a
study examining the performance of
different restraint systems in frontal
impact sled tests using both the THOR–
50M and HIII–50M, the THOR–50M was
found to be more sensitive to the
restraint conditions, as it was able to
differentiate between both crash severity
and restraint performance.35 Another
study investigated a novel air bag
system with three inflated chambers
with a connected sail panel to promote
earlier engagement with the occupant
and prevent lateral motion and head
rotation; sled testing using the THOR–
50M demonstrated a reduction in brain
injury risk due to head angular velocity,
as quantified using the Brain Injury
Criterion (BrIC).36 Other studies have
also implemented the THOR–50M to
assess and develop restraint systems.37
Adoption of the THOR–50M in Europe
In 2013, the European Commission
(EC) issued a final report detailing the
need for a new crash test dummy as a
means to implement regulatory
requirements for new vehicle safety
technologies, particularly those
technologies that reduce thorax injuries
in frontal crashes.38 At the time, the
35 Sunneva
˚ ng, C., Hynd, D., Carroll, J., Dahlgren,
M., ‘‘Comparison of the THORAX Demonstrator and
HIII Sensitivity to Crash Severity and Occupant
Restraint Variation,’’ Proceedings of the 2014
IRCOBI Conference, Paper No. IRC–14–42, 2014.
36 Hardesty, J. (2021). Next-Generation Passenger
Airbag. SAE Government-Industry Digital Summit
(oral only).
37 See also, e.g., Hu, J., Reed, M. P., Rupp, J. D.,
Fischer, K., Lange, P., & Adler, A. (2017).
Optimizing seat belt and airbag designs for rear seat
occupant protection in frontal crashes (No. 2017–
22–0004). SAE Technical Paper; Eggers, A.,
Eickhoff, B., Dobberstein, J., Zellmer, H., Adolph, T.
(2014). Effects of Variations in Belt Geometry,
Double Pretensioning and Adaptive Load Limiting
on Advanced Chest Measurements of THOR and
Hybrid III. Proceedings of the 2014 IRCOBI
Conference, Paper No. IRC–14–40; Hu, J., Fischer,
K., Schroeder, A., Boyle, K., Adler, A., & Reed, M.
(2019, October). Development of oblique restraint
countermeasures (Report No. DOT HS 812 814).
Washington, DC: National Highway Traffic Safety
Administration. Available at: https://
rosap.ntl.bts.gov/view/dot/44143.
38 European Commission, Seventh Framework
Programme, THORAX Project Final Report,
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THOR–50M was envisioned as the best
evaluation tool for this purpose. In
2015, United Nations Economic
Commission for Europe (UNECE)
Regulation No. 137 (R137) went into
effect. R137 specifies a 50 km/h, fullwidth rigid barrier frontal impact test
with driver and passenger HIII–50M and
HIII–5F dummies respectively. One
objective of the regulation was to
encourage better restraint systems across
a wider range of collision severities.39
In 2017, an ECE-funded study found
that the R137 condition and dummy
diversity were not sufficiently different
to existing UN Regulation No. 94 (R94)
to force improvements in restraint
systems. R94 involves a 56 km/h frontal
offset test which also prescribes the
HIII–50M in the driver and right front
seat. To deliver the expected benefits,
the 2017 final report recommended
implementation of the THOR–50M in
R137 as a replacement for the HIII–
50M.40 The THOR–50M was recognized
as being more biofidelic in its
representation of thoracic response and
prediction of thorax injuries, which are
the key serious and fatal injury types in
full-width collisions targeted by R137.
In 2018, the EC published a report on
the cost-effectiveness and the number of
future injuries and fatalities that could
be prevented at a European level for
different sets of vehicle safety
measures.41 Several new sets of safety
measures were considered for
mandatory implementation in new
vehicles starting from 2022. This
included the introduction of the THOR–
50M into R137. The THOR–50M was
considered for inclusion in a program
titled ‘‘Full-width Frontal Occupant
Protection with THOR (FFW–THO),’’
which would lower injury criteria
thresholds to encourage implementation
of adaptive restraints. It was envisioned
that the implementation of the THOR–
50M would result in an initial cost of 16
Thoracic injury assessment for improved vehicle
safety, 1/7/2013.
39 Seidl, M., Edwards, M., Barrow, A., Hynd, D.,
& Broertjes, P. (2017). The Expected Impact of UN
Regulation No. 137 Tests on European Cars and
Suggested Test Protocol Modifications to Maximise
Benefits. In 25th International Technical
Conference on the Enhanced Safety of Vehicles
(ESV).
40 Seidl M, Hynd D, McCarthy M, Martin P, Hunt
R, Mohan S, Krishnamurthy V and O’Connell S:
TRL Ltd. (2017). In depth cost-effectiveness analysis
of the identified measures and features regarding
the way forward for EU vehicle safety, Final Report,
ISBN 978–92–79–68704–4, European Commission,
08–31–2017.
41 Seidl, M., Khatry, R., Carroll, J., Hynd, D.,
Wallbank, C., Kent, J. (2018) Cost-effectiveness
analysis of Policy Options for the mandatory
implementation of different sets of vehicle safety
measures—Review of the General Safety and
Pedestrian Safety Regulations, Technical Annex to
GSR2 report SI2.733025.
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Euros per vehicle, for vehicles that
currently comply with UN Regulation
No. 137 with Hybrid III ATDs but not
with THOR–50M ATDs. It was
estimated that vehicles that comply
with FFW–THO would provide a 6%
increase in effectiveness in protecting
against serious injuries compared to
vehicles that comply with R137 alone.
In 2019, the EC presented work
priorities to WP.29 42 for 2019–2021 for
UNECE activities. An amendment to
introduce the THOR–50M into R137
was included. The target date for a
WP.29 vote was listed as Q4/2021.43 In
2020, Japan and the EC jointly initiated
discussions within WP.29 to establish a
priority for the new task. In preparation
for an eventual adoption into R137, the
E.C. commissioned TRL (Transport
Research Laboratory, UK) 44 to conduct
a survey of various stakeholders on the
readiness of the THOR–50M. ATD
manufacturers, crash test laboratories,
and crash safety research laboratories
were consulted. The results of the
survey are contained within Annex 7 of
a broader report on general safety
regulations, published by the E.C. in
2021.45 In the E.C. report, there are a
number of recommendations based on
stakeholder feedback. They include
revisions to the dummy design and
qualification procedures that may be
needed prior to adopting THOR–50M
into M.R. 1 46 and R137. Most
stakeholders recommended the
formation of either an Informal Working
42 This was a thrice-annual briefing on the
regulatory status within the various working parties
under WP.29’s World Forum for Harmonization of
Vehicle Regulations, including the status of R137
under the Working Party for Passive Safety (GRSP).
43 WP.29–177–18, 177th WP.29, 12–15 March
2019, EU Work priorities for 2019–2021 for UNECE
activities.
44 TRL serves as an independent advisory to the
E.C. TRL’s report was performed under contract
with the European Commission (E.C.), who sought
to update the General Safety Regulation for Europe
to include new and developing technologies with
the aim of reducing Europe’s annual road fatalities.
The report reflects TRL’s recommendations for
consideration by the E.C.
45 General Safety Regulation: Technical study to
assess and develop performance requirements and
test protocols for various measures implementing
the new General Safety Regulation, for accident
avoidance and vehicle occupant, pedestrian and
cyclist protection in case of collisions, Final Report,
March 2021, Publications Office of the EU
(europa.eu)), ISBN 978–92–76–08556–0, DOI
10.2873/499942, Catalogue number, ET–04–19–
467–EN–N. https://op.europa.eu/en/publicationdetail/-/publication/6987b729-a313-11eb-958501aa75ed71a1/language-en/format-PDF/source217672351 (last accessed 5/25/2023).
46 Mutual Resolution No. 1 (M.R.1) of the 1958
and the 1998 Agreements. Concerning the
description and performance of test tools and
devices necessary for the assessment of compliance
of wheeled vehicles, equipment and parts according
to the technical prescriptions specified in
Regulations and global technical regulations, ECE/
TRANS/WP.29/1101, 10 January 2013.
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Group or a Technical Evaluation Group
under the umbrella of UNECE WP.29 to
co-ordinate this activity. As of May
2023, a WP.29 working group has yet to
be established and timelines for
amendments to R137 and M.R. 1 are
undetermined. The areas for further
investigation identified in Annex 7 are
discussed in this NPRM.
Although the ECE has not yet
officially adopted the THOR–50M, the
European New Car Assessment
Programme (Euro NCAP) has been rating
vehicles using the dummy. Euro NCAP
has implemented a moving progressive
deformable barrier (MPDB) frontal
impact testing protocol with a THOR–
50M in the driver’s seat.47 The THOR–
50M used by Euro NCAP is specified in
Technical Bulletin 026 (TB026) 48
‘‘THOR Specification and
Certification.’’TB026 explicitly adopts—
with some variations—NHTSA’s 2018
technical data package (i.e., the 2018
drawing package,49 qualification
procedures,50 and PADI 51). The
variations to the 2018 technical data
package are relatively limited. For
example, TB026 specifies an onboard
(in-dummy) data acquisition system and
a variation to the adjustable spine to
facilitate data acquisition system (DAS)
installation; minor deviations in the
shoulder assembly; and the use of the
HIII–50M lower legs. These
modifications are discussed in more
detail in the relevant sections of the
preamble and are summarized in
Section IX, Consideration of
alternatives. NHTSA’s understanding is
that no regulatory authorities or thirdparty vehicle rating programs other than
Euro NCAP currently specify the
THOR–50M for use in vehicle crash
tests.
Motor vehicle and equipment
manufacturers’ interest in the design
and operation of the THOR–50M has
been heightened since the dummy was
introduced into Euro NCAP and plans
for R137 were announced. Discussions
are taking place within International
Standards Organization (ISO) Technical
Committee 22 (Road Vehicles), SubCommittee 36 (Safety and impact
testing), Working Group 5
(Anthropomorphic test devices) for
47 European New Car Assessment Programme
(2022). MPDB Frontal Impact Testing Protocol,
Version 1.1.3, available at: https://
www.euroncap.com/en/for-engineers/protocols/
adult-occupant-protection/.
48 European New Car Assessment Programme
(2023). THOR Specification and Certification,
Version 1.3, available at: https://
www.euroncap.com/en/for-engineers/supportinginformation/technical-bulletins/.
49 § 1.1.
50 § 2.1.
51 § 3.1.
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modifications suggested by
manufacturers. With no defined
European entity to maintain
configuration control, ISO has enlisted
Humanetics Innovative Solutions, Inc.
(Humanetics) to investigate its change
recommendations directly. In particular,
discussions have taken place regarding
modifications to the shoulder pad and
rib guide. These modifications are
discussed in the relevant sections of the
NPRM.
Need for This Rulemaking
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NHTSA expects a variety of benefits
from incorporating the THOR–50M in
Part 572. The THOR–50M is an
advanced dummy with many
advantages over existing dummies with
respect to biofidelity, instrumentation,
and injury prediction. NHTSA believes
that the THOR–50M’s enhancements
will lead to more effective restraint
system designs and more informative
comparisons of the safety of different
vehicles. Euro NCAP has adopted it, the
ECE is considering it for use in R137,
and it is likely being used by vehicle
and restraint manufacturers for testing,
research, and development. Therefore,
we believe vehicle manufacturers would
choose to certify new vehicles using the
THOR–50M if given the option, because
this would enable manufacturers to
streamline testing by using the same
dummy for research and development
and to verify compliance and vehicle
ratings. NHTSA is therefore also
considering a proposal to amend
FMVSS No. 208 to give vehicle
manufacturers the option of selecting
the THOR–50M for use in belted and
unbelted crash testing instead of the
HIII–50M.52
There would be other benefits as well.
For instance, the THOR–50M is wellsuited for the types of new seating
configurations brought on by vehicles
with Automated Driving Systems (ADS).
NHTSA is developing an adaptation of
the THOR–50M that is better suited for
reclined postures which may be
prevalent among ADS occupants.53
52 FMVSS No. 208 THOR–50M Compliance
Option (RIN 2127–AM21), Fall 2023 Unified
Agenda of Regulatory and Deregulatory Actions;
Department of Transportation, available at https://
www.reginfo.gov/public/do/eAgendaViewRule?
pubId=202304&RIN=2127-AM21. This rulemaking
would propose injury assessment reference values
for the THOR–50M comparable to the IARVs
currently specified for the HIII–50M.
53 Forman, J., Caudillo-Huerta, A., McMahon, J.,
Panzer, M., Marshall, W., Winter, D., Dyer, M.,
Lemmen, P. (2021). Modifications to the THOR–
50M for Improved Usability in Reclined Postures—
Update and Preliminary Findings. 2021 SAE
Government-Industry Digital Summit, available at:
https://www.nhtsa.gov/node/103691. The
adaptation to the THOR–50M design for use in
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NHTSA’s test dummies are also used in
a range of applications beyond FMVSS
compliance testing—such as NCAP
testing, standards and regulations in
other transportation modes, and
research. While the purpose of Part 572
is to describe the anthropomorphic test
devices that are to be used for
compliance testing of motor vehicles
and motor vehicle equipment with
motor vehicle safety standards,54 it also
serves as a definition of the ATD for
other purposes, such as consumer
information crash testing, standards and
regulations in other transportation
modes, and research. As such, it would
be to the benefit of government,
academia, and the multi-modal
transportation industry to include a
definition of the THOR–50M ATD in
Part 572.55
III. Design, Construction, and
Instrumentation
In this section we discuss the
anthropometry, design, construction,
and instrumentation of the THOR–50M.
A. Anthropometry
The THOR–50M is a physical model
of a 50th percentile male motor vehicle
occupant. It is intended for use in the
development and evaluation of vehicle
safety countermeasures and vehicle
safety performance in frontal crash tests.
To ensure that the dummy responds in
a human-like manner in a vehicle crash
environment, it is necessary that the
size and shape of the dummy, referred
to as anthropometry, provide an
accurate representation of a mid-sized
male. The anthropometry of the THOR–
50M is based on a study by the
University of Michigan Transportation
Research Institute that documented the
anthropometry of a mid-sized (50th
percentile in stature and weight) male
occupant in an automotive seating
posture (AMVO study).56 57 This study
reclined seating environments is outside of the
scope of this Part 572 NPRM.
54 49 CFR 572.1.
55 For example, American Public Transportation
Association standard APTA PR–CS–S–018–13 Rev.
1 describes the use of a THOR ATD in the testing
of fixed workstation tables in passenger rail cars.
American Public Transportation Association. (2015,
October). Fixed Workstation Tables in Passenger
Rail Cars. PR–CS–S–018–13, Rev. 1. Washington,
DC, available at: https://www.apta.com/wp-content/
uploads/Standards_Documents/APTA-PR-CS-S018-13-Rev-1.pdf.
56 Schneider, L.W., Robbins, D.H., Pflug, M.A.,
Snyder, R. G., ‘‘Development of Anthropometrically
Based Design Specifications for an Advanced Adult
Anthropomorphic Dummy Family; Volume 1Procedures, Summary Findings and Appendices,’’
U.S. Department of Transportation, DOT–HS–806–
715, 1985.
57 Robbins, D.H., ‘‘Development of
Anthropometrically Based Design Specifications for
an Advanced Adult Anthropomorphic Dummy
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defines an average male as 76.57 kg
(168.8 lb) in weight with a standing
height of 175.1 cm (68.9 in). The AMVO
study is currently internationally
accepted as the standard anthropometry
for the 50th percentile male ATD. The
THOR–50M has a mass of 77.37 kg
(170.6 lb) and a seated height of 101.8
cm (40.2 in). The standing height of the
ATD cannot be measured since the
pelvis does not allow a full standing
posture; however, since it was
developed using the AMVO body
segment geometry and seated
anthropometry, it is assumed that the
stature of the THOR–50M is also 175.1
cm.
The THOR–50M is consistent with the
AMVO anthropometry. NHTSA
compared the dimensions of a
representative dummy (S/N 9798) with
the AMVO target dimensions (Table
1).58 The AMVO procedure originally
used to collect measurements from
volunteers was adapted to collect the
same or similar measurements on the
THOR–50M.59 Most of these
measurements were taken with the
THOR–50M seated on the AMVO bench,
which has an angled seat and backrest.
One adaptation was necessary to collect
leg measurements on the AMVO bench:
the THOR–50M has an integrated
molded shoe that cannot be separated
from its foot, while the AMVO data
were collected on barefoot volunteers.
To remedy this situation, the THOR–
50M measurements were recorded after
removing the entire molded shoe
assembly and positioning the center of
the ankle joint at the same location as
the AMVO ankle landmark. Another
adaptation was that four of the
measurements were collected with the
THOR–50M seated on a 90-degree
bench, as specified on drawing 472–
0000, Sheet 4. NHTSA also compared
Family; Volume 2-Anthropometric Specifications
for mid-Sized Male Dummy; Volume 3Anthropometric Specifications for Small Female
and Large Male Dummies,’’ U.S. Department of
Transportation, DOT–HS–806–716 & 717, 1985.
58 A THOR–50M unit is a collection of serialized
parts that can be swapped out with other dummies,
so is not considered a ‘‘serialized’’ dummy. Indeed,
many of the subassemblies that were part of S/N
9798 when NHTSA took these measurements were
subsequently swapped out of the dummy. See
Section VII.A.
59 These AMVO measurements were collected as
an assessment of anthropometry; it is understood
that there is variation in initial position and
measurement methodology that prevents the use of
such measurements as a repeatable dimensional
assessment. In practice, a simplified set of
dimensional requirements are put in place as a
check for overall part fit, tolerance stack, and to
ensure that the dummy is assembled correctly.
These requirements are specified on drawing 472–
0000, Sheet 4, and are collected following the
‘‘Procedures for Measuring External Dimensions’’
section of the PADI.
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the body segment masses specified in
the proposed THOR drawing package
(472–0000, Sheet 5) with the AMVO
61903
body segment masses (Table 2), and the
masses were also consistent.
TABLE 1—THOR–50M ANTHROPOMETRY COMPARED TO AMVO
AMVO target
(Robbins et al
1983)
Dimensions
(all measurements in centimeters)
Height of top of head to floor ..................................................................................................................................
Height of shoulder to floor .......................................................................................................................................
H-point to knee joint distance (note 1) ....................................................................................................................
Buttock to knee end distance (note 2) ....................................................................................................................
Height of knee from floor .........................................................................................................................................
Head circumference .................................................................................................................................................
Head top-chin distance ............................................................................................................................................
Head breadth ...........................................................................................................................................................
Chest circumference ................................................................................................................................................
Chest breadth ..........................................................................................................................................................
Chest depth (note 3) ................................................................................................................................................
Abdomen circumference ..........................................................................................................................................
Abdomen breadth ....................................................................................................................................................
Abdomen depth (note 2) ..........................................................................................................................................
Pelvis breadth ..........................................................................................................................................................
Thigh max circumference ........................................................................................................................................
Thigh max breadth ...................................................................................................................................................
Mid thigh circumference ..........................................................................................................................................
Mid thigh breadth .....................................................................................................................................................
Calf circumference ...................................................................................................................................................
Calf breadth .............................................................................................................................................................
Calf depth ................................................................................................................................................................
1 THOR–50M
2 THOR–50M
3 THOR–50M
100.3
72.1
43.2
59.3
45.3
57.1
19.7
15.8
101.1
34.9
22.7
91.3
32.5
26.9
38.5
57.9
19.4
50.4
15.5
37.3
11.0
11.8
THOR–50M
S/N 9798
101.8
74.2
42.3
62.0
47.0
58.7
22.9
15.3
95.5
30.9
22.4
99.0
32.5
29.8
38.8
56.8
17.1
56.0
17.8
37.5
9.1
11.9
specified on 472–0000, Sh. 4, measurement F (Knee Pivot to Hip Pivot) as seated upright on a 90-degree bench.
and AMVO measured as seated upright on a 90-degree bench.
specified on 472–0000, Sh. 4, measurement I (Rib #3 depth) as seated upright on a 90-degree bench without jacket installed.
TABLE 2—THOR–50M BODY SEGMENT MASSES COMPARED TO AMVO
AMVO target
(Robbins et al
1983)
Body segment masses
(all measurements in kilograms)
Head ........................................................................................................................................................................
THOR–50M
specification *
Neck .........................................................................................................................................................................
Thorax ......................................................................................................................................................................
Lower Abdomen .......................................................................................................................................................
Pelvis .......................................................................................................................................................................
Upper Arm, Left or Right .........................................................................................................................................
Lower Arm with Hand, Left or Right ........................................................................................................................
Upper Leg, Left or Right ..........................................................................................................................................
Lower Legs, Left or Right ........................................................................................................................................
Feet, Left or Right including shoe ...........................................................................................................................
4.137
** (4.55)
0.965
23.763
2.365
11.414
1.769
2.022
8.614
3.587
*** 1.551
4.501
2.363
23.517
2.664
15.229
1.701
2.227
5.618
3.396
1.604
Total Weight .....................................................................................................................................................
76.562
77.366
* Listed on Drawing No. 472–0000, Sh. 5.
** Mass reported in Melvin JW, Weber, K. ‘‘Task B Final Report: Review of Biomechanical Impact Response and Injury in the Automotive Environment,’’ U.S. Department of Transportation, DOT–HS–807–042, 1985. The AMVO target is believed to be too low.
*** This adds the mass of a size 11 Oxford shoe (0.57 kg) specified for use in FMVSS No. 208 for the HIII–50M) to the AMVO specification of
0.981 kg so as to be comparable to the THOR’s foot-within-a-molded-shoe mass.
ddrumheller on DSK120RN23PROD with PROPOSALS4
B. Technical Data Package
The construction of the THOR–50M is
similar to other ATDs currently defined
in Part 572, with a metallic frame
largely covered in urethane and/or vinyl
representing flesh; body segments
connected by translational and
rotational joints; and deformable rubber
or foam elements to prevent hard
contact between metallic surfaces and to
provide human-like impact response.
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The kinematic and dynamic
biomechanical performance
requirements of the THOR–50M were
developed based on post-mortem
human subject (PMHS) and volunteer
response data, described in Section IV,
Biofidelity.
The THOR–50M that we are
proposing in this NPRM is the version
defined in the 2023 technical data
package (consisting of two-dimensional
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engineering drawings and a Parts list;
procedures for assembly, disassembly,
and inspection (PADI); and qualification
procedures). The 2023 technical data
package also includes an addendum
with the drawings and drawing/parts
list for an alternate configuration with
an in-dummy data acquisition system,
as discussed in Section III.N, Data
Acquisition System. It is anticipated
that, upon finalization of this proposal,
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the in-dummy DAS drawings will be
fully integrated within the relevant
technical data package components. The
technical data package is summarized in
Table 3. For these documents, the
NPRM cites to the document location in
the research docket. NHTSA is not
placing copies of these documents in
the rulemaking docket, in order to avoid
potential confusion from having
identical documents docketed at
different times in different dockets.
However, NHTSA intends these to be
included as part of the rulemaking
record. A memo explaining this is also
being included in the rulemaking
docket. In addition, as noted in the
background section, NHTSA began
publishing the technical data package to
its website starting in 2015. The 2023
technical data package updates the 2018
technical data package. These updates
were made to address typographical
errors, improve clarity, and add
alternative design elements. Table 4
summarizes these updates.
TABLE 3—THOR–50M TECHNICAL DATA PACKAGE
Title
Link
THOR 50th Percentile Male with Alternate Shoulders Frontal Crash
Test Dummy Drawings, External Dimensions, and Mass Properties.
*THOR–50M DAS Integration Kit Drawings, April 2023 ..........................
*Parts List, THOR–50M DAS Integration Kit, April 2023 .........................
Parts List, THOR 50th Percentile Male Frontal Crash Test Dummy with
Alternate Shoulders.
THOR 50th Percentile Male (THOR–50M): Procedures for Assembly,
Disassembly, and Inspection (PADI): June 2023.
THOR 50th Percentile Male (THOR–50M) Qualification Procedures and
Requirements, April 2023.
https://www.regulations.gov/document/NHTSA-2019-0106-0013.
https://www.regulations.gov/document/NHTSA-2019-0106-0019.
https://www.regulations.gov/document/NHTSA-2019-0106-0018.
https://www.regulations.gov/document/NHTSA-2019-0106-0015.
https://www.regulations.gov/document/NHTSA-2019-0106-0017.
https://www.regulations.gov/document/NHTSA-2019-0106-0010.
* The DAS Integration Kit drawings and drawing/parts list would not themselves be incorporated by reference into Part 572. It is anticipated
that, upon finalization of this proposal, these documents will be fully integrated within the relevant technical data package components.
TABLE 4—SUMMARY OF UPDATES MADE IN THE 2023 THOR–50M TECHNICAL DATA PACKAGE
Technical Data Package Element
Revisions in 2023 Version
Drawing Package .................................
Includes drawings for alternate shoulder, removal of notes suggesting that qualification specifications
supersede drawing specifications, and changes to correct typographical drawing errors. Complete
change log found in ‘‘THOR–50th Percentile Male with Alternate Shoulders (THOR–50M w/ALT.
SHOULDERS) Drawing Revisions’’.60
Minor typographical changes; complete change log found in Section 20 of ‘‘THOR 50th Percentile Male
(THOR–50M) Procedures for Assembly, Disassembly, and Inspection (PADI)’’.
Revised upper leg qualification test mode, adjusted language to be more prescriptive, removed unit
conversions, and corrected typographical errors. Complete change log found in Appendix B of
‘‘THOR 50th Percentile Male (THOR–50M) Qualification Procedures and Requirements, April 2023’’.
PADI .....................................................
Qualification Procedures ......................
ddrumheller on DSK120RN23PROD with PROPOSALS4
Below we briefly discuss several
aspects of the technical data package in
more detail.
Engineering Drawings and Parts List
The engineering drawings and parts
list specify the configuration of the
THOR–50M. Included in the drawings
are the required dimensions and
tolerances, material properties, and
component or material testing
requirements and associated
specifications. In a few instances, the
drawings specify quasi-static tests and/
or performance requirements for
individual parts (such as a compression
or flexion test for a molded part or
subassembly); however, passing a
specified performance (or qualification)
test is not an alternate criterion for
accepting a part that deviates from the
drawing specifications.61 All
60 See
Table 5.
the drawings which were part of the August
2018 technical data package, several notes state that
‘‘qualification takes precedence over design.’’ These
notes were unintentionally carried over from earlier
drawing versions used during THOR–50M
development, and have since been removed. These
61 In
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instruments are specified by
corresponding SA572-xxx drawings.62
SA drawings are included for associated
mounts and hardware that are not
otherwise needed when the dummy is
configured with a corresponding
structural replacement. Brand name
call-outs are only used for parts and
materials that have widespread
availability and are used for a wide
variety of non-ATD applications. It
includes materials widely identified by
their tradenames, such as Teflon,
Acetal, Lexan, and Nitinol. Call-outs are
also used for bonding agents, fasteners,
are reflected in the proposed 2023 technical data
package. In cases where some flexibility is allowed
in order to meet the qualification specification, a
‘‘REF.’’ prefix is added to specific dimensions or
material specifications.
62 This convention is used for all instruments on
all Part 572 dummies. SA572 simply indicates that
it is an instrument, and Sxx is the next-in-line
number assigned by NHTSA to the instrument.
Some load cells (and part numbers) are used on
different Part 572 subpart dummies. For THOR, this
applies to SA572–S4 (accelerometer) which is used
on many other dummies.
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and other items that are also widely
available for non-ATD applications.
In some instances, the drawing
package permits two different part or
instrumentation configurations that are
both fully specified. For example, the
head accelerometer mounting plate
assembly drawing (472–1200) calls out
three different angular rate sensors
(SA572–S56, SA572–S57, or SA572–
S58) which may be desired by the end
user depending on the implementation
of the ATD.63 In the sections below on
specific body regions we discuss the
proposed as well as alternate designs
and instrumentations that are not
included in the proposed specifications
but which we are considering specifying
in the final rule and on which we are
seeking comment. If NHTSA were to use
the dummy for FMVSS compliance
testing, NHTSA could test with any
alternative configurations at its own
discretion. Thus, the IARVs would have
63 Similar situations exist with currently
federalized ATDs, such as the HIII–10C, where
either a chest slider pot or an IR–TRACC is
permissible.
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to be met using a dummy with any
permissible configuration.
Manufacturers are not required to test
their products in any particular manner,
as long as they exercise due care that
their products will meet the
requirements when tested by NHTSA
under the procedures specified in the
standard, including the relevant dummy
specified in Part 572.64 However, a
manufacturer would not be able to claim
that a vehicle fully complies with a
standard if it meets the standard’s
requirements in only one of the
dummy’s configurations, but not the
other.
In addition to the engineering
drawings that would be incorporated by
reference, we are also providing
supplemental documentation on the
61905
form and function of the THOR–50M.
These reference materials are
summarized in Table 5. These files
would not be incorporated by reference
in Part 572 and would therefore not be
part of the THOR–50M specification.
Instead, they are intended only for
reference purposes (e.g., to facilitate
fabrication and inspection of parts with
intricate geometries).
TABLE 5—THOR–50M DESIGN REFERENCE DOCUMENTATION
Title
Link
THOR–50M Drawing Package—2D AutoCAD Jan 2023 ........................
https://static.nhtsa.gov/nhtsa/downloads/THOR_50M_Drawing_Package/NPRM/THOR-50M%20with%
20Alternate%20Shoulders%20Jan%202023-Auto
CAD%20DWG%20Files.zip.
https://static.nhtsa.gov/nhtsa/downloads/THOR_50M_Drawing_Package/NPRM/THOR-50M%20with%20Alternate%20Shoulders%20Jan%
202023-Inventor%20Files.zip.
https://static.nhtsa.gov/nhtsa/downloads/THOR_50M_Drawing_Package/NPRM/THOR-50M%20DAS%20Integration%20Kit-3D%
20STEP%20Files_April%202023.zip.
https://www.regulations.gov/document/NHTSA-2019-0106-0014.
THOR–50M Drawing Package—3D Inventor Format Jan 2023 ..............
THOR–50M Drawing Package—3D STEP Format Jan 2023 .................
THOR 50th Percentile Male with Alternate Shoulders Drawing Revisions, Jan 2023.
THOR–50M DAS Integration Kit—2D AutoCAD, April 2023 ...................
THOR–50M DAS Integration Kit—3D STEP Format, April 2023 ............
ddrumheller on DSK120RN23PROD with PROPOSALS4
THOR–50M DAS Integration Kit—Inventor Format, April 2023 ...............
https://static.nhtsa.gov/nhtsa/downloads/THOR_50M_Drawing_Package/NPRM/THOR-50M%20DAS%20Integration%20KitAutoCAD%20DWG%20Files_April%202023.zip.
https://static.nhtsa.gov/nhtsa/downloads/THOR_50M_Drawing_Package/NPRM/THOR-50M%20DAS%20Integration%20Kit3D%20STEP%20Files_April%202023.zip.
https://static.nhtsa.gov/nhtsa/downloads/THOR_50M_Drawing_Package/NPRM/THOR-50M%20DAS%20Integration%20KitInventor%20Files_April%202023.zip.
The THOR–50M used by Euro NCAP
is specified in Technical Bulletin 026,
‘‘THOR Specification and
Certification.’’ 65 TB026 explicitly
adopts—with some deviations—the
2018 drawing package.66 These
deviations in TB026 include
specification of an onboard (in-dummy)
data acquisition system and a variation
to the adjustable spine to facilitate DAS
installation; minor deviations in the
shoulder assembly; and the use of the
HIII–50M lower legs. These
modifications are discussed in more
detail in the relevant sections of the
preamble, and are summarized in
Section IX, Consideration of
alternatives. Euro NCAP TB026
specifies the 2018 drawing package,
while this proposal specifies the 2023
drawing package. However, given the
differences described in Table 4 above,
this deviation is likely to be
inconsequential. The deviations TB026
makes to the 2018 drawing package are
not accompanied by engineering
drawings, which may tend to lessen the
dummy’s overall objectivity. Objectivity
is a statutory necessity for ATDs in Part
572. While the lack of accompanying
drawings for these deviations may be
adequate for the Euro NCAP rating
program, it could lead to a future
population of THOR–50M units that are
sufficiently non-uniform as to render
them unsuited for FMVSS applications.
64 See, e.g., 38 FR 12934, 12935 (May 17, 1973)
(‘‘Manufacturers should understand that they are
not required to test their products in any particular
manner, as long as they exercise due care that their
products will meet the requirements when tested by
the NHTSA under the procedures specified in the
standard.’’).
65 European New Car Assessment Programme
(2023). THOR Specification and Certification,
Version 1.3, available at: https://
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PADI
The PADI provides step-by-step
procedures on how to properly assemble
the dummy. This includes instructions
on part alignment, torque settings, wire
routings, and other adjustments that are
not otherwise described in the
engineering drawings. The PADI
provides explicit installation
instructions for all instruments. Euro
NCAP TB026 specifies the 2018 PADI,67
while this proposal specifies the 2023
PADI. However, the differences between
the 2018 PADI and 2023 PADI are
primarily corrections to typographic
errors, so this deviation is likely to be
inconsequential. In some instances, the
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drawing package permits two different
part or instrumentation configurations
that are (or will be in the final rule) both
fully specified (for example, the IR–
TRACC and the S-Track for the chest
instrumentation). The proposed PADI
does not currently contain installation
instructions for the optional parts (e.g.
alternate shoulder) or instrumentation
(e.g., the S-Track). However, where
multiple optional configurations are
permitted and installation differences
are non-trivial, NHTSA anticipates
supplementing the PADI with such
instructions in the final rule.
Qualification Procedures
The qualification procedures describe
a series of impact tests performed on a
fully assembled dummy or subassembly. NHTSA has established
numeric bounds or acceptance intervals
for the ATD responses in these tests.
The qualification procedures are
discussed in Section V.
www.euroncap.com/en/for-engineers/supportinginformation/technical-bulletins/.
66 § 1.1.
67 § 3.1.
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Summary
NHTSA believes that the technical
data package adequately describes and
would ensure the uniformity of the
dummy. Upon finalization of this
proposal, a new subpart for the THOR–
50M would be added to Part 572, and
the technical data package documents
would be incorporated by reference.
NHTSA seeks comment on whether
the dummy is sufficiently specified to
ensure that dummies are uniform such
that they will provide repeatable and
reproducible measurements. We also
seek comment on whether it would be
useful to end-users of the dummy if
NHTSA created a list of suppliers used
by NHTSA to obtain various parts and
instrumentation, and/or general
specifications or operating
characteristics of a part (as provided by
a manufacturer’s specification sheet).
Such documentation would not be
incorporated into Part 572 but would be
provided as a reference aid for users and
could be periodically updated by
NHTSA.
ddrumheller on DSK120RN23PROD with PROPOSALS4
C. Head and Face
The head of the THOR–50M is
primarily constructed of a cast
aluminum skull covered in a urethane
head skin. It includes two features not
seen on the HIII–50M: spring towers and
a featureless face. The spring towers are
integral to the response of the head/neck
system, as they are the mounting
location of the cables that represent the
musculature of the neck (described
further in the following section). The
head is equipped with three uniaxial
accelerometers and three angular rate
sensors at the head center of gravity
(CG) to measure translational
acceleration and angular velocity,
respectively. The head also includes a
biaxial tilt sensor which measures the
quasi-static orientation of the head for
pre-test positioning purposes.
The face is constructed of an opencell urethane foam sandwiched between
the head skin and the face load
distribution plates. The featureless face
allows for more repeatable and
reproducible interactions with potential
contact surfaces and meets enhanced
biomechanical response requirements
which have not been implemented on
any existing ATDs. Additionally, the
face can be configured with five
uniaxial load cells: left and right eye,
left and right cheek, and chin.68
68 These load cells have not been used in any tests
currently available in NHTSA’s Vehicle or
Biomechanics databases, and are typically replaced
with structural replacements during testing. While
the THOR–50M Qualification Procedure does
include a face impact test which would exercise the
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D. Neck
The neck of the THOR–50M is visibly
and functionally different than the
ATDs currently defined in Part 572.
While typical ATD designs use only a
pin joint between the base of the head
and the upper neck load cell, the
THOR–50M neck is connected to the
head via three separate load paths: two
cables (one anterior and one posterior)
and a pin joint between the base of the
head and the upper neck load cell.
These load paths are independently
instrumented, allowing the isolation of
forces and moments on the components
representing bone and ligament from the
components representing muscles. This
is expected to allow for improved injury
prediction for the cervical spine because
the abbreviated injury scale (AIS) 2+
injuries 69 to the cervical spine in motor
vehicle crashes are most commonly
fractures, so the ability to measure
forces and moments acting on the bones
and ligaments separately from the forces
acting through the musculature allows a
more accurate prediction of these
fractures.70
The biomechanical basis of the
THOR–50M neck design is wellestablished.71 72 The construction of the
THOR–50M neck allows the head to
initially rotate relatively freely in the
fore and aft directions. This allows the
head/neck assembly to demonstrate the
phenomenon known as head lag
demonstrated by human volunteers in
restrained frontal loading conditions,
where the rotation of the head is
delayed relative to the rotation of the
neck.73 This phenomenon results from
the head initially translating forward
with respect to the base of the neck,
face load cells if installed, there are currently no
qualification specifications on face load cell forces.
69 The Abbreviated Injury Scale (AIS) ranks
individual injuries by body region on a scale of 1
to 6: 1=minor,
2=moderate, 3=serious, 4=severe, 5=critical, and
6=maximum (untreatable).
70 Craig, M., Parent, D., Lee, E., Rudd, R.,
Takhounts, E., Hasija, V. (2020). Injury Criteria for
the THOR 50th Male ATD. Docket ID NHTSA–
2019–0106–0008, available at: https://
www.regulations.gov/document/NHTSA-2019-01060008.
71 White RP., Zhoa Y., Rangarajan N., Haffner M.,
Eppinger R., Kleinberger M., ‘‘Development of an
Instrumented Biofidelic Neck for the NHTSA
Advanced Frontal Test Dummy,’’ The 15th
International Technical Conference on the
Enhanced Safety of Vehicles, Paper No. 96–210–W–
19, 1996.
72 Hoofman, M., van Ratingen, M., and Wismans,
J., ‘‘Evaluation of the Dynamic and Kinematic
Performance of the THOR Dummy: Neck
Performance,’’ Proceeding of the International
Conference on the Biomechanics of Injury (IRCOBI)
Conference, pp. 497–512, 1998.
73 Thunnissen, J., Wismans, J., Ewing, C.L.,
Thomas, D.J. (1995) Human Volunteer Head-Neck
Response in Frontal Flexion: A New Analysis. 39th
Stapp Car Crash Conference, SAE Paper # 952721.
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which is attached to the restrained
torso. The change in angle of the head
initially lags the change in angle of the
line between the head and the neck but
catches up by the time of peak
excursion.
The instrumentation in the neck
assembly includes spring load cells
which measure the compression at the
anterior and posterior spring locations,
six-axis load cells at the top and base of
the neck to measure the forces and
moments developed at these locations,
and a rotary potentiometer at the
occipital condyle pin to measure the
relative rotation between the head and
top of the neck. Due to the multiple load
paths of the neck, comparing THOR–
50M neck forces and moments to
traditional single-load-path ATD
designs is not straightforward; the
THOR–50M instrumentation would
require post-processing 74 to represent
the total neck forces and moments in
order to compare to the upper neck load
cell measurements of a HIII–50M ATD.
However, as described in the THOR–
50M Injury Criteria Report,75 postprocessing of the neck for calculation of
neck injury risk is not necessary.
E. Chest
Throughout the development of the
THOR–50M ATD, specific attention was
given to the human-like response and
injury prediction capability of the chest.
Below we discuss the design and
instrumentation of the THOR–50M
chest.
1. Design
The THOR–50M’s rib cage geometry is
more realistic than the HIII–50M
because the individual ribs are angled
downward to better match the human
rib orientation.76 Biomechanical
response requirements were selected to
ensure human-like behavior in response
to central chest impacts, oblique chest
impacts, and steering rim impacts to the
74 GESAC, Inc (2005). Users Manual: THOR
Instrumentation Data Processing Program, Version
2.3; Appendix C: Procedure for Calculating Head
Loads at the Occipital Condyle from Neck Load Cell
Measurements. National Highway Traffic Safety
Administration. Available at: https://one.nhtsa.gov/
DOT/NHTSA/NVS/Biomechanics%20&
%20Trauma/THOR-NT%20Advanced%20
Crash%20Test%20Dummy/THORTEST.zip.
75 Craig, M., Parent, D., Lee, E., Rudd, R.,
Takhounts, E., Hasija, V. (2020). Injury Criteria for
the THOR 50th Male ATD. Docket ID NHTSA–
2019–0106–0008, available at: https://
www.regulations.gov/document/NHTSA-2019-01060008.
76 Kent, R., Shaw, C.G., Lessley, D.J., Crandall, J.R.
and Svensson, M.Y, ‘‘Comparison of Belted Hybrid
III, THOR, and Cadaver Thoracic Responses in
Oblique Frontal and Full Frontal Sled Tests,’’ Proc.
SAE 2003 World Congress. Paper No. 2003–01–
0160, 2003.
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rib cage and upper abdomen.77 Better
chest anthropometry means that the
dummy’s interaction with the restraint
system is more representative of the
interaction a human would experience.
The design of the THOR–50M
includes a part known as a rib guide
(472–3310) which is intended to prevent
excessive downward motion of the
anterior thorax during an impact. The
rib guide is attached to the shoulder,
and when there is downward motion of
the ribs, the bottom of the rib damping
material on rib #1 (the superior-most rib
in the torso, 472–3310) can contact the
top of the rib guide. Over time, this can
result in an indent in the rib damping
material. This indent has been observed
on NHTSA-owned THOR–50M ATDs,
but it has not been a concern as this is
a sign of the rib guide performing its
intended function. While this indent is
not included on the drawing package, it
is understood that an indent is
acceptable as long as the qualification
specifications (specifically, those of the
upper thorax and lower thorax) are met,
and it is not so deep that it allows metalto-metal contact between the rib guide
and the steel of the rib.
While Euro NCAP TB026 adopts the
chest specified in the 2018 drawing
package without any modifications,
NHTSA is aware of two potential
changes that have been discussed. Both
of these changes appear to be intended
to help ensure that the dummy is able
to meet the upper thorax qualification
response requirements. (The TB026
upper thorax qualification response
requirements differ in a few ways from
the proposed qualification
requirements. This is discussed in more
detail in Section V, Qualification Tests.)
The first change that has been
discussed is a shorter rib guide.
Humanetics Innovative Solutions, Inc.
(Humanetics) reported to ISO WG5 (in
June 2020) that while the indent on the
damping material has been a known
issue since the THOR–NT, it has led to
concerns because it leads to issues
meeting the Euro NCAP upper thorax
qualification response requirements
(specifically, the Z-axis upper rib
deflection requirement) on a consistent
basis. Humanetics has therefore
suggested the use of a new, shorter rib
guide which would allow more Z-axis
deflection—primarily in the upper
77 National Highway Traffic Safety
Administration, ‘‘Biomechanical Response
Requirements of the THOR NHTSA Advanced
Frontal Dummy, Revision 2005.1,’’ Report No:
GESAC–05–03, U.S. Department of Transportation,
Washington, DC, March 2005. [https://
www.nhtsa.gov/DOT/NHTSA/NVS/
Biomechanics%20&%20Trauma/THORNT%20Advanced%20Crash%20Test%20Dummy/
thorbio05_1.pdf.
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thorax qualification test, but presumably
in other impact scenarios as well.
The second change is an additional
rib performance specification. NHTSA
is aware of a presentation made by the
Japanese Automobile Manufacturers
Association (in June 2020) to ISO WG5
describing an additional rib
performance specification (i.e., that
would be specified in the drawing
package) geared towards more
consistently meeting the TB026 upper
thorax qualification response
requirements. The presentation
included a procedure for an individual
rib test using the same apparatus as the
rib drop test for the ES–2re 50th
percentile adult male side impact test
dummy.78 It noted data showing that the
stiffness of the individual rib in the
drop test was correlated with the
thoracic impact response in the upper
thorax qualification test condition.
NHTSA has tentatively decided not to
implement either change. NHTSA’s
qualification testing of the dummy did
not reveal any issues with meeting the
proposed upper thorax qualification
requirements, so we do not believe such
changes are necessary. Moreover, before
implementing the rib guide
modification, it could be necessary to
evaluate whether it would influence the
dummy’s response in biofidelity or
thorax injury criteria test conditions. We
do note, however, that the additional rib
performance specification could be a
useful way for ATD manufacturers to
ensure that the fabricated ribs will result
in an upper thorax qualification
response consistent with upper thorax
qualification specifications.
We seek comment on these issues. In
particular, NHTSA requests comment
from THOR–50M users who have
evaluated alternative rib guide designs
and have data to support equivalence of
durability, repeatability and
reproducibility, and equivalence of
response in qualification, biofidelity,
injury criteria, and vehicle crash test
conditions.
2. Instrumentation
The THOR–50M is capable of
measuring detailed information about
how the chest responds in a crash.
While the HIII–50M can measure chest
deflection at only a single point (the
sternum), the THOR–50M measures
chest deflections at four points. This is
useful because thoracic trauma imparted
to restrained occupants does not always
occur at the same location on the rib
cage for all occupants in all frontal
78 49
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crashes.79 Measuring deflection from
multiple locations has been found to
improve injury prediction,80 and can
improve the assessment of thoracic
loading in a vehicle environment with
advanced occupant restraint
technologies.81 While the HIII–50M
measures the one-dimensional
deflection at a single point, the THOR–
50M can measure the three-dimensional
position time-history for four points on
the anterior rib cage relative to the local
spine segment of rib origination, with
two points on the upper chest, and two
points on the lower chest. Between the
upper and lower thorax instrumentation
attachment points is a flexible joint (the
Upper Thoracic Spine Flex Joint), so the
reference coordinate system for the
upper and lower thorax 3D motion
measurements can change dynamically
during a loading event. This
instrumentation, coupled with its
thoracic biofidelity,82 provides the
THOR–50M ATD with the ability to
better predict thoracic injuries and to
potentially drive more appropriate
restraint system countermeasures.83
NHTSA is proposing to specify two
deflection measurement devices, either
of which NHTSA could choose, at its
option, for use in the THOR–50M: the
IR–TRACC and the S-Track.
IR–TRACC
The 2023 drawing package specifies a
specific deflection measurement device,
the Infrared Telescoping Rod for
Assessment of Chest Compression (IR–
79 Morgan, R.M., Eppinger, R.H., Haffner, M.P.,
Yoganandan, N., Pintar, F.A., Sances, A., Crandall,
J.R., Pilkey, W.D., Klopp, G.S., Kallieris, D., Miltner,
E., Mattern, R., Kuppa, S.M., and Sharpless, C.L.,
‘‘Thoracic Trauma Assessment Formulations for
Restrained Drivers in Simulated Frontal Impacts,’’
Proc. 38th Stapp Car Crash Conference, pp. 15–34.
Society of Automotive Engineers, Warrendale, PA.,
1994.
80 Kuppa, S., Eppinger, R., ‘‘Development of an
Improved Thoracic Injury Criterion,’’ Proceedings
of the 42nd Stapp Car Crash Conference, SAE No.
983153, 1998 (data set consisting of 71 human
subjects in various restraint systems and crash
severities).
81 Yoganandan, N., Pintar, F., Rinaldi, J.,
‘‘Evaluation of the RibEye Deflection Measurement
System in the 50th Percentile Hybrid III Dummy.’’
National Highway Traffic Safety Administration,
DOT HS 811 102, March 2009.
82 Parent, D., Craig, M., Ridella, S., McFadden, J.,
‘‘Thoracic Biofidelity Assessment of the THOR Mod
Kit ATD,’’ The 23rd Enhanced Safety of Vehicles
Conference, Paper No. 13–0327, 2013.
83 In addition to the deflection measurement
system, the THOR–50M can also be instrumented
with a uniaxial sternum accelerometer, triaxial
accelerometers installed along the spine at the level
of T1, T6, and T12, and a five-axis (three forces, two
moments) load cell installed between the lumbar
spine pitch change mechanism and the lumbar
spine flex joint at the approximate anatomical level
of T12. Clavicle loads cells can also be installed, but
are not included in the THOR–50M described in the
2023 drawing package.
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ddrumheller on DSK120RN23PROD with PROPOSALS4
TRACC).84 The IR–TRACC improved on
the previous deflection measurement
systems (CRUX—Compact Rotary Unit;
DGSP—Double Gimbaled String
Potentiometer) in many ways. The 2023
drawing package specifies six IR–
TRACCs: four in the thorax and two in
the abdomen.85 Each IR–TRACC
measures the absolute point-to-point
distance along its length; this is used in
the calculation of thorax and abdomen
compression. The IR–TRACC is attached
to two rotational potentiometers; this
enables measurement of the threedimensional position of the anterior
attachment point at the rib or front of
the abdomen relative to the attachment
point at the spine.
While NHTSA has generally been
satisfied with the performance of the
IR–TRACC, the experience of NHTSA
and other users with IR–TRACCequipped THOR–50Ms has revealed a
few potential issues. Vehicle
manufacturers have raised several
concerns about the performance and
durability of the IR–TRACC, such as
having to frequently repair or replace
IR–TRACCs, and problems with the
abdomen IR–TRACCs.86 And during
NHTSA-sponsored testing (particularly
in the frontal oblique crash test mode),
NHTSA observed abrupt decreases in
the IR–TRACC voltage time-history.87
We believe this is noise (and not a
signal) because it occurs in all IR–
TRACC voltage channels of a single
ATD at the same points in time. As
explained later in this document
(Section VII.B.2) and in Appendix F to
the preamble,88 NHTSA testing has
shown that once the IR–TRACC voltage
signal is linearized, scaled, filtered, and
converted to three-dimensional
deflection, this noise is no longer
evident. Nonetheless, this presents a
84 Rouhana, S.W., Elhagediab, A.M., Chapp, J.J.
‘‘A high-speed sensor for measuring chest
deflection in crash test dummies.’’ Proceedings:
International Technical Conference on the
Enhanced Safety of Vehicles. Vol. 1998, Paper No.
98–S9–O–15. National Highway Traffic Safety
Administration, 1998.
85 See SA572–S117 and SA572–S121.
86 Alliance of Automobile Manufacturers, Inc.
(2016). Technical Considerations Concerning
NHTSA’s Proposal to Rework the Agency’s New Car
Assessment Program (NCAP). Regulations.gov
Docket ID NHTSA–2015–0119–0313, available at:
https://www.regulations.gov/contentStreamer?
documentId=NHTSA-2015-01190313&attachmentNumber=5&contentType=pdf.
87 See Figure 1 in Hagedorn, A., Murach, M.,
Millis, W., McFadden, J., Parent, D., (2019).
Comparison of the THOR–50M IR–TRACC
Measurement Device to an Alternative S-Track
Measurement Device. Proceedings of the FortySeventh International Workshop on Human
Subjects for Biomechanical Research.
88 NHTSA is placing a separate document,
‘‘Supplemental Technical Appendices to
Preamble,’’ in the docket for this rulemaking.
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risk of perceived or actual inaccuracies
in thoracic and abdominal injury
prediction during crash tests.
S-Track
In 2016 NHTSA issued a request for
proposals for commercially-available
devices capable of measuring the same
or greater deflection range (roughly 90
millimeters of deflection for the thorax
and 120 millimeters of deflection for the
abdomen) within the same packaging
space as the existing IR–TRACC
devices.89 Only one device—the STrack—was identified. The S-Track,
which is patented,90 is produced by
ATD-LabTech GmbH. (In 2022,
Humanetics acquired ATD-LabTech.)
Subsequent to the request for proposal,
NHTSA also became aware of two
additional deflection measurement
devices: the KIR–TRACC, sold by Kistler
Group, and the Spiral Track, sold by
JASTI. NHTSA does not know whether
these devices are congruent with the
current THOR–50M parts and SAdrawings that describe the configuration
and installation of IR–TRACCs. Because
NHTSA became aware of these devices
late in the development process (and
neither was identified in NHTSA’s
request for proposals), they have not
been considered for inclusion in the
proposal, although NHTSA is
considering evaluating whether they
would be suitable instrumentation for
the THOR–50M. Euro NCAP allows for
installation of the IR–TRACC, the STrack, and the KIR–TRACC.91
The S-Track is similar to the IR–
TRACC in that it is in-dummy
instrumentation that attaches to the
same points in the dummy as the IR–
TRACC. Both measure linear
displacement, and when coupled with
the gimballed potentiometers, their
signals can be post-processed to
calculate three-dimensional motion. It
differs in that the S-Track uses a
mechanical scissor mechanism coupled
to a linear potentiometer to measure
linear motion along its axis, while the
IR–TRACC uses a measurement of light
transmittance, which requires a
linearization calculation to estimate
linear motion.
89 National Highway Traffic Safety
Administration (2016). IR–TRACC Direct
Replacement Sensor. Solicitation Number
DTNH2216Q00014, available at https://sam.gov/
opp/d505f6119f9a31bcdfa36607ed669e6b/view.
90 Pheifer, G. (2020). U.S. Patent No. 10,713,974.
Washington, DC: U.S. Patent and Trademark Office.
91 European New Car Assessment Program (2022).
Euro NCAP Supplier List, Appendices I & II,
October 2022, TB 029, available at: https://
www.euroncap.com/en/for-engineers/supportinginformation/technical-bulletins/https://
www.euroncap.com/en/for-engineers/protocols/
adult-occupant-protection/.
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NHTSA has conducted a range of
testing to evaluate the performance and
equivalence of the S-Track. The testing,
which included a partial qualification
test series and sled tests, is briefly
summarized below.92 A more detailed
discussion of this material is available
in a previously published paper (except,
as noted below, the second set of sled
tests, for which a report is
forthcoming).93
• The range and linearity of the STrack and IR–TRACC sensors are
comparable. The range of measurement
of the S-Track is consistent with or
larger than the range of measurement of
the IR–TRACC, and all sensors were
within the manufacturer’s specification
for the maximum allowable linear error
as a percentage of full scale. This
specification (0.5%) is tighter compared
to the corresponding IR–TRACC
specification (2%), though only one of
the IR–TRACCs (right abdomen) showed
a linearity error greater than 0.5%.
• Calibration and 3D static
measurement assessments demonstrated
similar or better accuracy compared to
the IR–TRACC in the double-gimbal
configuration for the upper left thorax,
lower left thorax, and left abdomen. In
the upper and lower thorax
configurations, the S-Track showed less
error than the IR–TRACC, and in the
abdomen configuration, showed errors
similar to the IR–TRACC.
• The form, fit, and function is
comparable to the IR–TRACC. A full set
of six S-Tracks was installed in a
THOR–50M ATD. It did not present any
connectivity or interference issues and
appeared to be a plug-and-play
replacement to the IR–TRACCs. One
possible durability issue was identified
92 This evaluation of alternate thorax and
abdomen instrumentation only considered
replacement of the displacement transducer
component of the 3D IR–TRACC measurement
system. Though it was not available at the time of
purchase, a double gimbal kit to allow 3D
measurement is now available from the S-Track
manufacturer. ATD-Labtech GmbH (2017). 3D
Adaption THOR–50th upper Thorax left 20_303.
Available at: https://www.atd-labtech.com/files/atd/
uploads/produkte/s-track/produkte/4%20TH-3DAdapter-Upper-Thorax-left/data_sheet-3DAdaption_Thor-50th_upper_Thorax_
left%20Rev%2001.PDF. To evaluate whether the STrack 3D adaption kit would result in equivalent
measurement capabilities as the 3D IR–TRACC
measurement system, the testing described here
would be repeated, starting with the 3D static
measurement assessment.
93 Hagedorn, A., Murach, M., Millis, W.,
McFadden, J., Parent, D., (2019). Comparison of the
THOR–50M IR–TRACC Measurement Device to an
Alternative S-Track Measurement Device.
Proceedings of the Forty-Seventh International
Workshop on Human Subjects for Biomechanical
Research. Available at: https://wwwnrd.nhtsa.dot.gov/pdf/bio/proceedings/2019/
Hagdeorn_S-Track_
Biomechanics%20Workshop%202019_FINAL.pdf.
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(damage to the cable at the base of the
S-Track). This issue is mitigated if cable
routing documentation is followed or
the S-Track-specific double-gimbal
assembly is used.
• The S-Track performed equivalently
in qualification tests. NHTSA carried
out the qualification tests for the body
regions expected to be sensitive to a
difference in thorax and abdomen
instrumentation (upper thorax, lower
thorax, and abdomen) on a THOR–50M
in two different configurations: a
baseline configuration with IR–TRACCs
in all locations, and an alternate
configuration with S-Tracks in all
locations. Both configurations met the
qualification targets for all of the test
modes specified for those body regions,
which demonstrates that the difference
in measured deflections between the STrack and IR–TRACC were well within
expected test-to-test variation. In
addition, the deflection time-history
was qualitatively similar to the IR–
TRACC.
• The S-Track performed equivalently
to the IR–TRACC in most respects in a
series of sled tests. NHTSA conducted
sled tests in several conditions with the
THOR–50M in two configurations: one
with the IR–TRACC in all locations, and
one with the S-Track in all locations:
Æ The first series used a reinforced
buck representative of the front half of
a mid-sized passenger vehicle
(including seat belt, frontal air bag, and
side curtain air bag) and simulated a
near-side frontal oblique (20 degrees)
crash. The crash pulse was based on a
frontal oblique crash test of the same
vehicle. The S-Track proved to be
durable and did not demonstrate the
same noise artifacts as the IR–TRACC.
The S-Tracks in the thorax showed
similar measurements as the IR–
TRACCs, particularly in the upper right
thorax, the closest measurement
location to the shoulder belt. There were
some potential differences between the
abdomen measurements, but abdominal
deflection is not currently included as
an injury criterion in FMVSS No. 208
and is not currently included in the
rating calculation for frontal NCAP.94
Æ The second series of sled tests were
conducted in the Gold Standard 1 (40
km/h, 12g peak pulse, standard lap and
shoulder belt) and Gold Standard 2
(30km/h, 9g peak pulse, 3kN load
limited shoulder belt) test conditions,
which were used both in biofidelity
assessment and in the development of
94 Additional evaluation would be desirable in
cases where abdominal deflection is a critical
measurement, such as a rear seat environment
where submarining may be more likely to occur.
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thoracic injury criteria.95 The goal of
this testing was to determine if any
differences occurred between the IR–
TRACC and S-Track measurement
devices, and if so, whether the
magnitude of these differences would
affect the biofidelity and injury criteria
development analyses. NHTSA is
preparing a report on this second series
of sled tests, which will be placed in the
research docket when it is complete.
Based on this testing and analysis,
NHTSA believes that the S-Track is
equivalent to the IR–TRACC (with the
potential exception of the abdomen
deflection in a sled test environment).
Proposal
NHTSA proposes to specify both the
IR–TRACC and the S-track as
permissible instrumentation for the
THOR–50M. A THOR–50M configured
with all IR–TRACCs or all S-tracks
would conform to Part 572 and NHTSA
could perform compliance testing with
either device installed in the THOR–
50M. The dummy has not been tested in
a mixed configuration, with both
devices installed (e.g., IR–TRACCS in
the chest and S-Tracks the abdomen, or
with one IR–TRACC and three S-Tracks
in the chest). The overall effects of such
configurations are unknown. NHTSA
seeks comment on whether the final
specifications should allow such
configurations. The IR–TRACC is
specified in the 2023 drawing package
(in SA572–S117 and SA572–S121).
NHTSA has not yet published
engineering drawings and parts
packages to specify how the S-Track is
installed in the dummy, but intends to
integrate such documentation into the
associated technical data package
components upon finalization of this
proposal. NHTSA seeks comment on
this proposal.
F. Shoulder
The THOR–50M shoulder was
developed to allow a human-like range
of motion and includes a clavicle
linkage intended to better represent the
human shoulder interaction with
shoulder belt restraints.96 Clavicle load
cells that can be installed in the
proximal and distal ends of the clavicles
are commercially available, but these
95 The Gold Standard 1 test uses a flat rigid seat,
standard lap and shoulder belts, knees restrained,
and right front passenger restraint geometry. The
Gold Standard 2 test uses a flat rigid seat, a forcelimited shoulder belt and standard lap belt, knees
restrained, and right front passenger restraint
geometry.
96 To
¨ rnvall, F.V., Holmqvist, K., Davidsson, J.,
¨ hrn, H., ‘‘A New
Svensson, M.Y., Ha˚land, Y., O
THOR Shoulder Design: A Comparison with
Volunteers, the Hybrid III, and THOR NT,’’ Traffic
Injury Prevention, 8:2, 205–215, 2007.
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load cells are not currently defined in
the drawing package and NHTSA has
not evaluated them.
Below we discuss shoulder
components for which NHTSA is
proposing alternative permissible
specifications (the alternate shoulder) or
for which design modifications have
been developed by external THOR–50M
users but which NHTSA has tentatively
decided not to incorporate in the
drawing package (shoulder slip and
coracoid process).
1. Alternate Shoulder Specification
Portions of the shoulder assembly
specified in the 2018 drawing package
(referred to as the SD–3 shoulder) are
covered by a patent issued to
Humanetics. However, for the reasons
discussed in more detail in Section VIII,
NHTSA has generally avoided
specifying in Part 572 patented
components or copyrighted designs
without either securing agreement from
the rights-holder for the free use of the
item or to license it on reasonable terms
or developing an alternative
unencumbered by any rights claims.
NHTSA has therefore designed, built,
and tested an alternative design for a
part of the shoulder assembly referred to
as the shoulder pivot assembly that is
not subject to any intellectual property
claims. Accordingly, the proposed
drawing package (the 2023 drawing
package) includes specifications for the
SD–3 shoulder pivot assembly as well as
the alternate shoulder pivot assembly,
so that either may be used. We explain
this in more detail below.
SD–3 Shoulder
The SD–3 shoulder is notably
different from the shoulder specified for
the THOR–NT. The THOR–NT design
includes a clavicle linkage attached by
ball joints at the sternum and acromion,
a linkage between the acromion and the
scapula to which the upper arm
attaches, and a linkage representing the
scapula that attaches to the acromion
linkage and the spine with
unconstrained revolute joints. While
there were some benefits of the THOR–
NT design compared to existing ATDs at
the time, the range of motion of the
THOR–NT shoulder was found to be
lacking compared to the human
shoulder.97
An improved shoulder design was
independently initiated by the Chalmers
University of Technology (Chalmers), in
97 Shaw, G., Parent, D., Purtsezov, S., Lessley, D.,
Crandall, J., Tornvall, F., ‘‘Torso Deformation in
Frontal Sled Tests: Comparison Between THOR–
NT, THOR–NT with the Chalmers SD–1 Shoulder,
and PMHS,’’ Proceedings of the International
IRCOBI Conference, 2010.
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a project sponsored by Volvo and
Autoliv, that sought to improve the
prediction of occupant response in
offset and oblique frontal crashes.
Several prototype shoulder assemblies
were constructed and evaluated, the
most promising being labeled the
Shoulder Design 1 (SD–1).98 The SD–1
shoulder design includes a clavicle
linkage with human-like geometry,
connected by cardan joints to the
sternum and acromion; a linkage
representing the scapula that includes
attachment to the upper arm; and a twopart linkage connecting the scapula to
the spine which allows both upward
and anterior motion of the shoulder
assembly. The anterior rotation of the
scapula linkage about a vertical shaft is
governed by a coil spring within an
assembly mounted to the spine box.
Several rotation stops are installed
throughout the assembly to prevent
metal-to-metal contact at the extents of
the range-of-motion.
After evaluation of the SD–1 in
dynamic sled testing in comparison to
the standard THOR–NT shoulder and to
PMHS,99 several improvements were
proposed, including durability
improvements to the humerus joint,
decreasing the range of motion in the
anterior and superior directions, and
increasing the range of motion in the
posterior and medial directions. The
improved design, labelled as the SD–2
shoulder, was fabricated by GESAC to
Chalmers’ specifications, installed on a
THOR–50M ATD, and evaluated in sled
tests in the Gold Standard 1 and Gold
Standard 2 conditions at the University
of Virginia.100 Several additional
durability and usability concerns were
raised upon post-test inspection,
including deformation of the joint
between the clavicle and the acromion
and hard contact to the humerus joint.
Subsequently, an updated version of
the SD–2 shoulder, known as the SD–3,
was designed and fabricated as part of
the European Union’s Thoracic Injury
Assessment for Improved Vehicle Safety
(THORAX) project.101 Changes
introduced in the SD–3 design included
redesigned sterno-clavicular joint
anthropometry, an updated shoulder
cover, and improvements intended to
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98 To
¨ rnvall
et al. (2007), 205–215.
et al (2010).
100 Crandall, J. (2013). ATD Thoracic Response:
Effect of Shoulder Configuration on Thoracic
Deflection. NHTSA Biomechanics Database, Report
b11017R001, available at: https://www-nrd.nhtsa.
dot.gov/database/MEDIA/GetMedia.aspx?
tstno=11017&index=1&database=B&type=R.
101 Lemmen, P., Been, B., Carroll, J., Hynd, D.,
Davidsson, J., Song, E., and Lecuyer, E. (2012).
Development of an advanced frontal dummy thorax
demonstrator. Proceedings of the 2012 IRCOBI
Conference, Paper No. IRC–12–87, September 2012.
99 Shaw
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address the durability and usability
concerns raised by the University of
Virginia testing. These latter
improvements consisted of replacing the
clavicle U-joint with a spherical joint;
replacing the humerus joint with a
metric version of the HIII–50M upper
arm joint; and introducing a series of
washers and bushings to the bottom of
the vertical shaft to enable the resistance
of the assembly to be adjusted to allow
a more reproducible initial position.
The SD–3 shoulder was installed on
a THOR–50M ATD and sled testing was
again carried out at the University of
Virginia in the Gold Standard 1 and
Gold Standard 2 conditions, as well as
a variation of Gold Standard 1 with a
force-limited belt.102 The SD–3 shoulder
assembly was inspected in detail
throughout this testing, and no evidence
of damage was identified. The chest
deflection and torso motion was similar
to the SD–1 and SD–2 shoulders, while
durability was improved. NHTSA also
conducted an evaluation of blunt
thoracic impact response of several
configurations of THOR–50M ATDs and
found the iteration with the SD–3
shoulder assembly installed to have the
highest qualitative and quantitative
biofidelity.103 Given these findings,
NHTSA modified the drawing package
to include the SD–3 shoulder. The first
iteration of the drawing package to
include the SD–3 shoulder was
published as the September 2014
version.104
After the publication of the September
2014 drawing package, Humanetics filed
an application for a patent describing a
shoulder assembly as well as an upper
arm with an integrated load cell.105
Similar to the SD–3 shoulder, the design
patent describes a shoulder pivot
assembly which includes, among other
things, a coil spring and an adjustable
resistance element. After discussions
between NHTSA and Humanetics, a
disclaimer stating that portions of the
THOR–50M drawings were covered by a
102 Crandall, J. (2013). ATD Thoracic Response:
SD3 Shoulder Evaluation. NHTSA Biomechanics
Database, Report b11470R001, available at: https://
www-nrd.nhtsa.dot.gov/database/MEDIA/GetMedia.
aspx?tstno=11470&index=1&database=B&type=R.
103 Parent, D., Craig, M., Ridella, S., McFadden, J.,
‘‘Thoracic Biofidelity Assessment of the THOR Mod
Kit ATD,’’ The 23rd Enhanced Safety of Vehicles
Conference, Paper No. 13–0327, 2013.
104 National Highway Traffic Safety
Administration (2014). THOR 50th Percentile Male
Drawing Package, September 2014. available at:
https://www.nhtsa.gov/DOT/NHTSA/NVS/
Biomechanics%20&%20Trauma/
THOR%20Advanced%20
Crash%20Test%20Dummy/thoradv/THOR-M_PDF_
2014-09-29.pdf.
105 Been, B., & Burleigh, M. (2017). U.S. Patent
No. 9,799,234. Washington, DC: U.S. Patent and
Trademark Office.
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Humanetics patent was added first to
the NHTSA website where the drawings
were available for download, and later
to the drawings for the shoulder and
upper arm assemblies in the drawing
package itself.
NHTSA has generally avoided
specifying such parts, consistent with
the legislative history of the Safety Act.
(See Section VIII, Intellectual Property.)
For this reason, as explained below we
are also proposing, in addition to the
SD–3 shoulder, an alternative shoulder
pivot assembly design.
Alternate Shoulder Pivot Assembly
Design
To address the potential issues with
specifying only a proprietary shoulder
design, NHTSA has designed, built, and
tested an alternate shoulder pivot
assembly that is not subject to any
intellectual property claims. The
alternate shoulder pivot assembly does
not include any components to adjust
the resistance of the assembly, and does
not use a coil, clock, or watch-spring
mechanism. Instead, the alternate
shoulder pivot assembly design uses a
molded rubber cylinder acting as a
torsion bar. The top of the cylinder is
attached to the shoulder support
assembly and the bottom is attached to
the spring housing, so rotation of the
shoulder about the local Z-axis of the
ATD results in torsion of the rubber
cylinder. In order to adjust the
resistance of the assembly, the springs
must be removed and replaced.
NHTSA has evaluated the alternate
shoulder in a variety of tests and
tentatively concludes that its
performance is similar to the SD–3
shoulder based on testing carried out to
date. This testing, which included a
partial qualification test series and sled
tests, is briefly summarized below. A
more detailed discussion of this
material is available in a testing report
that NHTSA is preparing, and which
will be placed in the research docket
when it is completed. NHTSA is also
preparing another report that describes
additional sled testing that was
conducted; this report will be placed in
the research docket when it is complete.
First, the alternate shoulder was
installed in a THOR–50M without any
issues regarding the form, fit, or
function. Second, in a quasi-static
rotation test, the alternate shoulder
showed a similar moment-rotation
loading slope to the SD–3 shoulder in
both the forward and rearward rotation
directions. Third, the SD–3 and
alternate shoulder showed nearly
identical longitudinal motion in all
three loading directions in a quasi-static
biofidelity evaluation comparing each
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shoulder’s range of motion to that of
human volunteers; the responses of both
were generally similar to the human
volunteer response corridors. Fourth,
the qualification tests most likely to be
affected by shoulder response (upper
thorax and chest) were carried out; the
THOR–50M with the alternate shoulder
met all qualification specifications for
the upper thorax, and the forcedeflection characteristic of the chest was
nearly identical to that of a THOR–50M
with the SD–3 shoulder. Finally, sled
tests conducted in both a full frontal
and a far-side oblique condition did not
reveal any durability or usability issues,
and the response of the THOR–50M
with the alternate shoulder was within
the test-to-test variation of the THOR–
50M with the SD–3 shoulder.
NHTSA is therefore proposing the
alternative shoulder as an acceptable
optional subassembly. The shoulder
assemblies are specified on drawings
472–3810 (left) and 472–3840 (right).
Each shoulder assembly drawing
specifies that either the SD–3 shoulder
pivot assembly or the alternate shoulder
pivot assembly may be used. The
proposed specifications for the SD–3
shoulder pivot assembly are provided in
drawings 472–3811 and 472–3841, and
the proposed specifications for the
alternate shoulder pivot assembly are
provided in drawings 472–6810–1 and
472–6810–2. The drawing package
currently indicates that the selection of
which shoulder pivot assembly to use is
made separately for the left and right
shoulder assemblies, so that the dummy
could be fitted with the SD–3 shoulder
pivot assembly on one side, and the
alternate shoulder pivot assembly on the
other side. The dummy has not been
tested in such a mixed configuration,
and the overall effects of such
configurations are unknown. NHTSA
seeks comment on whether the final
specifications should allow such mixed
configurations.
NHTSA seeks comment on whether
the final drawing package should
include the SD3 shoulder, the alternate
shoulder, or both. NHTSA also seeks
comment from THOR–50M users who
have evaluated the proposed alternate
shoulder design, or other alternate
shoulder designs, and have data related
to equivalence with respect to
durability, repeatability and
reproducibility, and response in
qualification, biofidelity, injury and
vehicle crash test conditions.
2. Shoulder Slip
NHTSA is aware that some
researchers and regulatory authorities
have identified what they view as a
possible design flaw in the shoulder—
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that the shoulder belt may slip towards
the neck in a crash—and have
developed potential modifications to the
shoulder design to prevent this from
happening.
This concern was first raised in a
2018 conference paper describing
research conducted by Transport
Canada. Transport Canada conducted a
series of vehicle crash tests with the
THOR–50M in the driver seat in two
conditions: 40% offset and full frontal
rigid barrier.106 It was reported that the
upper portion of the shoulder belt could
translate towards the neck and become
entrapped in the gap between the neck
and the shoulder. This occurred in 33 of
the 45 offset tests and in 2 of the 13 full
frontal rigid barrier tests. Compared to
tests without shoulder belt slip, tests
with shoulder belt slip showed higher
measurements for lower neck shear (Xaxis and Y-axis force), higher chest
deflections in the upper left and lower
right quadrants, and lower clavicle axial
forces.
Following that research, a 2019
Humanetics study identified and
evaluated three prototype alternative
modifications to the shoulder specified
in the 2018 drawing package to prevent
the shoulder belt from entering the gap
between the neck and the shoulder.107
The study concluded that all three
prototype modifications prevented belt
entrapment and identified the preferred
design alternative (referred to as a
profiled split design). While the
shoulder specified by NHTSA uses the
same material for the entire shoulder
pad, the profiled split design replaces
the material closest to the neck with a
higher-stiffness plastic material. This is
intended to prevent the collar (the
portion of the shoulder pad closest to
the neck) from deforming and allowing
the shoulder belt to slip towards the
neck.
In addition, in recent discussions
with NHTSA, Euro NCAP has noted that
several instances of shoulder belt
slippage were observed in Euro NCAP
testing as well as research tests with the
mobile progressive deformable barrier.
Euro NCAP reported that it was
evaluating two potential shoulder
design modifications, and expected
these to be presented for approval in
2023.
While NHTSA has witnessed the
shoulder belt moving towards the neck
106 Tylko, S., Tang, K., Giguere, F., Bussieres, A.
(2018). Effects of Shoulder-belt Slip on the Kinetics
and Kinematics of THOR. Proceedings of the 2018
IRCOBI Conference.
107 Wang, Z.J., Fu, S., McInnis, J., Arthur, J.
(2019). Evaluation of Novel Designs to Address the
Shoulder-belt Entrapment for THOR–50M ATD.
Proceedings of the 2019 IRCOBI Conference.
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61911
in vehicle crash tests, this phenomenon
does not appear to influence dummy
measurements related to injury criteria.
NHTSA seeks comment on the
desirability of and specifications for a
modification to prevent belt slippage,
including data on testing with the
proposed shoulder design showing that
it is leading to belt slippage that has a
meaningful effect on test results.
NHTSA also requests comment from
THOR–50M users who have evaluated
the split shoulder pad (or any available
alternatives) and have data to support
equivalence of durability, repeatability
and reproducibility, and response in
qualification, biofidelity, injury criteria,
and vehicle crash test conditions.
G. Hands
The THOR–50M specified in the 2023
drawing package includes the same
hand design as the HIII–50M. The
drawing defining the hand assembly of
the THOR–50M 108 includes material
formulation (Solid Vinyl, Formulation
Portland Plastics, PM–7003) along with
two two-dimensional images and one
three-dimensional image of the hand.
Additionally, the three-dimensional
geometry of the hand assembly is
included in the computer-aided design
(CAD) files available through the
NHTSA website in both Autodesk
Inventor and generic STEP formats.
However, the vinyl call-out does not
sufficiently specify the hardness or the
stiffness of the material formulation and
may be insufficient to define the part.
NHTSA therefore seeks comment on
whether there is a need for a material
test (e.g., hardness measurement or a
quasi-static compression test of a
coupon of the material) or performance
test (e.g., quasi-static or dynamic impact
to the as-fabricated hand) to further
define the hand assembly of the THOR–
50M, and if so, what the test might be.
H. Spine
The spine of the THOR–50M ATD is
primarily constructed of steel. There are
two flexible elements (one in the
thoracic spine and one in the lumbar
spine) that are intended to allow
human-like spinal kinematics in both
frontal and oblique loading
conditions.109 Between the two flexible
elements is a posture adjustment joint
known as the lumbar spine pitch change
mechanism, which allows the posture of
the THOR–50M to be adjusted into
various seating configurations in three108 Drawing
472–6900–1/2.
M., Rangarajan, N., Artis, M., Beach,
D., Eppinger, R., Shams, T. (2001). Foundations and
Elements of the NHTSA THOR Alpha ATD Design.
The 17th International Technical Conference for the
Enhanced Safety of Vehicles, Paper No. 458.
109 Haffner,
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degree increments, including, but not
limited to, four designated positions
(erect, neutral, slouched, and super
slouched).110 The spine is instrumented
with a five-axis thoracic spine load cell
mounted below the lumbar spine pitch
change mechanism and above the
lumbar spine flex joint (a flexible joint
that allows the dummy to go into
flexion/extension in the lumbar region).
Triaxial accelerometers can be installed
in the nominal locations of the first,
sixth, and twelfth thoracic vertebra.
The proposed spine design differs
from the THOR–50M used by Euro
NCAP. Whereas the 2023 drawing
package specifies a lumbar spine pitch
change mechanism, TB026 specifies a
four-position lumbar spine box or an
‘‘alternative spine box’’ if ‘‘data has
been provided to show equivalence
between the NHTSA spine assembly
and modified spine assembly.’’ 111
Humanetics holds a patent on the fourposition spine. The four-position
lumbar spine is not specified further,
but it does differ from the spine
specified by the NHTSA drawings. The
spine pitch change mechanism specified
in the 2023 drawing package allows the
spine to be set at a multitude of flexion
or extension settings, not just four.
NHTSA understands that the Euro
NCAP design is intended to
accommodate the in-dummy installation
of some DAS brands by providing a
mounting surface for data loggers.
THOR–50M units built for Euro NCAP
are configured with in-dummy DAS
systems have the four-position spine.
NHTSA has tentatively decided not to
specify a lumbar spine pitch change
mechanism limited to four positions for
a few reasons. First, NHTSA has not
inspected, nor has it performed any
testing with, the four-position spine.
Second, NHTSA generally avoids
specifying patented components in Part
572 (see Section VIII, Intellectual
Property). Third, the proposed spine
specifications provide more
adjustability than the four-position
spine so the dummy may be used in a
wider range of applications. NHTSA
seeks comment on user experience with
the four-position spine, including any
data on equivalence with the THOR–
50M as specified in the 2023 drawing
package or biofidelity.
It is also NHTSA’s understanding that
members of Working Group 5 have
observed variations in the ATD
responses in the upper thorax
qualification tests that have led to
difficulties in meeting the Euro NCAP
qualification specifications. Some
110 See
Fig. 5–32 in the PADI.
111 § 1.4.3.
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manufacturers have suggested that this
variation in response is due to variation
in the spine flex joint (specifically, the
vertical displacement (Z-axis) of the ribs
is too high). One potential cause that
has been identified (by Porsche in
November 2019) is that that the
hardness of the material comprising the
spine flex joint was lower than the
specification called for.
NHTSA’s qualification testing did not
reveal any issues with meeting the
upper thorax qualification specifications
(See Section V.D). In any case, in light
of the potential concerns raised within
Working Group 5 of possible excessive
variation in the performance of the
spine flex joint, potentially traceable to
out-of-specification materials, NHTSA
conducted a limited modeling exercise
using the THOR–50M Finite Element
(FE) model to investigate this. This
analysis suggested that while variation
in the lumbar and thoracic spine flex
joints does influence the thoracic
response in both qualification and sled
test conditions, this variation is smaller
than the expected test-to-test and ATDto-ATD variation; specifically, a
decrease in stiffness of the spine flex
joints can influence the upper thorax
qualification response, but by a much
smaller magnitude than the width of the
qualification specifications and test-totest and ATD-to-ATD variations. For
more information on this issue and
NHTSA’s FE modelling, please see
Appendix B.
Nonetheless, a research effort is
currently underway to assess the
influence of the lumbar and thoracic
spine flex joints in physical
qualification tests (which would
provide additional validation data to the
computational analysis) and develop
isolated dynamic tests of the lumbar and
thoracic spine flex joints. Based on
these results, NHTSA could potentially
consider adding such a test(s) in the
drawing package, qualification
procedures, or laboratory test
procedures. NHTSA requests comment
from THOR–50M ATD users who have
data to demonstrate variation in THOR–
50M response that is believed to result
from spine flex joint variation,
specifically when the parts evaluated
met the specifications of the THOR–
50M drawing package. Additionally,
NHTSA requests comment on the need
for a thoracic spine and/or lumbar spine
flex joint specification beyond the
geometry and material properties
defined in the drawing package.
I. Abdomen
The abdomen of the THOR–50M
consists of two components, the upper
abdomen and the lower abdomen. The
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lower abdomen is the region between
the lower thoracic rib cage and the
pelvis. The upper abdomen is the region
on the dummy that represents the lower
thoracic cavity, which fills the volume
that exists between the lowest three ribs,
above the lower abdomen and in front
of the spine. The upper and lower
abdomen components of THOR–50M
are represented by structural fabric bags
containing foam inserts which define
the compression stiffness. Both
abdomen inserts are anchored
posteriorly to the spine, while the upper
abdomen insert is additionally anchored
to the lower rib cage. When the lumbar
spine pitch change joint is set to the
‘‘slouched’’ position, the abdomen
inserts are in contact with one another;
when in the ‘‘erect’’ and ‘‘neutral’’
positions, the gap between the
abdominal inserts is filled with the
lower abdomen neutral/erect position
foam. This gap is also spanned by two
steel stiffeners on each side that are
installed into the torso jacket. The
bottom surface of the lower abdomen
insert is coincident with the pelvis.
J. Pelvis
The THOR–50M pelvis is designed to
represent human pelvis bone structure
to better represent lap belt
interaction,112 113 and the pelvis flesh is
designed to represent uncompressed
geometry to allow human-like
interaction of the pelvis flesh with the
vehicle seat.114 The pelvis assembly is
constructed of a steel and aluminum
structure representing bone surrounded
by a molded foam-filled vinyl covering
representing flesh. The flesh is not
physically connected to the pelvis bone
but is held in place due to the tight fit
of protrusions of the pelvis bone into
recesses in the pelvis flesh, as well as
circular bosses in the pelvis flesh into
recesses in the pelvis bone. The pelvis
flesh includes a portion of the upper
thigh flesh, the interior surface of which
includes gaps around the femur bone to
allow articulation of the leg about the
hip joint.
The THOR–50M pelvis flesh is a
molded component, with a vinyl outer
112 Reynolds, H., Snow, C., Young, J., ‘‘Spatial
Geometry of the Human Pelvis,’’ U.S. Department
of Transportation, Technical Report No. FAA–AM–
82–9, 1982.
113 Haffner, M., Rangarajan, N., Artis, M., Beach,
D., Eppinger, R., Shams, T., ‘‘Foundations and
Elements of the NHTSA THOR Alpha ATD Design,’’
The 17th International Technical Conference for the
Enhanced Safety of Vehicles, Paper No. 458, 2001.
114 Shams, T., Rangarajan, N., McDonald, J.,
Wang, Y., Platten, G., Spade, C., Pope, P., Haffner,
M., ‘‘Development of THOR NT: Enhancement of
THOR Alpha—the NHTSA Advanced Frontal
Dummy,’’ The 19th International Technical
Conference for the Enhanced Safety of Vehicles,
Paper No. 05–0455, 2005.
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layer filled with expandable
polyurethane foam. The twodimensional drawing includes top, side,
front, and isometric views of the molded
pelvis flesh, while its three-dimensional
geometry is included in the CAD files
available through the NHTSA website in
both Autodesk Inventor and generic
STEP formats. The drawing package
specifies part weight and foam
density 115 but not a material response
or performance requirement for the
pelvis flesh.
NHTSA is considering adding a
performance specification for the pelvis
flesh similar to that defined in the HIII–
50M PADI. Such a performance
specification would dictate the amount
of allowable compression of the pelvis
flesh under a defined load. A similar
test was conducted on the pelvis flesh
during the THOR Alpha design
development.116 One such possible
requirement would be the compression
at a force of 500 N. Alternatively,
Porsche has suggested a dynamic impact
test using an impactor similar to that
used in the upper thorax qualification
test to impact the bottom of the pelvis
flesh at a velocity of 2 m/s. NHTSA
seeks comment on the need and
specifications for a pelvis compression
test, including whether it should be a
qualification requirement, a drawing
specification, or otherwise.
The pelvis is instrumented with bilateral triaxial load cells attached to the
acetabulum (in order to measure the
reaction force between the femur and
the pelvis) and a triaxial accelerometer
array at its center of gravity. The pelvis
is also instrumented with bi-lateral
anterior-superior iliac spine (ASIS) load
cells that measure contact force in a
nominally longitudinal axis and
moment about a nominally lateral axis.
The ASIS load cell is primarily used to
measure the force transferred to the
pelvis through the lap belt, in which
case the moments can be used to
determine the vertical level or center of
pressure of the lap belt force.
K. Upper Leg
The upper leg assembly is constructed
of steel and aluminum and includes a
rubber compressive element at the
middle of the femur shaft. This
compressive element consists of a steel
plunger that can translate axially along
the femur shaft through a guide system.
When the femur is loaded in axial
compression (e.g., pushing the knee
towards the pelvis parallel to the
115 Drawing
472–4100.
Jr, R.P., Rangarajan, N., Haffner, M.,
‘‘Development of the THOR Advanced Frontal
Crash Test Dummy’’, 34th Annual SAFE
Symposium, Conference paper, 1996.
116 White
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femur), the motion of the plunger is
resisted by a rubber element, which
allows a human-like compression
response.117 At the proximal end, the
femur is connected to the pelvis through
a ball joint in a socket attached to the
acetabulum load cell. At the distal end,
there is a six-axis load cell attaching the
femur to the knee assembly.
L. Knee
The THOR–50M knee is similar in
construction to that of the HIII–50M,
with a few differences. The primary
structure of the knee cap is fabricated
from aluminum, attached proximally to
the femur load cell. Inside of the
kneecap assembly, a slider mechanism
is installed to allow translational motion
of the tibia with respect to the knee. The
knee slider includes a stop assembly to
prevent metal-to-metal contact and to
define the force-deflection characteristic
of the tibia translation. Attached to the
slider is a string potentiometer to
measure the magnitude of tibia
translation relative to the knee. The
sides of the kneecap are enclosed by
urethane covers to protect the slider
mechanism, and the knee assembly is
wrapped in a foam-filled vinyl cover
representing knee flesh.
The design of the knee slider modifies
the HIII–50M design by changing the
geometry and material properties of the
molded slider assemblies (472–5320 and
472–5330) and stop assemblies (472–
5358).118 This change was made because
at levels of knee displacement below the
10.2-millimeter (mm) biofidelity
response requirement, the HIII–50M has
been found to be stiffer than PMHS
response corridors. Thus, during the
THOR–50M Mod Kit project,
biomechanical response requirements
were specified with an additional
measurement point at 5 mm of knee
displacement with a force between 100
and 500 N. The Mod Kit also relegated
the measurement point at 10.2 mm of
deflection to a secondary requirement,
as it was shown to be at the high end
of the underlying PMHS corridors.
While the 5 mm and 17.8 mm response
requirements were met by the revised
THOR–50M knee slider,119 the forcedeflection response was below the
human response corridor between 8 mm
and 15 mm of deflection, but above the
corridor after 18 mm of deflection.120 As
such, when the biofidelity was
117 Ridella, S., Parent, D., ‘‘Modifications to
Improve the Durability, Usability, and Biofidelity of
the THOR–NT Dummy,’’ The 22nd International
Technical Conference for the Enhanced Safety of
Vehicles, Paper No. 11–0312, 2011. See Figure 17.
118 Id. at Figure 16.
119 Id.
120 See Biofidelity Report, p. 254 (Fig. 45).
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evaluated using BioRank, the external
biofidelity score of 2.282 indicated that
the THOR–50M response was more than
two standard deviations from the PMHS
mean response. This BioRank score was
lower than the corresponding HIII–50M
score (1.070). This should be taken into
consideration when using the THOR–
50M to evaluate the risk of ligamentous
knee injury.
M. Lower Leg
The mechanical design of the THOR–
50M lower extremity includes a
compressive rubber section in the tibia
shaft, similar to the compliant femur
section, which provides more biofidelic
force transmission from the heel to the
knee. The spring damper Achilles
tendon system aids in producing
biofidelic ankle motion and torque
characteristics. The ankle design allows
rotation about three axes, representing
inversion/eversion, dorsi/plantarflexion, and axial rotation, and includes
molded rubber elements to define the
moment/rotation response and limit
metal-to-metal contact at the extents of
the range of motion. Different from
existing ATDs, the THOR–50M includes
a molded shoe design which integrates
the foot and shoe into a single part. This
feature, added in the 2016 update to the
THOR–50M drawing package,121 is
intended to reduce potential variability
in the response of commercially
available shoes.
Euro NCAP TB026 deviates from the
proposed drawing package in that it
specifies the HIII–50M lower legs,
including the military specification 122
shoes, knee slider sensor, and roller
ball-bearing knees. We believe the
THOR–50M specifications are
preferable, for the reasons given above
(e.g., biofidelity).
Each lower leg can be instrumented
with five-channel load cells in the
upper and lower tibia, a uniaxial load
cell to measure the Achilles cable force,
and three rotary potentiometers to
measure the rotation of the individual
ankle joints. Two uniaxial
accelerometers can be mounted to the
tibia and a tri-pack accelerometer
assembly can be mounted to each foot
plate.
N. Data Acquisition System
Testing with THOR–50M requires (as
does testing with any dummy) a data
121 National Highway Traffic Safety
Administration (2016). Parts List and Drawings
THOR–50M Advanced Frontal Crash Test Dummy
THOR–50M Male August 2016. Docket ID NHTSA–
2015–0119–0376.
122 Specification is not stated in Euro NCAP
TB026, but believed to be MIL–S–13192P as
specified in 49 CFR 571.208 S8.1.8.2.
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acquisition system (DAS). The data
acquisition system performs signal
conditioning, triggering, and data
collection to store measurements from
instrumentation installed in the dummy
during a test into nonvolatile memory.
As it relates to ATDs, there are
effectively two types of DAS: external
and internal (or in-dummy). As we
explain below, while the 2018 drawing
package does not specify a DAS
(because it assumes the use of an
external DAS), NHTSA is proposing to
specify an optional in-dummy DAS.123
An external DAS is, as the name
indicates, external to the dummy. The
instrumentation in the dummy is
connected to the external DAS via
wires, sometimes referred to as an
umbilical cable. The 2018 drawing
package does not explicitly specify a
DAS or related equipment, but the
drawings assume an external DAS: they
assume that the instrumentation wires
are long enough to be bundled into an
umbilical cable and connected to a DAS
located in the lab or mounted to the
vehicle in which the ATD is seated.
An internal DAS is installed within
the dummy itself. An internal DAS has
some advantages to an external DAS.
The primary advantage is related to the
mass properties of the dummy. With an
internal DAS system, there are no
external cables that may possibly affect
body segment masses; segment masses
are always the same no matter how the
dummy is used. While upfront cost is
higher, an internal DAS would reduce
per-test costs, eliminate the need for
interface cables to lab-specific DAS
systems (which have been a frequent
sources of instrumentation failures in
research testing), and reduce the
adjustments needed to arrive at the
target test vehicle weight. Feedback
from industry 124 as well as Euro NCAP
indicates that users prefer an in-dummy
DAS for its many usability advantages.
Euro NCAP TB026 requires an indummy DAS.125 While Euro NCAP
TB029 currently does not specify an
approved in-dummy DAS,126 earlier
123 We note that the 2023 drawing package itself
does not contain specifications for an in-dummy
DAS. Instead, the proposed in-dummy DAS
specifications are set out in an addendum that is
being docketed along with the 2023 drawing
package.
124 Alliance of Automobile Manufacturers, Inc.
(2016). Technical Considerations Concerning
NHTSA’s Proposal to Rework the Agency’s New Car
Assessment Program (NCAP). Regulations.gov
Docket ID NHTSA–2015–0119–0313, available at:
https://www.regulations.gov/contentStreamer?
documentId=NHTSA-2015-0119-0313&
attachmentNumber=5&contentType=pdf.
125 TB026 § 1.2.
126 European New Car Assessment Programme
(2022). Euro NCAP Supplier List, Version 4.0,
October 2022, TB 029, available at: https://
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versions of TB029 did specify a few
different approved in-dummy DAS
systems.127
In light of these potential advantages
and user preferences, NHTSA sponsored
development and testing of an indummy DAS. NHTSA published a
request for solicitation for an in-dummy
DAS.128 This was before Euro NCAP
began testing with the THOR–50M. The
solicitation favored a minimal redesign
of existing THOR–50M parts, in order to
facilitate interchangeability of parts
between THOR–50Ms with and without
in-dummy DASs. NHTSA contracted
Diversified Technical Systems (DTS) to
implement its SLICE6 data acquisition
system in a NHTSA-owned THOR–50M.
This included delivery of DAS
components, replacement
instrumentation compatible with the
DAS, and replacement ATD parts to
allow attachment of DAS components
and preservation of inertial properties.
The resulting implementation
distributes a series of small 6-channel
data acquisition modules throughout the
ATD, mounted directly on load cells or
sensors where possible, or close to the
sensor with short cables to the sensor.
The DAS modules are chain-networked
with four wiring harnesses which
connect to the SLICE6 Distributor, with
a single ATD exit cable connecting the
DAS to the full test system.
NHTSA evaluated the overall
performance and equivalence of the
THOR–50M with the in-dummy SLICE6
DAS in a full suite of qualification
testing and a variety of sled and vehicle
crash testing. This research and analysis
is described briefly below. The vehicle
crash testing is described in more detail
in the cited report. NHTSA is preparing
a report on the installation, qualification
testing, and sled testing of the SLICE6
in-dummy DAS, which will be placed in
the research docket when it is complete.
Additional information on the
durability of the THOR–50M with the
in-dummy DAS system is included in
Section VII.B, Durability and
Maintenance.
• It was possible to install the SLICE6
into the dummy with negligible changes
www.euroncap.com/en/for-engineers/supportinginformation/technical-bulletins/.
127 European New Car Assessment Programme
(2022). Euro NCAP Supplier List, Version 3.1, April
2021, TB 029, available at: https://
www.euroncap.com/en/for-engineers/supportinginformation/technical-bulletins/. The DTS TDAS
G5, SLICE Nano, and SLICE6; the Kistler DTI,
microDAU, and NXT32; and the Messring M=BUS.
128 National Highway Traffic Safety
Administration (2017). Implement and Install
THOR 50M In Dummy Data Acquisition System.
Solicitation Number DTNH2217Q00033, available
at https://sam.gov/opp/068c7821de797ebe7f9
e78a0f2b68dc4/view.
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to the mass, moment of inertia, and
center of gravity of the ATD and its
individual body segments. This did
require modifications to several THOR–
50M parts (e.g., the lower thoracic spine
assembly) in order to allow attachment
of the DAS hardware to the rigid
components of the ATD.
• NHTSA has been able to fully
qualify THOR–50M ATDs with the indummy DAS installed. Since the SLICE
system has been installed, we have used
the dummy in many tests and have
qualified it with no issues. The THOR–
50M with the in-dummy DAS was
tested in simplified sled tests. Sled tests
were conducted in the Gold Standard 1
(40 km/h, 12g peak pulse, standard lap
and shoulder belt) and Gold Standard 2
(30km/h, 9g peak pulse, 3kN load
limited shoulder belt) test conditions,
which were used both in biofidelity
assessment and in the development of
thoracic injury criteria. The goal of this
testing was to determine if any
differences occurred between the
external and internal DAS
configurations, and if so, whether the
magnitude of these differences would
affect the biofidelity and injury criteria
development analyses.
• NHTSA also tested the THOR–50M
with an in-dummy DAS in a series of
vehicle crash tests in the OMDB test
condition with three different
deformable barrier faces. While some of
the OMDB tests appeared to show
differences between the in-dummy DAS
and umbilical configurations, it was not
clear whether this was due to variation
in the dummy response or variation in
dummy positioning, vehicle response,
and/or restraint system response.129
Importantly, this testing did not
reveal any potential durability or
usability issues associated with the indummy DAS, with one possible
exception: The temperature inside the
thoracic cavity of the ATD can increase
beyond the ambient temperature
typically prescribed for regulatory and
consumer information crash tests.130 In
a more recent set of vehicle crash tests,
NHTSA closely monitored the rib
temperature of the THOR–50M with the
129 Saunders, J., Parent, D. (2023). Update on
NHTSA’s OMDB’s half barrier analysis. Proceedings
of the 27th Enhanced Safety of Vehicle Conference,
Yokohama, Japan.
130 The OVSC Laboratory Test Procedures for
FMVSS No. 208 specify an ambient temperature
measured within 36 inches of the ATD to be
between 69 and 72 degrees Fahrenheit. National
Highway Traffic Safety Administration (2008).
Laboratory Test Procedure for FMVSS 208,
Occupant Crash Protection, TP208–14, available at:
https://www.nhtsa.gov/sites/nhtsa.gov/files/
documents/tp-208-14_tag.pdf.
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in-dummy DAS.131 By routinely
limiting the ‘‘ON’’ time of the DAS,
NHTSA has been able to maintain the
temperature range. Additionally,
NHTSA has used a portable fume
extractor device to aid in maintaining
the temperature of the WorldSID–50M
side impact dummy, which also has
internal DAS system.132 133 This device
may also be employed in tests with the
THOR–50M.
Based on this testing, NHTSA has
tentatively concluded that the THOR–
50M with the in-dummy DAS is
equivalent to one with the external
DAS. NHTSA is therefore proposing an
internal DAS as permitted optional
instrumentation that it could use in its
testing. This necessitates changes to the
dummy to accommodate the DAS while
ensuring that there are no changes to the
mass, moment of inertia, and center of
gravity of the ATD and its individual
body segments. These changes may
differ from the Euro NCAP approach
specified in TB026, which permits the
four-position spine box (discussed in
Section III.H above) to accommodate the
installation of some DAS brands by
providing a mounting surface for data
loggers. Euro NCAP does not provide
part-by-part engineering drawings of the
various DAS packages, which is
necessary for THOR–50M to be
sufficiently objective.
NHTSA has therefore provided, in an
addendum to the 2023 drawing package,
further specifications for the dummy to
accommodate an internal DAS. It is
anticipated that, upon finalization of
this proposal, the in-dummy DAS
drawings will be fully integrated within
the relevant technical data package
components. These specifications
consist of descriptions of the
instrumentation and new drawings for
the dummy parts that require
modifications to accommodate the DAS.
The changes are specified such that the
131 Saunders, J., Parent, D., Martin, P. (2023).
THOR–50M fitness assessment in FMVSS No. 208
unbelted crash tests. Proceedings of the 27th
Enhanced Safety of Vehicle Conference, Yokohama,
Japan.
132 Tatem, W., Louden, A. (2023). WorldSID–50M
Fitness Assessment in FMVSS No. 214 Moving
Deformable Barrier and Oblique Pole Crash Tests.
Proceedings of the 27th Enhanced Safety of Vehicle
Conference, Yokohama, Japan.
133 This device is used to dissipate heat from the
dummy in the pre-test setup (for example, while
seating and positioning the dummy). Typically, a
tube is inserted into the dummy jacket and in
conjunction with the fan is used to vent heat from
the dummy to maintain an in-spec internal
temperature. The apparatus is detached from the
dummy immediately prior to the vehicle or sled
test. Use of such a fan may be specified in the OVSC
laboratory test procedure.
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dummy with the in-dummy DAS will
have the same inertial properties as the
dummy using the external DAS. The
drawings show DAS mass blanks in lieu
of the actual DAS components (battery,
data logger, etc.) with the exterior
dimensions of the blank matching those
of the corresponding SLICE6
component.
If an in-dummy DAS component is
not installed (for example, if lower leg
instrumentation is not needed for a
given test mode), the blank would be
filled with a material of a specified
density. The material of the blank is not
specified (although a reference
specification is provided) but would be
selected to provide an appropriate
density and may also have internal
flashing holes needed to attain the
desired mass, which is chosen to match
the mass of the actual DAS component.
It is anticipated that, upon finalization
of this proposal, the PADI will show
two sets of installation steps: one with
the ‘‘blank’’ component, and one with
the actual DAS parts. (This two-set
convention is also followed with load
cells and their structural replacements).
The proposed specifications are based
on, but not necessarily limited to, the
SLICE6 (the SLICE6 is not explicitly
specified or called-out by name), so that
another system fitting within the
defined specifications could also be
utilized.134
NHTSA seeks comment from users
who have experience with both
umbilical and in-dummy DAS
configurations of the THOR–50M, as to
whether they have seen any quantifiable
differences between the two. NHTSA
also seeks comment on whether any
additional changes should be made to
the proposed drawings specifying the
in-dummy DAS to make it more
amenable to additional DAS systems
that are already in the field.
IV. Biofidelity
Biofidelity is a measure of how well
the dummy replicates a human, and
includes anthropometry, mass
properties, range of motion, and impact
response. The impact biofidelity is
evaluated by comparing the response of
the dummy to the response of a postmortem human surrogate (PMHS or
cadaver) or human volunteer in a
variety of different test conditions (also
referred to as test modes). Some of these
134 While we are aware of in-dummy DASs
produced by other manufacturers, we have not
evaluated whether these systems would be
compatible with the in-dummy DAS addendum to
the 2023 drawing package.
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tests focus on individual dummy
components (head, neck, chest,
abdomen, upper leg, knee, lower leg)
and some evaluate the entire dummy as
a complete assembly.
To evaluate the biofidelity of THOR–
50M, NHTSA selected test conditions
based on relevance to frontal and frontal
oblique crash test applications and the
availability of data. For example, a neck
frontal flexion test was conducted by
attaching the base of the THOR–50M
neck to a sled and applying a certain
acceleration pulse. This was then
compared to the response measured on
human volunteers who were subjected
to a similar pulse. Specifically, the
impact biofidelity of the THOR–50M
was assessed in twenty-one test
conditions. The test conditions are
summarized in Table 6. Each test
produces a series of data points (e.g.,
force vs. time).
The test conditions have been
developed over the years by various
researchers to evaluate biofidelity and
have been published in peer-reviewed
journals. The PMHS and human
volunteer response data generally comes
from this published research. The
THOR–50M response data comes from
testing that NHTSA has been
conducting on the THOR–50M
throughout its development, all of
which is available in NHTSA’s
Biomechanics Test Database.135 NHTSA
also compared THOR–50M’s biofidelity
to that of the HIII–50M; many of the
tests conducted with THOR–50M were
paired with the same test conducted on
the HIII–50M. In our testing we
attempted to match the test conditions
as closely as possible to the test
conditions in the original PMHS or
volunteer tests.136
135 Available at https://www.nhtsa.gov/researchdata/research-testing-databases#/biomechanics.
136 Overall, while some assumptions were
necessary in the reproduction of the PMHS or
volunteer test conditions, we believe that these
assumptions should not affect the overall biofidelity
assessment of the THOR–50M. For instance,
NHTSA simplified some of the original tests in
order to facilitate ease of testing when we expected
the simplification to have a negligible influence on
the result, such evaluating neck flexion using only
the ATD’s head and neck, and not the entire
dummy. These assumptions and simplifications, as
well as any limitations to our analyses, are
discussed in detail in the docketed biofidelity
report. Parent, D., Craig, M., Moorhouse, K. 2017.
Biofidelity Evaluation of the THOR and Hybrid III
50th Percentile Male Frontal Impact
Anthropomorphic Test Devices. Stapp Car Crash
Journal, 61, 227–276, available at: https://
www.regulations.gov/document/NHTSA-2019-01060004.
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TABLE 6—BIOFIDELITY CONDITIONS CONSIDERED IN THE DESIGN OF THE HIII FRONTAL DUMMIES AND THOR–50M ATDS
Body region
Test condition
Subpart E, O, W
THOR–50M
Head ..............................................
Isolated Head Drop ..............................................................................
Whole-body Head Impact ....................................................................
Face Rigid Bar .....................................................................................
Face Rigid Disk ....................................................................................
Neck Flexion, Pendulum ......................................................................
Neck Extension, Pendulum ..................................................................
Neck Frontal Flexion, Sled ..................................................................
Neck Lateral Flexion, Sled ...................................................................
Neck Torsion ........................................................................................
Sternal Impact, 6.7 m/s ........................................................................
Sternal Impact, 4.3 m/s ........................................................................
Lower Ribcage Oblique .......................................................................
Upper Abdomen Steering Rim .............................................................
Lower Abdomen Rigid Bar ...................................................................
Abdomen Belt Loading ........................................................................
Femur Compression ............................................................................
Knee Shear ..........................................................................................
Dynamic Heel Impact ...........................................................................
Tibia Axial Compression ......................................................................
Dynamic Dorsiflexion ...........................................................................
Gold Standard 1 ...................................................................................
Gold Standard 2 ...................................................................................
Gold Standard 3 ...................................................................................
Far Side Oblique ..................................................................................
•
•
•
•
•
Neck ..............................................
Thorax ...........................................
Abdomen .......................................
KTH ...............................................
Lower Extremity ............................
Whole-body ...................................
The test conditions used to evaluate
the THOR–50M represent an
accumulation of biomechanics research.
All conditions are accompanied by a
well-specified, objective test procedure
and a well-founded set of human
response targets. The set of test
conditions has grown substantially over
the span of Part 572 rule makings. For
example, in NHTSA’s original 1998
proposal for the Subpart O HIII–5F
dummy,137 only six biofidelity
conditions were assessed.138 Since then,
the list has grown substantially; new
conditions have been developed for all
body regions, and whole-body sled test
conditions have been developed.139
NHTSA quantified how closely the
response of the THOR–50M matched the
response of the PMHS or human
volunteers using the Biofidelity Ranking
137 63
FR 46981.
H.J., Irwin, A.L., Melvin, J.W., Stanaker,
R.L., & Beebe, M. (1989). Size, weight and
biomechanical impact response requirements for
adult size small female and large male dummies
(No. 890756). SAE Technical Paper.
139 See National Highway Traffic Safety
Administration, ‘‘Biomechanical Response
Requirements of the THOR NHTSA Advanced
Frontal Dummy, Revision 2005.1,’’ Report No:
GESAC–05–03, U.S. Department of Transportation,
Washington, DC, March 2005 (available at https://
www.nhtsa.gov/DOT/NHTSA/NVS/
Biomechanics%20&%20Trauma/THORNT%20Advanced%20Crash%20Test%20Dummy/
thorbio05_1.pdf) and Ridella, S., Parent, D.,
‘‘Modifications to Improve the Durability, Usability,
and Biofidelity of the THOR–NT Dummy,’’ The
22nd International Technical Conference for the
Enhanced Safety of Vehicles, Paper No. 11–0312,
2011.
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138 Mertz,
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system (BioRank).140 BioRank has been
applied in other instances cited in the
literature 141 and in other NHTSA Part
572 rulemakings.142 This methodology
statistically compares the dummy
response to the average PMHS/volunteer
response (typically a time-series but
sometimes a point estimate). A BioRank
value of 0.0 indicates an ATD response
identical to the average PMHS/volunteer
response; a value of 1.0 indicates an
ATD response that is on average one
standard deviation 143 away from the
average PMHS/volunteer response; a
value of 2.0 indicates an ATD that is on
average two standard deviations away
from the average PMHS/volunteer
response; and so on. Therefore, the
lower the BioRank value, the better the
biofidelity. We computed BioRank
140 Rhule, H., Maltese, M., Donnelly, B., Eppinger,
R., Brunner, J., Bolte, J. (2002) Development of a
New Biofidelity Ranking System for
Anthropomorphic Test Devices. Stapp Car Crash
Journal 46: 477–512.
141 Rhule, H., Moorhouse, K., Donnelly, B.,
Stricklin, J. (2009) Comparison of WorldSID and
ES–2RE Biofidelity Using Updated Biofidelity
Ranking System. 21st ESV Conference, Paper
No.09–0563.
142 The analysis using Biorank described here
mirrors (with some exceptions) the approach used
in the assessment of the WorldSID 50th ATD. See,
e.g., 80 FR 78522, 78538 (Dec. 16, 2015) (New Car
Assessment Program Request for Comments); 71 FR
75304 (Dec. 14, 2006) (final rule for ES–2re Side
Impact Crash Test Dummy 50th Percentile Adult
Male); 71 FR 7534 (Dec. 14, 2006) (final rule for
SID–IIs Side Impact Crash Test Dummy 5th
Percentile Adult Female).
143 The standard deviation is a statistic that
measures the dispersion of a dataset relative to its
mean.
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•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
scores for both the THOR–50M and the
HIII–50M.
For each body region, we calculated
two BioRank scores: one for external
biofidelity (the extent to which the ATD
represents a human surrogate to the
vehicle or restraint system); and one for
internal biofidelity (the ability of the
ATD to represent the human responses
that relate to prediction of injury).
External biofidelity measures are
generally those recorded at the test
fixture level, such as pendulum force or
belt force; internal biofidelity measures
are generally those recorded by the
internal instrumentation of the ATD or
test equipment such as motion tracking
that records subject excursion.
NHTSA considered two other
methods of quantifying biofidelity. One
is the International Standards
Organization (ISO) 9790 Biofidelity
Classification System. ISO 9790 defines
the analysis process, response corridors,
and weighting factors for the
quantitative assessment of biofidelity of
side impact ATDs. Because the ISO
9790 response corridors and weighting
factors are specific to side-impact ATDs,
it could not be directly applied to a
frontal impact ATD such as the THOR–
50M, and we are not aware of a
corollary ISO standard for assessment of
frontal impact ATD biofidelity. While a
method similar to that described in ISO
9790 could be developed to assess
frontal impact ATD biofidelity, we
believe such a method may introduce
subjective bias because it contains many
subjective features, including weighting
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of test conditions and body regions.144
The BioRank system was developed to
minimize subjectivity in the areas of
corridor development, weighting, and
scoring. Another method NHTSA
considered is correlation and analysis
(CORA), which may be a useful tool to
carry out quantitative analysis.145
However, the vast array of tunable
parameters in the software can result in
unintentional subjectivity and poor
reproducibility. Further, there are no
known and accepted relationships
between CORA scores and biofidelity
classifications. Accordingly, we
evaluated biofidelity using BioRank.
We note that because many of the
biofidelity test conditions utilize
specialized instrumentation or test
equipment, they are not intended to be
carried out as certification or
qualification tests conducted between
crash tests or sets of crash tests to
confirm that specified ATD response
requirements are met. Instead, due to its
relative complexity, biofidelity testing is
carried out at the ATD design stage to
assess the biofidelity of the design.
Simplified and standardized versions of
the biofidelity test conditions have been
developed as qualification procedures
for some body regions. Because the
qualification response requirements are
based on the expected variation in
response of the ATD, not the underlying
human response, the qualification
requirements specify a much smaller
allowable range in response than the
biomechanical design targets. Therefore,
it is expected that all THOR–50M units
that meet the specifications of the
qualification procedures would
demonstrate similar biofidelity. The
proposed qualification response
requirements are discussed in Section
V.
A full description of NHTSA’s
biofidelity testing and analysis can be
found in the docketed biofidelity
report.146 We note that there are no
separate discussions in the report for the
shoulder, spine, or pelvis. Impact
biofidelity of the spine and pelvis, as
well as the dynamic biofidelity of the
shoulder, are intrinsically evaluated as
part of the whole-body biofidelity sled
test series.147 Shoulder biofidelity has
also been assessed quasi-statically and
found to be more similar to the human
volunteer corridors than existing ATDs.
NHTSA is finalizing a report on the
alternate shoulder design, which
includes the biofidelity evaluation
described here; once complete, this
report will be published to the research
docket.
61917
NHTSA believes that the THOR–50M
is sufficiently biofidelic for
incorporation into Part 572. The
biofidelity report shows that the THOR–
50M exhibits overall internal and
external BioRank scores of below 2.0.
See Table 7. Both internal and external
BioRank scores are lower than those of
the HIII–50M, which is defined in Part
572 (Subpart E) and used in regulatory
and consumer information frontal
impact crash testing. At the body region
level, the internal and external BioRank
scores for THOR–50M are all below 2.0
except for neck internal biofidelity and
abdomen external biofidelity. The
THOR–50M BioRank score for the neck
and abdomen external biofidelity are,
however, lower (better) than those for
the HIII–50M. Overall, the internal
BioRank scores for the THOR–50M were
lower than those of HIII–50M in 5 of the
7 body regions evaluated, and THOR–
50M external BioRank scores were
lower than those of HIII–50M in 6 of the
7 body regions evaluated. Thus, the
THOR–50M has generally improved
biofidelity in the individual body region
tests, which improves the accuracy of
injury predictions. The THOR–50M and
the HIII–50M have comparable
quantitative biofidelity in the wholebody sled test conditions.148
TABLE 7—BODY REGION INTERNAL AND EXTERNAL BIORANK SUMMARY
THOR–50M
HIII–50M
Body region
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Internal
External
Internal
External
Head ................................................................................................................
Neck .................................................................................................................
Thorax ..............................................................................................................
Abdomen ..........................................................................................................
KTH ..................................................................................................................
Lower Extremity ...............................................................................................
Whole-body ......................................................................................................
0.155
2.155
0.917
1.470
1.400
1.349
1.472
1.143
1.677
0.948
2.803
1.731
0.871
1.989
0.013
2.185
1.603
1.629
3.875
0.832
1.576
6.640
4.318
2.070
3.474
6.667
1.108
1.780
Overall ......................................................................................................
1.274
1.594
1.673
3.722
Since a majority of the test conditions
involved pure frontal loading, and
several involved oblique and lateral
loading (neck lateral flexion, neck
torsion, lower thorax oblique, Gold
Standard 3, and Far Side Oblique test
conditions), these findings are expected
to extend to frontal and frontal oblique
crash test conditions. The findings may
not, however, extend to other loading
conditions (such as pure lateral or rear
impacts) without further research.
144 Rhule, D., Rhule, H., Donnelly, B. (2005) The
Process of Evaluation and Documentation of Crash
Test Dummies for Part 572 of the Code of Federal
Regulations. 19th ESV Conference, Paper No. 05–
0284, pp. 9–10.
145 Gehre C, Gades H, Wernicke P (2009)
Objective rating of signals using test and simulation
responses, The 21st International Technical
Conference for the Enhanced Safety of Vehicles,
Paper No. 09–0407, 2009.
146 Parent, D., Craig, M., Moorhouse, K. 2017.
Biofidelity Evaluation of the THOR and Hybrid III
50th Percentile Male Frontal Impact
Anthropomorphic Test Devices. Stapp Car Crash
Journal, 61, 227–276, available at: https://
www.regulations.gov/document/NHTSA-2019-01060004.
147 The qualitative biofidelity of the shoulder is
also discussed in the Biofidelity Report, where the
role of the shoulder in belt retention (or lack
thereof) is discussed qualitatively. See p. 272–273.
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V. Qualification Tests
This NPRM proposes qualification
tests (also referred to as qualification
procedures) for THOR–50M. The
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qualification procedures describe a
series of impact tests performed on a
fully-assembled dummy or dummy subassembly. The tests assess the
components that play a key role in the
dummy’s performance in the intended
application of frontal and frontal
oblique crashes. We propose
148 This finding has been confirmed by
independent research; a 2018 study showed that the
HIII–50M and THOR–50M demonstrated similar
biofidelity scores in a sled test environment
representing a production vehicle. See Albert,
Devon L., Stephanie M. Beeman, and Andrew R.
Kemper. ‘‘Occupant kinematics of the Hybrid III,
THOR–M, and postmortem human surrogates under
various restraint conditions in full-scale frontal sled
tests.’’ Traffic Injury Prevention 19.sup1 (2018):
S50–S58.
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qualification tests for the head, face,
neck, upper thorax, lower thorax,
abdomen, upper leg, knee, and lower
leg. For some body regions (such as the
face) we propose a single test condition
(also referred to as a test mode), while
for other body regions (for example, the
neck) we propose a series of different
test conditions.
Each qualification test condition
consists of test procedures, test
parameters, and acceptance intervals.
The test procedures describe a detailed
series of steps that must be carried out
to perform the test. Test parameters
describe specific aspects of the
dummy’s response. Acceptance
intervals (or qualification targets) are
specified for each test parameter.
Acceptance intervals are a typically pair
of numeric values (a minimum value
and maximum value) within which the
dummy response must fall in order to
pass, but can also represent a minimum
or maximum value of the response. For
instance, one of the tests involves
striking the head with an impactor and
measuring the head’s acceleration,
which must be within the acceptance
interval 117 ± 11.7 Gs.
The qualification tests mirror the
dummy loading patterns observed in
frontal crash tests, including full frontal,
oblique, and offset modes. For the neck
assembly, we have specified separate
requirements in flexion, extension, and
lateral flexion. These bending modes
have all been observed in crash testing.
Additionally, a torsion test is prescribed
for the neck since it also twists along its
long axis to some degree. For the feet
and ankles, tests in inversion, eversion,
dorsiflexion, and axial loading through
the tibia are specified to account for the
various injurious loads that have been
observed in crash tests. For the head,
face, upper and lower thorax, abdomen,
upper legs, and knees, we have only
prescribed impact tests to anterior
aspects since injurious loads pass
primarily through those aspects during
crash testing. The impact speeds and
probe masses have been selected to
demonstrate that the various body
segments work properly at energy levels
at or near those associated with high
injury risks. For measurements not
associated with an injury criterion,
energy levels are chosen to exercise the
dummy approaching its functionality
limits, but without causing damage.
The qualification tests ensure that the
dummy is functioning properly. There
are a few inter-related aspects to this.
One is that qualification tests ensure
that dummy components and sensors
are properly assembled and functioning.
Qualification tests monitor the response
of components that may have become
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loosened or misaligned since initial
assembly. For each test, certain dummy
sensors and signal characteristics (such
as the magnitude and timing) have been
specified as qualification targets. Loose
or misaligned parts may become evident
when a signal does not conform to the
prescribed signal characteristics. By
monitoring these sensors, the
qualification tests ensure that the
dummy is functioning properly. The
tests also ensure that the sensors
themselves are working properly.
Another aspect is that qualification tests
help identify components that have
deteriorated over time, preventing the
dummy from meeting the qualification
targets; such parts need to be replaced
or refurbished. Many of the qualification
test protocols are very similar to the
dynamic tests used to assess biofidelity.
This helps to ensure that a qualified
dummy is also a biofidelic dummy.
Finally, they ensure that the dummy or
particular sub-assembly is responding in
a uniform and expected manner; if it is
not, certain dummy components might
need to be tuned or adjusted to obtain
a response within the qualification
targets.
NHTSA’s experience has shown that
the impact tests on body segments are
needed to ensure uniformity of dummy
responses in a subsequent vehicle crash
test. In other words, full conformance to
part and assembly specifications (in
accordance with the drawings and
PADI) is not enough to guarantee a
uniform dummy response in a crash
test.149 Qualification tests have proven
reliable and sound in qualifying
NHTSA’s other test dummies. Moreover,
some of the proposed qualification tests
use the same test equipment as other
ATDs, thus minimizing the amount of
new qualification equipment needed by
test laboratories that may already have
such equipment in place for qualifying
other ATDs. Meeting the qualification
tests helps ensure that the dummy is
capable of responding properly in a
compliance or research test. This in turn
helps to ensure that the dummy is an
objective test device suitable for the
assessment of occupant safety in
compliance tests specified in Federal
Motor Vehicle Safety Standards, and for
other testing purposes.
NHTSA proposes setting the
qualification targets at ± 10% of the
mean response for each qualification
parameter as reported in the
qualification test R&R study (discussed
in Section VI). In that study we
subjected multiple dummies to repeated
149 At the same time, conformance to a
qualification requirement is not a substitute for
parts that do not conform to drawing specifications.
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tests in each test condition at multiple
test laboratories. The repeatability
testing and analysis for the qualification
tests is described in more detail in
Section VI.A. We believe that 10% is
wide enough to account for normal
variations in ATD and laboratory
differences, and narrow enough to
ensure consistent and repeatable
measurements in standardized testing
with the ATD. This is also consistent
with the qualification limits for the
other Part 572 ATDs. For example, for
the Hybrid III 10-year-old child dummy,
the acceptance intervals are, on average,
set at ±9.9% from the nominal
midpoint, with a low of 8.4% (neck
rotation in the neck extension test) and
a high of 10.8% (in the neck moment in
the extension test and chest deflection
in the thorax impact test).150 For all Part
572 ATDs, the average acceptance
interval is ±11%.
We also considered setting the
qualification targets at plus or minus
two standard deviations from the mean
response observed in the testing
reported in the repeatability and
reproducibility study. This would have
narrowed the acceptance interval for
almost all responses, some of which
would have been unreasonably narrow.
For instance, the head impact test
results in the repeatability and
reproducibility study were very
uniform, with a CV for peak force of
0.9%. If the acceptance interval for peak
force were set to plus or minus two
standard deviations (±1.8%), 24 of the
26 trials would have resulted in a pass;
if it were set to ±2.5%, all 26 trials
would have resulted in a pass. This
result may have been a function of using
only three THOR–50M units in the test
series, all of which were brand new
when we tested them. Therefore, we
propose a greater allowance of ±10% for
all qualification requirements to account
for slight variations that may arise from
equipment and testing variations at
different test labs as well as a future
population of THOR–50M units from
dummy manufacturers in which lot-tolot differences in the fabrication of parts
from the same manufacturer may exist.
It also allows for slight changes to
individual THOR–50M units over time,
either due to aging of polymeric
components or wear and tear under
normal use. Table 8 summarizes the
proposed THOR–50M qualification
requirements.
150 HIII–10C,
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TABLE 8—PROPOSED THOR–50M QUALIFICATION REQUIREMENTS
Measurement
Units
1. Head Impact .....................
Peak Probe Force ...............................................................
Peak Head CG Resultant Acceleration ..............................
Peak Probe Force ...............................................................
Peak Head CG Resultant Acceleration ..............................
Peak Upper Neck My .........................................................
Upper Neck Fz Most Positive Value Prior to 40 ms ..........
Peak Head Angular Velocity ωy (relative to earth) .............
Peak Head Rotation (relative to pendulum) .......................
Peak Upper Neck My .........................................................
Peak Upper Neck Fz ..........................................................
Peak Head Angular Velocity ωy (relative to earth) .............
Peak Head Rotation (relative to pendulum) .......................
Upper Neck Mx first peak after 40.0 ms ............................
First Peak Head Angular Velocity ωx (relative to earth) .....
Peak Head Rotation (relative to pendulum) .......................
Peak Upper Neck Mz .........................................................
First Peak Upper Neck Angular Velocity ωz (relative to
earth).
Peak Neck Fixture Rotation ................................................
Peak Probe Force ...............................................................
Peak Upper Resultant Deflection .......................................
Difference Between Peak Left & Right Resultant Deflections.
Force at Peak Resultant Deflection ....................................
Peak Probe Force ...............................................................
Resultant Deflection at Peak Force ....................................
Peak Probe Force ...............................................................
Lower Abdomen X-axis Deflection at Time of Peak Force
Difference Between Peak Left & Right X-axis Deflections
Peak Probe Force ...............................................................
Peak Femur Force, Fz ........................................................
Peak Resultant Acetabulum Force .....................................
Peak Femur Z-axis Force ...................................................
Knee Deflection at Peak Femur Force ...............................
Peak Lower Tibia Fz ...........................................................
Peak Ankle Resistive Moment ............................................
Peak Ankle X-axis Rotation ................................................
Peak Lower Tibia Fz ...........................................................
Peak Ankle Resistive Moment ............................................
Peak Ankle X-axis Rotation ................................................
Peak Lower Tibia Fz ...........................................................
Peak Ankle Resistive Moment ............................................
Peak Ankle Y-axis Rotation (in dorsiflexion) ......................
Peak Lower Tibia Fz ...........................................................
N ...................
G ...................
N ...................
G ...................
N-m ...............
N ...................
deg/sec .........
deg ................
N-m ...............
N ...................
deg/sec .........
deg ................
N-m ...............
deg/sec .........
deg ................
N-m ...............
deg/sec .........
5580
117.0
7098
138
31.0
860
1975
64.5
23.0
2918
2061
65.0
49.7
1362
41.7
41.4
1390
5022–6138
105.3–128.7
6378–7796
124–152
27.9–34.1
774–946
1777–2172
58.1–71.0
20.7–25.3
2626–3210
1855–2267
58.5–71.5
44.8–54.7
1226–1498
37.6–45.9
37.3–45.6
1251–1529
deg ................
N ...................
mm ................
mm ................
47.9
3039
53.6
0
43.1–52.7
0–3039
48.3–59.0
¥5 to 5
N ...................
N ...................
mm ................
N ...................
N ...................
mm ................
N ...................
N ...................
N ...................
N ...................
mm ................
N ...................
N-m ...............
deg ................
N ...................
N-m ...............
deg ................
N ...................
N-m ...............
deg ................
N ...................
2677
3484
50.9
2918
83.0
0
8333
4920
2738
6506
20.2
505
39.1
34.5
571
43.0
29.6
3170
55.3
33.8
3162
2409–2944
3136–3832
45.8–56.0
2626–3210
74.7–91.3
¥8 to 8
7500–9166
4428–5412
2464–3012
5855–7156
18.2–22.2
454–555
35.2–43.0
31.0–37.9
514–629
38.7–47.3
26.6–32.5
2853–3487
49.8–60.8
30.4–37.2
2846–3478
2. Face Impact ......................
3. Neck Flexion .....................
4. Neck Extension .................
5. Neck Lateral ......................
6. Neck Torsion .....................
7. Upper Thorax ....................
8. Lower Thorax ....................
9. Lower Abdomen ................
10. Upper Leg .......................
11. Knee ................................
12. Ankle Inversion ...............
13. Ankle Eversion ................
14. Ball of Foot .....................
15. Heel .................................
Nominal target
Acceptance
interval
Test
ddrumheller on DSK120RN23PROD with PROPOSALS4
Note: For comparison purposes, unless otherwise noted, only positive values are shown for the Nominal Target and Acceptance Range. Some
targets, such as Neck Flexion Angular Velocity (wy = –1362 deg/sec), are defined by negative values.
The proposed qualification
requirements are the same as the 2018
version except for the upper leg; this is
discussed in the section below for the
upper leg.
Euro NCAP TB026 explicitly adopts
NHTSA’s 2018 qualification
procedures 151 with a couple of
differences. First, there are a few
differences between the proposal and
TB026 with respect to the tests or test
parameters. TB026 specifies somewhat
different qualification metrics for the
upper thorax test and does not include
a face impact test. TB026 prescribes the
upper leg test described in NHTSA’s
2018 qualification procedures, which
we are proposing to update. And,
151 § 2.1.
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because TB026 specifies the HIII–50M
lower extremities, the corresponding
qualification tests are not the same as
those proposed. Second, although
TB026 adopts the rest of the 2018
qualification test procedures and test
parameters, it specifies acceptance
intervals that differ from the proposed
acceptance intervals with respect to
both the width and midpoint of the
interval. While the proposed acceptance
intervals are ±10% around the mean (as
calculated from our R&R testing), the
width of the acceptance intervals
specified in TB026 range from 1% to
10%, with many of them less than 10%.
In addition, the midpoint of these
intervals differs from the means NHTSA
calculated based on its R&R testing. For
nine of the parameters, the TB026
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specifications are fully contained within
the proposed acceptance intervals. Of
the remaining parameters, there is a
minimum of 82% overlap between the
Euro NCAP specifications and the
proposed acceptance intervals.
Therefore, it is feasible, but not
guaranteed, for a THOR–50M which
meets the Euro NCAP acceptance
intervals to also meet the proposed
acceptance intervals. NHTSA has
tentatively decided not to adopt
narrower acceptance intervals, such as
those specified in TB026, for the reasons
given above. Moreover, NHTSA is
unaware of the data on which the Euro
NCAP specifications are based, whereas
the proposed specifications are based on
NHTSA’s carefully-controlled study.
The differences between the proposed
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qualification tests and those specified in
TB026 are discussed in more detail in
the relevant sub-sections below. In
addition, the proposed qualification test
parameters and acceptance intervals and
the corresponding TB026 values are
summarized in Appendix G.
We propose to set out the
qualification procedures in a separate
document that would be incorporated
by reference into Part 572. See Section
XI, Incorporation by reference. This
would be a departure from the other
ATDs currently specified in Part 572, for
which the qualification tests are set out
in full in the regulatory text in each of
the relevant paragraphs (corresponding
to that ATD) in part 572. We are
proposing a separate qualification
procedures document for THOR–50M
because the THOR–50M qualification
procedures contain many photographs
and diagrams that are not amenable to
publication in the CFR; we believe this
extra level of detail will be helpful for
end users who are attempting to qualify
the ATD.
NHTSA seeks comment on the
proposed qualification tests. NHTSA
also seeks any qualification data
commenters are able to provide, as long
as the data are from THOR–50M ATDs
conforming to the 2023 drawing package
and were collected following the April
2023 Qualification Procedures Based on
any comments and data received,
NHTSA might consider changing the
qualification targets to reflect the larger
population of THOR–50M units in the
field. However, before doing so we
would assess the effect that any change
could have on the biofidelity of the
dummy and the applicability of injury
risk functions. We also seek comment
on whether we should incorporate the
qualification procedures by reference, or
whether it would be preferable to locate
a much-simplified set of qualification
procedures directly in Part 572 and put
additional detail and documentation in
the Office of Vehicle Safety Compliance
(OVSC) laboratory test manual or
similar document that would not be
incorporated by reference but instead
provided as guidance to DOT
contractors and other ATD end users.
A. Head Impact
The head qualification test is identical
to the whole-body head impact
biofidelity assessment, where a fullyassembled THOR–50M is seated on a
table and impacted on the forehead with
a 23.36 kg rigid impactor at 2.00 ± 0.05
m/s. This test serves as a surrogate for
the isolated head drop test used by other
ATDs; due to the construction of the
head and neck of the THOR–50M ATD
(specifically, the integration of the neck
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spring cables into the skull), separation
of the head from the neck is not feasible.
The test assesses the performance of the
head skin and CG accelerometers, which
are used to calculate HIC15.152 The
probe force and the head CG resultant
acceleration are measured and would
have to be within the proposed
acceptance intervals.
B. Face Impact
The face qualification test is identical
to the face rigid disk impact biofidelity
assessment, where a fully-assembled
THOR–50M is seated on a table and
impacted on the face with a 13 kg rigid
impactor with a 152.4 mm diameter flat
disk impact surface at 6.73 ± 0.05 m/s.
This test assesses the impact response of
the face, which is driven primarily by
the face foam insert (Part No. 472–1401).
Additionally, as this test is more severe
than the head impact test, it assesses the
head CG accelerometers (which are used
to calculate HIC15) at a level of severity
closer to that expected from vehicle
crash tests. FMVSS No. 208 specifies a
maximum calculated HIC15 value of 700
for the HIII–50M, and the average HIC15
measurement from a set of 29 vehicle
crash tests in either the full frontal rigid
barrier or OMDB crash test modes was
285.153 The head impact test, however,
results in an average HIC15 of 157
(probability of AIS 3+ injury of 0.05%),
while the face impact is more severe,
with an average HIC15 of around 450
(probability of AIS 3+ injury of 3.5%).
Therefore, compared to the head impact
test, the face impact test is a better
assessment of the head response at a
severity level expected from vehicle
crash tests, as it results in a HIC15 that
is closer to the current FMVSS No. 208
injury assessment reference value.
During these tests, the probe force and
the head center of gravity (CG) resultant
acceleration are measured and would
have to be within the proposed response
corridors.
C. Neck
The proposed neck qualification test
series, in which the entire head-neck
assembly is removed from the ATD and
affixed to the conventional Part 572
swinging pendulum to apply a
prescribed impulse to the neck, includes
six tests: flexion, extension, left lateral
flexion, right lateral flexion, left torsion,
and right torsion. The swinging
152 Craig, M., Parent, D., Lee, E., Rudd, R.,
Takhounts, E., Hasija, V. (2020). Injury Criteria for
the THOR 50th Male ATD. Regulations.gov Docket
ID NHTSA–2019–0106–0008, available at: https://
www.regulations.gov/document/NHTSA-2019-01060008.
153 The range was 104–1262 and the standard
deviation was 210.
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pendulum apparatus serves as a
surrogate for the more complex neck
biofidelity assessment, which is carried
out in a sled test configuration. The
neck qualification tests assess the
collective performance of the molded
neck column, the occipital condyle cam
and associated bump stops, and the
neck spring towers. In the process, the
neck qualification tests assess the
performance of the upper neck load cell,
from which the Z-axis force and Y-axis
moment are used to calculate Nij.154
The neck axial force, neck moment
about the relevant axis, and neck
rotation about the relevant axis are
measured and would have to be within
the proposed acceptance intervals. The
neck flexion and extension qualification
tests are similar to those specified for
the HIII–50M 155 in that they use the
same pendulum and similar
deceleration specifications.
D. Upper Thorax
This test involves impacting the chest
of a fully-assembled THOR–50M seated
on a table with a rigid impactor. The
upper thorax qualification test is
configured similarly to that carried out
on the HIII–50M,156 using the same
pendulum (23.36 kg, 152.40 mm
diameter) to impact the mid-sternum,
but at a lower impact velocity of 4.3
meters per second. This test assesses the
dynamic thoracic response to sternal
impact as well as the functionality of
the upper left and upper right thoracic
deflection instrumentation. This test
condition is identical to the associated
biofidelity assessment, though the
qualification test uses only internal
deflection measurements so that motion
tracking or other external
instrumentation is not required. Several
measurements must be within the
proposed acceptance intervals: the peak
overall probe force, the peak upper left
and upper right resultant deflections,
the difference between the peak left and
right resultant deflections, and the
probe force at the peak left and right
resultant deflections.
In the 2016 qualification procedures,
the upper thorax qualification required
individual X-axis and Z-axis deflection
specifications for both the upper left
and upper right thorax. This was revised
in the 2018 qualification procedures by
specifying the peak resultant deflection
instead, which better aligns with the
peak resultant deflection measure used
to evaluate thoracic injury risk.157
154 Craig et al (2020), Injury Criteria for the THOR
50th Male ATD.
155 49 CFR 572.33 Neck.
156 49 CFR 572.34 Thorax.
157 Craig et al (2020), Injury Criteria for the THOR
50th Male ATD.
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Applying specifications on the resultant
deflection instead of two individual
components allows for a reduction in
the overall number of required
measurements, while still capturing the
physical response of the dummy since
the X-axis and Z-axis deflections are the
primary components of the resultant
deflection in this test condition.
The Euro NCAP qualification
response requirements differ from the
proposal in three ways. First, they
include an additional parameter: the
ratio of Z-axis to X-axis deflection.
Second, they do not require a maximum
difference between left and right peak
resultant deflection, whereas the
proposed qualification targets limit the
left-to-right difference to 5 millimeters.
Using the Euro NCAP targets, the
difference between the left and right
peak resultant deflections could be as
high as 7.2 millimeters. Third, as noted
above, the qualification targets are
narrower than the proposed
qualification targets.
NHTSA has tentatively decided not to
specify the ratio of Z-axis to X-axis
deflection because doing so would
effectively revert to the 2016 approach
of individual X-axis and Z-axis
deflection requirements, which would
increase the difficulty in meeting the
qualification specification without a
direct link to injury prediction, as the
peak resultant deflection specification is
of primary importance because it is the
metric used in the calculation of
thoracic injury risk.
NHTSA is aware that the upper thorax
qualification specification has been a
topic of frequent discussion within the
International Standards Organization
(ISO) working groups (particularly ISO/
TC 22/SC 36, Safety and impact testing,
Working Groups 5, Anthropomorphic
Test Devices, and 6, Performance
criteria expressed in biomechanical
terms). NHTSA understands that those
discussions have focused on potential
modifications to the drawing package to
meet the upper thorax qualification
response requirements (in the context of
testing related to Euro NCAP). Those
modifications—specifically, the shorter
rib guide, the individual rib
performance test, and changes in the
area of the coracoid process—have been
discussed as describe in Section III,
Design, Construction, and
Instrumentation.158 NHTSA does not
158 In addition, some members of Working Group
5 have observed variations in the ATD responses in
the upper thorax qualification tests that have led to
difficulties in meeting the Euro NCAP qualification
specifications, and have suggested that this may
result from variation in the spine flex joint,
potentially due to material that was not as hard as
the specification called for.
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believe the modifications are necessary
to meet the proposed upper thorax
qualification requirements because
NHTSA’s repeatability and
reproducibility testing showed that
those requirements were achieved by
three different THOR–50M units at three
different test labs. See Section VI,
Repeatability and Reproducibility.
Moreover, it is not clear whether these
changes would preclude a THOR–50M
from meeting the proposed qualification
requirements, though since the Euro
NCAP specifications are narrower, any
variation caused by these changes may
be within the NHTSA’s proposed
acceptance intervals. Before
implementing any of these design
changes, the performance of the
prototype parts would need to be
evaluated.
In an effort to further investigate these
contemplated changes to THOR–50M,
NHTSA analyzed its upper thorax
qualification test data. NHTSA’s limited
analysis suggests that the difficulty
meeting the Euro NCAP upper thorax
qualification requirements might stem
not from the dummy design, but from
the smaller allowable range of peak
resultant deflection and the addition of
the deflection ratio corridor specified in
TB026. However, it would be necessary
to know how the Euro NCAP upper
thorax qualification requirements were
determined to carry out a complete
analysis. This preliminary analysis is
discussed in more detail in Appendix A.
instrumentation. As in the upper thorax
condition, the lower thorax qualification
mode uses internal deflection
measurements so that motion tracking
or other external instrumentation is not
required. During this test, the peak
overall probe force and the peak
resultant thoracic deflection at the time
of peak probe force are measured and
would have to be within the proposed
acceptance intervals.
E. Lower Thorax
The lower thorax qualification test is
unique to the THOR–50M. This test
involves impacting the lower thorax of
a fully-assembled THOR–50M seated on
a table with a rigid impactor. It is
similar to the upper thorax qualification
test, as it uses the same pendulum
(23.36 kg, 152.40 mm diameter) at the
same impact velocity (4.3 meters per
second). The test assesses the dynamic
impact response of the lower torso, to
which the rib cage and the upper and
lower abdomen assemblies contribute,
while at the same time assessing the
functionality of the lower left and upper
right thoracic deflection
instrumentation. The lower thorax
qualification test is a simplification of
the lower ribcage oblique impact
biofidelity condition. In the biofidelity
condition, the torso is rotated by 15
degrees and a chestband is used to
measure external deflection. In the
qualification condition, the torso is not
rotated, but instead offset relative to the
line of travel of the pendulum such that
the pendulum is centered on the lower
left or lower right anterior attachment
point of the thoracic deflection
G. Upper Leg
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F. Abdomen
This test (which is unique to the
THOR–50M) impacts the lower
abdomen of a fully-assembled THOR–
50M with a 177.8 mm by 50.8 mm rigid
rectangular face impactor, weighing
32.00 kg, at 3.30 m/s. It was originally
based on the lower abdomen rigid bar
biofidelity condition, though several
modifications were made over time to
increase its objectivity and improve its
utility as a qualification test. This test
assesses the dynamic response of the
lower abdomen, including the jacket,
lower abdomen foam inserts, and lower
abdomen bag, as well as the
functionality of the abdominal
deflection instrumentation. The peak
overall probe force, the peak left and
right X-axis abdomen deflection at the
time of peak probe force, and the
difference between the left and right Xaxis deflection at the time of peak probe
force are measured and would have to
be within the proposed acceptance
intervals.
The upper leg qualification test
assesses the dynamic impact
performance of the knee flesh, knee
flesh insert, and femur compression
element, while evaluating the
functionality of the femur and
acetabulum load cells. The full THOR–
50M is seated on a table with a posterior
restraint adjacent to the pelvis flesh and
impacted at the knee by a 12.00 kg
impactor with a 76.2 mm diameter rigid
disk impact surface at 3.3 ± 0.05 m/s
parallel to the femur. The peak probe
force, peak femur Z-axis force, and peak
resultant acetabulum force would have
to be within the proposed acceptance
intervals.
This differs from the test procedure in
the 2018 Qualification Procedures
Manual in the THOR–50M research
docket. The 2018 draft qualification test
procedures for impacting the knee
specifies the use of a 5.0 kg impactor at
2.6 m/s. NHTSA’s repeatability and
reproducibility testing of the
qualification procedures, however—
which used the 2018 draft procedures—
resulted in coefficients of variation
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(CVs) 159 above 10%, particularly for the
peak resultant acetabulum force.
NHTSA therefore conducted a detailed
review of the qualification test
procedure.160 This review led NHTSA
to conclude that the impact energy was
unrealistically low, leading to two
problems. First, the low test energy did
not load the acetabulum at a magnitude
similar to that produced in vehicle crash
tests or associated with a meaningful
injury risk. This is particularly
important because the upper leg test
mode is the only qualification test that
assesses the acetabulum load cells, and
peak resultant acetabulum force is used
in calculating the acetabulum injury
risk. Second, and relatedly, the
measurement values were so low, it was
difficult to distinguish the signal from
the noise.
Accordingly, NHTSA revised the test
parameters by increasing the impactor
mass and velocity and installing a
backer plate behind the pelvis to
prevent any rearward motion during the
test. These are the parameters that we
are proposing and for which data is
presented (and acceptance intervals
calculated) in the qualification
repeatability and reproducibility study.
As we explain in Section VI.A, the
revised test procedures resulted in
repeatability and reproducibility CVs of
5% or lower for all test measurements
including peak resultant acetabulum
force. Additionally, the average
acetabulum force recorded in the
improved upper leg qualification is
more representative of the forces
recorded in frontal rigid barrier and
OMDB vehicle crash tests, and
represents a non-negligible injury risk.
H. Knee and Lower Leg
NHTSA is also proposing
qualification tests for the knee and
lower leg (ankle, ball of foot, and heel).
The knee qualification test is a
simplification of the knee shear
biofidelity condition. The test assesses
the response of the anterior-posterior
translation of the tibia with respect to
the femur at the knee joint, the
translational resistance of the knee
slider and the stiffness of the stop
assembly, and the functionality of the
knee slider string potentiometer. To
conduct the knee impact test, the left or
right knee assembly (detached at the
base of the femur load cell) is removed
from the ATD and mounted to a rigid
surface, and a load distribution bracket
159 See
infra Section VI.A.
W. (2021). An Improvement to the
THOR–50M Upper Leg Qualification Test
Methodology. 2021 SAE Government-Industry
Digital Summit, available at: https://
www.nhtsa.gov/node/103666.
160 Millis,
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is attached to the knee slider assembly.
The load distribution bracket is
impacted with a 12.00 kg impactor with
a 76.2 mm diameter rigid disk impact
surface at 2.20 ± 0.05 m/s. Unlike the
HIII–50M knee slider test, no foam pad
is used on the impact surface for this
test. During these tests, the femur Z-axis
force and knee slider deflection at peak
femur force are measured and would
have to be within the proposed
acceptance intervals.
We propose four different
qualification tests to assess the lower leg
responses: ankle inversion, ankle
eversion, ball of foot impact, and heel
impact. All four test setups are similar.
In each, the lower legs are removed from
the dummy and each leg is tested
separately. The leg is affixed to a rigid
fixture and struck by a pendulum
parallel to the tibia. The alignment of
the pendulum differs for each test: for
the heel impact, it is in-line with the
tibia; for the ball of foot impact, it
produces dorsiflexion of the foot; for the
inversion impact; it is offset medially
from the tibia; for the eversion impact,
it is offset laterally from the tibia. For
the inversion and eversion impacts, the
shoe is removed and replaced with a
special striker plate that interfaces with
the pendulum.
Euro NCAP TB026 specifies different
qualification requirements for the knee
and lower leg because TB026 specifies
that the THOR–50M be fitted with the
HIII–50M knee and lower leg.
VI. Repeatability and Reproducibility
Any ATD that is to be used for
Federal regulatory testing must have an
acceptable level of repeatability and
reproducibility to ensure confidence in
the responses provided by the dummy.
In the context of dummy evaluation,
repeatability refers to the similarity of
responses from a single dummy when
repeatedly subjected to a particular test
condition. Reproducibility refers to the
similarity of the responses from
multiple dummies repeatedly subjected
to a particular test condition. NHTSA
also evaluated the repeatability and
reproducibility of the qualification tests
themselves, in addition to the dummy.
To evaluate whether the THOR–50M
ATD yields consistent results, NHTSA
undertook an extensive series of testing.
NHTSA systematically investigated
the repeatability and reproducibility
(R&R) of the THOR–50M by conducting
an extensive series of qualification and
sled tests. Qualification test
measurements are especially useful for
evaluating dummy R&R because they
are relatively simple tests on individual
dummy components that can be tightly
controlled so that variability in the test
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measurements is more likely to come
from the dummy than from other
potential sources of variability, such as
the test procedures or vehicle structures
and materials. Sled testing is useful
because it offers insight into the
dummy’s performance as a complete
system in an environment similar to that
of an actual vehicle—e.g., the
consistency of its kinematics, its impact
response as an assembly, and the
integrity of the dummy’s structure. Sled
tests are therefore more challenging for
the dummy, while at the same time
much more tightly controlled than a
vehicle test, which does not provide a
desirable environment for R&R testing
due to the uncontrollable variation in
vehicle structural materials and
manufacturing variability. Qualification
and sled tests together provide a basis
for assessing whether the dummy will
yield consistent results when it is
ultimately used in full-scale vehicle
tests. NHTSA’s R&R testing also served
several other important functions, such
as developing the qualification corridors
and further validating the usability and
durability of the dummy.
NHTSA’s R&R analysis of
qualification and sled testing is briefly
summarized in the next two sections.
For more detailed information, the
reader is referred to the docketed report
‘‘THOR–50M Repeatability and
Reproducibility of Qualification Tests’’
(R&R Report).161
A note about dummy reproducibility:
At the time NHTSA conducted this R&R
testing (both qualification tests and sled
tests) it only owned—and tested—
THOR–50M units manufactured by
Humanetics. Therefore, the
reproducibility analyses reported here
concerned dummy reproducibility
(same lab, different dummies) and test
reproducibility (same dummy, different
labs).162 However, another aspect of
reproducibility is whether dummies
fabricated by different manufacturers
perform in a uniform manner. To this
end, NHTSA has purchased THOR–50M
units from JASTI, Cellbond, and Kistler,
161 National Highway Traffic Safety
Administration (2022). THOR–50M Repeatability
and Reproducibility of Qualification Tests, May
2021, available at https://downloads.
regulations.gov/NHTSA-2019-0106-0009/
attachment_2.pdf. We note that for the sled test
R&R analysis, there are no previously-published
reports that provide this analysis. However, this
analysis is provided in the paragraphs below on
sled testing (and in the relevant appendices) and
the underlying data is available in the NHTSA crash
test database in either the biomechanics or vehicle
paragraphs (the specific location is provided in the
relevant discussion below).
162 NHTSA did not examine lab-to-lab
reproducibility of the sled tests.
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and may test with these units prior to
the final rule.
A. Qualification Tests
NHTSA has completed an R&R study
of the qualification tests. This study has
three main purposes. One is to assess
the repeatability and reproducibility of
the dummy. Another is to determine the
acceptance intervals for the
qualification tests. Third, is to assess the
R&R of the qualification tests
themselves. Assessing the R&R of the
qualification tests is important for at
least two reasons: it aids in determining
whether the variation in measurements
are attributable to the dummy, the test
procedures, or the testing practices of
different laboratories, and it helps
ensure that the qualification test
procedures themselves are as consistent
and replicable as possible so that,
ultimately, the test measurements
obtained in a compliance test are
uniform across dummies and test
laboratories. In addition to these main
purposes, the qualification R&R testing
also helped NHTSA to identify and
resolve potential issues with the
qualification procedures; reveal and
resolve potential issues with, and
functional limitations of, the dummy.
Below, we first summarize our
methodology for the qualification R&R
analysis, and then proceed to briefly
summarize the results of the R&R
assessment for each THOR–50M body
region.
Methodology
In the qualification test series, the
data points of each trial are considered
on their own and not as being
representative of a large population.
Thus, the sample-based standard
deviation is applied in which s is an
estimate of the standard deviation based
on a sample.165 It is computed using the
following formula, where x¯ is the
average value of the trials (sample
mean) and n is the number of trials
(sample size).
163 40
FR 33466 (Aug. 8, 1975).
e.g., 85 FR 69898, 69904–69905 (Nov. 3,
2020) (final rule for Q3s ATD).
165 The population-based standard deviation,
which is always lower than the sample-based
standard deviation, is not appropriate because only
a limited number of NHTSA-owned THOR–50M
units were tested, and the tests were carried out at
a limited number of test facilities.
BILLING CODE 4910–59–P
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164 See,
For each qualification test parameter
(e.g., head impact peak probe force)
specified for each test condition (e.g.,
head impact), we computed the mean,
standard deviation, and coefficient of
variation. More specifically, to
investigate dummy repeatability and
test repeatability, we calculated these
summary statistics for the five tests of
each test condition performed on each
of the three dummies at VRTC. To
investigate dummy reproducibility, we
pooled the data for the three dummies
tested at VRTC. Finally, to investigate
test reproducibility, we pooled the data
for the dummy that was tested at VRTC,
Calspan, and Humanetics.
We used the following approach to
assess R&R:
• CV <5%: No further investigation.
We believe that a set of responses with
a CV below 5% indicates a highly
repeatable and reproducible condition.
• 5% ≥ CV ≤ 10%: sources of
variability investigated.
• CV >10%: Test procedure
thoroughly reviewed and dummy(ies)
inspected.
When the CV was greater than or
equal to 5%, we investigated the source
of the variability. In all cases, we were
able to determine the source of the
variation with reasonable confidence.
Once NHTSA had refined the
qualification test procedures it only
obtained a CV greater than 10% in two
instances—repeatability of the face
foam, and test reproducibility in one
measurement in the neck extension
mode. Prior to refining the test
procedures, NHTSA obtained a CV
greater than 10% for the upper leg test.
A full investigation led to a new and
improved test procedure. That new test
procedure is reflected in the R&R report,
and the resulting CVs all less than 10%.
Table 9 and Table 10 summarize the
CVs that we calculated for each test
parameter for each qualification test
condition. Table 11 summarizes the
variability sources and resolutions seen
in the qualification R&R test series.
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The proposed qualification tests were
carried out on three THOR–50M ATDs
manufactured by Humanetics. The
ATDs conformed to the proposed
drawing package. Every ATD was
subjected to five repeat tests in each
qualification test condition at NHTSA’s
Vehicle Research and Test Center
(VRTC) and one of the three dummies
was tested at two other labs,
Humanetics and Calspan (with some
exceptions as described in the following
paragraphs). All tests were used in
development of the proposed
qualification acceptance intervals, with
some exceptions as explained below
where the input velocity did not meet
the specification. For qualification test
conditions where one ATD component
is tested in both the left and the right
direction, only the left direction is
included in the analysis, as the dummy
design is symmetric and not expected to
differ between the two sides. For
qualification test conditions in which
multiple ATD components are tested,
data from the left and right tests or
measurements are combined.
We evaluated R&R of both the dummy
and the qualification tests using a
statistical analysis of variance referred
to as the coefficient of variation (CV).
The CV approach was first introduced
by NHTSA as a means for evaluating
dummy repeatability when the original
subpart B Hybrid II 50th percentile male
ATD was proposed.163 Since then, the
agency has used this approach for other
Part 572 rulemakings.164 The CV is a
measure of variability expressed as a
percentage of the mean. It is defined as
the percentage of the sample standard
deviation divided by the mean of the
data set:
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TABLE 11—SUMMARY OF QUALIFICATION TEST VARIABILITY SOURCES AND RESOLUTIONS
Test mode
Source of varibility; control solution
Head .....................................
Face .....................................
Neck Extension ....................
None.
Face foam degradation occurs cumulatively with successive impacts; monitor and swap out foam as needed.
The inverse relationship between My and Fz may be balanced by adjusting the input pulse through the selection
of the pendulum’s honeycomb cell configuraton.
For a new molded neck, My and Fz may be elevated in initial test only. Also, the pendulum’s honeycomb cell
configuration may need attention to control input pulse.
None.
None.
None.
The asymmetric test setup requires a high level of diligence from operator in aligning the dummy with the probe.
Operator diligence is needed to ensure a symmetric test setup. Otherwise, right vs. left discrepancies in force and
deflection measurements will occur.
If a high femur Fz occurs, a test lab may need to experiment with set-ups and dummy positioning (within allowable tolerances).
Low femur Fz measurements may be resolved at the test labs by experimenting with setups and dummy positioning.
Ankle inversion and eversion tests are run on the same apparatus and are nearly identical. The ankle moment,
tibia Fz, and ankle rotation may be slightly low in an initial qualification test if there has been an extended period of non-use of the Ensolite pad on the test fixture. This is only a concern if the tibia force and moment are
just below the upper qualification limits, since subsequent tests may be expected to produce slightly higher moments and forces (which might be out of the qualification range). Labs can simply perform an additional test to
confirm that the response of the ankle is within the requirements.
Test labs may need to adjust their set-ups and fixtures (within allowable tolerances) to attain a reponse within
10% of the target for ankle moment.
In cases where passing qualification results cannot be achieved, a test lab may need to replace the molded shoe
assembly (472–7800–1 (left) or –2(right)) and/or the upper tibia complaint bushing assembly (472–7315) in
order to attain a peak lower tibia Fz within 10% of the target.
Neck Lateral .........................
Neck Torsion ........................
Upper Thorax .......................
Lower Thorax .......................
Abdomen ..............................
Upper Leg ............................
Knee .....................................
Ankle Inversion .....................
Ankle Eversion .....................
Ball of Foot ...........................
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Heel ......................................
Our investigation of the sources of
variability also gives us additional
confidence that the proposed
acceptance intervals (± 10% of the mean
response reported in the R&R study) are
both achievable and sufficient to ensure
that the dummy is providing uniform
responses. In NHTSA’s testing, when
the CV was below 5%, the responses in
all the tests were always within the
proposed acceptance intervals. When
the CV exceeded 5%, however, we
observed a response outside the
proposed acceptance interval in at least
one test. When the CV exceeded 10%,
several tests were outside the
qualification corridor.
NHTSA seeks comment on this
methodology. Although the
qualification R&R study utilizes only
NHTSA’s test data, NHTSA is open to
considering qualification data provided
by commenters in the finalization of the
qualification specifications, provided
that the data are from THOR–50M ATDs
conforming to the 2023 drawing package
and collected following the proposed
Qualification Procedures.
Head Impact
In the head impact qualification test
mode, all CVs for repeatability and
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reproducibility were below 5%, and the
responses in all the tests were within
the proposed qualification acceptance
intervals.
Face Impact
We used a slightly different approach
to evaluating the R&R of the face than
we did for the other qualification tests.
Our approach was motivated by two
characteristics of the THOR–50M face.
First was the response of the face
foam. The impact response of the face
is driven primarily by the face foam
insert, which is constructed of a
memory foam that necessitates an
extensive recovery period after a
dynamic impact; the THOR–50M
Qualification Procedures specifies at
least 24 hours of recovery between tests.
Even with this extended recovery
period, however, the foam progressively
degrades after each impact so that the
peak probe force and peak head
resultant acceleration increases with
each test. We were able to conduct eight
to nine tests with a new face foam insert
before the face fell outside the upper
bound of the face rigid disc impact
biofidelity corridor (4,400 N to 8,200 N).
Second, because the face foam
degrades, any variations in the dummy
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response are likely to be masked by the
significant variations caused by the
foam. That is, most of the observed
variation in the face qualification test is
essentially due to the face foam
response; any contributions of other
components or lab-to-lab differences
were negligible.166
In light of these characteristics, we
modified the R&R test methodology for
the face impact tests. Our testing
consisted of evaluating one dummy
(DO9799) at VRTC, using three different
new, unused, face foams (as opposed to
testing three different ATDs); we
deemed it unnecessary to test multiple
ATDs because the variation in response
was predominantly due to the face
foam, not the ATD. We also did not test
lab-to-lab variability (test
reproducibility), because this would
require testing the same face foam
successively at multiple laboratories,
which the degradation of the face foam
prevented us from doing. We allowed 24
hours between tests as specified in the
Qualifications Procedures. We tested
each dummy until the peak probe force
166 This is seen in the head impact test series, in
which the headskins were found to be repeatable
and reproducible, with repeated impacts to the
head yielding nearly identical responses.
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Neck Flexion ........................
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fell out of the biofidelity corridor (until
the peak probe force exceeded 8,200 N).
Only those tests which fell within the
peak probe force biofidelity corridor
were then included in the repeatability
analysis and used to set the
qualification targets. This gave us eightto-nine tests for each of the three face
foams we tested.
For two of the face foam inserts
tested, repeatability CVs were below
10%. The third face foam insert resulted
in CVs for peak probe force and peak
head CG resultant acceleration of 10.1%
and 12.1%. Though not reported in the
R&R paper, CVs for the HIC15 values
associated with the head resultant
accelerations recorded in the face
impact test are within 1% of the CVs for
peak resultant head CG acceleration.
However, in practice, we would likely
not observe this level of variability
because in several of the tests used to
calculate CV, the peak probe force was
outside of the qualification targets
(either too high or too low) and so the
dummy would have been further
adjusted before being used in a
compliance (or research) test. We
observed that when the response of a
new face foam insert is too low, it likely
indicates the need for an additional
‘‘break in’’ test, in which case the face
impact test would be repeated. If the
response is too high, it likely indicates
that the face foam needs to be replaced,
in which case a new face foam insert
will be installed and the face impact test
repeated. Therefore, we believe that the
face impact test is sufficiently
repeatable. Moreover, although we did
not test at multiple labs to evaluate
reproducibility due to face foam
degradation, we also believe that the
face impact test is reproducible. The
head impact test uses essentially the
same test apparatus and a similar
impact condition as the face impact test.
Because the test reproducibility was
very good in the head impact test, we
expect that there will be acceptable
levels of lab-to-lab variability for the
face impact test as well.
Neck
For the neck qualification tests, the
entire head-neck assembly is removed
from the THOR–50M, so the serial
numbers listed in Table 9 are those of
the individual head-neck assemblies
and not the ATD itself.
With respect to repeatability, across
all four neck test modes (flexion,
extension, lateral flexion, and torsion),
CVs for repeatability were below 10%
for all qualification test parameters and
for all necks, and were below 5% except
in the neck flexion test mode for two of
the necks: peak upper neck Y-axis
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moment (5.8%) and peak upper neck Zaxis force (6.0%) for neck EB6007, and
peak upper neck Y-axis moment for
neck EB6006 (5.1%). For both of these
necks, the first test resulted in a peak
upper neck Y-axis moment higher than
the resulting qualification targets; thus
this first test would have been re-run in
practice. If this first test were discarded,
the resulting repeatability CVs would be
at or below 5% for all necks. Labs may
find that while the first neck flexion test
performed on a new neck produces a Yaxis moment greater than the
qualification targets, subsequent tests
result in lower values within the
acceptance interval. Also, labs may need
to adjust the input pulse by
experimenting with honeycomb cell
configurations to achieve the target
response.
Reproducibility CVs were below 5%,
except in four instances, two for the
neck flexion test mode, and two for the
neck extension test mode.
In the neck flexion test mode, the
dummy reproducibility CV for peak
upper neck Y-axis moment was 5.4%.
This likely results from the same breakin issue described above. Also in the
neck flexion test mode, the test
reproducibility CV for peak upper neck
Z-axis force was 7.5%. In this case,
there were two tests each at Calspan and
Humanetics that would not have met
the resulting qualification
specifications,167 though discarding
these tests would still result in a
reproducibility CV of 6.4% for peak
upper neck Z-axis force. However, we
believe that this variance is not likely to
lead to inconsistent compliance test
outcomes because the average peak
upper neck Z-axis force (860 N)
represents a very low probability of
injury (0.7% risk of AIS 3+ injury).
Although NHTSA has not yet
established injury assessment reference
values (IARVs) for the THOR, when it
does (NHTSA anticipates rulemaking in
the near future to add the THOR–50M
to FMVSS No. 208 as an optional test
device) an IARV for neck flexion would
almost certainly be specified to
correspond to a risk of AIS 3+ injury
much higher than 0.7%, i.e.,
corresponding to a much higher Z-axis
force than 860 N.168
In the neck extension test mode, two
test reproducibility CVs were above 5%:
peak upper neck Y-axis moment (5.6%)
and peak upper neck Z-axis force
(12.2%). These elevated CVs result from
the tests on neck EB6007 at Calspan, for
167 R&R
Report, Table 6–14.
neck Fz is currently specified in FMVSS
NO. 208 as an injury criterion for the HIII–50M and
is also a component of THOR-specific Nij criterion.
168 Upper
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which the first four tests resulted in
peak upper neck Z-axis forces lower in
magnitude than the resulting
qualification targets, while the last test
resulted in a peak upper neck Y-axis
moment higher in magnitude than the
resulting qualification targets, and at
Humanetics, for which four of the five
tests resulted in peak upper neck Z-axis
forces higher in magnitude than the
qualification targets, though by not more
than 32 N.169 However, since all of the
remaining tests on neck EB6007 at
VRTC (15 tests) would have met the
qualification targets, and the associated
test reproducibility CVs would be below
3% for all test parameters except for the
Calspan observations, this finding likely
results from either an issue with test
execution at Calspan, or an issue
specific to neck EB6007, such as damage
or unintended adjustment of the neck
spring cables after it was tested at both
VRTC and Humanetics.
While the input parameters for the
tests conducted on EB6007 were all
within the qualification specifications,
the pendulum velocity at 20 and 30
milliseconds after T-zero was notably
higher at Calspan compared to VRTC
and Humanetics, which may explain the
differences in results. As such, it may be
worth considering narrower
specifications on the pendulum velocity
input parameters. On the other hand, if
the differing results at Calspan resulted
from issues with the neck itself, then the
fact that the qualification specifications
were not met indicates that the
qualification tests successfully
identified a damaged or improperly
configured neck.
Upper Thorax
In the upper thorax qualification test
mode, all CVs for repeatability and
reproducibility were below 5%, which
indicates that the qualification
specifications were achievable by three
different THOR–50M ATDs and at three
different test labs. Further, as all CVs
were below 3.7%, this indicates that all
tests were within the ±10% target.
Lower Thorax
In the lower thorax qualification test
mode, all but one of the CVs for
repeatability were below 5%. One
repeatability assessment, peak resultant
deflection at peak probe force for ATD
DO9798, had a CV of 5.2%. For this
ATD, peak resultant deflections on the
right side were closer to the upper end
of the corridor, while those on the left
side were closer to the lower end of the
corridor. CVs for dummy
reproducibility were below 5%. Test
169 R&R
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reproducibility CVs were slightly above
5%. Here, one of the tests at Humanetics
would not have met the resulting peak
probe force qualification specifications,
while four of the tests at Calspan would
not have met the resultant deflection at
peak force specification.170 If the tests
that would not fall within the
qualification specifications were
excluded, as would be done in practice,
reproducibility CVs would be below
5%. Overall, the lower thorax
qualification specifications were
achievable by three different THOR–
50M ATDs and at three different test
labs.
Abdomen
When the abdomen qualification
repeatability and reproducibility testing
was conducted, all three THOR–50M
ATDs were not available.
As an alternative, three different
abdomen assemblies were tested on the
same ATD. We believe this modification
is acceptable because the abdomen foam
inserts and the structure of the abdomen
bag are responsible for a majority of the
variation in the lower abdomen
qualification test, whereas the
remainder of the THOR–50M is
essentially a ballast.
All of the CVs for repeatability and
reproducibility of peak probe force were
below 5%. All of the CVs for
repeatability and reproducibility of the
peak left and right X-axis deflection at
the time of peak force were between 5%
and 6%. Of these tests, three at Calspan
resulted in right abdomen X-axis
deflections lower in magnitude than the
qualification specifications. While not
included in the CV calculation, the
difference between left and right X-axis
deflection measurement highlighted the
fact that all tests at VRTC had a positive
difference of at least 6.8 millimeters,
indicating that the magnitude of right Xaxis deflection was greater than the
magnitude of left X-axis deflection in all
tests. The opposite was true at Calspan,
where three of the tests showed notably
higher magnitude deflections on the left
side. In total, six of the abdomen
qualification tests (five at VRTC and one
at Calspan) were beyond the 8
millimeter difference specified by the
qualification specifications. Further
examination of the test setup at VRTC
showed that the ATD was consistently
rotated slightly about the Z-axis,
resulting in the right side of the
abdomen being closer to the probe than
the left side, and subsequently recording
more deflection. The test configuration
at VRTC has since been corrected. This
issue is not expected to introduce
170 R&R
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variability in test results in the future
because such tests outside the
qualification targets would necessitate
dummy adjustment and re-running the
test. If only tests that were within the
maximum difference in left-to-right
deflection specification were included,
both the dummy and test
reproducibility CVs would be 5.0% or
below.
Upper Leg
As we explained earlier (Section VI,
Qualification Tests), the proposed upper
leg qualification test procedure reflects
revisions to the 2018 Qualification Test
Procedures that we made in light of our
R&R testing. The CVs for repeatability
and reproducibility for the revised test
procedure for all three measurements
were at or below 5%, demonstrating that
the upper leg qualification
specifications can be met by three
different THOR–50M ATDs at three
different test labs.
Knee
For the knee qualification test, all CVs
for repeatability were below 5%. For
dummy reproducibility, CVs were 5.0%
and below for both measures. For test
reproducibility, the CV for knee
deflection at peak femur Z-axis force
was below 5%, while the CV for peak
femur Z-axis force was 5.9%. This
elevated CV appears to result from the
tests at Calspan, which were all
generally lower in magnitude than at
VRTC and Humanetics, and three of the
tests resulted in peak femur Z-axis force
lower than the qualification
specification. As the three tests that
were outside of the qualification
specifications were the first or second
tests in the series, it is possible that the
lower forces resulted from misalignment
of the load distribution plate or other
slack in the system that was corrected
in the remaining tests. In light of this,
we believe that the knee qualification
repeatability and reproducibility test
series demonstrated that the
qualification specifications could be
achieved by six different THOR–50M
knees at three different test labs.
Lower Leg
As used by VRTC, the lower legs are
considered modular, and are typically
assigned to a THOR–50M on
deployment and not necessarily tied to
a specific THOR–50Ms serial number.
As such, the repeatability and
reproducibility qualification study was
carried out by testing three different
lower legs at VRTC, followed by testing
two of those legs at both Humanetics
and Calspan. This resulted in a total of
15 tests for the dummy reproducibility
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61931
assessment, and 30 tests for the
reproducibility assessment (although
several of the tests at Calspan were not
included because they did not meet the
test velocity input specifications).
For all the lower leg test modes,
repeatability CVs were all below 5%,
indicating that the qualification
specifications are achievable by three
different THOR–50M ATDs. There were,
however, a few test mode/parameters for
which reproducibility CVs were above
5%.
In the ankle inversion test mode, test
reproducibility for the peak lower tibia
Z-axis force measurement was 5.3%.
The source of this elevated CV appears
to be the first test of leg DL5405 at
VRTC, where the peak lower tibia Z-axis
force was ¥451 N, which was just
outside the acceptance interval (¥454
to ¥555 N). In practice, this test would
have been re-run, and all the remaining
tests on this leg would have met the
qualification targets. Removing this test
from the CV calculation would result in
a test reproducibility CV of 4.9%.
In the ankle eversion test mode,
dummy reproducibility was above 5%
for the peak lower tibia Z-axis force
(5.7%), and test reproducibility was
above 5% for lower tibia Z-axis force
(6.0%) and peak ankle resistive moment
(5.1%). These elevated CVs appear to
result from the first tests on DL0202 at
VRTC, where the peak lower tibia Z-axis
force (¥512 N) was just outside the
acceptance interval (¥514 N to ¥629
N), and at Calspan, where the peak
lower tibia Z-axis force (¥454 N) and
the peak angle resistive moment (35.6
Nm) were both below the lower end of
the associated qualification
specifications (¥514 N and 38.7 Nm,
respectively). In practice, these tests
would have been re-run, and all the
remaining tests on this leg at both labs
would have met the qualification
specification. Removing these two tests
from the CV calculation would result in
reproducibility CVs all below 5%,
which demonstrates that the ankle
eversion qualification specifications can
be met by six different legs at three
different test labs.
In the ball-of-foot test mode, which
assesses both the impact response of the
ball-of-foot portion of the molded shoe
and the dorsiflexion response of the
ankle, the only CV above 5% was the
test reproducibility of the peak ankle
resistive moment (6.9%). In the tests at
Calspan, only two of the five tests on the
left leg (DL0202) met the qualification
specification for input velocity. The
three tests that did not meet the
qualification specification were
considered invalid tests and therefore
were not included in the test
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reproducibility assessment, so only
seven tests from Calspan were included
as opposed to 10 tests from each of the
other labs. Of the tests run by Calspan
on the right leg (DL5404), four of the
five resulted in peak ankle resistive
moments of 61.3 to 61.8 Nm, just above
the upper end of the qualification
specification (60.8 Nm). As the tests at
Calspan were consistently higher in
peak ankle resistive moment than those
at VRTC and Humanetics, it is possible
that this finding results from either an
issue with test execution at Calspan, or
an issue specific to leg DL5404, such as
damage or unintended adjustment of the
Achilles spring cables after it was tested
at both VRTC and Humanetics.
Reviewing the time-history data for
ankle resistive moment from exemplar
tests from Calspan, VRTC, and
Humanetics (Figure 1), there are some
differences early in the event (note the
large positive moment before 10
milliseconds in the Calspan test) that
suggest differences in test setup and/or
impactor hardware.
In the heel impact test, which assesses
both the impact response of the heel
portion of the molded shoe and the tibia
compliant element, the repeatability
CVs were all under 5%, but both the
dummy (6.4%) and test (5.9%)
reproducibility CVs were over 5%. If the
test CVs are calculated independently
for the left and right legs, the resulting
CVs are much lower (2.1% and 3.0%,
respectively). This suggests that the test
itself is repeatable (as all repeatability
CVs were 1.6% or below) and
reproducible, but that there is some
ATD-to-ATD (in this case, leg-to-leg)
variation. Nonetheless, the qualification
specifications for the heel impact test
can be met using three different legs in
at least two different test labs.
gives us further confidence that the
qualification tests are reproducible.
Therefore, NHTSA tentatively
concludes that there is a sufficiently
high degree of uniformity in the
construction of the dummy components
being tested and in the procedures
followed by the labs for that test
requirement for the THOR–50M to be
incorporated into Part 572.
test series conducted to assess THOR–
50M’s performance in low-speed
unbelted crashes.
In summary, while there were several
cases where the variation from test to
test of the same THOR–50M ATD was
greater than 10%, these cases can be
explained by either differences in
physical interactions (e.g., contact of the
head with the arm in the rear seat sled
test), which can be addressed by careful
pre-test positioning of the ATD, or by
the low magnitude of the measurements,
as demonstrated through the use of
normalized CV to identify cases where
the variation occurs at a much lower
level than would be associated with a
risk of injury.
This is discussed in more detail in the
sections that follow. We begin by
explaining our methodology, and then
proceed to discuss the three different
test series.
ddrumheller on DSK120RN23PROD with PROPOSALS4
Additional Qualification Test Lab
We performed a variety of vehicle
tests (discussed in Section VIII, Overall
Usability and Performance) where
multiple dummies were qualified at two
different labs, including a lab (Applus+
IDIADA KARCO Engineering LLC) that
was not one of the laboratories used to
develop the qualification specifications,
and it was possible to qualify the
dummies. This qualitative information
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B. Sled Tests
THOR–50M repeatability was also
assessed through sled tests representing
several different vehicle crash
environments, including unbelted,
standard, and load-limited three-point
belt configurations at different speeds
for both the driver and right front
passenger seating positions, as well as
several restraint configurations in the
rear seat. NHTSA’s sled test
repeatability analysis is based on data
from three different sled test series that
NHTSA ran in the course of developing
THOR–50M. One is a sled test series
conducted to develop thoracic injury
criteria for the THOR–50M. Another is
a sled test series conducted to assess the
performance of THOR–50M in lowspeed belted crashes. The third is a sled
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1. Methodology
As with the qualification R&R
analysis, we assessed repeatability using
the coefficient of variation. The CVs
were calculated for each of the injury
criteria described in the THOR–50M
injury criteria report, as well as for peak
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values from a few other key data
channels: 171 lap belt, upper shoulder
belt, and lower shoulder belt.
The CV analysis was the same as in
the qualification test R&R study, with
two modifications. As with the
qualification test R&R study, CVs below
5% were considered to require no
further investigation; for CVs between
5% and 10% we reviewed the results for
outliers; and for CVs greater than 10%
we thoroughly investigated the sources
of variability in the test procedure and
the ATD. However, our assessment
differed in two ways from the CV
assessment in the qualification R&R
study.
First, we used the population
standard deviation instead of the sample
standard deviation to calculate the CV
because these test series are the only
sled test series that have been run.172
Accordingly,
Second, in addition to the CVs we
also considered the normalized CVs. A
potential limitation of the CV
calculation is that when the magnitude
of a given measurement is relatively
low, as is the case with off-axis sensor
channels, the standard deviation can be
high relative to the mean, leading to CVs
over 10%. However, this result is not
necessarily meaningful: although the
amount of variation might be high
relative to the mean, it might not be
high with respect to say, a critical value
of the measurement being evaluated
(e.g., in the context of a compliance test
involving an ATD, it might not be high
with respect to the IARV). This was
generally not an issue in the
qualification test R&R analysis because
the qualification modes, test parameters,
and targets were all selected because
they are meaningful to the test mode
and/or are in the primary load path, so
that the resulting measurements were
generally of sufficient magnitude for a
reliable CV calculation. In sled and
vehicle crash tests, on the other hand,
it is not known in advance which sensor
channels will be of sufficient magnitude
for a reliable CV assessment. For this
reason, researchers often disregard high
CV values when the magnitude of the
measurement is relatively low.
61933
However, determining the level of the
measurement below which CV is not
reliable is inherently subjective.
Accordingly, for CVs above 10% we
also considered normalized CVs. To
calculate normalized CV, the mean (m)
in the CV calculation (Eqn. 1) is
replaced with a meaningful, predetermined reference value. Such a
reference value could be an IARV or a
measurement value that corresponds to
an injury risk similar to the risk that
would correspond to an IARV. Because
IARVs for the THOR–50M have not yet
been finalized, in most cases we
calculated the normalized CV using the
value associated with a 50% risk of AIS
3+ (above the pelvis) or AIS 2+ (below
the pelvis) injury as the reference
value.173 However, there is not a known
risk function that relates belt forces to
risk of injury, so for this metric we
normalized using the average shoulder
belt force from the thoracic injury
criteria development data set, for which
just over 50% of the subjects sustained
AIS 3+ thoracic injuries (a denominator
of 5,000 N).174 The normalization
denominators used for each of the
measurements are shown in Table 12.
Metric
Normalization factor
HIC15 ......................................................................................
BrIC .........................................................................................
Neck Tension ..........................................................................
Neck Compression ..................................................................
Nij ............................................................................................
Chest Peak Res. Defl. ............................................................
Left Femur Axial Force ...........................................................
Right Femur Axial Force .........................................................
Peak Femur Axial Force .........................................................
Lap Belt Force .........................................................................
Upper Shoulder Belt Force .....................................................
Lower Shoulder Belt Force .....................................................
1724 .......................
0.96.
4,662 N ..................
¥5,017 N.
1.11 ........................
51.4 mm.
10,577 N ................
10,577 N.
10,577 N.
5,000 N ..................
5,000 N.
5,000 N.
Normalization rationale
50% risk of AIS 3+ injury.
50% risk of AIS 3+ injury when used in Nij risk function.
50% risk of AIS 3+ injury.
50% risk of AIS 2+ injury.
Average from thoracic injury criteria development data set.
As an example, consider a repeated
test with peak femur forces of 500 N,
1,000 N, and 1,500 N. For these tests,
the calculated CV would be 41%
(standard deviation of 408 N divided by
average of 1000 N), which would
require a thorough investigation of the
test procedure and ATD. However, these
femur forces are all well below 10,577
N, the force at which 50% risk of AIS
2+ injury occurs. Thus, calculating a
normalized CV may provide a more
meaningful assessment. In this case, the
normalized CV would be 4% (standard
deviation of 408 N divided by 50% risk
of AIS 2+ injury of 10,577 N), which
would require no further investigation.
171 The low-speed sled tests have fewer metrics
than the thoracic injury criteria set (11 vs. 12)
because lower shoulder belt loads were not
recorded in the low-speed sled tests.
172 This differs from the qualification tests, for
which it is known that the data set is a sample of
a larger population (because NHTSA and other test
labs have run the qualification tests on other
THOR–50M ATDs).
173 Fifty percent risk of a given injury severity is
a widely-used tolerance level in ATD research.
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test series conducted to develop
thoracic injury criteria for the THOR–
50M. This involved conducting
matched-pair tests of PMHS and a
THOR–50M ATD in a variety of sled
2. Thoracic Injury Criteria Development
Sled Tests
One source of data NHTSA looked at
to further assess repeatability is a sled
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IARVs specified in the FMVSS may or may not
correspond to a 50% risk.
174 We used the shoulder belt force to normalize
the lap belt force because there was not meaningful
lap belt force data in some of the thoracic injury
criteria development test conditions.
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TABLE 12—NORMALIZATION DENOMINATORS FOR CALCULATION OF NORMALIZED CV
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test conditions.175 This series tested the
same THOR–50M unit in three to four
repeat tests in each of six different test
conditions: Gold Standard 1, 2, and 3;
Rear Standard; Rear Load-limited (Rear
LL); and Rear Inflatable (Table 13).176
TABLE 13—THOR–50M THORACIC INJURY CRITERIA DEVELOPMENT TEST MATRIX
TSTNO
11117
11118
11119
11120
11121
11122
11514
11515
11516
11517
11143
11144
11145
11140
11141
11142
11137
11138
11139
TSTREF
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
.........................
Nominal test
speed
(km/h)
S0156
S0157
S0158
S0159
S0160
S0161
UVAS0309
UVAS0310
UVAS0311
UVAS0312
S0199
S0200
S0201
S0196
S0197
S0198
S0193
S0194
S0195
Test condition name, description
40
Gold Standard 1: flat rigid seat, standard lap and shoulder belts, knees restrained,
right front passenger restraint geometry.
30
Gold Standard 2: flat rigid seat, force-limited shoulder belt and standard lap belt,
knees restrained, right front passenger restraint geometry..
30
Gold Standard 3: flat rigid seat angled 30 degrees counterclockwise, force-limited
shoulder belt and standard lap belt, knees restrained, right front passenger restraint
geometry.
48
Rear Standard: rear passenger in 2004 Ford Taurus buck; 3-point standard belt.
48
Rear LL: rear passenger in 2004 Ford Taurus buck; 3-point load-limited belt with
pretensioner.
48
Rear Inflatable: rear passenger in 2004 Ford Taurus buck; 3-point inflatable force-limited belt with pretensioner.
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Notes: All tests were on THOR–50M S/N 9207. These tests are available in the NHTSA biomechanics database.
We calculated CVs and normalized
CVs for each of the injury criteria
described in the THOR–50M injury
criteria report, as well as a few other key
data channels, for a total of 12 metrics
for each of the six test conditions. See
Table 14 (CVs) and Table 12
(normalization denominators). Sixty-
175 Craig, M., Parent, D., Lee, E., Rudd, R.,
Takhounts, E., Hasija, V. (2020). Injury Criteria for
the THOR 50th Male ATD. Docket ID NHTSA–
2019–0106–0008, available at: https://
www.regulations.gov/document/NHTSA-2019-01060008.
176 Our testing included a seventh test condition:
Far-Side Oblique (representing the right front
passenger in an oblique moving deformable barrier
crash test). The THOR–50M setup and positioning,
however, differed in each of these tests. These tests
were not valid for the purposes of the repeatability
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five of the seventy-two CVs calculated
were below 10%, while seven CVs were
10% or above.
BILLING CODE 4910–59–P
analysis, because the differences in setup and
positioning is expected to—and in fact did—lead to
a wider variation in results. Specifically, the CVs
for 8 of the 15 measurements exceeded 10%, with
most of these over 20%, and some as high as 72%.
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We believe that this data supports our
tentative conclusion that the THOR–
50M is sufficiently objective for
inclusion in Part 572. Almost all the
CVs were below 10%, and many were
at or below 5%. For the seven CVs at or
above 10%, we believe that these do not
indicate that the dummy does not yield
repeatable results. These seven
measurements with CVs above 10%
were: Gold Standard 1 condition for
neck compression, Nij, and lap belt
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load; rear-seat standard belt condition
neck tension; rear-seat load-limited
condition for BrIC and neck
compression; and rear-seat inflatable
belt condition for HIC15). When
normalized, however, none of these CVs
were above 10%. This suggests that the
variability in these measurements
would not likely lead to variability in
actual testing outcomes. The variability
in these measurements is much lower
than the magnitudes of these
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61935
measurements that would be used as an
IARV specified in FMVSS No. 208.
For instance, the individual
measurements for neck compression in
the Gold Standard 1 tests were –394 N,
¥427 N, and ¥328 N. These have an
average of ¥383 N and a standard
deviation of 41 N, resulting in an
unadjusted CV of 11%. While this is
greater than 10%—potentially
suggesting that the source of this
variability needs investigation—these
measurements are all much lower in
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magnitude than the compression force
that would result in a 50% risk of AIS
3+ injury (¥5017 N). When the
standard deviation is compared to this
compression force instead of the average
neck compression, we obtain a
normalized CV of 0.8%. This suggests
that the magnitudes of the neck
compression measurements are low
compared to the magnitude of
compression that corresponds to a
meaningful injury risk.
There was one measurement for
which the unadjusted CV was below
10% but the normalized CV was above
10%: the peak lap belt force in the rearseat inflatable belt condition, which had
a normalized CV of 11.7%. In this
instance, the average lap belt load (6,701
N) was higher than the normalizing
denominator (5,000 N), resulting in an
inflated normalized CV. As stated
earlier, there is not a known risk
function that relates belt forces to risk
of injury, so this elevated normalized
CV is not of particular concern.
Otherwise, the highest normalized CV
occurred in the BrIC measurement in
the rear seat load-limited and
pretensioned condition (9.6%). This
appears to result from inconsistent
initial positioning of the left arm, which
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is more of a test procedure concern than
a THOR–50M concern.
3. Low-Speed Belted Sled Tests
Another source of data NHTSA
looked at to assess repeatability is a sled
test series conducted to assess the
performance of THOR–50M in lowspeed belted conditions. These tests
were based on the rigid barrier,
perpendicular impact belted crash test
specified in FMVSS No. 208 for the
HIII–50M. Sled tests were conducted at
crash pulses representing three frontal
rigid barrier impact velocities (24, 32,
and 40 km/h) (15, 20, and 25 mph). This
range of speeds was selected because
FMVSS No. 208 specifies a speed of up
to 56 km/h (35 mph) for this crash test,
and air bag deployment thresholds are
typically around 24 km/h (15 mph); we
spanned the 24–40 km/h (15–25 mph)
range and selected a mid-point of 32
km/h (20 mph) to conduct a crash test
and get a crash pulse. In each test, the
THOR–50M was seated in either the
driver or right front passenger seating
locations of a buck representing a midsized passenger car.177 Three tests were
conducted at each impact velocity, for a
total of 9 tests. The test buck was
177 A HIII–50M was seated in the other front
outboard seat.
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created from an actual vehicle, and
included seat belts, front air bags, kneebolsters, and pretensioners. The test
matrix and additional information about
the test setup is provided in Appendix
D.
As with the thoracic injury criteria
development test series, both CVs and
normalized CVs (Table 15) were
calculated for each of the relevant injury
metrics described in the THOR–50M
Injury Criteria Report, as well as femur
and seat belt loads, for 11 metrics for
each of the six test conditions. Of these
66 CVs, 31 were under 5%, 17 were
between 5% and 10%, and 18 were
above 10%.
We believe that this data supports our
tentative conclusion that THOR–50M is
sufficiently objective to include in Part
572. Most of the CVs were under 10%
and many were under 5%. None of the
18 measurements for which the CV was
above 10% had a normalized CV over
10%, and only five were above 5%. This
is not surprising, as the low-speed
belted test condition presents a low
likelihood of injury. Thus, while there
may be variations in the injury metrics,
these variations are small relative to the
values that would represent a
meaningful injury risk.
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Another source of data NHTSA
looked at to assess repeatability is a sled
test series conducted to assess the
performance of THOR–50M in a lowspeed unbelted condition. Sled tests
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were conducted at crash pulses
representing two frontal rigid barrier
impact velocities, 32 km/h (20 mph) and
40 km/h (25 mph), with the THOR–50M
in both the driver and right front
passenger seating locations of a test
buck. Three tests were conducted at
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each impact velocity. The test buck was
identical to that used in the low-speed
belted tests except for some minor
modifications. The test matrix and
additional information about the test
setup is provided in Appendix E.
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As with the thoracic injury criteria
development and belted test series, CVs
and normalized CVs were calculated for
each of the relevant injury metrics
described in the THOR–50M Injury
Criteria Report, as well as femur loads,
for nine metrics for each of the two
crash pulses. Of these 36 CVs, 12 were
less than 5%, 20 were between 5% and
10%, and four were above 10% (Table
16).
We believe this supports our tentative
conclusion that the THOR–50M is
objective. Almost all the CVs were
under 10%, and many were under 5%.
Three of the four measurements with a
CV over 10% had a normalized CV
under 10% (neck tension for driver 32
km/h and RFP 40km/h, and HIC15 for
RFP 40 km/h), suggesting that the
variation is small relative to the values
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that would represent a meaningful
injury risk. The low magnitudes of neck
tension occur because there is no torso
restraint in these unbelted tests, so that
the tension force acting on the neck due
to the deceleration of the torso is
minimal (below 500 N). The HIC15
measurements were relatively low
because the frontal air bags minimized
the contact of the head with hard
surfaces or at least decelerated the head
before contact. The highest average
HIC15 (360) occurred in the right front
passenger 40 km/h condition, where
individual measurements of 309, 349,
and 423 resulted in a standard deviation
of 47.3 and a CV of 13.1.
Only one of those four measurements
that had a CV over 10% also had a
normalized CV over 10% (BrIC in the
Driver 40 km/h condition, 14%).
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NHTSA’s analysis of the test procedure
and ATD revealed that the variation in
this case appears to result from a
difference in head interaction with the
sun visor and underlying roof structure,
brought about by small differences in
the timing and/or position of the head
at the time of contact. This variation
could be brought on by initial position
differences, differences in interaction of
the pelvis and thighs with the seat
cushion during initial forward
translation, or differences in knee
interaction with the knee bolster and/or
knee bolster air bag. For additional
information on this analysis, see
Appendix E.
There was one measurement with a
relatively low CV, but an associated
normalized CV above 10%. This
occurred for the Nij measurement in the
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driver 40 km/h condition, where the CV
was 4.7% and the normalized CV was
10.7%. Because we normalized by the
value of Nij associated with a 50%
injury risk, this indicates that the
average value of Nij from the three tests
in the driver 40 km/h condition were
above an Nij associated with 50% risk
of injury. Closer inspection of the data
revealed several peaks that cannot be
explained by the interaction of the
dummy with the restraint system and
vehicle interior. This suggests possible
damage to a load cell or cabling. For
additional information on this analysis,
see Appendix E.
VII. Overall Usability and Performance
NHTSA’s extensive testing with the
THOR–50M has also enabled it to assess
THOR–50M’s overall usability and
performance. This includes durability,
ease and frequency of maintenance, and
how the ATD fits and responds in the
vehicle environment. We discuss these
issues in the sections that follow.
A. Assembly and Qualification
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Based on NHTSA’s experience with
the dummy at VRTC, assembling the
THOR–50M following the instructions
in the PADI takes roughly 80 hours, as
detailed in Table 17.
We note that NHTSA treats its THOR–
50M units not so much as a serialized
dummy, but as a set of serialized parts
and sub-assemblies. NHTSA’s THOR–
50M units typically undergo a routine
breakdown and inspection after each
application; when the dummy is
reassembled, different parts may be
introduced (for example, if a part
needed to be refurbished before it could
be used again). In addition, parts or sub-
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assemblies may be taken out of service
at regular intervals and set aside to
await preventative maintenance. For
example, a head and neck sub-assembly
(both of which are serialized) may be
taken out of service at regular intervals
and set aside to await preventative
maintenance; once clear, the head and
neck sub-assembly may end up in
another serialized dummy. Therefore, a
serialized dummy does not typically
define the dummy well because
different parts are constantly being
interchanged. The parts and assemblies
which are serialized, either by the
manufacturer or by NHTSA upon
delivery of a new ATD or part, are listed
in Appendix C.
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Based on NHTSA’s experience at
VRTC, a complete qualification test
series of 24 tests takes roughly 80 hours,
assuming that the qualification
specifications are met (Table 18). If the
qualification specifications are not met,
it may take additional time to inspect,
replace parts where necessary, and retest. Table 19 describes the equipment
required to carry out the THOR–50M
qualification tests, along with the
associated setup procedures. Some of
this equipment is the same or similar to
the equipment required for qualification
of ATDs currently defined in Part 572.
For example, the THOR–50M
qualification procedures for the neck
and the upper thorax use the same
equipment as used in qualification of
TABLE 17—ESTIMATED TIME TO
CARRY OUT ASSEMBLY AND ASSOCI- the HIII–50M. For equipment not
ATED PROCEDURES DESCRIBED IN currently defined in Part 572, the
necessary drawings are included in the
THE THOR–50M PADI
THOR–50M drawing package with two
exceptions: the impactors for the face
PADI assembly time
qualification test and upper leg and
Time
knee qualification tests. We believe that
Body region or procedure
(hrs)
existing impactors (such as the knee
Head .............................................
4 impact probe for the HIII–5F 178) can be
Neck ..............................................
8 modified or ballasted to achieve the
Spine .............................................
4 required mass.
Thorax ...........................................
Shoulder .......................................
Upper Abdomen ...........................
Lower Abdomen ...........................
Pelvis ............................................
Upper Leg .....................................
Lower Extremity ............................
Arm ...............................................
Jacket and Clothing ......................
Bundling Cables ...........................
Polarity Check ..............................
Documentation ..............................
8
4
4
4
8
4
8
4
4
4
4
8
Total .......................................
80
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178 49
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CFR 572.137(b).
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TABLE 19—EQUIPMENT REQUIRED FOR QUALIFICATION TESTS
Test fixture description
[±0.02 kg, ±0.25 mm]
Reference
Title
Rigid disk impactor 23.36 kg, 152.4 mm
diameter disk.
Rigid disk impactor 13.0 kg, 152.4 mm
diameter disk.
Neck pendulum ......................................
CFR Title 49, § 572.36(a); DL500–325
THOR neck twist fixture .........................
Lower abdomen probe face assembly ...
Rigid disk impactor 12.0 kg, 76.2 mm
diameter disk.
Dynamic impactor ..................................
DL472–1000 ..........................................
DL472–3000 ..........................................
THOR–50M Qualification Procedures,
Section 11.2.
TLX–9000–013 ......................................
12, 13, 14
External positioning bracket ...................
Dynamic inversion/eversion bracket ......
Lower leg mounting bracket assembly ..
TLX–9000–016M ...................................
TLX–9000–015 ......................................
DL472–4100 ..........................................
12, 14
12
12, 13
Lower leg zero bracket ..........................
DL472–3500 ..........................................
3.4
Achilles fixture complete assembly ........
Load cell mounting assembly ................
Knee slider load distribution bracket assembly.
Tibia adaptor ..........................................
DL472–4000 ..........................................
DL472–4200 ..........................................
DL472–5000 ..........................................
3.5
3.5
11
Ankle Inversion and Eversion, Ball of
Foot, Heel.
Ankle Inversion and Eversion, Heel.
Ankle Inversion and Eversion.
Ankle Inversion and Eversion, Ball of
Foot
Ankle Rotary Potentiometer Zeroing
Procedure.
Achilles Cable Adjustment Procedure.
Achilles Cable Adjustment Procedure.
Knee.
DL472–4300 ..........................................
14
Heel.
THOR–50M Qualification Procedures,
Section 5.2.
Figure A–2; CFR Title 49, § 572.33(c)3
B. Durability and Maintenance
In previous sections of the NPRM, we
have discussed NHTSA’s biofidelity
testing, qualification testing, and sled
tests. In this testing, we generally
observed that THOR–50M stood up well
during testing and required
maintenance consistent with existing
Part 572 ATDs. In addition to that
testing, NHTSA has conducted a variety
of other tests over the last several years
as development of THOR–50M has
progressed. With respect to evaluating
THOR’s durability and maintenance
needs, three series of tests are especially
useful because they subject the THOR–
50M to more severe or challenging
crashes: elevated energy qualification
tests; OMDB testing; and unbelted
FMVSS No. 208 tests. We discuss this
testing in the sections that follow.
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Section(s)
1. Elevated Energy Qualification Test
Series
In order to assess THOR–50M’s
durability, NHTSA conducted an
additional series of qualification tests at
elevated energy levels (for example,
impactor velocities that exceeded the
levels specified in the qualification test
procedures).179 A series of five tests was
conducted for each of the qualification
test modes (except, as explained below,
the abdomen). The first test in each set
179 National Highway Traffic Safety
Administration (2020). THOR–50M Durability
Report. Regulations.gov Docket ID NHTSA–2019–
0106–0003, available at: https://
www.regulations.gov/document/NHTSA-2019-01060003.
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4, 7, 8
5
6.6, 6.7, 6.8, 6.9
6.6
9
11
was a baseline test performed according
to the qualification, except that if the
response measurement did not either
represent at least a 50% risk of injury
or have a magnitude greater than the
mean plus one standard deviation of the
same measurement in a set of 18 oblique
vehicle crash tests,180 the test speed was
increased until either of those targets
were met; this was then considered the
baseline speed. There were two test
modes where the test speed specified in
the qualification procedures did not
reach either of these targets: upper leg
impact and heel impact.181 The next
three tests were at speeds corresponding
to energy level increases of 10 percent,
20 percent, and 30 percent. A final
baseline test was then performed at the
prescribed qualification test velocity.
The results were considered to show
acceptable durability if the final
baseline test demonstrated a response
similar to the initial baseline test and
within the qualification targets, and
visual inspection revealed no damage to
any of the dummy components. For a
majority of the qualification test modes,
durability was found to be acceptable.
180 Saunders, J., Parent, D., Ames, E., 2015.
NHTSA oblique crash test results: vehicle
performance and occupant injury risk assessment in
vehicles with small overlap countermeasures. In:
Proceedings of the 24th International Technical
Conference for the Enhanced Safety of Vehicles (No.
15–0108). Available at https://
downloads.regulations.gov/NHTSA-2019-01060008/attachment_1.pdf.
181 The increase in energy of the upper leg impact
test was later implemented in the revised
qualification procedure.
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Head, Upper Thorax, Lower Thorax.
Face.
Neck Torsion, Neck Frontal Flexion,
Neck Extension, Neck Lateral Flexion.
Neck Torsion.
Abdomen.
Upper Leg, Knee.
No visible damage was observed in any
of the tested components after the series
of five tests. Two exceptions to these
findings occurred in the face and the
abdomen qualification test modes.
In the face impact test, the final
baseline peak probe force and peak head
CG resultant acceleration were higher
than the qualification specifications.
This is consistent with the results of the
qualification R&R study (Section VI.A).
While not ideal, we believe that,
because this is now a known issue, it
can be managed with the replacement of
a face foam insert when the face
qualification test results are higher in
magnitude than the qualification
specification. Moreover, the
deterioration in the face foam insert
probably would not meaningfully affect
crash test results because, in a vehicle
test, more energy will likely be absorbed
by a vehicle interior component and/or
restraint system compared to the rigid
qualification impact probe. However,
NHTSA would consider specifying a
different face foam material or design
that had improved durability, as long as
the material or design does not
introduce unintended consequences
such as negatively impacting biofidelity,
changes to the inertial properties of the
head, degradation of repeatability and
reproducibility, overall usability, or
other concerns.
We did not conduct elevated-energy
tests for the abdomen because the
qualification test already demonstrates a
higher energy condition than a vehicle
crash test. Accordingly, impacts at a
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higher energy level could cause damage
due to exhausting the stroke of the
abdomen instrumentation. Moreover,
this would not be meaningful as it
would represent a loading condition not
representative of the front seat vehicle
crash test environment. However, we do
recognize that our testing has shown
that damage to the abdomen deflection
instrumentation can occur in vehicle
crash test environments where
submarining is possible, such as
reclined rear seats. For example, several
rear seat sled tests were conducted at
VRTC in 2015 in which the IR–TRACCs
installed in the abdomen experienced
dislodged internal retaining rings and
damage including pinched cables. These
issues are believed to have resulted from
interaction of the IR–TRACC tubes with
the foam inserts inside of the lower
abdomen bag. To address this, the lower
abdomen sewing assembly (472–4763)
was redesigned in late 2015, and an
inspection procedure was added to the
drawing package (472–8320) to ensure
that the lower abdomen foam inserts
remain aligned once installed in the
assembled lower abdomen bag.
We seek comment on these issues,
especially on alternative equivalent face
foams.
2. Oblique OMDB Test Series
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In developing THOR–50M, NHTSA
ran a series of full-vehicle oblique tests
with a moving deformable test barrier
(OMDB).182 Three crash tests were
conducted on the same make/model
vehicle (a 2016 Mazda CX–5) at three
different test facilities. ATDs were
seated in both front outboard seats and
were fully qualified. Two THOR–50M
ATDs were successfully implemented in
182 Saunders, J., & Parent, D. (2018). Repeatability
and reproducibility of oblique moving deformable
barrier test procedure (No. 2018–01–1055). SAE
Technical Paper, available at https://
www.regulations.gov/document/NHTSA-2019-01060005. The discussion here briefly summarizes some
of the relevant results from this report. This testing
is not being considered as an evaluation of the
ATD’s repeatability and reproducibility because in
order to provide a meaningful ATD R&R analysis,
control of the test conditions must be exercised.
Component tests, such as the qualification tests, are
more readily controlled and thus may be expected
to provide the best estimates of a dummy’s R&R.
Sled testing provides an efficient alternative to
vehicle crash testing and offers insight into the
dummy’s performance as a complete system. In fullvehicle crash testing, however, the variation
contributed by the vehicle (e.g., variation in
structural materials) and the overall test procedure
make it difficult to identify the variability
attributable to the dummy itself. Additionally, the
severity of the test conditions utilized for R&R
assessment must also be considered. For example,
if the test conditions are so severe that the
responses are near or beyond the dummy’s
mechanical limits or electronic capacity, then the
corresponding R&R analysis may not be meaningful.
See generally Rhule et al (2005).
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a total of nine vehicle crash tests, with
qualification tests before and after each
set of three tests. In this test condition,
there were no signs of damage beyond
normal wear and tear, and there were no
sensor failures that were critical to the
calculation of injury risk. The dummies
were inspected after each test.
There were no signs of damage
beyond normal wear and tear, and no
part replacements were necessary. We
did observe some sensor anomalies or
failures to sensors, but almost all the
sensors that failed were non-critical—
for example off-axis channels (e.g., right
femur X-axis force) or sensors not used
in the calculation of injury criteria (e.g.,
lower neck load cell, foot
accelerometers). See Appendix F. Such
sensor anomalies can also occur in other
Part 572 ATDs, such as the HIII–50M
and HIII–05F used in Frontal NCAP
testing. In the past six years of Frontal
NCAP testing, there was an average of
one failed ATD sensor channel per crash
test (0.68 ± 1.08), with five of those
instances occurring in a critical channel.
Many of these anomalies were the
results of loose Amphenol pins. These
are the electrical contacts inside of the
connectors used to interface the THOR–
50M umbilical cables with the specific
data acquisition system of the test
facility. These connectors are used to
prevent the need for cutting wires and
attaching lab-specific connectors each
time an ATD is sent to a new facility
with a different data acquisition system.
In practice, ATDs sent to test facilities
for the execution of regulation or
consumer information testing will often
remain on-site for an extended period of
time, which makes laboratory-specific
connectors more feasible. Such issues
would not exist for THOR–50M ATDs
with in-dummy data acquisition
systems. Many of the sensor failures that
occurred were in non-critical
instrumentation, for example off-axis
channels or sensors not used in the
calculation of injury criteria. For
research tests, a larger number of
sensors are recorded for the sake of
completeness and post-test
investigation; in a regulatory or
consumer information testing
environment, these channels may not be
recorded. If the user does want to record
such sensors, they would need to be
repaired or replaced before pre-test
qualification for the next vehicle crash
test.
The only sensor anomalies related to
the calculation of injury criteria were in
the chest and abdomen, but, once
linearized, scaled, filtered, and
converted to three-dimensional
resultant deflection local spine
coordinate system, these ‘‘blips’’ were
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no longer evident; thus they would not
influence the calculation of injury risk
for this occupant. These voltage drops
are characteristic of the abrupt decreases
in the IR–TRACC voltage time-history
described in Section III.E.2. See
Appendix F.
3. FMVSS No. 208 Unbelted Vehicle
Crash Tests
NHTSA performed a series of
unbelted vehicle crash tests required in
FMVSS No. 208. The results are briefly
summarized in this section and are
discussed in more detail in the
referenced paper.183 FMVSS No. 208
specifies a frontal crash test into a rigid
barrier with the barrier angle at 0
degrees to ± 30 degrees at between 20
mph (32 km/h) and 25 mph (40 km/h),
inclusive, with an unbelted 50th
percentile male dummy seated at either
front outboard seat.184
NHTSA ran two sets of tests. First, we
ran this test at the highest regulatory
speed of 40 km/h (25 mph) for crash
geometries of 30 degrees to the left, 30
degrees to the right, and perpendicular
(12 tests). Second, we ran a modified
version of this test, with an elevated
speed of 48 km/h (30 mph) for crash
geometries of 30 degrees to the left and
right (six tests). We tested with two
different THOR–50M ATDs, both
manufactured by Humanetics and built
to the 2018 drawing package (except
that one ATD (EG2595) was fitted with
the proposed optional in-dummy DAS).
For these tests, the laboratory test
procedures for FMVSS No. 208 185 were
followed, with the exception of the
seating procedure, for which the
Revised THOR 50th Percentile Male
Dummy Seating Procedure 186 was
followed. The ATD was instrumented so
that all injury criteria defined for the
HIII–50M in FMVSS No. 208 and in the
THOR–50M Injury Criteria Report could
be calculated. A total of 19 tests were
run on four different vehicle models
183 Saunders, J., Parent, D., Martin, P., 2023.
THOR–50M Fitness Assessment In FMVSS No. 208
Unbelted Crash Tests. In: Proceedings of the 24th
International Technical Conference for the
Enhanced Safety of Vehicles (No. 23–0339).
Available at: https://www-esv.nhtsa.dot.gov/
Proceedings/27/27ESV-000339.pdf.
184 S14.5.2; S5.1.2(b).
185 National Highway Traffic Safety
Administration (2008). Laboratory Test Procedure
for FMVSS 208, Occupant Crash Protection, TP208–
14.
186 National Highway Traffic Safety
Administration (2020). Revised THOR 50th
Percentile Male Dummy Seating Procedure, June
2019. Regulations.gov Docket ID NHTSA–2019–
0106–0006, available at https://
www.regulations.gov/document/NHTSA-2019-01060006.
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(the Honda Accord, Mazda CX–5,
Chevrolet Equinox, and Ford Escape).
This study showed that the THOR–
50M, when exercised in unbelted frontal
rigid barrier testing, experienced only
minor issues. We performed a full set of
qualification tests before the test series,
a partial qualification test series 187 after
each test, and a full qualification test
series halfway through the test series. In
all cases, the THOR–50Ms met the
qualification specifications without
need for part replacement or other
refurbishment. In addition, each ATD
was inspected after each test for damage
and to investigate sensor anomalies.
While no parts were found to be in need
of replacement, there were some sensor
anomalies and damage. One of the ATDs
did not experience any sensor
anomalies or damage during testing,
while the other ATD experienced some
sensor anomalies that were repairable,
while others were not. The sensors that
were not repaired were non-critical
channels (for example, the left tibia
mid-shaft X-axis accelerometer), thus a
decision was made to continue testing
instead of repairing or replacing the
sensors, which would have caused
delays in the test schedule. The quantity
and severity of sensor anomalies were
similar to those experienced in testing
with the HIII–50M, especially
considering increased sensor count and
level of complexity of the THOR–50M.
Aside from minor wear and tear (e.g.,
scrapes on the top of the head skin of
one ATD were noted after one test) there
was no damage to either ATD and both
met all qualification specifications.
Based on these observations, NHTSA
tentatively concludes that THOR–50M
is sufficiently durable for use in FMVSS
No. 208 unbelted testing, even at an
elevated closing speed. Overall, this
unbelted test series provides additional
assurance that the THOR–50M units are
durable and stand up well under testing,
with the amount of wear and tear
normal for our test dummies, and that
NHTSA’s THOR–50M design
specifications have resulted in highly
uniform and durable units.
C. Sensitivity to Restraint System
Performance
NHTSA’s testing with the THOR–50M
has also highlighted its ability to detect
differences in restraint system
performance. One example of this
occurred in the Oblique OMDB testing
187 To maximize efficiency, the partial
qualification test series only included the tests that
did not require any disassembly of dummy
components: head, upper thorax, lower thorax,
lower abdomen, and left/right upper leg. The face
impact test was not included because direct impact
to the face was not expected during this test series.
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described above in Section VII.B.2.188
This testing involved vehicles of the
same model and model year with a
THOR–50M seated in each front
outboard seat. In one series of tests
which included three Oblique OMDB
crash tests of the same vehicle make and
model, the THOR–50Ms seated in the
right front passenger seat showed a
much wider variation in injury
assessment values related to head injury
risk than the THOR–50Ms seated in the
driver’s seat. A thorough investigation
of the test data, including inspection of
the high-speed video, revealed that the
right front passenger air bag did not
function consistently to manage the
ride-down of the occupant: the highspeed images revealed differences in air
bag deployment, interaction between
the head and the air bag, and contact
between the head and the instrument
panel. Inspection of the air bag revealed
tears in the air bags in two of the three
tests, with the largest tears associated
with the highest injury assessment
values.189 This is one example of how
the innovative features of the THOR–
50M can help lead to improved vehicle
safety.
VIII. Intellectual Property
While there is no specific prohibition
on specifying a patented component,
copyrighted design, or name-brand
product in Part 572, NHTSA has been
mindful of the legislative history of the
Safety Act and its own responsibility
under statute to make all information,
patents, and developments related to a
research and development activity
available to the public where it makes
more than a minimal contribution to the
activity.190 This understanding has
guided dummy development at NHTSA
for many years and explains why
NHTSA has not incorporated into final
rules materials owned by third parties
except in rare cases (discussed below).
The legislative history of the Safety Act
shows that while Congress explicitly
declined to include a provision
preventing use of patents by the agency
in standards, Congress did ‘‘assume[ ]
that the Secretary is not likely to adopt
a standard which can be met only by
using a single patented device, and that
the Secretary would, before doing so,
take steps to obtain an understanding
188 Saunders, J., & Parent, D. (2018). Repeatability
and reproducibility of oblique moving deformable
barrier test procedure (No. 2018–01–1055).
189 These results were shared with the vehicle
manufacturer, which instituted a series of
modifications. In a later test of the vehicle, there
were no passenger air bag tears evident, and the
head injury criteria were similar to those measured
in the previous tests that did not appear to result
in air bag tears.
190 49 U.S.C. 30182(f).
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from the patent holder that he would
supply the item or grant licenses on
reasonable terms.’’ 191 In addition,
NHTSA itself plays a significant role in
the testing, evaluation and performance
verification of dummies and provides a
substantial amount of information to the
public to identify the basis for
improvement in testing devices to
ensure the repeatability and
reproducibility of results. The outcome
of the agency’s involvement has been an
interest in making sure the test device
is available for use without restriction to
the public.
To be clear, there are also several
potential concerns with specifying
proprietary components. They may be
modified by the proprietary source such
that original is no longer available, and
the new part no longer fits. The
proprietary source may alter the part in
ways that change the response of the
dummy, such that dummies with the
newer part do not provide the same
response as dummies with the older
part. Components produced by only one
manufacturer are not subject to
competitive sales pressures. And the
manufacturer of a sole-source part may
simply cease manufacturing the part.
For these reasons, NHTSA has
generally avoided specifying in Part 572
patented components or copyrighted
designs without either securing
agreement from the rights-holder for the
free use of the item or to license it on
reasonable terms 192 or developing an
alternative unencumbered by any rights
claims.193
As noted earlier in the preamble
(Section III), we are specifying some
patented parts but not without
specifying suitable alternates where no
intellectual property claims apply. We
briefly discuss these below.
Shoulder
As explained earlier, we are
proposing to include two alternative
shoulder specifications: the SD–3
shoulder and the alternate shoulder.
Humanetics has two patents on the
SD–3 shoulder: one describes a
mechanical shoulder joint assembly and
the other describes an upper arm
191 S. Rep. No. 89–1301, at 15, reprinted in
U.S.C.C.A.N. 2709, 2723.
192 See, e.g., 38 FR 8455 (Apr. 2, 1973) (NPRM for
the initial 50th percentile male dummy) (‘‘To the
knowledge of this agency, the only patent on a
component of the specified dummy is one on the
knee held by Alderson, and that company has
stated to the NHTSA that it will license production
under its patent for a reasonable royalty.’’)
193 See, e.g., 65 FR 17180, 17187 (Mar. 31, 2000)
(final rule for twelve-month-old child dummy)
(declining to incorporate a copyrighted PADI
developed by an ATD manufacturer and instead
incorporating a NHTSA-authored PADI).
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assembly with a load cell.194 The
shoulder joint is formed using a pivot
connected to a spring element inside of
a housing, which has an adjustable
element to control the friction of the
joint. Humanetics is currently the sole
manufacturer of the SD–3 shoulder in
the United States.
In order to avoid potential concerns
with specifying a patented part as the
sole specification, NHTSA has
developed an alternative to the SD–3
shoulder. The alternate shoulder does
not include the adjustable friction
element, and does not use a coil, clock,
or watch spring mechanism. Instead, the
alternate shoulder design uses a molded
rubber cylinder acting as a torsion bar.
The response of the rubber cylinder can
be tuned by both changes in material
and changes in geometry, such as
removal of material to create voids of
different sizes and shapes. This lack of
a friction adjustment in the alternate
shoulder is a change in the functional
aspect of the design. Accordingly, with
the significant differences noted, we are
proposing to specify the use of either
the alternate shoulder or the SD–3
shoulder.
Chest Instrumentation
NHTSA is proposing the IR–TRACC
and the S-Track as permissible alternate
instrumentation. While NHTSA is not
aware of any patent protection on the
IR–TRACC, it is manufactured only by
Humanetics. There is a patent on the STrack, and NHTSA’s understanding is
that the S-Track is currently
manufactured only by ATD-LabTech,
which was recently acquired by
Humanetics.
We believe that specifying the design
such that either the IR–TRACC or the STrack could be used would be sufficient
to ensure instrumentation availability to
dummy users. We seek comment on
this.
IX. Consideration of Alternatives
NHTSA is not aware of a 50th
percentile male ATD intended for use in
frontal or frontal oblique crash tests and
more advanced than the HIII–50M, other
than the THOR–50M. Throughout this
document we have discussed various
alternative configurations,
specifications, and tests that we have
considered in developing the proposal
and on which we are seeking comment.
As discussed in more detail in the
rulemaking analyses section, Executive
Order 13609 provides that international
regulatory cooperation can reduce,
eliminate, or prevent unnecessary
differences in regulatory requirements.
Similarly, § 24211 of the Infrastructure,
Investment, and Jobs Act 195 instructs
DOT to harmonize the FMVSS with
global regulations to the maximum
extent practicable (for example, to the
extent that harmonization would be
consistent with the Safety Act).
The only regulatory authority or
consumer ratings program we are aware
of that currently uses the THOR–50M is
Euro NCAP. Euro NCAP TB026
references the August 2018 drawing
package,196 the September 2018
Qualification Procedures,197 and the
August 2018 PADI.198 Although TB026
largely follows these documents, it does
depart from them in several ways. Those
differences have been identified and
discussed in the relevant sections of the
preamble and are summarized in Table
20. The tentative reasons for those
differences are explained in detail in the
relevant section of the preamble. In
general, we believe that those
differences are justified given NHTSA’s
experience testing with the THOR–50M
in frontal rigid barrier and frontal
oblique vehicle crash test modes, and
the necessity of ensuring that a dummy
specified for use in regulatory
compliance testing be objectively
specified.
TABLE 20—SUMMARY OF DIFFERENCES BETWEEN THE THOR–50M AS PROPOSED AND AS SPECIFIED FOR USE IN EURO
NCAP
Issue
Proposal
Design & Construction:
Split shoulder pad ......................................
Spine ..........................................................
Lower Leg ...................................................
Instrumentation:
S-Track/IR–TRACC ....................................
In-dummy DAS ...........................................
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Qualification Tests:
Acceptance interval midpoint .....................
Acceptance interval width ..........................
Upper thorax ...............................................
Face impact test .........................................
Knee slider .................................................
Lower legs .........................................................
194 U.S. Patent Nos. 9,514,659 (upper arm
assembly) and 9,799,234 (shoulder joint assembly).
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Euro NCAP
Not proposed ....................................................
Spine Pitch Change Joint .................................
THOR-specific lower leg ..................................
Under consideration.
Four-Position Spine Box.
HIII–50M lower leg.
IR–TRACC or S-Track .....................................
IR–TRACC, S-Track, or KIR–TRACC
Does not specify the systems part-by-part with
engineering drawings.
TB026 requires an in-dummy DAS. TB029
currently does not specify any specific indummy DAS, although earlier versions of
TB029 did specify a few different approved
in-dummy DAS systems.
Does not specify the systems part-by-part with
engineering drawings.
Permitted as optional configuration with partby-part engineering drawings compatible
with the SLICE6 and any other similarlyconfigured system.
Based on R&R test data ..................................
± 10% of midpoint ............................................
Ratio of Z-axis to X-axis deflection not specified as test parameter.
Specified ...........................................................
Specified ...........................................................
Ankle inversion/eversion; Ball of foot; heel ......
195 H.R.
3684 (117th Congress) (2021).
196 § 1.1.
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Basis not identified in TB026.
Varies from ±1% to ±10%.
Specifies ratio of Z-axis to X-axis deflection as
test parameter.
Not specified.
Certified to SAE J2876.
Certified to Annex 10 of ECE Regulation No.
94.
197 § 2.1.
198 § 3.1.
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X. Lead Time
Since this rulemaking action itself
would not impose requirements on
anyone, we are proposing that the final
rule would be effective on publication
in the Federal Register.
XI. Incorporation by Reference
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Under regulations issued by the Office
of the Federal Register (1 CFR 51.5(a)),
an agency, as part of a final rule that
includes material incorporated by
reference, must summarize in the
preamble of the final rule the material
it incorporates by reference and discuss
the ways the material is reasonably
available to interested parties or how
the agency worked to make materials
available to interested parties.
In this proposed rule, NHTSA
incorporates by reference a technical
data package for the THOR–50M. The
technical data package consists of twodimensional engineering drawings and a
parts list; procedures for assembly,
disassembly, and inspection (PADI); and
qualification procedures. Copies of
these documents are available in the
research docket identified earlier in this
document. Interested persons can
download a copy of the materials or
view the materials online by accessing
www.Regulations.gov. The material is
also available for inspection at the
Department of Transportation, Docket
Operations, Room W12–140, 1200 New
Jersey Avenue SE, Washington, DC
Telephone: 202–366–9826. If the
proposed rule is finalized, final versions
of these documents would be placed in
a docket that would be readily available
to the public online (via regulations.gov)
and in-person at DOT headquarters.
Although agency-created documents
are presumptively ineligible for
incorporation by reference, they may be
approved for incorporation by the Office
of the Federal Register if they (among
other things) consist of criteria,
specifications, or illustrations; are
reasonably available to the class of
persons affected; are easy to handle; and
possesses other unique or highly
unusual qualities.199
199 See 1 CFR 51.7(b) (‘‘The Director will assume
that a publication produced by the same agency that
is seeking its approval is inappropriate for
incorporation by reference. A publication produced
by the agency may be approved, if, in the judgment
of the Director, it meets the requirements of
paragraph (a) and possesses other unique or highly
unusual qualities. A publication may be approved
if it cannot be printed using the Federal Register/
Code of Federal Regulations printing system.’’);
(a)(2)(i)(‘‘published data, criteria, standards,
specifications, techniques, illustrations, or similar
material’’); (a)(3)(‘‘reasonably available to and
usable by the class of persons affected’’);
(a)(3)(i)(‘‘The completeness and ease of handling of
the publication’’).
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Executive Order (E.O.) 12866, E.O.
13563, E.O. 14094, and DOT Regulatory
Policies and Procedures
NHTSA has considered the impacts of
this regulatory action under Executive
Orders 12866, 13563, 14094, and the
Department of Transportation’s
regulatory policies and procedures.201
This rulemaking action was not
reviewed by the Office of Management
and Budget under E.O. 12866. It is also
not considered ‘‘of special note to the
Department’’ under DOT Order
2100.6A. We have considered the
qualitative costs and benefits of the
proposed rule under the principles of
E.O. 12866.
This document would amend 49 CFR
part 572 by adding design and
performance specifications for an
advanced test dummy representative of
a 50th percentile adult male that the
agency would possibly use in FMVSS
No. 208 front crash tests and for
research purposes. This Part 572
proposed rule would not impose any
requirements on anyone. Businesses are
affected only if they choose to
manufacture or test with the dummy.
There are benefits associated with this
rulemaking but they are not readily
quantifiable. The THOR–50M is an
advanced dummy with advantages over
existing dummies with respect to
biofidelity, instrumentation, injury
prediction, and evaluation of vehicle
performance. The dummy is currently
used for testing by Euro NCAP, and may
be incorporated in ECE R137. It is also
likely being used by vehicle and
restraint manufacturers for testing,
research, and development.
Accordingly, NHTSA is considering a
proposal to incorporate the THOR–50M
into FMVSS No. 208, ‘‘Occupant crash
protection,’’ for use in frontal crash
compliance testing at the manufacturers’
option.202 This contemplated
rulemaking action would permit
manufacturers to direct NHTSA to use
the THOR–50M in belted and unbelted
barrier crash testing of the vehicles they
produce instead of the HIII–50M ATD in
NHTSA’s compliance tests.
Incorporating the dummy in Part 572
will enable manufacturers and others to
streamline testing, choosing to use
THOR–50M in place of the HIII–50M,
potentially reducing the number of tests
they run, and leveraging the value of the
tests they do run.
Incorporating the THOR–50M into
Part 572 would also have other benefits
beyond use in NHTSA’s compliance
testing. The ability of the THOR–50M to
potentially monitor additional injury
modes and its improved biofidelity may
facilitate the development and
introduction of innovative occupant
crash protection features. While the
purpose of Part 572 is to ‘‘describe the
anthropomorphic test devices that are to
be used for compliance testing of motor
vehicles and motor vehicle equipment
with motor vehicle safety standards,’’ it
also serves as a definition of the ATD for
other purposes as well, such as
consumer information crash testing,
standards and regulations in other
transportation modes, and research. As
such, it would be to the benefit of
government, academia, and the multimodal transportation industry to
include a definition of the THOR–50M
ATD in Part 572. In addition, the
availability of this dummy in a
regulated format would be beneficial by
providing a suitable, stabilized, and
objective test tool to the safety
community for use in better protecting
occupants in frontal impacts.
The costs associated with the THOR–
50M only affect those who choose to use
the THOR–50M. This rule would not
impose any requirements on anyone. If
incorporated into FMVSS No. 208,
NHTSA would use the dummy in its
compliance testing of the requirements
200 The qualification procedures document states
that the photographs are provided for reference
only.
201 49 CFR, Part 5, Subpart B; Department of
Transportation Order 2100.6A, Rulemaking and
Guidance Procedures, June 7, 2021.
202 FMVSS No. 208 THOR–50M Compliance
Option (RIN 2127–AM21), Fall 2023 Unified
Agenda of Regulatory and Deregulatory Actions;
Department of Transportation, available at https://
www.reginfo.gov/public/do/eAgendaViewRule?
pubId=202304&RIN=2127-AM21.
We believe these documents (which
were created by NHTSA) meet these
criteria. Except for the qualification
procedures, NHTSA typically
incorporates these elements of the
technical data package by reference.
NHTSA has not typically incorporated
the qualification procedures by
reference. Doing so is a departure from
the other ATDs currently specified in
Part 572, for which the qualification
tests are set out in full in the regulatory
text in each of the relevant paragraphs
(corresponding to that ATD) in part 572.
We are proposing a separate
qualification procedures document for
the THOR–50M because the THOR–50M
qualification procedures involve
procedures that are made clearer by
photographs and diagrams that are not
amenable to publication in the CFR.200
We believe this extra level of detail will
be helpful for end users who are
attempting to qualify the ATD. We seek
comment on this.
XII. Regulatory Analyses
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at the option of a regulated entity, but
regulated entities are not required to use
the dummy or assess the performance of
their products in the manner specified
in the FMVSSs.
NHTSA has found that the cost of a
THOR–50M corresponding to the 2023
drawing package has been
approximately $550,000 to $750,000
depending on whether an in-dummy
DAS is installed and the level of
instrumentation. The minimum set of
instrumentation needed for qualification
testing includes 66 channels. If the STrack were used instead of the IR–
TRACC, the total cost would be roughly
the same.
In addition to these costs, as with any
ATD, dummy refurbishments and part
replacements are an inherent part of
ATD testing. Various parts will likely
have to be refurbished or replaced, but
we generally do not know which parts
are likely to be worked on the most. As
we note in the NPRM, however, the face
foam appears to need more frequent
replacement but this should not add
appreciably to the overall cost. Because
the dummies are designed to be
reusable, costs of the dummies and of
parts can be amortized over a number of
tests. While the expected maintenance
costs for the THOR–50M are expected to
be higher than those for less complex
dummies such as the HIII–50M, these
costs are expected to be similar to
advanced dummies such as the
WorldSID.
There are minor costs associated with
conducting the qualification tests. Most
of the qualification fixtures are common
with those used to qualify other Part 572
dummies (including the neck pendulum
and the probes used in the head, upper
thorax and lower thorax tests). Some
additional equipment unique to the
THOR–50M may be fabricated from
drawings within the technical data
package, for an estimated cost of about
$50,000. This includes the cost to
fabricate the torsion fixture for the neck
torsion test, the lower abdomen probe
face assembly, impact probes not used
for other Part 572 dummies (or weighted
collars to achieve the specified mass),
and test apparatus for the lower leg tests
(including the dynamic impactor,
external positioning bracket, dynamic
inversion/eversion bracket, lower leg
mounting bracket, lower leg zero
bracket, Achilles fixture, load cell
mounting assembly, knee slider load
distribution bracket, and tibia adapter).
The costs of the instrumentation
equipment needed to perform the
qualification tests amounts to about an
additional $4,400 (two angular rate
sensors, $850 apiece; two test probe
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accelerometers, $800 apiece; one rotary
potentiometer, $1,100).
Regulatory Flexibility Act
Pursuant to the Regulatory Flexibility
Act (5 U.S.C. 601 et seq., as amended by
the Small Business Regulatory
Enforcement Fairness Act (SBREFA) of
1996), whenever an agency is required
to publish a proposed or final rule, it
must prepare and make available for
public comment a regulatory flexibility
analysis that describes the effect of the
rule on small entities (i.e., small
businesses, small organizations, and
small governmental jurisdictions),
unless the head of the agency certifies
the rule will not have a significant
economic impact on a substantial
number of small entities. The Small
Business Administration’s regulations at
13 CFR part 121 define a small business,
in part, as a business entity ‘‘which
operates primarily within the United
States.’’ (13 CFR 121.105(a)).
We have considered the effects of this
rulemaking under the Regulatory
Flexibility Act. I hereby certify that this
rulemaking action would not have a
significant economic impact on a
substantial number of small entities.
This action would not have a significant
economic impact on a substantial
number of small entities because the
addition of the test dummy to Part 572
would not impose any requirements on
anyone. This NPRM only proposes to
include the dummy in NHTSA’s
regulation for crash test dummies; it
does not propose NHTSA’s use of the
ATD in agency testing or require anyone
to manufacture the dummy or to test
motor vehicles or motor vehicle
equipment with it.
National Environmental Policy Act
NHTSA has analyzed this proposed
rule for the purposes of the National
Environmental Policy Act and
determined that it would not have any
significant impact on the quality of the
human environment.
Executive Order 13045 and 13132
(Federalism)
Executive Order 13045 (62 FR 19885,
April 23, 1997) applies to any rule that:
(1) is determined to be ‘‘economically
significant’’ as defined under E.O.
12866, and (2) concerns an
environmental, health, or safety risk that
NHTSA has reason to believe may have
a disproportionate effect on children. If
the regulatory action meets both criteria,
we must evaluate the environmental
health or safety effects of the planned
rule on children and explain why the
planned regulation is preferable to other
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potentially effective and reasonably
feasible alternatives considered by us.
This proposed rule is not subject to
the Executive Order because it is not
economically significant as defined in
E.O. 12866.
NHTSA has examined this proposed
rule pursuant to Executive Order 13132
(64 FR 43255, August 10, 1999) and
concluded that no additional
consultation with States, local
governments or their representatives is
mandated beyond the rulemaking
process. The agency has concluded that
the proposed rule would not have
federalism implications because the
proposed rule would not have
‘‘substantial direct effects on the States,
on the relationship between the national
government and the States, or on the
distribution of power and
responsibilities among the various
levels of government.’’ This proposed
rule would not impose any
requirements on anyone. Businesses
will be affected only if they choose to
manufacture or test with the dummy.
Further, no consultation is needed to
discuss the preemptive effect of this
proposed rule. While NHTSA’s safety
standards can have preemptive effect,
the proposed rule would amend 49 CFR
part 572 and is not a safety standard.
This Part 572 proposed rule would not
impose any requirements on anyone.
Civil Justice Reform
With respect to the review of the
promulgation of a new regulation,
section 3(b) of Executive Order 12988,
‘‘Civil Justice Reform’’ (61 FR 4729,
February 7, 1996) requires that
Executive agencies make every
reasonable effort to ensure that the
regulation: (1) Clearly specifies the
preemptive effect; (2) clearly specifies
the effect on existing Federal law or
regulation; (3) provides a clear legal
standard for affected conduct, while
promoting simplification and burden
reduction; (4) clearly specifies the
retroactive effect, if any; (5) adequately
defines key terms; and (6) addresses
other important issues affecting clarity
and general draftsmanship under any
guidelines issued by the Attorney
General. This document is consistent
with that requirement.
Pursuant to this Order, NHTSA notes
as follows.
The issue of preemption is discussed
above in connection with E.O. 13132.
NHTSA notes further that there is no
requirement that individuals submit a
petition for reconsideration or pursue
other administrative proceeding before
they may file suit in court.
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Paperwork Reduction Act
Under the Paperwork Reduction Act
of 1995, a person is not required to
respond to a collection of information
by a Federal agency unless the
collection displays a valid control
number from the Office of Management
and Budget (OMB). This proposed rule
would not have any requirements that
are considered to be information
collection requirements as defined by
the OMB in 5 CFR part 1320.
National Technology Transfer and
Advancement Act
Section 12(d) of the National
Technology Transfer and Advancement
Act of 1995 (NTTAA), Public Law 104–
113, section 12(d) (15 U.S.C. 272)
directs NHTSA to use voluntary
consensus standards in its regulatory
activities unless doing so would be
inconsistent with applicable law or
otherwise impractical. Voluntary
consensus standards are technical
standards (e.g., materials specifications,
test methods, sampling procedures, and
business practices) that are developed or
adopted by voluntary consensus
standards bodies. The NTTAA directs
NHTSA to provide Congress, through
OMB, explanations when the agency
decides not to use available and
applicable voluntary consensus
standards.
The following voluntary consensus
standards have been used in developing
the THOR–50M:
• SAE J211–1, Instrumentation for
impact test—Part 1: Electronic
Instrumentation, Version 2014–03–31
• SAE J1733, Sign Convention for
Vehicle Crash Testing, Version 2007–
11–02.
• SAE J2570, Performance
specifications for anthropomorphic test
device transducers, Version 2009–08–
12.
• SAE J2876, Low Speed Knee Slider
Test Procedure for the Hybrid III 50th
Male Dummy, Version 2015–05–07.
• ISO–MME Task Force, 2015–04–15
proposed mnemonic codes for the
THOR–50M.
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Unfunded Mandates Reform Act
The Unfunded Mandates Reform Act
of 1995 (Pub. L. 104–4) (UMRA)
requires agencies to prepare a written
assessment of the costs, benefits, and
other effects of proposed or final rules
that include a Federal mandate likely to
result in the expenditures by States,
local or tribal governments, in the
aggregate, or by the private sector, of
$100 million or more (adjusted annually
for inflation with base year of 1995) in
any one year. Adjusting this amount by
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the implicit gross domestic product
price deflator for 2022 results in $177
million (111.416/75.324 = 1.48). The
assessment may be included in
conjunction with other assessments, as
it is here. UMRA requires the agency to
select the ‘‘least costly, most costeffective or least burdensome alternative
that achieves the objectives of the rule.’’
This proposed rule would not impose
any unfunded mandates under the
UMRA. This proposed rule does not
meet the definition of a Federal mandate
because it does not impose requirements
on anyone. It amends 49 CFR part 572
by adding design and performance
specifications for a 50th percentile adult
male frontal crash test dummy that the
agency could use in FMVSS No. 208
and for research purposes. This
proposed rule would affect only those
businesses that choose to manufacture
or test with the dummy. It would not
result in costs of $100 million or more
(adjusted for inflation) to either State,
local, or tribal governments, in the
aggregate, or to the private sector.
Plain Language
Executive Order 12866 and E.O.
13563 require each agency to write all
rules in plain language. Application of
the principles of plain language
includes consideration of the following
questions:
• Have we organized the material to
suit the public’s needs?
• Are the requirements in the rule
clearly stated?
• Does the rule contain technical
language or jargon that isn’t clear?
• Would a different format (grouping
and order of sections, use of headings,
paragraphing) make the rule easier to
understand?
• Would more (but shorter) sections
be better?
• Could we improve clarity by adding
tables, lists, or diagrams?
• What else could we do to make the
rule easier to understand?
If you have any responses to these
questions, please include them in your
comments on this proposal.
Regulation Identifier Number
The Department of Transportation
assigns a regulation identifier number
(RIN) to each regulatory action listed in
the Unified Agenda of Federal
Regulations. The Regulatory Information
Service Center publishes the Unified
Agenda in April and October of each
year. You may use the RIN contained in
the heading at the beginning of this
document to find this action in the
Unified Agenda.
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Privacy Act
In accordance with 5 U.S.C. 553(c),
DOT solicits comments from the public
to better inform its rulemaking process.
DOT posts these comments, without
edit, to www.regulations.gov, as
described in the system of records
notice, DOT/ALL–14 FDMS, accessible
through www.dot.gov/privacy. In order
to facilitate comment tracking and
response, we encourage commenters to
provide their name, or the name of their
organization; however, submission of
names is completely optional. Anyone
is able to search the electronic form of
all comments received into any of our
dockets by the name of the individual
submitting the comment (or signing the
comment, if submitted on behalf of an
association, business, labor union, etc.).
You may review DOT’s complete
Privacy Act Statement in the Federal
Register published on April 11, 2000
(Volume 65, Number 70; Pages 19477–
78).
XIII. Public Participation
How do I prepare and submit
comments?
Your comments must be written and
in English. To ensure that your
comments are correctly filed in the
Docket, please include the agency name
and the docket number or Regulatory
Identification Number (RIN) in your
comments.
Your comments must not be more
than 15 pages long. (49 CFR 553.21). We
established this limit to encourage you
to write your primary comments in a
concise fashion. However, you may
attach necessary additional documents
to your comments. There is no limit on
the length of the attachments.
If you are submitting comments
electronically as a PDF (Adobe) file,
NHTSA asks that the documents be
submitted using the Optical Character
Recognition (OCR) process, thus
allowing NHTSA to search and copy
certain portions of your submissions.
Please note that pursuant to the Data
Quality Act, in order for substantive
data to be relied upon and used by the
agency, it must meet the information
quality standards set forth in the OMB
and DOT Data Quality Act guidelines.
Accordingly, we encourage you to
consult the guidelines in preparing your
comments. OMB’s guidelines may be
accessed at https://
www.transportation.gov/regulations/
dot-information-dissemination-qualityguidelines.
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How can I be sure that my comments
were received?
If you wish the Docket to notify you
upon its receipt of your comments,
enclose a self-addressed, stamped
postcard in the envelope containing
your comments. Upon receiving your
comments, the Docket will return the
postcard by mail.
How do I submit confidential business
information?
You should submit a redacted ‘‘public
version’’ of your comment (including
redacted versions of any additional
documents or attachments) to the docket
using any of the methods identified
under ADDRESSES. This ‘‘public version’’
of your comment should contain only
the portions for which no claim of
confidential treatment is made and from
which those portions for which
confidential treatment is claimed has
been redacted. See below for further
instructions on how to do this.
You also need to submit a request for
confidential treatment directly to the
Office of Chief Counsel. Requests for
confidential treatment are governed by
49 CFR part 512. Your request must set
forth the information specified in Part
512. This includes the materials for
which confidentiality is being requested
(as explained in more detail below);
supporting information, pursuant to Part
512.8; and a certificate, pursuant to Part
512.4(b) and Part 512, Appendix A.
You are required to submit to the
Office of Chief Counsel one unredacted
‘‘confidential version’’ of the
information for which you are seeking
confidential treatment. Pursuant to Part
512.6, the words ‘‘ENTIRE PAGE
CONFIDENTIAL BUSINESS
INFORMATION’’ or ‘‘CONFIDENTIAL
BUSINESS INFORMATION
CONTAINED WITHIN BRACKETS’’ (as
applicable) must appear at the top of
each page containing information
claimed to be confidential. In the latter
situation, where not all information on
the page is claimed to be confidential,
identify each item of information for
which confidentiality is requested
within brackets: ‘‘[ ].’’
You are also required to submit to the
Office of Chief Counsel one redacted
‘‘public version’’ of the information for
which you are seeking confidential
treatment. Pursuant to Part 512.5(a)(2),
the redacted ‘‘public version’’ should
include redactions of any information
for which you are seeking confidential
treatment (i.e., the only information that
should be unredacted is information for
which you are not seeking confidential
treatment).
NHTSA is currently treating
electronic submission as an acceptable
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method for submitting confidential
business information to the agency
under Part 512. Please do not send a
hardcopy of a request for confidential
treatment to NHTSA’s headquarters.
The request should be sent to Dan
Rabinovitz in the Office of the Chief
Counsel at Daniel.Rabinovitz@dot.gov.
You may either submit your request via
email or request a secure file transfer
link. If you are submitting the request
via email, please also email a courtesy
copy of the request to John Piazza at
John.Piazza@dot.gov.
Authority: 49 U.S.C. 322, 30111, 30115,
30117 and 30166; delegation of authority at
49 CFR 1.95.
Will the agency consider late
comments?
§ 572.220
We will consider all comments
received before the close of business on
the comment closing date indicated
above under DATES. To the extent
possible, we will also consider
comments that the docket receives after
that date. If the docket receives a
comment too late for us to consider in
developing a final rule (assuming that
one is issued), we will consider that
comment as an informal suggestion for
future rulemaking action.
How can I read the comments submitted
by other people?
You may read the comments received
by the docket at the address given above
under ADDRESSES. The hours of the
docket are indicated above in the same
location. You may also see the
comments on the internet. To read the
comments on the internet, go to https://
www.regulations.gov. Follow the online
instructions for accessing the dockets.
Please note that even after the
comment closing date, we will continue
to file relevant information in the docket
as it becomes available. Further, some
people may submit late comments.
Accordingly, we recommend that you
periodically check the Docket for new
material. You can arrange with the
docket to be notified when others file
comments in the docket. See
www.regulations.gov for more
information.
List of Subjects in 49 CFR Part 572
Motor vehicle safety, Incorporation by
reference.
Proposed Regulatory Text
In consideration of the foregoing,
NHTSA proposes to amend 49 CFR part
572 as follows:
PART 572—ANTHROPOMORPHIC
TEST DEVICES
1. The authority citation for part 572
continues to read as follows:
■
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2. Add Subpart X, consisting of
§§ 572.220 through 572.221, to read as
follows:
■
Subpart X—THOR–50M 50th Percentile Male
Frontal Impact Test Dummy
Secs.
572.220 Incorporation by reference.
572.221 General description.
Subpart X—THOR–50M 50th Percentile
Male Frontal Impact Test Dummy
Incorporation by reference.
Certain material is incorporated by
reference (IBR) into this part with the
approval of the Director of the Federal
Register under 5 U.S.C. 552(a) and 1
CFR part 51. To enforce any edition
other than that specified in this section,
NHTSA must publish a document in the
Federal Register and the material must
be available to the public. This material
is available for inspection at the
Department of Transportation, the
National Archives and Records
Administration (NARA), and in
electronic format through
regulations.gov. Contact DOT at:
Department of Transportation, Docket
Operations, Room W12–140, 1200 New
Jersey Avenue SE, Washington DC
20590, telephone 202–366–9826. For
information on the availability of this
material at NARA, email fr.inspection@
nara.gov or go to www.archives.gov/
federal-register/cfr/ibr-locations. To
locate the material on regulations.gov,
search for Docket No. NHTSA–202X–
XXXX. The material may be obtained
from the source:
(a) NHTSA Technical Information
Services, 1200 New Jersey Ave. SE,
Washington, DC 20590, telephone 202–
366–5965.
(1) A drawing package entitled,
‘‘THOR–50th Percentile Male with
Alternate Shoulders Frontal Crash Test
Dummy (THOR–50M Male w/Alt.
Shoulders) Drawings, External
Dimensions, and Mass Properties,’’
dated (and revised) January 2023
(Drawings and Specifications); IBR
approved for § 572.221.
(2) A parts list entitled, ‘‘Parts List,
THOR–50th Percentile Male Frontal
Crash Test Dummy with Alternate
Shoulders (THOR–50M w/Alt.
Shoulders)’’ dated (and revised) January
2023 (Parts List); IBR approved for
§ 572.221.
(3) A procedures document entitled
‘‘THOR 50th Percentile Male (THOR–
50M) Procedures for Assembly,
Disassembly, and Inspection (PADI)’’
dated (and revised) June 2023 (PADI);
IBR approved for § 572.221.
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(4) A procedures document entitled
‘‘THOR 50th Percentile Male (THOR–
50M) Qualification Procedures and
Requirements’’ dated (and revised)
April 2023 (Qualification Procedures);
IBR approved for § 572.221.
§ 572.221
General description.
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(a) The THOR–50M 50th percentile
male test dummy is defined by the
following materials:
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(1) The Drawings and Specifications
(incorporated by reference, see
§ 572.220);
(2) The Parts List (incorporated by
reference, see § 572.220);
(3) The PADI (incorporated by
reference, see § 572.220);
(4) The Qualification Procedures
(incorporated by reference, see
§ 572.220).
PO 00000
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Issued under authority delegated in 49 CFR
1.95, 501.4, and 501.
Ann Carlson,
Acting Administrator.
[FR Doc. 2023–19008 Filed 9–6–23; 8:45 am]
BILLING CODE 4910–59–P
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]]>Agencies
[Federal Register Volume 88, Number 172 (Thursday, September 7, 2023)]
[Proposed Rules]
[Pages 61896-61949]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-19008]
[[Page 61895]]
Vol. 88
Thursday,
No. 172
September 7, 2023
Part VI
Department of Transportation
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National Highway Traffic Safety Administration
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49 CFR Part 572
Anthropomorphic Test Devices; THOR 50th Percentile Adult Male Test
Dummy; Incorporation by Reference; Proposed Rule
Federal Register / Vol. 88, No. 172 / Thursday, September 7, 2023 /
Proposed Rules
[[Page 61896]]
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DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration
49 CFR Part 572
[Docket No. NHTSA-2023-0031]
RIN 2127-AM20
Anthropomorphic Test Devices; THOR 50th Percentile Adult Male
Test Dummy; Incorporation by Reference
AGENCY: National Highway Traffic Safety Administration (NHTSA),
Department of Transportation (DOT).
ACTION: Notice of proposed rulemaking (NPRM).
-----------------------------------------------------------------------
SUMMARY: This document proposes to amend NHTSA's regulations to include
an advanced crash test dummy, the Test Device for Human Occupant
Restraint (THOR) 50th percentile adult male (THOR-50M). The dummy
represents an adult male of roughly average height and weight and is
designed for use in frontal crash tests. NHTSA plans to issue a
separate NPRM to amend Federal Motor Vehicle Safety Standard (FMVSS)
No. 208, ``Occupant crash protection,'' to specify the THOR-50M as an
alternative (at the vehicle manufacturer's option) to the 50th
percentile adult male dummy currently specified in FMVSS No. 208 for
use in frontal crash compliance tests.
DATES: You should submit your comments early enough to be received not
later than November 6, 2023.
Proposed Effective Date: Since this rulemaking action would not
impose requirements on anyone, we are proposing that the final rule
would be effective on publication in the Federal Register.
ADDRESSES: You may submit comments electronically to the docket
identified in the heading of this document by visiting the Federal
eRulemaking Portal at https://www.regulations.gov. Follow the online
instructions for submitting comments.
Alternatively, you can file comments using the following methods:
Mail: Docket Management Facility: U.S. Department of
Transportation, 1200 New Jersey Avenue SE, West Building Ground Floor,
Room W12-140, Washington, DC 20590-0001.
Hand Delivery or Courier: West Building Ground Floor, Room
W12-140, 1200 New Jersey Avenue SE, between 9 a.m. and 5 p.m. ET,
Monday through Friday, except Federal holidays. To be sure someone is
there to help you, please call (202) 366-9826 before coming.
Fax: (202) 493-2251.
Instructions: All submissions must include the agency name and
docket number or Regulatory Information Number (RIN) for this
rulemaking. For detailed instructions on submitting comments and
additional information on the rulemaking process, see the Public
Participation heading of the Supplementary Information section of this
document. Note that all comments received will be posted without change
to https://www.regulations.gov, including any personal information
provided. Please see the Privacy Act heading below.
Docket: For access to the docket to read background documents or
comments received, go to https://www.regulations.gov. You may also
access the docket at 1200 New Jersey Avenue SE, West Building, Room
W12-140, Washington, DC 20590, between 9 a.m. and 5 p.m., Monday
through Friday, except Federal Holidays. Telephone: 202-366-9826.
Confidential Business Information: If you claim that any of the
information in your comment (including any additional documents or
attachments) constitutes confidential business information within the
meaning of 5 U.S.C. 552(b)(4) or is protected from disclosure pursuant
to 18 U.S.C. 1905, please see the detailed instructions given under the
Public Participation heading of the Supplementary Information section
of this document.
Privacy Act: Please see the Privacy Act heading under the
Regulatory Analyses section of this document.
FOR FURTHER INFORMATION CONTACT: For non-legal issues, you may contact
Mr. Garry Brock, Office of Crashworthiness Standards, Telephone: (202)
366-1740; Email: [email protected]; Facsimile: (202) 493-2739. For
legal issues, you may contact Mr. John Piazza, Office of Chief Counsel,
Telephone: (202) 366-2992; Email: [email protected]; Facsimile: (202)
366-3820. The address of these officials is: the National Highway
Traffic Safety Administration, 1200 New Jersey Avenue SE, Washington,
DC 20590.
SUPPLEMENTARY INFORMATION:
Table of Contents
I. Executive Summary
II. Background
III. Design, Construction, and Instrumentation
A. Anthropometry
B. Technical Data Package
C. Head and Face
D. Neck
E. Chest
1. Design
2. Instrumentation
F. Shoulder
1. Alternate Shoulder Specification
2. Shoulder Slip
G. Hands
H. Spine
I. Abdomen
J. Pelvis
K. Upper Leg
L. Knee
M. Lower Leg
N. Data Acquisition System
IV. Biofidelity
V. Qualification Tests
A. Head Impact
B. Face Impact
C. Neck
D. Upper Thorax
E. Lower Thorax
F. Abdomen
G. Upper Leg
H. Knee and Lower Leg
VI. Repeatability and Reproducibility
A. Qualification Tests
B. Sled Tests
1. Methodology
2. Thoracic Injury Criteria Development Sled Tests
3. Low-Speed Belted Sled Tests
4. Low-Speed Unbelted Sled Tests
VII. Overall Usability and Performance
A. Assembly and Qualification
B. Durability and Maintenance
1. Elevated Energy Qualification Test Series
2. Oblique OMDB Test Series
3. FMVSS No. 208 Unbelted Vehicle Crash Tests
C. Sensitivity to Restraint System Performance
VIII. Intellectual Property
IX. Consideration of Alternatives
X. Lead Time
XI. Incorporation by Reference
XII. Regulatory Analyses
XIII. Public Participation
Proposed Regulatory Text
I. Executive Summary
This document proposes to amend NHTSA's regulation on
anthropomorphic test devices--or, more colloquially, crash test
dummies--to include an advanced crash test dummy, the Test Device for
Human Occupant Restraint (THOR) 50th percentile adult male (THOR-50M).
The dummy represents an adult male of roughly average height and weight
and is designed for use in frontal crash tests.
Crash test dummies are complex instruments that simulate the
response of a human occupant in a crash. Each type of test dummy is
designed for use in specific types of crashes (for instance, frontal or
side) and is instrumented with sensors to measure the forces that would
have been experienced by a human occupant in a similar crash in the
real world. These measurements are then used to assess the potential
for injury.
Crash test dummies are used by NHTSA and by the broader vehicle
safety community in a variety of ways.
[[Page 61897]]
NHTSA uses crash test dummies to test vehicles for compliance with
Federal Motor Vehicle Safety Standards (FMVSSs) and to determine
vehicle crashworthiness ratings for the New Car Assessment Program's
(NCAP) 5-Star Safety Ratings, as well as to conduct vehicle safety
research. Crash test dummies are also used by regulatory authorities in
other countries and regions, third-party vehicle rating programs, motor
vehicle and equipment manufacturers, and others to evaluate vehicle
safety and design safer vehicles and equipment.
The dummies NHTSA currently uses in FMVSS compliance testing and
NCAP are documented in 49 CFR part 572, Anthropomorphic Test Devices.
Part 572 sets out detailed design information, including engineering
drawings and procedures for assembly and inspection. These are intended
to describe the dummy with sufficient detail so that it is an objective
measuring tool that produces consistent responses. NHTSA has codified
numerous dummies that range in sex, size, age, and measurement
capability. This includes dummies representing midsize adult males,
small-stature adult females, infants, toddlers, and older children.\1\
These dummies are meant to provide a range of body types in order to
maximize data and test results that can assess injury and fatality
risks in a range of crash outcomes. The 50th percentile male dummy
currently defined in Part 572 for frontal impacts is the Hybrid III-
50M, which NHTSA uses to test for compliance with the frontal crash
test requirements in FMVSS No. 208, ``Occupant crash protection'' and
to rate vehicles for NCAP. NHTSA added the HIII-50M to Part 572 in
1986.
---------------------------------------------------------------------------
\1\ This reflects a ``bookend'' approach to testing vehicles for
crashworthiness, in which a range of occupant types, bookended by an
average male and a small-stature female, is tested. NHTSA is
currently supporting research to assess the possible benefits of
developing new crash test dummies, such as a 50th percentile female
crash test dummy.
---------------------------------------------------------------------------
NHTSA is continually researching and improving its test dummies and
has been researching advanced test dummies since the implementation of
the HIII-50M. An initial THOR-50M design was published in 2001. There
are currently two different THOR dummies, the THOR-50M, and one under
development that represents a small-statured adult female, the THOR 5th
percentile adult female (THOR-05F). Although this proposal is limited
to the THOR-50M, we anticipate publishing a rulemaking proposal in the
near future to add the THOR-05F to Part 572.
The THOR-50M improves on the HIII-50M in a number of ways. It
responds more like a human occupant in a crash and its advanced
instrumentation enables it to more accurately measure the forces acting
on the dummy. As a result, it is better able to predict the risk of
injury to a human occupant. This should help vehicle designers develop
and test improved occupant restraint systems (e.g., advanced seat belts
and air bags) as well as the types of novel vehicle seating
configurations likely to be used in highly automated vehicles.
NHTSA has tentatively concluded that the THOR-50M is sufficiently
biofidelic, exhibits repeatable and reproducible performance, and is
sufficiently durable. As such, we believe that it would be suitable for
use in regulatory compliance testing and is therefore suitable for
incorporation into Part 572. NHTSA and others have already taken
advantage of the THOR-50M's advanced capabilities. NHTSA, vehicle and
restraint manufacturers, and vehicle safety researchers have used the
THOR-50M to evaluate vehicle crashworthiness and develop occupant
protection countermeasures for frontal and oblique crashes. The
European New Car Assessment Programme (Euro NCAP) has officially
adopted the THOR-50M and is currently rating vehicles using the dummy.
Moreover, the Economic Commission for Europe is considering adopting
the THOR-50M for use in frontal crash testing under its vehicle safety
regulations.
NHTSA expects a variety of benefits from incorporating the THOR-50M
into Part 572. The definition of the THOR-50M in Part 572 will enable
its use in regulatory and consumer information programs, both within
NHTSA and externally. NHTSA believes that the THOR-50M's enhancements
will lead to more effective restraint system designs and more
informative comparisons of the safety of different vehicles. Because of
this--as well as the fact that manufacturers are already using the
dummy--we believe vehicle manufacturers would choose to certify
vehicles to FMVSS No. 208 using the THOR-50M if given the option. This
would enable manufacturers to streamline testing by using the same
dummy for research and development and to verify compliance. NHTSA
anticipates issuing a proposal in the near future to amend FMVSS No.
208 to specify the THOR-50M as an alternative (at the vehicle
manufacturer's option) to the HIII-50M test dummy for use in frontal
crash compliance tests. There would be other benefits as well. For
instance, NHTSA's test dummies are used in a range of applications
beyond FMVSS compliance testing--such as NCAP testing, standards and
regulations in other transportation modes, and research. Including the
dummy design in Part 572 will help provide a suitable, standardized,
and objective test tool for the safety community.
II. Background
This document proposes to amend 49 CFR part 572, Anthropomorphic
Test Devices, to include an advanced test dummy representing a 50th
percentile adult male, the Test Device for Human Occupant Restraint
(THOR-50M).\2\ The THOR-50M is a test dummy designed for use in frontal
crash tests. It has several advanced capabilities and advantages over
the Hybrid III 50th percentile male test dummy (HIII-50M) that is
currently specified in Part 572 and used in frontal crash testing under
FMVSS No. 208, ``Occupant crash protection,'' and the U.S. New Car
Assessment Program (NCAP).\3\ NHTSA plans to issue a proposal in the
near future to amend FMVSS No. 208 to specify the THOR-50M as an
alternative to the HIII-50M for use in frontal crash tests.\4\
---------------------------------------------------------------------------
\2\ NHTSA has registered the term ``THOR'' as a trademark (U.S.
Registration No. 5,104,395).
\3\ The HIII-50M is also specified for use in FMVSS No. 202a,
Head Restraints, in an optional rear impact dynamic test.
\4\ FMVSS No. 208 THOR-50M Compliance Option (RIN 2127-AM21),
Spring 2023 Unified Agenda of Regulatory and Deregulatory Actions;
Department of Transportation, available at https://www.reginfo.gov/public/do/eAgendaViewRule?pubId=202304&RIN=2127-AM21.
---------------------------------------------------------------------------
This document proposes incorporating by reference in Part 572 a
parts list, design drawings, qualification procedures, and procedures
for assembly, disassembly, and inspection, to ensure that THOR-50M
dummies are uniform in design, construction, and response. This section
provides background on NHTSA's crash test dummies, the development of
the THOR-50M, and its use in other jurisdictions, among other topics.
Overview of Use of Vehicle Crash Test Dummies
Anthropomorphic Test Devices (ATDs)--or crash test dummies--are
complex instruments that serve as human surrogates in vehicle crash
tests (among other types of tests \5\). Test dummies simulate the
response of a human occupant in a crash and measure
[[Page 61898]]
the effects of the crash forces on the occupant. They are used to
estimate the severity of the injuries that would have been experienced
by a human occupant in a similar crash in the real world. Each type of
test dummy is designed for use in specific types of crashes (frontal,
side, etc.), and is instrumented with a wide array of sensors to
measure the forces that would be relevant in the type of crash for
which it is designed and to assess the potential for injury. The more
closely a dummy represents how an actual human would respond, the more
biofidelic the dummy is considered to be.
---------------------------------------------------------------------------
\5\ NHTSA also uses ATDs in sled tests (which simulate a vehicle
crash by using a simplified test buck to represent a vehicle), and
out-of-position air bag tests. ATDs are also used outside the
vehicle safety context to measure human responses in a variety of
other areas, such as aviation and aeronautics.
---------------------------------------------------------------------------
NHTSA and the vehicle safety community use crash test dummies in a
variety of ways. NHTSA uses crash test dummies for vehicle compliance
testing, safety ratings, and safety research. NHTSA's Federal Motor
Vehicle Safety Standards establish mandatory minimum safety performance
requirements for motor vehicles and motor vehicle equipment. Vehicles
and equipment manufactured for sale in the United States must be
certified to comply with all applicable FMVSSs. A number of the FMVSSs
specify crash tests, using specified dummies, that the vehicle must be
certified as passing.\6\ NHTSA's vehicle safety compliance program
selects vehicles (and equipment) for compliance testing every year;
this includes crash testing vehicles to ensure that they comply with
the performance requirements that are evaluated by means of crash
tests. NHTSA's NCAP also evaluates vehicle performance in crash tests
using dummies as part of its 5-Star Safety Ratings. Finally, NHTSA's
vehicle safety research program uses crash test dummies to evaluate new
vehicle safety countermeasures and develop new vehicle crash testing
protocols. Dummies are also used outside of NHTSA by regulatory
authorities in other countries and regions, for third-party ratings
(such as Insurance Institute for Highway Safety ratings), and by
industry and the vehicle safety community to measure performance and
design safer vehicles.
---------------------------------------------------------------------------
\6\ The FMVSS specify the procedures NHTSA will use in
compliance testing, including what dummies it will use for testing.
Part 572 specifies the dummies. While manufacturers must exercise
reasonable care in certifying that their products meet applicable
standards, they are not required to follow the compliance test
procedures set forth in a standard or use the dummy specified in
Part 572. See, e.g., 38 FR 12934, 12935 (May 17, 1973)
(``Manufacturers should understand that they are not required to
test their products in any particular manner, as long as they
exercise due care that their products will meet the requirements
when tested by the NHTSA under the procedures specified in the
standard.'').
---------------------------------------------------------------------------
The dummies NHTSA currently uses in FMVSS compliance testing and in
NCAP are documented in 49 CFR part 572, Anthropomorphic Test Devices.
Part 572 sets out detailed design information, including engineering
drawings and procedures for assembly and inspection. These are all
intended to describe the dummy with sufficient detail so that it
produces consistent responses when it is tested under similar
conditions in repeated tests at the same laboratory (repeatability) or
between multiple dummies manufactured to the same specification used at
different test laboratories (reproducibility).
FMVSS No. 208 Frontal Crash Tests Using a 50th Percentile Male Dummy
FMVSS No. 208, ``Occupant crash protection,'' specifies a variety
of different requirements using crash test dummies. This includes
frontal crash tests in which the vehicle is moving and tests that are
performed with a stationary vehicle and are intended to help ensure
that air bags do not harm small-stature occupants and children. The
test dummies used in FMVSS No. 208 were designed to evaluate vehicle
performance in frontal crashes and are fitted with a variety of
instruments to measure the forces typically experienced by an occupant
in a frontal crash.\7\ The 50th percentile male dummy that is currently
specified for use in FMVSS No. 208 is the Hybrid III-50M.\8\ The HIII-
50M has been specified in FMVSS No. 208 since 1986,\9\ and replaced an
even earlier dummy, the Hybrid II. FMVSS No. 208 also specifies tests
using dummies representing a 5th percentile female, a 6-year-old, a 3-
year-old, and an infant.\10\
---------------------------------------------------------------------------
\7\ Other FMVSS specify different types of crash or sled tests
that use different dummies. For example, FMVSS No. 214, Side Impact
Protection, specifies two crash tests (simulating a side impact with
a vehicle and a pole impact). This test uses two different side
impact dummies.
\8\ Part 572, Subpart E.
\9\ 51 FR 26688 (July 25, 1986) (final rule adding HIII-50M).
The Hybrid III-50M was developed by General Motors and added to Part
572 and for use in FMVSS No. 208 in response to a petition for
rulemaking from GM.
\10\ This reflects a ``bookend'' approach to testing vehicles
for crashworthiness, in which a range of occupant types, bookended
by an average male and a small-stature female, is tested. NHTSA is
currently supporting research to assess the possible benefits of
developing new crash test dummies, such as a 50th percentile female
crash test dummy.
---------------------------------------------------------------------------
FMVSS No. 208 specifies two tests (both of which are crash tests)
using the HIII-50M: a crash test in which the dummy is belted and the
test vehicle, traveling up to 35 mph, impacts a rigid barrier at a
ninety-degree angle or perpendicular; \11\ and a crash test in which
the dummy is unbelted and the test vehicle, traveling 20-25 mph,
impacts a rigid barrier at an angle ranging from 30
degrees oblique from perpendicular.\12\ NCAP also evaluates vehicle
performance in a frontal crash test at 35 mph using a belted HIII-50M
dummy.
---------------------------------------------------------------------------
\11\ S5.1.1(b)(2), S14.5.1(b).
\12\ S5.1.2(b), S14.5.2.
---------------------------------------------------------------------------
FMVSS No. 208 regulates vehicle performance in these crash tests by
specifying injury criteria and associated injury assessment reference
values (IARVs). Injury criteria and their respective risk functions
relate instrumentation measurements to a predicted risk of human
injury. Each IARV is a maximum value or threshold for a specific injury
criterion that may not be exceeded when the vehicle is tested with the
specified dummy under the specified test conditions and procedures. For
example, FMVSS No. 208 specifies a head injury criterion,
HIC15, with an IARV of 700. Thus, if NHTSA runs a compliance
frontal crash test and the calculated HIC15 value exceeds
700, this would be considered an apparent noncompliance. FMVSS No. 208
specifies the following injury criteria for the HIII-50M: a head injury
criterion (HIC15); \13\ a thoracic acceleration criterion;
\14\ a chest deflection criterion; \15\ a criterion based on the
maximum force transmitted axially through the upper leg (femur); \16\
and three neck injury criteria.\17\
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\13\ S6.2(b).
\14\ S6.3.
\15\ S6.4.
\16\ S6.5.
\17\ S6.6.
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Development of the THOR ATDs
NHTSA has continually conducted research into advancements in crash
safety, including the development of advanced dummies.\18\ The goal of
this research has been to create ATDs that represent the responses of
human occupants in modern vehicle environments with advanced restraint
systems. This research has led to the development of the two Test
Device for Human Occupant Restraint (THOR) ATDs, designed primarily for
use in frontal and frontal oblique motor vehicle crash environments.
There are currently two main implementations of the THOR design, both
representing seated motor vehicle occupants: one representing a 50th
percentile male and
[[Page 61899]]
one representing a 5th percentile female.
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\18\ Haffner, M., Rangarajan, N., Artis, M., Beach, D.,
Eppinger, R., Shams, T., ``Foundations and Elements of the NHTSA
THOR Alpha ATD Design,'' The 17th International Technical Conference
for the Enhanced Safety of Vehicles, Paper No. 458, 2001.
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Development of THOR-50M
The initial design version of the THOR-50M, introduced in 2001, was
the THOR Alpha.\19\ The THOR Alpha, which integrated some components
from the earlier prototype demonstrator known as the Trauma Assessment
Device, introduced some of the features that exist in the current
version of THOR-50M, including the multi-direction neck, human-like
ribcage geometry and impact response, multi-point thorax and abdomen
deflection measurement system, and instrumented lower extremities.
NHTSA refined the THOR Alpha design and reintroduced it in 2005 as the
THOR-NT,\20\ which included updates to anthropometry, durability,
usability, biofidelity, and fit and finish. In 2011, NHTSA, in
coordination with the SAE International (SAE) THOR Evaluation Task
Group, introduced a modification package (Mod Kit) intended to enhance
the biofidelity, repeatability, durability, and usability of the THOR-
NT.\21\ After the introduction of the THOR Mod Kit, an upgrade to the
Chalmers shoulder assembly that was developed through the European
Union's THORAX project was integrated into the THOR-50M design.\22\ The
THOR-50M drawing package was then converted from the traditional
measurement system to the metric system through soft conversion (where
any non-metric measurements are mathematically converted to metric
equivalents without changes to the physical dimensions). All fasteners
were also replaced with the nearest metric equivalents. NHTSA made this
integrated drawing package (with incremental improvements and
corrections) publicly available online in 2015,\23\ 2016,\24\ 2020,\25\
and 2023.\26\ The version published in 2023 is referred to as the 2023
drawing package, which consists of two-dimensional drawings and a Parts
list; this, together with the Procedures for Assembly, Disassembly, and
Inspection (PADI), and qualification procedures, is referred to as the
2023 technical data package. (The version published in 2020 is referred
to as the ``2018 drawing package'' or the ``2018 technical data
package.'') The version of THOR that is being proposed is the version
defined in the 2023 technical data package. In 2019, NHTSA began
publishing THOR-50M documentation in a new docket titled, ``NHTSA
Crashworthiness Research--THOR-50M Documentation.'' \27\ In addition to
the documents that make up the 2018 and 2023 technical data packages,
the docket folder includes the following: durability report; seating
procedure; injury criteria; biofidelity report; Oblique Moving
Deformable Barrier (OMDB) Repeatability and Reproducibility (R&R); and
Qualification test R&R. This documentation is discussed further in
Section III.B and in the relevant sections of this preamble.\28\ NHTSA
has tentatively concluded that the THOR-50M is sufficiently biofidelic,
exhibits repeatable and reproducible performance, and is sufficiently
durable. As such, we believe that it would be suitable for use in
regulatory compliance testing and is therefore suitable for
incorporation into Part 572. A more detailed discussion of the
technical data package is provided in Section III.B.
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\19\ Id.
\20\ Shams, T., Rangarajan, N., McDonald, J., Wang, Y., Platten,
G., Spade, C., Pope, P., Haffner, M., ``Development of THOR NT:
Enhancement of THOR Alpha--the NHTSA Advanced Frontal Dummy,'' The
19th International Technical Conference for the Enhanced Safety of
Vehicles, Paper No. 05-0455, 2005.
\21\ Ridella, S., Parent, D., ``Modifications to Improve the
Durability, Usability, and Biofidelity of the THOR-NT Dummy,'' The
22nd International Technical Conference for the Enhanced Safety of
Vehicles, Paper No. 11-0312, 2011.
\22\ Lemmen, P., Been, B., Carroll, J., Hynd, D., Davidsson, J.,
Song, E., Lecuyer, E., ``Development of an advanced frontal dummy
thorax demonstrator,'' Proceedings of the 2012 IRCOBI Conference,
2012.
\23\ National Highway Traffic Safety Administration (2015).
Parts List and Drawings, THOR-M Advanced Frontal Crash Test Dummy,
September 2015. Regulations.gov Docket ID NHTSA-2015-0119-0005,
available at: https://www.regulations.gov/document/NHTSA-2015-0119-0005 (NCAP docket).
\24\ National Highway Traffic Safety Administration (2016).
Parts List and Drawings, THOR-50M Advanced Frontal Crash Test Dummy,
August 2016, available at: https://www.nhtsa.gov/es/document/thor-50m-drawing-package-august-2016.pdf.
\25\ National Highway Traffic Safety Administration. Parts List
and Drawings, THOR-50M Advanced Frontal Crash Test Dummy, August
2018. Regulations.gov Docket ID NHTSA-2019-0106-0002, available at:
https://www.regulations.gov/document/NHTSA-2019-0106-0002.
\26\ National Highway Traffic Safety Administration. THOR 50th
Percentile Male with Alternate Shoulders Frontal Crash Test Dummy
Drawings, External Dimensions, and Mass Properties, THOR-50M
Advanced Frontal Crash Test Dummy, August 2018. Regulations.gov
Docket ID NHTSA-2019-0106-0013, available at: https://www.regulations.gov/document/NHTSA-2019-0106-0013.
\27\ Docket NHTSA-2019-0106.
\28\ These documents are located in the research docket, Docket
No. NHTSA-2019-0106. NHTSA is not placing copies of these documents
in the docket for this rulemaking action in order to avoid potential
confusion from having identical documents docketed at different
times in different dockets. Nevertheless, NHTSA intends these to be
included as part of the rulemaking record for this rulemaking
action. A memorandum explaining this is also being placed in the
docket for this rulemaking.
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Development of THOR-05F
NHTSA understands that the risk of injury in a crash can depend on
the occupant's physical characteristics (e.g., height, weight, bone
density) and how they interact with the restraint system and vehicle
environment. To that end, NHTSA has developed comprehensive research
plans to address differences in crashworthiness safety testing and
outcomes, including differences in injury risk. Human body modeling
research efforts are underway to consider female and male occupants and
vulnerable road users of various ages, shapes, and sizes. This includes
continuing and accelerating research efforts to address differences in
motor vehicle safety based on physical characteristics, including sex,
and making data-driven decisions supported by the research outcomes. A
series of efforts is specifically focused on female occupant crash
safety, spanning field data analysis, tool development, demonstration,
and application.\29\
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\29\ See National Highway Traffic Safety Administration (2022).
NHTSA Female Crash Safety Research Plan, November 2022.
Regulations.gov Docket ID NHTSA-2022-0091-0002, available at:
https://www.regulations.gov/document/NHTSA-2022-0091-0002.
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As part of these efforts, NHTSA has been developing the THOR 5th
percentile adult female frontal crash test dummy (THOR-05F). The THOR-
05F represents a small adult female and has a seated height of 81.3 cm
(32.0 in), approximate standing height of 151 cm (59.4 in), and weight
of 49 kg (108.0 lbs). The THOR-05F has improved measurement
capabilities over the Hybrid III-5F, which is specified in FMVSS No.
208 and documented in Part 572. The THOR-05F's instrumentation is
similar to that of the THOR-50M. Improved designs resulting from the
development of the THOR-50M related to the head, neck, thorax, and
lower extremities have also been incorporated into the design of the
THOR-05F. Currently, NHTSA is evaluating the THOR-05F's biofidelity and
durability, developing design updates, injury criteria, and
documentation, and assessing its utility in full-scale crash testing.
NHTSA anticipates completing the research and testing necessary to
support a rulemaking for the THOR-05F
[[Page 61900]]
in 2023.\30\ Possible test modes in which THOR-05F may be used include
FMVSS No. 208 testing and NCAP frontal crash tests. NHTSA has placed
documentation and research for the THOR-05F in an online docket and
will continue adding additional research and information to this docket
as it becomes available.\31\
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\30\ Part 572 THOR 5th Female Crash Test Dummy (RIN 2127-AM56),
Spring 2023 Unified Agenda of Regulatory and Deregulatory Actions;
Department of Transportation, available at https://www.reginfo.gov/public/do/eAgendaViewRule?pubId=202304&RIN=2127-AM56. This
rulemaking would amend 49 CFR part 572 by adding design and
performance specifications for a new test dummy known as the THOR-
05F.
\31\ See Docket No. NHTSA-2019-0107, available at
regulations.gov.
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Innovative Features of the THOR-50M
Frontal crashes are the leading cause of injuries and fatalities in
occupants of motor vehicle crashes on U.S. public roadways. The vehicle
front is the initial point of impact in a majority of crashes in the
U.S. In 2021, 15,570 occupants of passenger cars or light trucks died,
and 1,144,169 were injured, in frontal crashes.\32\ This suggests that
even though occupant protection systems have improved over the years
and saved many lives,\33\ improvements to occupant protection in
frontal crashes still need to be made.
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\32\ Data Sources: Fatality Analysis Reporting System (FARS):
2017-2020 Final File and 2021 Annual Report File (ARF); Report
Generated: Wednesday, June 28, 2023 (12:48:52 p.m.); VERSION 5.6,
RELEASED MAY 19, 2023
\33\ Charles J. Kahane, Lives Saved by Vehicle Safety
Technologies and Associated Federal Motor Vehicle Safety Standards,
1960 to 2012--Passenger Cars and LTVs--With Reviews of 26 FMVSS and
the Effectiveness of Their Associated Safety Technologies in
Reducing Fatalities, Injuries, and Crashes. 89 DOT HS 812 069 at 89,
Department of Transportation, National Highway Traffic Safety
Administration (2015).
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The THOR-50M is designed to better evaluate the effectiveness of
modern vehicle restraint systems and address the types of injuries that
continue to occur. These improvements include the following:
Improved biofidelity. Biofidelity is a measure of how well a dummy
replicates the response of a human. The THOR-50M was designed with
advanced features that enable it to have improved biofidelity compared
to the HIII-50M. The dummy's head includes a deformable facial insert
that emulates human response to impact. The components in the neck
representing bone and ligament structure are separate from those
representing muscular structure, improving both kinematic response and
injury prediction. The thorax simulates the shape and impact response
of the human rib cage. The spine incorporates flexible joints in the
thoracic and lumbar spine, allowing dynamic spine flexion as well as
static adjustment in the neck and lumbar spine to accommodate seating
in various postures. The upper leg has a compressive element in the
femur and the lower leg has a compressive element in the tibia and an
Achilles tendon load path to achieve human-like impact response. The
biofidelity of the THOR-50M has been assessed in a wide array of both
component and full-body test conditions for which human response is
known and was found to be both qualitatively and quantitatively
congruent with human response corridors.
Improved instrumentation. The THOR-50M has both improved and
additional instrumentation compared to the HIII-50M. The thorax
instrumentation measures the three-dimensional deformation of the rib
cage at four locations. The abdomen is also designed with a multi-point
measurement system that monitors three-dimensional deformation of the
abdomen at two locations. The upper leg includes an acetabulum load
cell in the pelvis to measure load transfer from the femur to the hip.
The lower leg has extensive instrumentation to support injury risk
calculation.
Improved injury prediction. The biofidelity of the THOR-50M,
combined with its extensive instrumentation, provides an enhanced
capability to measure expected human response and predict injury.
Injury criteria and injury risk functions, which relate instrumentation
measurements to a predicted risk of human injury, have been developed
for the head, neck, chest, abdomen, pelvis, upper leg, and lower leg of
the THOR-50M.\34\ These include injury criteria analogous to those
currently specified for the HIII-50M in FMVSS No. 208 as well as injury
criteria that are not currently specified for the HIII-50M in FMVSS No.
208. We believe this enhanced injury prediction capability will
translate into restraint system designs that have the potential to
enhance occupant protection. NHTSA and others, including vehicle
manufacturers, have already taken advantage of these capabilities in
the research arena.
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\34\ Craig, M., Parent, D., Lee, E., Rudd, R., Takhounts, E.,
Hasija, V. (2020). Injury Criteria for the THOR 50th Male ATD.
Regulations.gov Docket ID NHTSA-2019-0106-0008, available at:
https://www.regulations.gov/document/NHTSA-2019-0106-0008.
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Improved evaluation of vehicle performance. These enhancements
allow the THOR-50M to better differentiate the performance of different
vehicles and restraint systems. The more sophisticated measurement
capabilities of an advanced ATD are better suited to develop and test
more sophisticated and highly tunable contemporary restraint systems
with features such as multi-stage air bags and force-limiting/
pretensioning seat belts. Motor vehicle manufacturers and restraint
suppliers have already used the THOR-50M to evaluate vehicle
crashworthiness and develop occupant protection countermeasures.
Numerous conference and journal articles describing the use of the
THOR-50M have been published. For example, in a study examining the
performance of different restraint systems in frontal impact sled tests
using both the THOR-50M and HIII-50M, the THOR-50M was found to be more
sensitive to the restraint conditions, as it was able to differentiate
between both crash severity and restraint performance.\35\ Another
study investigated a novel air bag system with three inflated chambers
with a connected sail panel to promote earlier engagement with the
occupant and prevent lateral motion and head rotation; sled testing
using the THOR-50M demonstrated a reduction in brain injury risk due to
head angular velocity, as quantified using the Brain Injury Criterion
(BrIC).\36\ Other studies have also implemented the THOR-50M to assess
and develop restraint systems.\37\
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\35\ Sunnev[aring]ng, C., Hynd, D., Carroll, J., Dahlgren, M.,
``Comparison of the THORAX Demonstrator and HIII Sensitivity to
Crash Severity and Occupant Restraint Variation,'' Proceedings of
the 2014 IRCOBI Conference, Paper No. IRC-14-42, 2014.
\36\ Hardesty, J. (2021). Next-Generation Passenger Airbag. SAE
Government-Industry Digital Summit (oral only).
\37\ See also, e.g., Hu, J., Reed, M. P., Rupp, J. D., Fischer,
K., Lange, P., & Adler, A. (2017). Optimizing seat belt and airbag
designs for rear seat occupant protection in frontal crashes (No.
2017-22-0004). SAE Technical Paper; Eggers, A., Eickhoff, B.,
Dobberstein, J., Zellmer, H., Adolph, T. (2014). Effects of
Variations in Belt Geometry, Double Pretensioning and Adaptive Load
Limiting on Advanced Chest Measurements of THOR and Hybrid III.
Proceedings of the 2014 IRCOBI Conference, Paper No. IRC-14-40; Hu,
J., Fischer, K., Schroeder, A., Boyle, K., Adler, A., & Reed, M.
(2019, October). Development of oblique restraint countermeasures
(Report No. DOT HS 812 814). Washington, DC: National Highway
Traffic Safety Administration. Available at: https://rosap.ntl.bts.gov/view/dot/44143.
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Adoption of the THOR-50M in Europe
In 2013, the European Commission (EC) issued a final report
detailing the need for a new crash test dummy as a means to implement
regulatory requirements for new vehicle safety technologies,
particularly those technologies that reduce thorax injuries in frontal
crashes.\38\ At the time, the
[[Page 61901]]
THOR-50M was envisioned as the best evaluation tool for this purpose.
In 2015, United Nations Economic Commission for Europe (UNECE)
Regulation No. 137 (R137) went into effect. R137 specifies a 50 km/h,
full-width rigid barrier frontal impact test with driver and passenger
HIII-50M and HIII-5F dummies respectively. One objective of the
regulation was to encourage better restraint systems across a wider
range of collision severities.\39\
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\38\ European Commission, Seventh Framework Programme, THORAX
Project Final Report, Thoracic injury assessment for improved
vehicle safety, 1/7/2013.
\39\ Seidl, M., Edwards, M., Barrow, A., Hynd, D., & Broertjes,
P. (2017). The Expected Impact of UN Regulation No. 137 Tests on
European Cars and Suggested Test Protocol Modifications to Maximise
Benefits. In 25th International Technical Conference on the Enhanced
Safety of Vehicles (ESV).
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In 2017, an ECE-funded study found that the R137 condition and
dummy diversity were not sufficiently different to existing UN
Regulation No. 94 (R94) to force improvements in restraint systems. R94
involves a 56 km/h frontal offset test which also prescribes the HIII-
50M in the driver and right front seat. To deliver the expected
benefits, the 2017 final report recommended implementation of the THOR-
50M in R137 as a replacement for the HIII-50M.\40\ The THOR-50M was
recognized as being more biofidelic in its representation of thoracic
response and prediction of thorax injuries, which are the key serious
and fatal injury types in full-width collisions targeted by R137.
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\40\ Seidl M, Hynd D, McCarthy M, Martin P, Hunt R, Mohan S,
Krishnamurthy V and O'Connell S: TRL Ltd. (2017). In depth cost-
effectiveness analysis of the identified measures and features
regarding the way forward for EU vehicle safety, Final Report, ISBN
978-92-79-68704-4, European Commission, 08-31-2017.
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In 2018, the EC published a report on the cost-effectiveness and
the number of future injuries and fatalities that could be prevented at
a European level for different sets of vehicle safety measures.\41\
Several new sets of safety measures were considered for mandatory
implementation in new vehicles starting from 2022. This included the
introduction of the THOR-50M into R137. The THOR-50M was considered for
inclusion in a program titled ``Full-width Frontal Occupant Protection
with THOR (FFW-THO),'' which would lower injury criteria thresholds to
encourage implementation of adaptive restraints. It was envisioned that
the implementation of the THOR-50M would result in an initial cost of
16 Euros per vehicle, for vehicles that currently comply with UN
Regulation No. 137 with Hybrid III ATDs but not with THOR-50M ATDs. It
was estimated that vehicles that comply with FFW-THO would provide a 6%
increase in effectiveness in protecting against serious injuries
compared to vehicles that comply with R137 alone.
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\41\ Seidl, M., Khatry, R., Carroll, J., Hynd, D., Wallbank, C.,
Kent, J. (2018) Cost-effectiveness analysis of Policy Options for
the mandatory implementation of different sets of vehicle safety
measures--Review of the General Safety and Pedestrian Safety
Regulations, Technical Annex to GSR2 report SI2.733025.
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In 2019, the EC presented work priorities to WP.29 \42\ for 2019-
2021 for UNECE activities. An amendment to introduce the THOR-50M into
R137 was included. The target date for a WP.29 vote was listed as Q4/
2021.\43\ In 2020, Japan and the EC jointly initiated discussions
within WP.29 to establish a priority for the new task. In preparation
for an eventual adoption into R137, the E.C. commissioned TRL
(Transport Research Laboratory, UK) \44\ to conduct a survey of various
stakeholders on the readiness of the THOR-50M. ATD manufacturers, crash
test laboratories, and crash safety research laboratories were
consulted. The results of the survey are contained within Annex 7 of a
broader report on general safety regulations, published by the E.C. in
2021.\45\ In the E.C. report, there are a number of recommendations
based on stakeholder feedback. They include revisions to the dummy
design and qualification procedures that may be needed prior to
adopting THOR-50M into M.R. 1 \46\ and R137. Most stakeholders
recommended the formation of either an Informal Working Group or a
Technical Evaluation Group under the umbrella of UNECE WP.29 to co-
ordinate this activity. As of May 2023, a WP.29 working group has yet
to be established and timelines for amendments to R137 and M.R. 1 are
undetermined. The areas for further investigation identified in Annex 7
are discussed in this NPRM.
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\42\ This was a thrice-annual briefing on the regulatory status
within the various working parties under WP.29's World Forum for
Harmonization of Vehicle Regulations, including the status of R137
under the Working Party for Passive Safety (GRSP).
\43\ WP.29-177-18, 177th WP.29, 12-15 March 2019, EU Work
priorities for 2019-2021 for UNECE activities.
\44\ TRL serves as an independent advisory to the E.C. TRL's
report was performed under contract with the European Commission
(E.C.), who sought to update the General Safety Regulation for
Europe to include new and developing technologies with the aim of
reducing Europe's annual road fatalities. The report reflects TRL's
recommendations for consideration by the E.C.
\45\ General Safety Regulation: Technical study to assess and
develop performance requirements and test protocols for various
measures implementing the new General Safety Regulation, for
accident avoidance and vehicle occupant, pedestrian and cyclist
protection in case of collisions, Final Report, March 2021,
Publications Office of the EU (europa.eu)), ISBN 978-92-76-08556-0,
DOI 10.2873/499942, Catalogue number, ET-04-19-467-EN-N. https://op.europa.eu/en/publication-detail/-/publication/6987b729-a313-11eb-9585-01aa75ed71a1/language-en/format-PDF/source-217672351 (last
accessed 5/25/2023).
\46\ Mutual Resolution No. 1 (M.R.1) of the 1958 and the 1998
Agreements. Concerning the description and performance of test tools
and devices necessary for the assessment of compliance of wheeled
vehicles, equipment and parts according to the technical
prescriptions specified in Regulations and global technical
regulations, ECE/TRANS/WP.29/1101, 10 January 2013.
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Although the ECE has not yet officially adopted the THOR-50M, the
European New Car Assessment Programme (Euro NCAP) has been rating
vehicles using the dummy. Euro NCAP has implemented a moving
progressive deformable barrier (MPDB) frontal impact testing protocol
with a THOR-50M in the driver's seat.\47\ The THOR-50M used by Euro
NCAP is specified in Technical Bulletin 026 (TB026) \48\ ``THOR
Specification and Certification.''TB026 explicitly adopts--with some
variations--NHTSA's 2018 technical data package (i.e., the 2018 drawing
package,\49\ qualification procedures,\50\ and PADI \51\). The
variations to the 2018 technical data package are relatively limited.
For example, TB026 specifies an onboard (in-dummy) data acquisition
system and a variation to the adjustable spine to facilitate data
acquisition system (DAS) installation; minor deviations in the shoulder
assembly; and the use of the HIII-50M lower legs. These modifications
are discussed in more detail in the relevant sections of the preamble
and are summarized in Section IX, Consideration of alternatives.
NHTSA's understanding is that no regulatory authorities or third-party
vehicle rating programs other than Euro NCAP currently specify the
THOR-50M for use in vehicle crash tests.
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\47\ European New Car Assessment Programme (2022). MPDB Frontal
Impact Testing Protocol, Version 1.1.3, available at: https://www.euroncap.com/en/for-engineers/protocols/adult-occupant-protection/.
\48\ European New Car Assessment Programme (2023). THOR
Specification and Certification, Version 1.3, available at: https://www.euroncap.com/en/for-engineers/supporting-information/technical-bulletins/.
\49\ Sec. 1.1.
\50\ Sec. 2.1.
\51\ Sec. 3.1.
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Motor vehicle and equipment manufacturers' interest in the design
and operation of the THOR-50M has been heightened since the dummy was
introduced into Euro NCAP and plans for R137 were announced.
Discussions are taking place within International Standards
Organization (ISO) Technical Committee 22 (Road Vehicles), Sub-
Committee 36 (Safety and impact testing), Working Group 5
(Anthropomorphic test devices) for
[[Page 61902]]
modifications suggested by manufacturers. With no defined European
entity to maintain configuration control, ISO has enlisted Humanetics
Innovative Solutions, Inc. (Humanetics) to investigate its change
recommendations directly. In particular, discussions have taken place
regarding modifications to the shoulder pad and rib guide. These
modifications are discussed in the relevant sections of the NPRM.
Need for This Rulemaking
NHTSA expects a variety of benefits from incorporating the THOR-50M
in Part 572. The THOR-50M is an advanced dummy with many advantages
over existing dummies with respect to biofidelity, instrumentation, and
injury prediction. NHTSA believes that the THOR-50M's enhancements will
lead to more effective restraint system designs and more informative
comparisons of the safety of different vehicles. Euro NCAP has adopted
it, the ECE is considering it for use in R137, and it is likely being
used by vehicle and restraint manufacturers for testing, research, and
development. Therefore, we believe vehicle manufacturers would choose
to certify new vehicles using the THOR-50M if given the option, because
this would enable manufacturers to streamline testing by using the same
dummy for research and development and to verify compliance and vehicle
ratings. NHTSA is therefore also considering a proposal to amend FMVSS
No. 208 to give vehicle manufacturers the option of selecting the THOR-
50M for use in belted and unbelted crash testing instead of the HIII-
50M.\52\
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\52\ FMVSS No. 208 THOR-50M Compliance Option (RIN 2127-AM21),
Fall 2023 Unified Agenda of Regulatory and Deregulatory Actions;
Department of Transportation, available at https://www.reginfo.gov/public/do/eAgendaViewRule?pubId=202304&RIN=2127-AM21. This
rulemaking would propose injury assessment reference values for the
THOR-50M comparable to the IARVs currently specified for the HIII-
50M.
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There would be other benefits as well. For instance, the THOR-50M
is well-suited for the types of new seating configurations brought on
by vehicles with Automated Driving Systems (ADS). NHTSA is developing
an adaptation of the THOR-50M that is better suited for reclined
postures which may be prevalent among ADS occupants.\53\ NHTSA's test
dummies are also used in a range of applications beyond FMVSS
compliance testing--such as NCAP testing, standards and regulations in
other transportation modes, and research. While the purpose of Part 572
is to describe the anthropomorphic test devices that are to be used for
compliance testing of motor vehicles and motor vehicle equipment with
motor vehicle safety standards,\54\ it also serves as a definition of
the ATD for other purposes, such as consumer information crash testing,
standards and regulations in other transportation modes, and research.
As such, it would be to the benefit of government, academia, and the
multi-modal transportation industry to include a definition of the
THOR-50M ATD in Part 572.\55\
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\53\ Forman, J., Caudillo-Huerta, A., McMahon, J., Panzer, M.,
Marshall, W., Winter, D., Dyer, M., Lemmen, P. (2021). Modifications
to the THOR-50M for Improved Usability in Reclined Postures--Update
and Preliminary Findings. 2021 SAE Government-Industry Digital
Summit, available at: https://www.nhtsa.gov/node/103691. The
adaptation to the THOR-50M design for use in reclined seating
environments is outside of the scope of this Part 572 NPRM.
\54\ 49 CFR 572.1.
\55\ For example, American Public Transportation Association
standard APTA PR-CS-S-018-13 Rev. 1 describes the use of a THOR ATD
in the testing of fixed workstation tables in passenger rail cars.
American Public Transportation Association. (2015, October). Fixed
Workstation Tables in Passenger Rail Cars. PR-CS-S-018-13, Rev. 1.
Washington, DC, available at: https://www.apta.com/wp-content/uploads/Standards_Documents/APTA-PR-CS-S-018-13-Rev-1.pdf.
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III. Design, Construction, and Instrumentation
In this section we discuss the anthropometry, design, construction,
and instrumentation of the THOR-50M.
A. Anthropometry
The THOR-50M is a physical model of a 50th percentile male motor
vehicle occupant. It is intended for use in the development and
evaluation of vehicle safety countermeasures and vehicle safety
performance in frontal crash tests. To ensure that the dummy responds
in a human-like manner in a vehicle crash environment, it is necessary
that the size and shape of the dummy, referred to as anthropometry,
provide an accurate representation of a mid-sized male. The
anthropometry of the THOR-50M is based on a study by the University of
Michigan Transportation Research Institute that documented the
anthropometry of a mid-sized (50th percentile in stature and weight)
male occupant in an automotive seating posture (AMVO
study).56 57 This study defines an average male as 76.57 kg
(168.8 lb) in weight with a standing height of 175.1 cm (68.9 in). The
AMVO study is currently internationally accepted as the standard
anthropometry for the 50th percentile male ATD. The THOR-50M has a mass
of 77.37 kg (170.6 lb) and a seated height of 101.8 cm (40.2 in). The
standing height of the ATD cannot be measured since the pelvis does not
allow a full standing posture; however, since it was developed using
the AMVO body segment geometry and seated anthropometry, it is assumed
that the stature of the THOR-50M is also 175.1 cm.
---------------------------------------------------------------------------
\56\ Schneider, L.W., Robbins, D.H., Pflug, M.A., Snyder, R. G.,
``Development of Anthropometrically Based Design Specifications for
an Advanced Adult Anthropomorphic Dummy Family; Volume 1-Procedures,
Summary Findings and Appendices,'' U.S. Department of
Transportation, DOT-HS-806-715, 1985.
\57\ Robbins, D.H., ``Development of Anthropometrically Based
Design Specifications for an Advanced Adult Anthropomorphic Dummy
Family; Volume 2-Anthropometric Specifications for mid-Sized Male
Dummy; Volume 3- Anthropometric Specifications for Small Female and
Large Male Dummies,'' U.S. Department of Transportation, DOT-HS-806-
716 & 717, 1985.
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The THOR-50M is consistent with the AMVO anthropometry. NHTSA
compared the dimensions of a representative dummy (S/N 9798) with the
AMVO target dimensions (Table 1).\58\ The AMVO procedure originally
used to collect measurements from volunteers was adapted to collect the
same or similar measurements on the THOR-50M.\59\ Most of these
measurements were taken with the THOR-50M seated on the AMVO bench,
which has an angled seat and backrest. One adaptation was necessary to
collect leg measurements on the AMVO bench: the THOR-50M has an
integrated molded shoe that cannot be separated from its foot, while
the AMVO data were collected on barefoot volunteers. To remedy this
situation, the THOR-50M measurements were recorded after removing the
entire molded shoe assembly and positioning the center of the ankle
joint at the same location as the AMVO ankle landmark. Another
adaptation was that four of the measurements were collected with the
THOR-50M seated on a 90-degree bench, as specified on drawing 472-0000,
Sheet 4. NHTSA also compared
[[Page 61903]]
the body segment masses specified in the proposed THOR drawing package
(472-0000, Sheet 5) with the AMVO body segment masses (Table 2), and
the masses were also consistent.
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\58\ A THOR-50M unit is a collection of serialized parts that
can be swapped out with other dummies, so is not considered a
``serialized'' dummy. Indeed, many of the subassemblies that were
part of S/N 9798 when NHTSA took these measurements were
subsequently swapped out of the dummy. See Section VII.A.
\59\ These AMVO measurements were collected as an assessment of
anthropometry; it is understood that there is variation in initial
position and measurement methodology that prevents the use of such
measurements as a repeatable dimensional assessment. In practice, a
simplified set of dimensional requirements are put in place as a
check for overall part fit, tolerance stack, and to ensure that the
dummy is assembled correctly. These requirements are specified on
drawing 472-0000, Sheet 4, and are collected following the
``Procedures for Measuring External Dimensions'' section of the
PADI.
Table 1--THOR-50M Anthropometry Compared to AMVO
------------------------------------------------------------------------
AMVO target
Dimensions (all measurements in (Robbins et al THOR-50M S/N
centimeters) 1983) 9798
------------------------------------------------------------------------
Height of top of head to floor.......... 100.3 101.8
Height of shoulder to floor............. 72.1 74.2
H-point to knee joint distance (note 1). 43.2 42.3
Buttock to knee end distance (note 2)... 59.3 62.0
Height of knee from floor............... 45.3 47.0
Head circumference...................... 57.1 58.7
Head top-chin distance.................. 19.7 22.9
Head breadth............................ 15.8 15.3
Chest circumference..................... 101.1 95.5
Chest breadth........................... 34.9 30.9
Chest depth (note 3).................... 22.7 22.4
Abdomen circumference................... 91.3 99.0
Abdomen breadth......................... 32.5 32.5
Abdomen depth (note 2).................. 26.9 29.8
Pelvis breadth.......................... 38.5 38.8
Thigh max circumference................. 57.9 56.8
Thigh max breadth....................... 19.4 17.1
Mid thigh circumference................. 50.4 56.0
Mid thigh breadth....................... 15.5 17.8
Calf circumference...................... 37.3 37.5
Calf breadth............................ 11.0 9.1
Calf depth.............................. 11.8 11.9
------------------------------------------------------------------------
\1\ THOR-50M specified on 472-0000, Sh. 4, measurement F (Knee Pivot to
Hip Pivot) as seated upright on a 90-degree bench.
\2\ THOR-50M and AMVO measured as seated upright on a 90-degree bench.
\3\ THOR-50M specified on 472-0000, Sh. 4, measurement I (Rib #3 depth)
as seated upright on a 90-degree bench without jacket installed.
Table 2--THOR-50M Body Segment Masses Compared to AMVO
------------------------------------------------------------------------
AMVO target THOR-50M
Body segment masses (all measurements in (Robbins et al specification
kilograms) 1983) *
------------------------------------------------------------------------
Head.................................... 4.137 4.501
** (4.55)
Neck.................................... 0.965 2.363
Thorax.................................. 23.763 23.517
Lower Abdomen........................... 2.365 2.664
Pelvis.................................. 11.414 15.229
Upper Arm, Left or Right................ 1.769 1.701
Lower Arm with Hand, Left or Right...... 2.022 2.227
Upper Leg, Left or Right................ 8.614 5.618
Lower Legs, Left or Right............... 3.587 3.396
Feet, Left or Right including shoe...... *** 1.551 1.604
-------------------------------
Total Weight........................ 76.562 77.366
------------------------------------------------------------------------
* Listed on Drawing No. 472-0000, Sh. 5.
** Mass reported in Melvin JW, Weber, K. ``Task B Final Report: Review
of Biomechanical Impact Response and Injury in the Automotive
Environment,'' U.S. Department of Transportation, DOT-HS-807-042,
1985. The AMVO target is believed to be too low.
*** This adds the mass of a size 11 Oxford shoe (0.57 kg) specified for
use in FMVSS No. 208 for the HIII-50M) to the AMVO specification of
0.981 kg so as to be comparable to the THOR's foot-within-a-molded-
shoe mass.
B. Technical Data Package
The construction of the THOR-50M is similar to other ATDs currently
defined in Part 572, with a metallic frame largely covered in urethane
and/or vinyl representing flesh; body segments connected by
translational and rotational joints; and deformable rubber or foam
elements to prevent hard contact between metallic surfaces and to
provide human-like impact response. The kinematic and dynamic
biomechanical performance requirements of the THOR-50M were developed
based on post-mortem human subject (PMHS) and volunteer response data,
described in Section IV, Biofidelity.
The THOR-50M that we are proposing in this NPRM is the version
defined in the 2023 technical data package (consisting of two-
dimensional engineering drawings and a Parts list; procedures for
assembly, disassembly, and inspection (PADI); and qualification
procedures). The 2023 technical data package also includes an addendum
with the drawings and drawing/parts list for an alternate configuration
with an in-dummy data acquisition system, as discussed in Section
III.N, Data Acquisition System. It is anticipated that, upon
finalization of this proposal,
[[Page 61904]]
the in-dummy DAS drawings will be fully integrated within the relevant
technical data package components. The technical data package is
summarized in Table 3. For these documents, the NPRM cites to the
document location in the research docket. NHTSA is not placing copies
of these documents in the rulemaking docket, in order to avoid
potential confusion from having identical documents docketed at
different times in different dockets. However, NHTSA intends these to
be included as part of the rulemaking record. A memo explaining this is
also being included in the rulemaking docket. In addition, as noted in
the background section, NHTSA began publishing the technical data
package to its website starting in 2015. The 2023 technical data
package updates the 2018 technical data package. These updates were
made to address typographical errors, improve clarity, and add
alternative design elements. Table 4 summarizes these updates.
Table 3--THOR-50M Technical Data Package
------------------------------------------------------------------------
Title Link
------------------------------------------------------------------------
THOR 50th Percentile Male with https://www.regulations.gov/
Alternate Shoulders Frontal Crash Test document/NHTSA-2019-0106-0013.
Dummy Drawings, External Dimensions,
and Mass Properties.
*THOR-50M DAS Integration Kit Drawings, https://www.regulations.gov/
April 2023. document/NHTSA-2019-0106-0019.
*Parts List, THOR-50M DAS Integration https://www.regulations.gov/
Kit, April 2023. document/NHTSA-2019-0106-0018.
Parts List, THOR 50th Percentile Male https://www.regulations.gov/
Frontal Crash Test Dummy with document/NHTSA-2019-0106-0015.
Alternate Shoulders.
THOR 50th Percentile Male (THOR-50M): https://www.regulations.gov/
Procedures for Assembly, Disassembly, document/NHTSA-2019-0106-0017.
and Inspection (PADI): June 2023.
THOR 50th Percentile Male (THOR-50M) https://www.regulations.gov/
Qualification Procedures and document/NHTSA-2019-0106-0010.
Requirements, April 2023.
------------------------------------------------------------------------
* The DAS Integration Kit drawings and drawing/parts list would not
themselves be incorporated by reference into Part 572. It is
anticipated that, upon finalization of this proposal, these documents
will be fully integrated within the relevant technical data package
components.
Table 4--Summary of Updates Made in the 2023 THOR-50M Technical Data
Package
------------------------------------------------------------------------
Technical Data Package
Element Revisions in 2023 Version
------------------------------------------------------------------------
Drawing Package.............. Includes drawings for alternate shoulder,
removal of notes suggesting that
qualification specifications supersede
drawing specifications, and changes to
correct typographical drawing errors.
Complete change log found in ``THOR-50th
Percentile Male with Alternate Shoulders
(THOR-50M w/ALT. SHOULDERS) Drawing
Revisions''.\60\
PADI......................... Minor typographical changes; complete
change log found in Section 20 of ``THOR
50th Percentile Male (THOR-50M)
Procedures for Assembly, Disassembly,
and Inspection (PADI)''.
Qualification Procedures..... Revised upper leg qualification test
mode, adjusted language to be more
prescriptive, removed unit conversions,
and corrected typographical errors.
Complete change log found in Appendix B
of ``THOR 50th Percentile Male (THOR-
50M) Qualification Procedures and
Requirements, April 2023''.
------------------------------------------------------------------------
Below we briefly discuss several aspects of the technical data
package in more detail.
---------------------------------------------------------------------------
\60\ See Table 5.
---------------------------------------------------------------------------
Engineering Drawings and Parts List
The engineering drawings and parts list specify the configuration
of the THOR-50M. Included in the drawings are the required dimensions
and tolerances, material properties, and component or material testing
requirements and associated specifications. In a few instances, the
drawings specify quasi-static tests and/or performance requirements for
individual parts (such as a compression or flexion test for a molded
part or subassembly); however, passing a specified performance (or
qualification) test is not an alternate criterion for accepting a part
that deviates from the drawing specifications.\61\ All instruments are
specified by corresponding SA572-xxx drawings.\62\ SA drawings are
included for associated mounts and hardware that are not otherwise
needed when the dummy is configured with a corresponding structural
replacement. Brand name call-outs are only used for parts and materials
that have widespread availability and are used for a wide variety of
non-ATD applications. It includes materials widely identified by their
tradenames, such as Teflon, Acetal, Lexan, and Nitinol. Call-outs are
also used for bonding agents, fasteners, and other items that are also
widely available for non-ATD applications.
---------------------------------------------------------------------------
\61\ In the drawings which were part of the August 2018
technical data package, several notes state that ``qualification
takes precedence over design.'' These notes were unintentionally
carried over from earlier drawing versions used during THOR-50M
development, and have since been removed. These are reflected in the
proposed 2023 technical data package. In cases where some
flexibility is allowed in order to meet the qualification
specification, a ``REF.'' prefix is added to specific dimensions or
material specifications.
\62\ This convention is used for all instruments on all Part 572
dummies. SA572 simply indicates that it is an instrument, and Sxx is
the next-in-line number assigned by NHTSA to the instrument. Some
load cells (and part numbers) are used on different Part 572 subpart
dummies. For THOR, this applies to SA572-S4 (accelerometer) which is
used on many other dummies.
---------------------------------------------------------------------------
In some instances, the drawing package permits two different part
or instrumentation configurations that are both fully specified. For
example, the head accelerometer mounting plate assembly drawing (472-
1200) calls out three different angular rate sensors (SA572-S56, SA572-
S57, or SA572-S58) which may be desired by the end user depending on
the implementation of the ATD.\63\ In the sections below on specific
body regions we discuss the proposed as well as alternate designs and
instrumentations that are not included in the proposed specifications
but which we are considering specifying in the final rule and on which
we are seeking comment. If NHTSA were to use the dummy for FMVSS
compliance testing, NHTSA could test with any alternative
configurations at its own discretion. Thus, the IARVs would have
[[Page 61905]]
to be met using a dummy with any permissible configuration.
Manufacturers are not required to test their products in any particular
manner, as long as they exercise due care that their products will meet
the requirements when tested by NHTSA under the procedures specified in
the standard, including the relevant dummy specified in Part 572.\64\
However, a manufacturer would not be able to claim that a vehicle fully
complies with a standard if it meets the standard's requirements in
only one of the dummy's configurations, but not the other.
---------------------------------------------------------------------------
\63\ Similar situations exist with currently federalized ATDs,
such as the HIII-10C, where either a chest slider pot or an IR-TRACC
is permissible.
\64\ See, e.g., 38 FR 12934, 12935 (May 17, 1973)
(``Manufacturers should understand that they are not required to
test their products in any particular manner, as long as they
exercise due care that their products will meet the requirements
when tested by the NHTSA under the procedures specified in the
standard.'').
---------------------------------------------------------------------------
In addition to the engineering drawings that would be incorporated
by reference, we are also providing supplemental documentation on the
form and function of the THOR-50M. These reference materials are
summarized in Table 5. These files would not be incorporated by
reference in Part 572 and would therefore not be part of the THOR-50M
specification. Instead, they are intended only for reference purposes
(e.g., to facilitate fabrication and inspection of parts with intricate
geometries).
Table 5--THOR-50M Design Reference Documentation
------------------------------------------------------------------------
Title Link
------------------------------------------------------------------------
THOR-50M Drawing Package--2D AutoCAD https://static.nhtsa.gov/nhtsa/
Jan 2023. downloads/
THOR_50M_Drawing_Package/NPRM/
THOR-
50M%20with%20Alternate%20Shoul
ders%20Jan%202023-
AutoCAD%20DWG%20Files.zip.
THOR-50M Drawing Package--3D Inventor https://static.nhtsa.gov/nhtsa/
Format Jan 2023. downloads/
THOR_50M_Drawing_Package/NPRM/
THOR-
50M%20with%20Alternate%20Shoul
ders%20Jan%202023-
Inventor%20Files.zip.
THOR-50M Drawing Package--3D STEP https://static.nhtsa.gov/nhtsa/
Format Jan 2023. downloads/
THOR_50M_Drawing_Package/NPRM/
THOR-
50M%20DAS%20Integration%20Kit-
3D%20STEP%20Files_April%202023
.zip.
THOR 50th Percentile Male with https://www.regulations.gov/
Alternate Shoulders Drawing Revisions, document/NHTSA-2019-0106-0014.
Jan 2023.
THOR-50M DAS Integration Kit--2D https://static.nhtsa.gov/nhtsa/
AutoCAD, April 2023. downloads/
THOR_50M_Drawing_Package/NPRM/
THOR-
50M%20DAS%20Integration%20Kit-
AutoCAD%20DWG%20Files_April%20
2023.zip.
THOR-50M DAS Integration Kit--3D STEP https://static.nhtsa.gov/nhtsa/
Format, April 2023. downloads/
THOR_50M_Drawing_Package/NPRM/
THOR-
50M%20DAS%20Integration%20Kit-
3D%20STEP%20Files_April%202023
.zip.
THOR-50M DAS Integration Kit--Inventor https://static.nhtsa.gov/nhtsa/
Format, April 2023. downloads/
THOR_50M_Drawing_Package/NPRM/
THOR-
50M%20DAS%20Integration%20Kit-
Inventor%20Files_April%202023.
zip.
------------------------------------------------------------------------
The THOR-50M used by Euro NCAP is specified in Technical Bulletin
026, ``THOR Specification and Certification.'' \65\ TB026 explicitly
adopts--with some deviations--the 2018 drawing package.\66\ These
deviations in TB026 include specification of an onboard (in-dummy) data
acquisition system and a variation to the adjustable spine to
facilitate DAS installation; minor deviations in the shoulder assembly;
and the use of the HIII-50M lower legs. These modifications are
discussed in more detail in the relevant sections of the preamble, and
are summarized in Section IX, Consideration of alternatives. Euro NCAP
TB026 specifies the 2018 drawing package, while this proposal specifies
the 2023 drawing package. However, given the differences described in
Table 4 above, this deviation is likely to be inconsequential. The
deviations TB026 makes to the 2018 drawing package are not accompanied
by engineering drawings, which may tend to lessen the dummy's overall
objectivity. Objectivity is a statutory necessity for ATDs in Part 572.
While the lack of accompanying drawings for these deviations may be
adequate for the Euro NCAP rating program, it could lead to a future
population of THOR-50M units that are sufficiently non-uniform as to
render them unsuited for FMVSS applications.
---------------------------------------------------------------------------
\65\ European New Car Assessment Programme (2023). THOR
Specification and Certification, Version 1.3, available at: https://www.euroncap.com/en/for-engineers/supporting-information/technical-bulletins/.
\66\ Sec. 1.1.
---------------------------------------------------------------------------
PADI
The PADI provides step-by-step procedures on how to properly
assemble the dummy. This includes instructions on part alignment,
torque settings, wire routings, and other adjustments that are not
otherwise described in the engineering drawings. The PADI provides
explicit installation instructions for all instruments. Euro NCAP TB026
specifies the 2018 PADI,\67\ while this proposal specifies the 2023
PADI. However, the differences between the 2018 PADI and 2023 PADI are
primarily corrections to typographic errors, so this deviation is
likely to be inconsequential. In some instances, the drawing package
permits two different part or instrumentation configurations that are
(or will be in the final rule) both fully specified (for example, the
IR-TRACC and the S-Track for the chest instrumentation). The proposed
PADI does not currently contain installation instructions for the
optional parts (e.g. alternate shoulder) or instrumentation (e.g., the
S-Track). However, where multiple optional configurations are permitted
and installation differences are non-trivial, NHTSA anticipates
supplementing the PADI with such instructions in the final rule.
---------------------------------------------------------------------------
\67\ Sec. 3.1.
---------------------------------------------------------------------------
Qualification Procedures
The qualification procedures describe a series of impact tests
performed on a fully assembled dummy or sub-assembly. NHTSA has
established numeric bounds or acceptance intervals for the ATD
responses in these tests. The qualification procedures are discussed in
Section V.
[[Page 61906]]
Summary
NHTSA believes that the technical data package adequately describes
and would ensure the uniformity of the dummy. Upon finalization of this
proposal, a new subpart for the THOR-50M would be added to Part 572,
and the technical data package documents would be incorporated by
reference.
NHTSA seeks comment on whether the dummy is sufficiently specified
to ensure that dummies are uniform such that they will provide
repeatable and reproducible measurements. We also seek comment on
whether it would be useful to end-users of the dummy if NHTSA created a
list of suppliers used by NHTSA to obtain various parts and
instrumentation, and/or general specifications or operating
characteristics of a part (as provided by a manufacturer's
specification sheet). Such documentation would not be incorporated into
Part 572 but would be provided as a reference aid for users and could
be periodically updated by NHTSA.
C. Head and Face
The head of the THOR-50M is primarily constructed of a cast
aluminum skull covered in a urethane head skin. It includes two
features not seen on the HIII-50M: spring towers and a featureless
face. The spring towers are integral to the response of the head/neck
system, as they are the mounting location of the cables that represent
the musculature of the neck (described further in the following
section). The head is equipped with three uniaxial accelerometers and
three angular rate sensors at the head center of gravity (CG) to
measure translational acceleration and angular velocity, respectively.
The head also includes a biaxial tilt sensor which measures the quasi-
static orientation of the head for pre-test positioning purposes.
The face is constructed of an open-cell urethane foam sandwiched
between the head skin and the face load distribution plates. The
featureless face allows for more repeatable and reproducible
interactions with potential contact surfaces and meets enhanced
biomechanical response requirements which have not been implemented on
any existing ATDs. Additionally, the face can be configured with five
uniaxial load cells: left and right eye, left and right cheek, and
chin.\68\
---------------------------------------------------------------------------
\68\ These load cells have not been used in any tests currently
available in NHTSA's Vehicle or Biomechanics databases, and are
typically replaced with structural replacements during testing.
While the THOR-50M Qualification Procedure does include a face
impact test which would exercise the face load cells if installed,
there are currently no qualification specifications on face load
cell forces.
---------------------------------------------------------------------------
D. Neck
The neck of the THOR-50M is visibly and functionally different than
the ATDs currently defined in Part 572. While typical ATD designs use
only a pin joint between the base of the head and the upper neck load
cell, the THOR-50M neck is connected to the head via three separate
load paths: two cables (one anterior and one posterior) and a pin joint
between the base of the head and the upper neck load cell. These load
paths are independently instrumented, allowing the isolation of forces
and moments on the components representing bone and ligament from the
components representing muscles. This is expected to allow for improved
injury prediction for the cervical spine because the abbreviated injury
scale (AIS) 2+ injuries \69\ to the cervical spine in motor vehicle
crashes are most commonly fractures, so the ability to measure forces
and moments acting on the bones and ligaments separately from the
forces acting through the musculature allows a more accurate prediction
of these fractures.\70\
---------------------------------------------------------------------------
\69\ The Abbreviated Injury Scale (AIS) ranks individual
injuries by body region on a scale of 1 to 6: 1=minor,
2=moderate, 3=serious, 4=severe, 5=critical, and 6=maximum
(untreatable).
\70\ Craig, M., Parent, D., Lee, E., Rudd, R., Takhounts, E.,
Hasija, V. (2020). Injury Criteria for the THOR 50th Male ATD.
Docket ID NHTSA-2019-0106-0008, available at: https://www.regulations.gov/document/NHTSA-2019-0106-0008.
---------------------------------------------------------------------------
The biomechanical basis of the THOR-50M neck design is well-
established.71 72 The construction of the THOR-50M neck
allows the head to initially rotate relatively freely in the fore and
aft directions. This allows the head/neck assembly to demonstrate the
phenomenon known as head lag demonstrated by human volunteers in
restrained frontal loading conditions, where the rotation of the head
is delayed relative to the rotation of the neck.\73\ This phenomenon
results from the head initially translating forward with respect to the
base of the neck, which is attached to the restrained torso. The change
in angle of the head initially lags the change in angle of the line
between the head and the neck but catches up by the time of peak
excursion.
---------------------------------------------------------------------------
\71\ White RP., Zhoa Y., Rangarajan N., Haffner M., Eppinger R.,
Kleinberger M., ``Development of an Instrumented Biofidelic Neck for
the NHTSA Advanced Frontal Test Dummy,'' The 15th International
Technical Conference on the Enhanced Safety of Vehicles, Paper No.
96-210-W-19, 1996.
\72\ Hoofman, M., van Ratingen, M., and Wismans, J.,
``Evaluation of the Dynamic and Kinematic Performance of the THOR
Dummy: Neck Performance,'' Proceeding of the International
Conference on the Biomechanics of Injury (IRCOBI) Conference, pp.
497-512, 1998.
\73\ Thunnissen, J., Wismans, J., Ewing, C.L., Thomas, D.J.
(1995) Human Volunteer Head-Neck Response in Frontal Flexion: A New
Analysis. 39th Stapp Car Crash Conference, SAE Paper # 952721.
---------------------------------------------------------------------------
The instrumentation in the neck assembly includes spring load cells
which measure the compression at the anterior and posterior spring
locations, six-axis load cells at the top and base of the neck to
measure the forces and moments developed at these locations, and a
rotary potentiometer at the occipital condyle pin to measure the
relative rotation between the head and top of the neck. Due to the
multiple load paths of the neck, comparing THOR-50M neck forces and
moments to traditional single-load-path ATD designs is not
straightforward; the THOR-50M instrumentation would require post-
processing \74\ to represent the total neck forces and moments in order
to compare to the upper neck load cell measurements of a HIII-50M ATD.
However, as described in the THOR-50M Injury Criteria Report,\75\ post-
processing of the neck for calculation of neck injury risk is not
necessary.
---------------------------------------------------------------------------
\74\ GESAC, Inc (2005). Users Manual: THOR Instrumentation Data
Processing Program, Version 2.3; Appendix C: Procedure for
Calculating Head Loads at the Occipital Condyle from Neck Load Cell
Measurements. National Highway Traffic Safety Administration.
Available at: https://one.nhtsa.gov/DOT/NHTSA/NVS/Biomechanics%20&%20Trauma/THOR-NT%20Advanced%20Crash%20Test%20Dummy/THORTEST.zip.
\75\ Craig, M., Parent, D., Lee, E., Rudd, R., Takhounts, E.,
Hasija, V. (2020). Injury Criteria for the THOR 50th Male ATD.
Docket ID NHTSA-2019-0106-0008, available at: https://www.regulations.gov/document/NHTSA-2019-0106-0008.
---------------------------------------------------------------------------
E. Chest
Throughout the development of the THOR-50M ATD, specific attention
was given to the human-like response and injury prediction capability
of the chest. Below we discuss the design and instrumentation of the
THOR-50M chest.
1. Design
The THOR-50M's rib cage geometry is more realistic than the HIII-
50M because the individual ribs are angled downward to better match the
human rib orientation.\76\ Biomechanical response requirements were
selected to ensure human-like behavior in response to central chest
impacts, oblique chest impacts, and steering rim impacts to the
[[Page 61907]]
rib cage and upper abdomen.\77\ Better chest anthropometry means that
the dummy's interaction with the restraint system is more
representative of the interaction a human would experience.
---------------------------------------------------------------------------
\76\ Kent, R., Shaw, C.G., Lessley, D.J., Crandall, J.R. and
Svensson, M.Y, ``Comparison of Belted Hybrid III, THOR, and Cadaver
Thoracic Responses in Oblique Frontal and Full Frontal Sled Tests,''
Proc. SAE 2003 World Congress. Paper No. 2003-01-0160, 2003.
\77\ National Highway Traffic Safety Administration,
``Biomechanical Response Requirements of the THOR NHTSA Advanced
Frontal Dummy, Revision 2005.1,'' Report No: GESAC-05-03, U.S.
Department of Transportation, Washington, DC, March 2005. [https://www.nhtsa.gov/DOT/NHTSA/NVS/Biomechanics%20&%20Trauma/THOR-NT%20Advanced%20Crash%20Test%20Dummy/thorbio05_1.pdf.
---------------------------------------------------------------------------
The design of the THOR-50M includes a part known as a rib guide
(472-3310) which is intended to prevent excessive downward motion of
the anterior thorax during an impact. The rib guide is attached to the
shoulder, and when there is downward motion of the ribs, the bottom of
the rib damping material on rib #1 (the superior-most rib in the torso,
472-3310) can contact the top of the rib guide. Over time, this can
result in an indent in the rib damping material. This indent has been
observed on NHTSA-owned THOR-50M ATDs, but it has not been a concern as
this is a sign of the rib guide performing its intended function. While
this indent is not included on the drawing package, it is understood
that an indent is acceptable as long as the qualification
specifications (specifically, those of the upper thorax and lower
thorax) are met, and it is not so deep that it allows metal-to-metal
contact between the rib guide and the steel of the rib.
While Euro NCAP TB026 adopts the chest specified in the 2018
drawing package without any modifications, NHTSA is aware of two
potential changes that have been discussed. Both of these changes
appear to be intended to help ensure that the dummy is able to meet the
upper thorax qualification response requirements. (The TB026 upper
thorax qualification response requirements differ in a few ways from
the proposed qualification requirements. This is discussed in more
detail in Section V, Qualification Tests.)
The first change that has been discussed is a shorter rib guide.
Humanetics Innovative Solutions, Inc. (Humanetics) reported to ISO WG5
(in June 2020) that while the indent on the damping material has been a
known issue since the THOR-NT, it has led to concerns because it leads
to issues meeting the Euro NCAP upper thorax qualification response
requirements (specifically, the Z-axis upper rib deflection
requirement) on a consistent basis. Humanetics has therefore suggested
the use of a new, shorter rib guide which would allow more Z-axis
deflection--primarily in the upper thorax qualification test, but
presumably in other impact scenarios as well.
The second change is an additional rib performance specification.
NHTSA is aware of a presentation made by the Japanese Automobile
Manufacturers Association (in June 2020) to ISO WG5 describing an
additional rib performance specification (i.e., that would be specified
in the drawing package) geared towards more consistently meeting the
TB026 upper thorax qualification response requirements. The
presentation included a procedure for an individual rib test using the
same apparatus as the rib drop test for the ES-2re 50th percentile
adult male side impact test dummy.\78\ It noted data showing that the
stiffness of the individual rib in the drop test was correlated with
the thoracic impact response in the upper thorax qualification test
condition.
---------------------------------------------------------------------------
\78\ 49 CFR 572.185(b) Individual rib drop test.
---------------------------------------------------------------------------
NHTSA has tentatively decided not to implement either change.
NHTSA's qualification testing of the dummy did not reveal any issues
with meeting the proposed upper thorax qualification requirements, so
we do not believe such changes are necessary. Moreover, before
implementing the rib guide modification, it could be necessary to
evaluate whether it would influence the dummy's response in biofidelity
or thorax injury criteria test conditions. We do note, however, that
the additional rib performance specification could be a useful way for
ATD manufacturers to ensure that the fabricated ribs will result in an
upper thorax qualification response consistent with upper thorax
qualification specifications.
We seek comment on these issues. In particular, NHTSA requests
comment from THOR-50M users who have evaluated alternative rib guide
designs and have data to support equivalence of durability,
repeatability and reproducibility, and equivalence of response in
qualification, biofidelity, injury criteria, and vehicle crash test
conditions.
2. Instrumentation
The THOR-50M is capable of measuring detailed information about how
the chest responds in a crash. While the HIII-50M can measure chest
deflection at only a single point (the sternum), the THOR-50M measures
chest deflections at four points. This is useful because thoracic
trauma imparted to restrained occupants does not always occur at the
same location on the rib cage for all occupants in all frontal
crashes.\79\ Measuring deflection from multiple locations has been
found to improve injury prediction,\80\ and can improve the assessment
of thoracic loading in a vehicle environment with advanced occupant
restraint technologies.\81\ While the HIII-50M measures the one-
dimensional deflection at a single point, the THOR-50M can measure the
three-dimensional position time-history for four points on the anterior
rib cage relative to the local spine segment of rib origination, with
two points on the upper chest, and two points on the lower chest.
Between the upper and lower thorax instrumentation attachment points is
a flexible joint (the Upper Thoracic Spine Flex Joint), so the
reference coordinate system for the upper and lower thorax 3D motion
measurements can change dynamically during a loading event. This
instrumentation, coupled with its thoracic biofidelity,\82\ provides
the THOR-50M ATD with the ability to better predict thoracic injuries
and to potentially drive more appropriate restraint system
countermeasures.\83\
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\79\ Morgan, R.M., Eppinger, R.H., Haffner, M.P., Yoganandan,
N., Pintar, F.A., Sances, A., Crandall, J.R., Pilkey, W.D., Klopp,
G.S., Kallieris, D., Miltner, E., Mattern, R., Kuppa, S.M., and
Sharpless, C.L., ``Thoracic Trauma Assessment Formulations for
Restrained Drivers in Simulated Frontal Impacts,'' Proc. 38th Stapp
Car Crash Conference, pp. 15-34. Society of Automotive Engineers,
Warrendale, PA., 1994.
\80\ Kuppa, S., Eppinger, R., ``Development of an Improved
Thoracic Injury Criterion,'' Proceedings of the 42nd Stapp Car Crash
Conference, SAE No. 983153, 1998 (data set consisting of 71 human
subjects in various restraint systems and crash severities).
\81\ Yoganandan, N., Pintar, F., Rinaldi, J., ``Evaluation of
the RibEye Deflection Measurement System in the 50th Percentile
Hybrid III Dummy.'' National Highway Traffic Safety Administration,
DOT HS 811 102, March 2009.
\82\ Parent, D., Craig, M., Ridella, S., McFadden, J.,
``Thoracic Biofidelity Assessment of the THOR Mod Kit ATD,'' The
23rd Enhanced Safety of Vehicles Conference, Paper No. 13-0327,
2013.
\83\ In addition to the deflection measurement system, the THOR-
50M can also be instrumented with a uniaxial sternum accelerometer,
triaxial accelerometers installed along the spine at the level of
T1, T6, and T12, and a five-axis (three forces, two moments) load
cell installed between the lumbar spine pitch change mechanism and
the lumbar spine flex joint at the approximate anatomical level of
T12. Clavicle loads cells can also be installed, but are not
included in the THOR-50M described in the 2023 drawing package.
---------------------------------------------------------------------------
NHTSA is proposing to specify two deflection measurement devices,
either of which NHTSA could choose, at its option, for use in the THOR-
50M: the IR-TRACC and the S-Track.
IR-TRACC
The 2023 drawing package specifies a specific deflection
measurement device, the Infrared Telescoping Rod for Assessment of
Chest Compression (IR-
[[Page 61908]]
TRACC).\84\ The IR-TRACC improved on the previous deflection
measurement systems (CRUX--Compact Rotary Unit; DGSP--Double Gimbaled
String Potentiometer) in many ways. The 2023 drawing package specifies
six IR-TRACCs: four in the thorax and two in the abdomen.\85\ Each IR-
TRACC measures the absolute point-to-point distance along its length;
this is used in the calculation of thorax and abdomen compression. The
IR-TRACC is attached to two rotational potentiometers; this enables
measurement of the three-dimensional position of the anterior
attachment point at the rib or front of the abdomen relative to the
attachment point at the spine.
---------------------------------------------------------------------------
\84\ Rouhana, S.W., Elhagediab, A.M., Chapp, J.J. ``A high-speed
sensor for measuring chest deflection in crash test dummies.''
Proceedings: International Technical Conference on the Enhanced
Safety of Vehicles. Vol. 1998, Paper No. 98-S9-O-15. National
Highway Traffic Safety Administration, 1998.
\85\ See SA572-S117 and SA572-S121.
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While NHTSA has generally been satisfied with the performance of
the IR-TRACC, the experience of NHTSA and other users with IR-TRACC-
equipped THOR-50Ms has revealed a few potential issues. Vehicle
manufacturers have raised several concerns about the performance and
durability of the IR-TRACC, such as having to frequently repair or
replace IR-TRACCs, and problems with the abdomen IR-TRACCs.\86\ And
during NHTSA-sponsored testing (particularly in the frontal oblique
crash test mode), NHTSA observed abrupt decreases in the IR-TRACC
voltage time-history.\87\ We believe this is noise (and not a signal)
because it occurs in all IR-TRACC voltage channels of a single ATD at
the same points in time. As explained later in this document (Section
VII.B.2) and in Appendix F to the preamble,\88\ NHTSA testing has shown
that once the IR-TRACC voltage signal is linearized, scaled, filtered,
and converted to three-dimensional deflection, this noise is no longer
evident. Nonetheless, this presents a risk of perceived or actual
inaccuracies in thoracic and abdominal injury prediction during crash
tests.
---------------------------------------------------------------------------
\86\ Alliance of Automobile Manufacturers, Inc. (2016).
Technical Considerations Concerning NHTSA's Proposal to Rework the
Agency's New Car Assessment Program (NCAP). Regulations.gov Docket
ID NHTSA-2015-0119-0313, available at: https://www.regulations.gov/contentStreamer?documentId=NHTSA-2015-0119-0313&attachmentNumber=5&contentType=pdf.
\87\ See Figure 1 in Hagedorn, A., Murach, M., Millis, W.,
McFadden, J., Parent, D., (2019). Comparison of the THOR-50M IR-
TRACC Measurement Device to an Alternative S-Track Measurement
Device. Proceedings of the Forty-Seventh International Workshop on
Human Subjects for Biomechanical Research.
\88\ NHTSA is placing a separate document, ``Supplemental
Technical Appendices to Preamble,'' in the docket for this
rulemaking.
---------------------------------------------------------------------------
S-Track
In 2016 NHTSA issued a request for proposals for commercially-
available devices capable of measuring the same or greater deflection
range (roughly 90 millimeters of deflection for the thorax and 120
millimeters of deflection for the abdomen) within the same packaging
space as the existing IR-TRACC devices.\89\ Only one device--the S-
Track--was identified. The S-Track, which is patented,\90\ is produced
by ATD-LabTech GmbH. (In 2022, Humanetics acquired ATD-LabTech.)
Subsequent to the request for proposal, NHTSA also became aware of two
additional deflection measurement devices: the KIR-TRACC, sold by
Kistler Group, and the Spiral Track, sold by JASTI. NHTSA does not know
whether these devices are congruent with the current THOR-50M parts and
SA-drawings that describe the configuration and installation of IR-
TRACCs. Because NHTSA became aware of these devices late in the
development process (and neither was identified in NHTSA's request for
proposals), they have not been considered for inclusion in the
proposal, although NHTSA is considering evaluating whether they would
be suitable instrumentation for the THOR-50M. Euro NCAP allows for
installation of the IR-TRACC, the S-Track, and the KIR-TRACC.\91\
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\89\ National Highway Traffic Safety Administration (2016). IR-
TRACC Direct Replacement Sensor. Solicitation Number DTNH2216Q00014,
available at https://sam.gov/opp/d505f6119f9a31bcdfa36607ed669e6b/view.
\90\ Pheifer, G. (2020). U.S. Patent No. 10,713,974. Washington,
DC: U.S. Patent and Trademark Office.
\91\ European New Car Assessment Program (2022). Euro NCAP
Supplier List, Appendices I & II, October 2022, TB 029, available
at: https://www.euroncap.com/en/for-engineers/supporting-information/technical-bulletins/https://www.euroncap.com/en/for-engineers/protocols/adult-occupant-protection/.
---------------------------------------------------------------------------
The S-Track is similar to the IR-TRACC in that it is in-dummy
instrumentation that attaches to the same points in the dummy as the
IR-TRACC. Both measure linear displacement, and when coupled with the
gimballed potentiometers, their signals can be post-processed to
calculate three-dimensional motion. It differs in that the S-Track uses
a mechanical scissor mechanism coupled to a linear potentiometer to
measure linear motion along its axis, while the IR-TRACC uses a
measurement of light transmittance, which requires a linearization
calculation to estimate linear motion.
NHTSA has conducted a range of testing to evaluate the performance
and equivalence of the S-Track. The testing, which included a partial
qualification test series and sled tests, is briefly summarized
below.\92\ A more detailed discussion of this material is available in
a previously published paper (except, as noted below, the second set of
sled tests, for which a report is forthcoming).\93\
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\92\ This evaluation of alternate thorax and abdomen
instrumentation only considered replacement of the displacement
transducer component of the 3D IR-TRACC measurement system. Though
it was not available at the time of purchase, a double gimbal kit to
allow 3D measurement is now available from the S-Track manufacturer.
ATD-Labtech GmbH (2017). 3D Adaption THOR-50th upper Thorax left
20_303. Available at: https://www.atd-labtech.com/files/atd/uploads/produkte/s-track/produkte/4%20TH-3D-Adapter-Upper-Thorax-left/data_sheet-3D-Adaption_Thor-50th_upper_Thorax_left%20Rev%2001.PDF.
To evaluate whether the S-Track 3D adaption kit would result in
equivalent measurement capabilities as the 3D IR-TRACC measurement
system, the testing described here would be repeated, starting with
the 3D static measurement assessment.
\93\ Hagedorn, A., Murach, M., Millis, W., McFadden, J., Parent,
D., (2019). Comparison of the THOR-50M IR-TRACC Measurement Device
to an Alternative S-Track Measurement Device. Proceedings of the
Forty-Seventh International Workshop on Human Subjects for
Biomechanical Research. Available at: https://www-nrd.nhtsa.dot.gov/pdf/bio/proceedings/2019/Hagdeorn_S-Track_Biomechanics%20Workshop%202019_FINAL.pdf.
---------------------------------------------------------------------------
The range and linearity of the S-Track and IR-TRACC
sensors are comparable. The range of measurement of the S-Track is
consistent with or larger than the range of measurement of the IR-
TRACC, and all sensors were within the manufacturer's specification for
the maximum allowable linear error as a percentage of full scale. This
specification (0.5%) is tighter compared to the corresponding IR-TRACC
specification (2%), though only one of the IR-TRACCs (right abdomen)
showed a linearity error greater than 0.5%.
Calibration and 3D static measurement assessments
demonstrated similar or better accuracy compared to the IR-TRACC in the
double-gimbal configuration for the upper left thorax, lower left
thorax, and left abdomen. In the upper and lower thorax configurations,
the S-Track showed less error than the IR-TRACC, and in the abdomen
configuration, showed errors similar to the IR-TRACC.
The form, fit, and function is comparable to the IR-TRACC.
A full set of six S-Tracks was installed in a THOR-50M ATD. It did not
present any connectivity or interference issues and appeared to be a
plug-and-play replacement to the IR-TRACCs. One possible durability
issue was identified
[[Page 61909]]
(damage to the cable at the base of the S-Track). This issue is
mitigated if cable routing documentation is followed or the S-Track-
specific double-gimbal assembly is used.
The S-Track performed equivalently in qualification tests.
NHTSA carried out the qualification tests for the body regions expected
to be sensitive to a difference in thorax and abdomen instrumentation
(upper thorax, lower thorax, and abdomen) on a THOR-50M in two
different configurations: a baseline configuration with IR-TRACCs in
all locations, and an alternate configuration with S-Tracks in all
locations. Both configurations met the qualification targets for all of
the test modes specified for those body regions, which demonstrates
that the difference in measured deflections between the S-Track and IR-
TRACC were well within expected test-to-test variation. In addition,
the deflection time-history was qualitatively similar to the IR-TRACC.
The S-Track performed equivalently to the IR-TRACC in most
respects in a series of sled tests. NHTSA conducted sled tests in
several conditions with the THOR-50M in two configurations: one with
the IR-TRACC in all locations, and one with the S-Track in all
locations:
[cir] The first series used a reinforced buck representative of the
front half of a mid-sized passenger vehicle (including seat belt,
frontal air bag, and side curtain air bag) and simulated a near-side
frontal oblique (20 degrees) crash. The crash pulse was based on a
frontal oblique crash test of the same vehicle. The S-Track proved to
be durable and did not demonstrate the same noise artifacts as the IR-
TRACC. The S-Tracks in the thorax showed similar measurements as the
IR-TRACCs, particularly in the upper right thorax, the closest
measurement location to the shoulder belt. There were some potential
differences between the abdomen measurements, but abdominal deflection
is not currently included as an injury criterion in FMVSS No. 208 and
is not currently included in the rating calculation for frontal
NCAP.\94\
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\94\ Additional evaluation would be desirable in cases where
abdominal deflection is a critical measurement, such as a rear seat
environment where submarining may be more likely to occur.
---------------------------------------------------------------------------
[cir] The second series of sled tests were conducted in the Gold
Standard 1 (40 km/h, 12g peak pulse, standard lap and shoulder belt)
and Gold Standard 2 (30km/h, 9g peak pulse, 3kN load limited shoulder
belt) test conditions, which were used both in biofidelity assessment
and in the development of thoracic injury criteria.\95\ The goal of
this testing was to determine if any differences occurred between the
IR-TRACC and S-Track measurement devices, and if so, whether the
magnitude of these differences would affect the biofidelity and injury
criteria development analyses. NHTSA is preparing a report on this
second series of sled tests, which will be placed in the research
docket when it is complete.
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\95\ The Gold Standard 1 test uses a flat rigid seat, standard
lap and shoulder belts, knees restrained, and right front passenger
restraint geometry. The Gold Standard 2 test uses a flat rigid seat,
a force-limited shoulder belt and standard lap belt, knees
restrained, and right front passenger restraint geometry.
---------------------------------------------------------------------------
Based on this testing and analysis, NHTSA believes that the S-Track
is equivalent to the IR-TRACC (with the potential exception of the
abdomen deflection in a sled test environment).
Proposal
NHTSA proposes to specify both the IR-TRACC and the S-track as
permissible instrumentation for the THOR-50M. A THOR-50M configured
with all IR-TRACCs or all S-tracks would conform to Part 572 and NHTSA
could perform compliance testing with either device installed in the
THOR-50M. The dummy has not been tested in a mixed configuration, with
both devices installed (e.g., IR-TRACCS in the chest and S-Tracks the
abdomen, or with one IR-TRACC and three S-Tracks in the chest). The
overall effects of such configurations are unknown. NHTSA seeks comment
on whether the final specifications should allow such configurations.
The IR-TRACC is specified in the 2023 drawing package (in SA572-S117
and SA572-S121). NHTSA has not yet published engineering drawings and
parts packages to specify how the S-Track is installed in the dummy,
but intends to integrate such documentation into the associated
technical data package components upon finalization of this proposal.
NHTSA seeks comment on this proposal.
F. Shoulder
The THOR-50M shoulder was developed to allow a human-like range of
motion and includes a clavicle linkage intended to better represent the
human shoulder interaction with shoulder belt restraints.\96\ Clavicle
load cells that can be installed in the proximal and distal ends of the
clavicles are commercially available, but these load cells are not
currently defined in the drawing package and NHTSA has not evaluated
them.
---------------------------------------------------------------------------
\96\ T[ouml]rnvall, F.V., Holmqvist, K., Davidsson, J.,
Svensson, M.Y., H[aring]land, Y., [Ouml]hrn, H., ``A New THOR
Shoulder Design: A Comparison with Volunteers, the Hybrid III, and
THOR NT,'' Traffic Injury Prevention, 8:2, 205-215, 2007.
---------------------------------------------------------------------------
Below we discuss shoulder components for which NHTSA is proposing
alternative permissible specifications (the alternate shoulder) or for
which design modifications have been developed by external THOR-50M
users but which NHTSA has tentatively decided not to incorporate in the
drawing package (shoulder slip and coracoid process).
1. Alternate Shoulder Specification
Portions of the shoulder assembly specified in the 2018 drawing
package (referred to as the SD-3 shoulder) are covered by a patent
issued to Humanetics. However, for the reasons discussed in more detail
in Section VIII, NHTSA has generally avoided specifying in Part 572
patented components or copyrighted designs without either securing
agreement from the rights-holder for the free use of the item or to
license it on reasonable terms or developing an alternative
unencumbered by any rights claims. NHTSA has therefore designed, built,
and tested an alternative design for a part of the shoulder assembly
referred to as the shoulder pivot assembly that is not subject to any
intellectual property claims. Accordingly, the proposed drawing package
(the 2023 drawing package) includes specifications for the SD-3
shoulder pivot assembly as well as the alternate shoulder pivot
assembly, so that either may be used. We explain this in more detail
below.
SD-3 Shoulder
The SD-3 shoulder is notably different from the shoulder specified
for the THOR-NT. The THOR-NT design includes a clavicle linkage
attached by ball joints at the sternum and acromion, a linkage between
the acromion and the scapula to which the upper arm attaches, and a
linkage representing the scapula that attaches to the acromion linkage
and the spine with unconstrained revolute joints. While there were some
benefits of the THOR-NT design compared to existing ATDs at the time,
the range of motion of the THOR-NT shoulder was found to be lacking
compared to the human shoulder.\97\
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\97\ Shaw, G., Parent, D., Purtsezov, S., Lessley, D., Crandall,
J., Tornvall, F., ``Torso Deformation in Frontal Sled Tests:
Comparison Between THOR-NT, THOR-NT with the Chalmers SD-1 Shoulder,
and PMHS,'' Proceedings of the International IRCOBI Conference,
2010.
---------------------------------------------------------------------------
An improved shoulder design was independently initiated by the
Chalmers University of Technology (Chalmers), in
[[Page 61910]]
a project sponsored by Volvo and Autoliv, that sought to improve the
prediction of occupant response in offset and oblique frontal crashes.
Several prototype shoulder assemblies were constructed and evaluated,
the most promising being labeled the Shoulder Design 1 (SD-1).\98\ The
SD-1 shoulder design includes a clavicle linkage with human-like
geometry, connected by cardan joints to the sternum and acromion; a
linkage representing the scapula that includes attachment to the upper
arm; and a two-part linkage connecting the scapula to the spine which
allows both upward and anterior motion of the shoulder assembly. The
anterior rotation of the scapula linkage about a vertical shaft is
governed by a coil spring within an assembly mounted to the spine box.
Several rotation stops are installed throughout the assembly to prevent
metal-to-metal contact at the extents of the range-of-motion.
---------------------------------------------------------------------------
\98\ T[ouml]rnvall et al. (2007), 205-215.
---------------------------------------------------------------------------
After evaluation of the SD-1 in dynamic sled testing in comparison
to the standard THOR-NT shoulder and to PMHS,\99\ several improvements
were proposed, including durability improvements to the humerus joint,
decreasing the range of motion in the anterior and superior directions,
and increasing the range of motion in the posterior and medial
directions. The improved design, labelled as the SD-2 shoulder, was
fabricated by GESAC to Chalmers' specifications, installed on a THOR-
50M ATD, and evaluated in sled tests in the Gold Standard 1 and Gold
Standard 2 conditions at the University of Virginia.\100\ Several
additional durability and usability concerns were raised upon post-test
inspection, including deformation of the joint between the clavicle and
the acromion and hard contact to the humerus joint.
---------------------------------------------------------------------------
\99\ Shaw et al (2010).
\100\ Crandall, J. (2013). ATD Thoracic Response: Effect of
Shoulder Configuration on Thoracic Deflection. NHTSA Biomechanics
Database, Report b11017R001, available at: https://www-nrd.nhtsa.dot.gov/database/MEDIA/GetMedia.aspx?tstno=11017&index=1&database=B&type=R.
---------------------------------------------------------------------------
Subsequently, an updated version of the SD-2 shoulder, known as the
SD-3, was designed and fabricated as part of the European Union's
Thoracic Injury Assessment for Improved Vehicle Safety (THORAX)
project.\101\ Changes introduced in the SD-3 design included redesigned
sterno-clavicular joint anthropometry, an updated shoulder cover, and
improvements intended to address the durability and usability concerns
raised by the University of Virginia testing. These latter improvements
consisted of replacing the clavicle U-joint with a spherical joint;
replacing the humerus joint with a metric version of the HIII-50M upper
arm joint; and introducing a series of washers and bushings to the
bottom of the vertical shaft to enable the resistance of the assembly
to be adjusted to allow a more reproducible initial position.
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\101\ Lemmen, P., Been, B., Carroll, J., Hynd, D., Davidsson,
J., Song, E., and Lecuyer, E. (2012). Development of an advanced
frontal dummy thorax demonstrator. Proceedings of the 2012 IRCOBI
Conference, Paper No. IRC-12-87, September 2012.
---------------------------------------------------------------------------
The SD-3 shoulder was installed on a THOR-50M ATD and sled testing
was again carried out at the University of Virginia in the Gold
Standard 1 and Gold Standard 2 conditions, as well as a variation of
Gold Standard 1 with a force-limited belt.\102\ The SD-3 shoulder
assembly was inspected in detail throughout this testing, and no
evidence of damage was identified. The chest deflection and torso
motion was similar to the SD-1 and SD-2 shoulders, while durability was
improved. NHTSA also conducted an evaluation of blunt thoracic impact
response of several configurations of THOR-50M ATDs and found the
iteration with the SD-3 shoulder assembly installed to have the highest
qualitative and quantitative biofidelity.\103\ Given these findings,
NHTSA modified the drawing package to include the SD-3 shoulder. The
first iteration of the drawing package to include the SD-3 shoulder was
published as the September 2014 version.\104\
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\102\ Crandall, J. (2013). ATD Thoracic Response: SD3 Shoulder
Evaluation. NHTSA Biomechanics Database, Report b11470R001,
available at: https://www-nrd.nhtsa.dot.gov/database/MEDIA/GetMedia.aspx?tstno=11470&index=1&database=B&type=R.
\103\ Parent, D., Craig, M., Ridella, S., McFadden, J.,
``Thoracic Biofidelity Assessment of the THOR Mod Kit ATD,'' The
23rd Enhanced Safety of Vehicles Conference, Paper No. 13-0327,
2013.
\104\ National Highway Traffic Safety Administration (2014).
THOR 50th Percentile Male Drawing Package, September 2014. available
at: https://www.nhtsa.gov/DOT/NHTSA/NVS/Biomechanics%20&%20Trauma/THOR%20Advanced%20Crash%20Test%20Dummy/thoradv/THOR-M_PDF_2014-09-29.pdf.
---------------------------------------------------------------------------
After the publication of the September 2014 drawing package,
Humanetics filed an application for a patent describing a shoulder
assembly as well as an upper arm with an integrated load cell.\105\
Similar to the SD-3 shoulder, the design patent describes a shoulder
pivot assembly which includes, among other things, a coil spring and an
adjustable resistance element. After discussions between NHTSA and
Humanetics, a disclaimer stating that portions of the THOR-50M drawings
were covered by a Humanetics patent was added first to the NHTSA
website where the drawings were available for download, and later to
the drawings for the shoulder and upper arm assemblies in the drawing
package itself.
---------------------------------------------------------------------------
\105\ Been, B., & Burleigh, M. (2017). U.S. Patent No.
9,799,234. Washington, DC: U.S. Patent and Trademark Office.
---------------------------------------------------------------------------
NHTSA has generally avoided specifying such parts, consistent with
the legislative history of the Safety Act. (See Section VIII,
Intellectual Property.) For this reason, as explained below we are also
proposing, in addition to the SD-3 shoulder, an alternative shoulder
pivot assembly design.
Alternate Shoulder Pivot Assembly Design
To address the potential issues with specifying only a proprietary
shoulder design, NHTSA has designed, built, and tested an alternate
shoulder pivot assembly that is not subject to any intellectual
property claims. The alternate shoulder pivot assembly does not include
any components to adjust the resistance of the assembly, and does not
use a coil, clock, or watch-spring mechanism. Instead, the alternate
shoulder pivot assembly design uses a molded rubber cylinder acting as
a torsion bar. The top of the cylinder is attached to the shoulder
support assembly and the bottom is attached to the spring housing, so
rotation of the shoulder about the local Z-axis of the ATD results in
torsion of the rubber cylinder. In order to adjust the resistance of
the assembly, the springs must be removed and replaced.
NHTSA has evaluated the alternate shoulder in a variety of tests
and tentatively concludes that its performance is similar to the SD-3
shoulder based on testing carried out to date. This testing, which
included a partial qualification test series and sled tests, is briefly
summarized below. A more detailed discussion of this material is
available in a testing report that NHTSA is preparing, and which will
be placed in the research docket when it is completed. NHTSA is also
preparing another report that describes additional sled testing that
was conducted; this report will be placed in the research docket when
it is complete.
First, the alternate shoulder was installed in a THOR-50M without
any issues regarding the form, fit, or function. Second, in a quasi-
static rotation test, the alternate shoulder showed a similar moment-
rotation loading slope to the SD-3 shoulder in both the forward and
rearward rotation directions. Third, the SD-3 and alternate shoulder
showed nearly identical longitudinal motion in all three loading
directions in a quasi-static biofidelity evaluation comparing each
[[Page 61911]]
shoulder's range of motion to that of human volunteers; the responses
of both were generally similar to the human volunteer response
corridors. Fourth, the qualification tests most likely to be affected
by shoulder response (upper thorax and chest) were carried out; the
THOR-50M with the alternate shoulder met all qualification
specifications for the upper thorax, and the force-deflection
characteristic of the chest was nearly identical to that of a THOR-50M
with the SD-3 shoulder. Finally, sled tests conducted in both a full
frontal and a far-side oblique condition did not reveal any durability
or usability issues, and the response of the THOR-50M with the
alternate shoulder was within the test-to-test variation of the THOR-
50M with the SD-3 shoulder.
NHTSA is therefore proposing the alternative shoulder as an
acceptable optional subassembly. The shoulder assemblies are specified
on drawings 472-3810 (left) and 472-3840 (right). Each shoulder
assembly drawing specifies that either the SD-3 shoulder pivot assembly
or the alternate shoulder pivot assembly may be used. The proposed
specifications for the SD-3 shoulder pivot assembly are provided in
drawings 472-3811 and 472-3841, and the proposed specifications for the
alternate shoulder pivot assembly are provided in drawings 472-6810-1
and 472-6810-2. The drawing package currently indicates that the
selection of which shoulder pivot assembly to use is made separately
for the left and right shoulder assemblies, so that the dummy could be
fitted with the SD-3 shoulder pivot assembly on one side, and the
alternate shoulder pivot assembly on the other side. The dummy has not
been tested in such a mixed configuration, and the overall effects of
such configurations are unknown. NHTSA seeks comment on whether the
final specifications should allow such mixed configurations.
NHTSA seeks comment on whether the final drawing package should
include the SD3 shoulder, the alternate shoulder, or both. NHTSA also
seeks comment from THOR-50M users who have evaluated the proposed
alternate shoulder design, or other alternate shoulder designs, and
have data related to equivalence with respect to durability,
repeatability and reproducibility, and response in qualification,
biofidelity, injury and vehicle crash test conditions.
2. Shoulder Slip
NHTSA is aware that some researchers and regulatory authorities
have identified what they view as a possible design flaw in the
shoulder--that the shoulder belt may slip towards the neck in a crash--
and have developed potential modifications to the shoulder design to
prevent this from happening.
This concern was first raised in a 2018 conference paper describing
research conducted by Transport Canada. Transport Canada conducted a
series of vehicle crash tests with the THOR-50M in the driver seat in
two conditions: 40% offset and full frontal rigid barrier.\106\ It was
reported that the upper portion of the shoulder belt could translate
towards the neck and become entrapped in the gap between the neck and
the shoulder. This occurred in 33 of the 45 offset tests and in 2 of
the 13 full frontal rigid barrier tests. Compared to tests without
shoulder belt slip, tests with shoulder belt slip showed higher
measurements for lower neck shear (X-axis and Y-axis force), higher
chest deflections in the upper left and lower right quadrants, and
lower clavicle axial forces.
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\106\ Tylko, S., Tang, K., Giguere, F., Bussieres, A. (2018).
Effects of Shoulder-belt Slip on the Kinetics and Kinematics of
THOR. Proceedings of the 2018 IRCOBI Conference.
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Following that research, a 2019 Humanetics study identified and
evaluated three prototype alternative modifications to the shoulder
specified in the 2018 drawing package to prevent the shoulder belt from
entering the gap between the neck and the shoulder.\107\ The study
concluded that all three prototype modifications prevented belt
entrapment and identified the preferred design alternative (referred to
as a profiled split design). While the shoulder specified by NHTSA uses
the same material for the entire shoulder pad, the profiled split
design replaces the material closest to the neck with a higher-
stiffness plastic material. This is intended to prevent the collar (the
portion of the shoulder pad closest to the neck) from deforming and
allowing the shoulder belt to slip towards the neck.
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\107\ Wang, Z.J., Fu, S., McInnis, J., Arthur, J. (2019).
Evaluation of Novel Designs to Address the Shoulder-belt Entrapment
for THOR-50M ATD. Proceedings of the 2019 IRCOBI Conference.
---------------------------------------------------------------------------
In addition, in recent discussions with NHTSA, Euro NCAP has noted
that several instances of shoulder belt slippage were observed in Euro
NCAP testing as well as research tests with the mobile progressive
deformable barrier. Euro NCAP reported that it was evaluating two
potential shoulder design modifications, and expected these to be
presented for approval in 2023.
While NHTSA has witnessed the shoulder belt moving towards the neck
in vehicle crash tests, this phenomenon does not appear to influence
dummy measurements related to injury criteria. NHTSA seeks comment on
the desirability of and specifications for a modification to prevent
belt slippage, including data on testing with the proposed shoulder
design showing that it is leading to belt slippage that has a
meaningful effect on test results. NHTSA also requests comment from
THOR-50M users who have evaluated the split shoulder pad (or any
available alternatives) and have data to support equivalence of
durability, repeatability and reproducibility, and response in
qualification, biofidelity, injury criteria, and vehicle crash test
conditions.
G. Hands
The THOR-50M specified in the 2023 drawing package includes the
same hand design as the HIII-50M. The drawing defining the hand
assembly of the THOR-50M \108\ includes material formulation (Solid
Vinyl, Formulation Portland Plastics, PM-7003) along with two two-
dimensional images and one three-dimensional image of the hand.
Additionally, the three-dimensional geometry of the hand assembly is
included in the computer-aided design (CAD) files available through the
NHTSA website in both Autodesk Inventor and generic STEP formats.
However, the vinyl call-out does not sufficiently specify the hardness
or the stiffness of the material formulation and may be insufficient to
define the part. NHTSA therefore seeks comment on whether there is a
need for a material test (e.g., hardness measurement or a quasi-static
compression test of a coupon of the material) or performance test
(e.g., quasi-static or dynamic impact to the as-fabricated hand) to
further define the hand assembly of the THOR-50M, and if so, what the
test might be.
---------------------------------------------------------------------------
\108\ Drawing 472-6900-1/2.
---------------------------------------------------------------------------
H. Spine
The spine of the THOR-50M ATD is primarily constructed of steel.
There are two flexible elements (one in the thoracic spine and one in
the lumbar spine) that are intended to allow human-like spinal
kinematics in both frontal and oblique loading conditions.\109\ Between
the two flexible elements is a posture adjustment joint known as the
lumbar spine pitch change mechanism, which allows the posture of the
THOR-50M to be adjusted into various seating configurations in three-
[[Page 61912]]
degree increments, including, but not limited to, four designated
positions (erect, neutral, slouched, and super slouched).\110\ The
spine is instrumented with a five-axis thoracic spine load cell mounted
below the lumbar spine pitch change mechanism and above the lumbar
spine flex joint (a flexible joint that allows the dummy to go into
flexion/extension in the lumbar region). Triaxial accelerometers can be
installed in the nominal locations of the first, sixth, and twelfth
thoracic vertebra.
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\109\ Haffner, M., Rangarajan, N., Artis, M., Beach, D.,
Eppinger, R., Shams, T. (2001). Foundations and Elements of the
NHTSA THOR Alpha ATD Design. The 17th International Technical
Conference for the Enhanced Safety of Vehicles, Paper No. 458.
\110\ See Fig. 5-32 in the PADI.
---------------------------------------------------------------------------
The proposed spine design differs from the THOR-50M used by Euro
NCAP. Whereas the 2023 drawing package specifies a lumbar spine pitch
change mechanism, TB026 specifies a four-position lumbar spine box or
an ``alternative spine box'' if ``data has been provided to show
equivalence between the NHTSA spine assembly and modified spine
assembly.'' \111\ Humanetics holds a patent on the four-position spine.
The four-position lumbar spine is not specified further, but it does
differ from the spine specified by the NHTSA drawings. The spine pitch
change mechanism specified in the 2023 drawing package allows the spine
to be set at a multitude of flexion or extension settings, not just
four. NHTSA understands that the Euro NCAP design is intended to
accommodate the in-dummy installation of some DAS brands by providing a
mounting surface for data loggers. THOR-50M units built for Euro NCAP
are configured with in-dummy DAS systems have the four-position spine.
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\111\ Sec. 1.4.3.
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NHTSA has tentatively decided not to specify a lumbar spine pitch
change mechanism limited to four positions for a few reasons. First,
NHTSA has not inspected, nor has it performed any testing with, the
four-position spine. Second, NHTSA generally avoids specifying patented
components in Part 572 (see Section VIII, Intellectual Property).
Third, the proposed spine specifications provide more adjustability
than the four-position spine so the dummy may be used in a wider range
of applications. NHTSA seeks comment on user experience with the four-
position spine, including any data on equivalence with the THOR-50M as
specified in the 2023 drawing package or biofidelity.
It is also NHTSA's understanding that members of Working Group 5
have observed variations in the ATD responses in the upper thorax
qualification tests that have led to difficulties in meeting the Euro
NCAP qualification specifications. Some manufacturers have suggested
that this variation in response is due to variation in the spine flex
joint (specifically, the vertical displacement (Z-axis) of the ribs is
too high). One potential cause that has been identified (by Porsche in
November 2019) is that that the hardness of the material comprising the
spine flex joint was lower than the specification called for.
NHTSA's qualification testing did not reveal any issues with
meeting the upper thorax qualification specifications (See Section
V.D). In any case, in light of the potential concerns raised within
Working Group 5 of possible excessive variation in the performance of
the spine flex joint, potentially traceable to out-of-specification
materials, NHTSA conducted a limited modeling exercise using the THOR-
50M Finite Element (FE) model to investigate this. This analysis
suggested that while variation in the lumbar and thoracic spine flex
joints does influence the thoracic response in both qualification and
sled test conditions, this variation is smaller than the expected test-
to-test and ATD-to-ATD variation; specifically, a decrease in stiffness
of the spine flex joints can influence the upper thorax qualification
response, but by a much smaller magnitude than the width of the
qualification specifications and test-to-test and ATD-to-ATD
variations. For more information on this issue and NHTSA's FE
modelling, please see Appendix B.
Nonetheless, a research effort is currently underway to assess the
influence of the lumbar and thoracic spine flex joints in physical
qualification tests (which would provide additional validation data to
the computational analysis) and develop isolated dynamic tests of the
lumbar and thoracic spine flex joints. Based on these results, NHTSA
could potentially consider adding such a test(s) in the drawing
package, qualification procedures, or laboratory test procedures. NHTSA
requests comment from THOR-50M ATD users who have data to demonstrate
variation in THOR-50M response that is believed to result from spine
flex joint variation, specifically when the parts evaluated met the
specifications of the THOR-50M drawing package. Additionally, NHTSA
requests comment on the need for a thoracic spine and/or lumbar spine
flex joint specification beyond the geometry and material properties
defined in the drawing package.
I. Abdomen
The abdomen of the THOR-50M consists of two components, the upper
abdomen and the lower abdomen. The lower abdomen is the region between
the lower thoracic rib cage and the pelvis. The upper abdomen is the
region on the dummy that represents the lower thoracic cavity, which
fills the volume that exists between the lowest three ribs, above the
lower abdomen and in front of the spine. The upper and lower abdomen
components of THOR-50M are represented by structural fabric bags
containing foam inserts which define the compression stiffness. Both
abdomen inserts are anchored posteriorly to the spine, while the upper
abdomen insert is additionally anchored to the lower rib cage. When the
lumbar spine pitch change joint is set to the ``slouched'' position,
the abdomen inserts are in contact with one another; when in the
``erect'' and ``neutral'' positions, the gap between the abdominal
inserts is filled with the lower abdomen neutral/erect position foam.
This gap is also spanned by two steel stiffeners on each side that are
installed into the torso jacket. The bottom surface of the lower
abdomen insert is coincident with the pelvis.
J. Pelvis
The THOR-50M pelvis is designed to represent human pelvis bone
structure to better represent lap belt interaction,112 113
and the pelvis flesh is designed to represent uncompressed geometry to
allow human-like interaction of the pelvis flesh with the vehicle
seat.\114\ The pelvis assembly is constructed of a steel and aluminum
structure representing bone surrounded by a molded foam-filled vinyl
covering representing flesh. The flesh is not physically connected to
the pelvis bone but is held in place due to the tight fit of
protrusions of the pelvis bone into recesses in the pelvis flesh, as
well as circular bosses in the pelvis flesh into recesses in the pelvis
bone. The pelvis flesh includes a portion of the upper thigh flesh, the
interior surface of which includes gaps around the femur bone to allow
articulation of the leg about the hip joint.
---------------------------------------------------------------------------
\112\ Reynolds, H., Snow, C., Young, J., ``Spatial Geometry of
the Human Pelvis,'' U.S. Department of Transportation, Technical
Report No. FAA-AM-82-9, 1982.
\113\ Haffner, M., Rangarajan, N., Artis, M., Beach, D.,
Eppinger, R., Shams, T., ``Foundations and Elements of the NHTSA
THOR Alpha ATD Design,'' The 17th International Technical Conference
for the Enhanced Safety of Vehicles, Paper No. 458, 2001.
\114\ Shams, T., Rangarajan, N., McDonald, J., Wang, Y.,
Platten, G., Spade, C., Pope, P., Haffner, M., ``Development of THOR
NT: Enhancement of THOR Alpha--the NHTSA Advanced Frontal Dummy,''
The 19th International Technical Conference for the Enhanced Safety
of Vehicles, Paper No. 05-0455, 2005.
---------------------------------------------------------------------------
The THOR-50M pelvis flesh is a molded component, with a vinyl outer
[[Page 61913]]
layer filled with expandable polyurethane foam. The two-dimensional
drawing includes top, side, front, and isometric views of the molded
pelvis flesh, while its three-dimensional geometry is included in the
CAD files available through the NHTSA website in both Autodesk Inventor
and generic STEP formats. The drawing package specifies part weight and
foam density \115\ but not a material response or performance
requirement for the pelvis flesh.
---------------------------------------------------------------------------
\115\ Drawing 472-4100.
---------------------------------------------------------------------------
NHTSA is considering adding a performance specification for the
pelvis flesh similar to that defined in the HIII-50M PADI. Such a
performance specification would dictate the amount of allowable
compression of the pelvis flesh under a defined load. A similar test
was conducted on the pelvis flesh during the THOR Alpha design
development.\116\ One such possible requirement would be the
compression at a force of 500 N. Alternatively, Porsche has suggested a
dynamic impact test using an impactor similar to that used in the upper
thorax qualification test to impact the bottom of the pelvis flesh at a
velocity of 2 m/s. NHTSA seeks comment on the need and specifications
for a pelvis compression test, including whether it should be a
qualification requirement, a drawing specification, or otherwise.
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\116\ White Jr, R.P., Rangarajan, N., Haffner, M., ``Development
of the THOR Advanced Frontal Crash Test Dummy'', 34th Annual SAFE
Symposium, Conference paper, 1996.
---------------------------------------------------------------------------
The pelvis is instrumented with bi-lateral triaxial load cells
attached to the acetabulum (in order to measure the reaction force
between the femur and the pelvis) and a triaxial accelerometer array at
its center of gravity. The pelvis is also instrumented with bi-lateral
anterior-superior iliac spine (ASIS) load cells that measure contact
force in a nominally longitudinal axis and moment about a nominally
lateral axis. The ASIS load cell is primarily used to measure the force
transferred to the pelvis through the lap belt, in which case the
moments can be used to determine the vertical level or center of
pressure of the lap belt force.
K. Upper Leg
The upper leg assembly is constructed of steel and aluminum and
includes a rubber compressive element at the middle of the femur shaft.
This compressive element consists of a steel plunger that can translate
axially along the femur shaft through a guide system. When the femur is
loaded in axial compression (e.g., pushing the knee towards the pelvis
parallel to the femur), the motion of the plunger is resisted by a
rubber element, which allows a human-like compression response.\117\ At
the proximal end, the femur is connected to the pelvis through a ball
joint in a socket attached to the acetabulum load cell. At the distal
end, there is a six-axis load cell attaching the femur to the knee
assembly.
---------------------------------------------------------------------------
\117\ Ridella, S., Parent, D., ``Modifications to Improve the
Durability, Usability, and Biofidelity of the THOR-NT Dummy,'' The
22nd International Technical Conference for the Enhanced Safety of
Vehicles, Paper No. 11-0312, 2011. See Figure 17.
---------------------------------------------------------------------------
L. Knee
The THOR-50M knee is similar in construction to that of the HIII-
50M, with a few differences. The primary structure of the knee cap is
fabricated from aluminum, attached proximally to the femur load cell.
Inside of the kneecap assembly, a slider mechanism is installed to
allow translational motion of the tibia with respect to the knee. The
knee slider includes a stop assembly to prevent metal-to-metal contact
and to define the force-deflection characteristic of the tibia
translation. Attached to the slider is a string potentiometer to
measure the magnitude of tibia translation relative to the knee. The
sides of the kneecap are enclosed by urethane covers to protect the
slider mechanism, and the knee assembly is wrapped in a foam-filled
vinyl cover representing knee flesh.
The design of the knee slider modifies the HIII-50M design by
changing the geometry and material properties of the molded slider
assemblies (472-5320 and 472-5330) and stop assemblies (472-5358).\118\
This change was made because at levels of knee displacement below the
10.2-millimeter (mm) biofidelity response requirement, the HIII-50M has
been found to be stiffer than PMHS response corridors. Thus, during the
THOR-50M Mod Kit project, biomechanical response requirements were
specified with an additional measurement point at 5 mm of knee
displacement with a force between 100 and 500 N. The Mod Kit also
relegated the measurement point at 10.2 mm of deflection to a secondary
requirement, as it was shown to be at the high end of the underlying
PMHS corridors. While the 5 mm and 17.8 mm response requirements were
met by the revised THOR-50M knee slider,\119\ the force-deflection
response was below the human response corridor between 8 mm and 15 mm
of deflection, but above the corridor after 18 mm of deflection.\120\
As such, when the biofidelity was evaluated using BioRank, the external
biofidelity score of 2.282 indicated that the THOR-50M response was
more than two standard deviations from the PMHS mean response. This
BioRank score was lower than the corresponding HIII-50M score (1.070).
This should be taken into consideration when using the THOR-50M to
evaluate the risk of ligamentous knee injury.
---------------------------------------------------------------------------
\118\ Id. at Figure 16.
\119\ Id.
\120\ See Biofidelity Report, p. 254 (Fig. 45).
---------------------------------------------------------------------------
M. Lower Leg
The mechanical design of the THOR-50M lower extremity includes a
compressive rubber section in the tibia shaft, similar to the compliant
femur section, which provides more biofidelic force transmission from
the heel to the knee. The spring damper Achilles tendon system aids in
producing biofidelic ankle motion and torque characteristics. The ankle
design allows rotation about three axes, representing inversion/
eversion, dorsi/plantar-flexion, and axial rotation, and includes
molded rubber elements to define the moment/rotation response and limit
metal-to-metal contact at the extents of the range of motion. Different
from existing ATDs, the THOR-50M includes a molded shoe design which
integrates the foot and shoe into a single part. This feature, added in
the 2016 update to the THOR-50M drawing package,\121\ is intended to
reduce potential variability in the response of commercially available
shoes.
---------------------------------------------------------------------------
\121\ National Highway Traffic Safety Administration (2016).
Parts List and Drawings THOR-50M Advanced Frontal Crash Test Dummy
THOR-50M Male August 2016. Docket ID NHTSA-2015-0119-0376.
---------------------------------------------------------------------------
Euro NCAP TB026 deviates from the proposed drawing package in that
it specifies the HIII-50M lower legs, including the military
specification \122\ shoes, knee slider sensor, and roller ball-bearing
knees. We believe the THOR-50M specifications are preferable, for the
reasons given above (e.g., biofidelity).
---------------------------------------------------------------------------
\122\ Specification is not stated in Euro NCAP TB026, but
believed to be MIL-S-13192P as specified in 49 CFR 571.208 S8.1.8.2.
---------------------------------------------------------------------------
Each lower leg can be instrumented with five-channel load cells in
the upper and lower tibia, a uniaxial load cell to measure the Achilles
cable force, and three rotary potentiometers to measure the rotation of
the individual ankle joints. Two uniaxial accelerometers can be mounted
to the tibia and a tri-pack accelerometer assembly can be mounted to
each foot plate.
N. Data Acquisition System
Testing with THOR-50M requires (as does testing with any dummy) a
data
[[Page 61914]]
acquisition system (DAS). The data acquisition system performs signal
conditioning, triggering, and data collection to store measurements
from instrumentation installed in the dummy during a test into
nonvolatile memory. As it relates to ATDs, there are effectively two
types of DAS: external and internal (or in-dummy). As we explain below,
while the 2018 drawing package does not specify a DAS (because it
assumes the use of an external DAS), NHTSA is proposing to specify an
optional in-dummy DAS.\123\
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\123\ We note that the 2023 drawing package itself does not
contain specifications for an in-dummy DAS. Instead, the proposed
in-dummy DAS specifications are set out in an addendum that is being
docketed along with the 2023 drawing package.
---------------------------------------------------------------------------
An external DAS is, as the name indicates, external to the dummy.
The instrumentation in the dummy is connected to the external DAS via
wires, sometimes referred to as an umbilical cable. The 2018 drawing
package does not explicitly specify a DAS or related equipment, but the
drawings assume an external DAS: they assume that the instrumentation
wires are long enough to be bundled into an umbilical cable and
connected to a DAS located in the lab or mounted to the vehicle in
which the ATD is seated.
An internal DAS is installed within the dummy itself. An internal
DAS has some advantages to an external DAS. The primary advantage is
related to the mass properties of the dummy. With an internal DAS
system, there are no external cables that may possibly affect body
segment masses; segment masses are always the same no matter how the
dummy is used. While upfront cost is higher, an internal DAS would
reduce per-test costs, eliminate the need for interface cables to lab-
specific DAS systems (which have been a frequent sources of
instrumentation failures in research testing), and reduce the
adjustments needed to arrive at the target test vehicle weight.
Feedback from industry \124\ as well as Euro NCAP indicates that users
prefer an in-dummy DAS for its many usability advantages. Euro NCAP
TB026 requires an in-dummy DAS.\125\ While Euro NCAP TB029 currently
does not specify an approved in-dummy DAS,\126\ earlier versions of
TB029 did specify a few different approved in-dummy DAS systems.\127\
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\124\ Alliance of Automobile Manufacturers, Inc. (2016).
Technical Considerations Concerning NHTSA's Proposal to Rework the
Agency's New Car Assessment Program (NCAP). Regulations.gov Docket
ID NHTSA-2015-0119-0313, available at: https://www.regulations.gov/contentStreamer?documentId=NHTSA-2015-0119-0313&attachmentNumber=5&contentType=pdf.
\125\ TB026 Sec. 1.2.
\126\ European New Car Assessment Programme (2022). Euro NCAP
Supplier List, Version 4.0, October 2022, TB 029, available at:
https://www.euroncap.com/en/for-engineers/supporting-information/technical-bulletins/.
\127\ European New Car Assessment Programme (2022). Euro NCAP
Supplier List, Version 3.1, April 2021, TB 029, available at:
https://www.euroncap.com/en/for-engineers/supporting-information/technical-bulletins/. The DTS TDAS G5, SLICE Nano, and SLICE6; the
Kistler DTI, microDAU, and NXT32; and the Messring M=BUS.
---------------------------------------------------------------------------
In light of these potential advantages and user preferences, NHTSA
sponsored development and testing of an in-dummy DAS. NHTSA published a
request for solicitation for an in-dummy DAS.\128\ This was before Euro
NCAP began testing with the THOR-50M. The solicitation favored a
minimal redesign of existing THOR-50M parts, in order to facilitate
interchangeability of parts between THOR-50Ms with and without in-dummy
DASs. NHTSA contracted Diversified Technical Systems (DTS) to implement
its SLICE6 data acquisition system in a NHTSA-owned THOR-50M. This
included delivery of DAS components, replacement instrumentation
compatible with the DAS, and replacement ATD parts to allow attachment
of DAS components and preservation of inertial properties. The
resulting implementation distributes a series of small 6[hyphen]channel
data acquisition modules throughout the ATD, mounted directly on load
cells or sensors where possible, or close to the sensor with short
cables to the sensor. The DAS modules are chain[hyphen]networked with
four wiring harnesses which connect to the SLICE6 Distributor, with a
single ATD exit cable connecting the DAS to the full test system.
---------------------------------------------------------------------------
\128\ National Highway Traffic Safety Administration (2017).
Implement and Install THOR 50M In Dummy Data Acquisition System.
Solicitation Number DTNH2217Q00033, available at https://sam.gov/opp/068c7821de797ebe7f9e78a0f2b68dc4/view.
---------------------------------------------------------------------------
NHTSA evaluated the overall performance and equivalence of the
THOR-50M with the in-dummy SLICE6 DAS in a full suite of qualification
testing and a variety of sled and vehicle crash testing. This research
and analysis is described briefly below. The vehicle crash testing is
described in more detail in the cited report. NHTSA is preparing a
report on the installation, qualification testing, and sled testing of
the SLICE6 in-dummy DAS, which will be placed in the research docket
when it is complete. Additional information on the durability of the
THOR-50M with the in-dummy DAS system is included in Section VII.B,
Durability and Maintenance.
It was possible to install the SLICE6 into the dummy with
negligible changes to the mass, moment of inertia, and center of
gravity of the ATD and its individual body segments. This did require
modifications to several THOR-50M parts (e.g., the lower thoracic spine
assembly) in order to allow attachment of the DAS hardware to the rigid
components of the ATD.
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\129\ Saunders, J., Parent, D. (2023). Update on NHTSA's OMDB's
half barrier analysis. Proceedings of the 27th Enhanced Safety of
Vehicle Conference, Yokohama, Japan.
\130\ The OVSC Laboratory Test Procedures for FMVSS No. 208
specify an ambient temperature measured within 36 inches of the ATD
to be between 69 and 72 degrees Fahrenheit. National Highway Traffic
Safety Administration (2008). Laboratory Test Procedure for FMVSS
208, Occupant Crash Protection, TP208-14, available at: https://www.nhtsa.gov/sites/nhtsa.gov/files/documents/tp-208-14_tag.pdf.
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NHTSA has been able to fully qualify THOR-50M ATDs with
the in-dummy DAS installed. Since the SLICE system has been installed,
we have used the dummy in many tests and have qualified it with no
issues. The THOR-50M with the in-dummy DAS was tested in simplified
sled tests. Sled tests were conducted in the Gold Standard 1 (40 km/h,
12g peak pulse, standard lap and shoulder belt) and Gold Standard 2
(30km/h, 9g peak pulse, 3kN load limited shoulder belt) test
conditions, which were used both in biofidelity assessment and in the
development of thoracic injury criteria. The goal of this testing was
to determine if any differences occurred between the external and
internal DAS configurations, and if so, whether the magnitude of these
differences would affect the biofidelity and injury criteria
development analyses.
NHTSA also tested the THOR-50M with an in-dummy DAS in a
series of vehicle crash tests in the OMDB test condition with three
different deformable barrier faces. While some of the OMDB tests
appeared to show differences between the in-dummy DAS and umbilical
configurations, it was not clear whether this was due to variation in
the dummy response or variation in dummy positioning, vehicle response,
and/or restraint system response.\129\
Importantly, this testing did not reveal any potential durability
or usability issues associated with the in-dummy DAS, with one possible
exception: The temperature inside the thoracic cavity of the ATD can
increase beyond the ambient temperature typically prescribed for
regulatory and consumer information crash tests.\130\ In a more recent
set of vehicle crash tests, NHTSA closely monitored the rib temperature
of the THOR-50M with the
[[Page 61915]]
in-dummy DAS.\131\ By routinely limiting the ``ON'' time of the DAS,
NHTSA has been able to maintain the temperature range. Additionally,
NHTSA has used a portable fume extractor device to aid in maintaining
the temperature of the WorldSID-50M side impact dummy, which also has
internal DAS system.132 133 This device may also be employed
in tests with the THOR-50M.
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\131\ Saunders, J., Parent, D., Martin, P. (2023). THOR-50M
fitness assessment in FMVSS No. 208 unbelted crash tests.
Proceedings of the 27th Enhanced Safety of Vehicle Conference,
Yokohama, Japan.
\132\ Tatem, W., Louden, A. (2023). WorldSID-50M Fitness
Assessment in FMVSS No. 214 Moving Deformable Barrier and Oblique
Pole Crash Tests. Proceedings of the 27th Enhanced Safety of Vehicle
Conference, Yokohama, Japan.
\133\ This device is used to dissipate heat from the dummy in
the pre-test setup (for example, while seating and positioning the
dummy). Typically, a tube is inserted into the dummy jacket and in
conjunction with the fan is used to vent heat from the dummy to
maintain an in-spec internal temperature. The apparatus is detached
from the dummy immediately prior to the vehicle or sled test. Use of
such a fan may be specified in the OVSC laboratory test procedure.
---------------------------------------------------------------------------
Based on this testing, NHTSA has tentatively concluded that the
THOR-50M with the in-dummy DAS is equivalent to one with the external
DAS. NHTSA is therefore proposing an internal DAS as permitted optional
instrumentation that it could use in its testing. This necessitates
changes to the dummy to accommodate the DAS while ensuring that there
are no changes to the mass, moment of inertia, and center of gravity of
the ATD and its individual body segments. These changes may differ from
the Euro NCAP approach specified in TB026, which permits the four-
position spine box (discussed in Section III.H above) to accommodate
the installation of some DAS brands by providing a mounting surface for
data loggers. Euro NCAP does not provide part-by-part engineering
drawings of the various DAS packages, which is necessary for THOR-50M
to be sufficiently objective.
NHTSA has therefore provided, in an addendum to the 2023 drawing
package, further specifications for the dummy to accommodate an
internal DAS. It is anticipated that, upon finalization of this
proposal, the in-dummy DAS drawings will be fully integrated within the
relevant technical data package components. These specifications
consist of descriptions of the instrumentation and new drawings for the
dummy parts that require modifications to accommodate the DAS. The
changes are specified such that the dummy with the in-dummy DAS will
have the same inertial properties as the dummy using the external DAS.
The drawings show DAS mass blanks in lieu of the actual DAS components
(battery, data logger, etc.) with the exterior dimensions of the blank
matching those of the corresponding SLICE6 component.
If an in-dummy DAS component is not installed (for example, if
lower leg instrumentation is not needed for a given test mode), the
blank would be filled with a material of a specified density. The
material of the blank is not specified (although a reference
specification is provided) but would be selected to provide an
appropriate density and may also have internal flashing holes needed to
attain the desired mass, which is chosen to match the mass of the
actual DAS component. It is anticipated that, upon finalization of this
proposal, the PADI will show two sets of installation steps: one with
the ``blank'' component, and one with the actual DAS parts. (This two-
set convention is also followed with load cells and their structural
replacements). The proposed specifications are based on, but not
necessarily limited to, the SLICE6 (the SLICE6 is not explicitly
specified or called-out by name), so that another system fitting within
the defined specifications could also be utilized.\134\
---------------------------------------------------------------------------
\134\ While we are aware of in-dummy DASs produced by other
manufacturers, we have not evaluated whether these systems would be
compatible with the in-dummy DAS addendum to the 2023 drawing
package.
---------------------------------------------------------------------------
NHTSA seeks comment from users who have experience with both
umbilical and in-dummy DAS configurations of the THOR-50M, as to
whether they have seen any quantifiable differences between the two.
NHTSA also seeks comment on whether any additional changes should be
made to the proposed drawings specifying the in-dummy DAS to make it
more amenable to additional DAS systems that are already in the field.
IV. Biofidelity
Biofidelity is a measure of how well the dummy replicates a human,
and includes anthropometry, mass properties, range of motion, and
impact response. The impact biofidelity is evaluated by comparing the
response of the dummy to the response of a post-mortem human surrogate
(PMHS or cadaver) or human volunteer in a variety of different test
conditions (also referred to as test modes). Some of these tests focus
on individual dummy components (head, neck, chest, abdomen, upper leg,
knee, lower leg) and some evaluate the entire dummy as a complete
assembly.
To evaluate the biofidelity of THOR-50M, NHTSA selected test
conditions based on relevance to frontal and frontal oblique crash test
applications and the availability of data. For example, a neck frontal
flexion test was conducted by attaching the base of the THOR-50M neck
to a sled and applying a certain acceleration pulse. This was then
compared to the response measured on human volunteers who were
subjected to a similar pulse. Specifically, the impact biofidelity of
the THOR-50M was assessed in twenty-one test conditions. The test
conditions are summarized in Table 6. Each test produces a series of
data points (e.g., force vs. time).
The test conditions have been developed over the years by various
researchers to evaluate biofidelity and have been published in peer-
reviewed journals. The PMHS and human volunteer response data generally
comes from this published research. The THOR-50M response data comes
from testing that NHTSA has been conducting on the THOR-50M throughout
its development, all of which is available in NHTSA's Biomechanics Test
Database.\135\ NHTSA also compared THOR-50M's biofidelity to that of
the HIII-50M; many of the tests conducted with THOR-50M were paired
with the same test conducted on the HIII-50M. In our testing we
attempted to match the test conditions as closely as possible to the
test conditions in the original PMHS or volunteer tests.\136\
---------------------------------------------------------------------------
\135\ Available at https://www.nhtsa.gov/research-data/research-testing-databases#/biomechanics.
\136\ Overall, while some assumptions were necessary in the
reproduction of the PMHS or volunteer test conditions, we believe
that these assumptions should not affect the overall biofidelity
assessment of the THOR-50M. For instance, NHTSA simplified some of
the original tests in order to facilitate ease of testing when we
expected the simplification to have a negligible influence on the
result, such evaluating neck flexion using only the ATD's head and
neck, and not the entire dummy. These assumptions and
simplifications, as well as any limitations to our analyses, are
discussed in detail in the docketed biofidelity report. Parent, D.,
Craig, M., Moorhouse, K. 2017. Biofidelity Evaluation of the THOR
and Hybrid III 50th Percentile Male Frontal Impact Anthropomorphic
Test Devices. Stapp Car Crash Journal, 61, 227-276, available at:
https://www.regulations.gov/document/NHTSA-2019-0106-0004.
[[Page 61916]]
Table 6--Biofidelity Conditions Considered in the Design of the HIII
Frontal Dummies and THOR-50M ATDs
------------------------------------------------------------------------
Subpart
Body region Test condition E, O, W THOR-50M
------------------------------------------------------------------------
Head......................... Isolated Head Drop...
Whole-body Head ........
Impact.
Face Rigid Bar....... ........
Face Rigid Disk...... ........
Neck......................... Neck Flexion, ........
Pendulum.
Neck Extension, ........
Pendulum.
Neck Frontal Flexion, ........
Sled.
Neck Lateral Flexion, ........
Sled.
Neck Torsion......... ........
Thorax....................... Sternal Impact, 6.7 m/ ........
s.
Sternal Impact, 4.3 m/ ........
s.
Lower Ribcage Oblique ........
Abdomen...................... Upper Abdomen ........
Steering Rim.
Lower Abdomen Rigid ........
Bar.
Abdomen Belt Loading. ........
KTH.......................... Femur Compression....
Knee Shear...........
Lower Extremity.............. Dynamic Heel Impact.. ........
Tibia Axial ........
Compression.
Dynamic Dorsiflexion. ........
Whole-body................... Gold Standard 1...... ........
Gold Standard 2...... ........
Gold Standard 3...... ........
Far Side Oblique..... ........
------------------------------------------------------------------------
The test conditions used to evaluate the THOR-50M represent an
accumulation of biomechanics research. All conditions are accompanied
by a well-specified, objective test procedure and a well-founded set of
human response targets. The set of test conditions has grown
substantially over the span of Part 572 rule makings. For example, in
NHTSA's original 1998 proposal for the Subpart O HIII-5F dummy,\137\
only six biofidelity conditions were assessed.\138\ Since then, the
list has grown substantially; new conditions have been developed for
all body regions, and whole-body sled test conditions have been
developed.\139\
---------------------------------------------------------------------------
\137\ 63 FR 46981.
\138\ Mertz, H.J., Irwin, A.L., Melvin, J.W., Stanaker, R.L., &
Beebe, M. (1989). Size, weight and biomechanical impact response
requirements for adult size small female and large male dummies (No.
890756). SAE Technical Paper.
\139\ See National Highway Traffic Safety Administration,
``Biomechanical Response Requirements of the THOR NHTSA Advanced
Frontal Dummy, Revision 2005.1,'' Report No: GESAC-05-03, U.S.
Department of Transportation, Washington, DC, March 2005 (available
at https://www.nhtsa.gov/DOT/NHTSA/NVS/Biomechanics%20&%20Trauma/THOR-NT%20Advanced%20Crash%20Test%20Dummy/thorbio05_1.pdf) and
Ridella, S., Parent, D., ``Modifications to Improve the Durability,
Usability, and Biofidelity of the THOR-NT Dummy,'' The 22nd
International Technical Conference for the Enhanced Safety of
Vehicles, Paper No. 11-0312, 2011.
---------------------------------------------------------------------------
NHTSA quantified how closely the response of the THOR-50M matched
the response of the PMHS or human volunteers using the Biofidelity
Ranking system (BioRank).\140\ BioRank has been applied in other
instances cited in the literature \141\ and in other NHTSA Part 572
rulemakings.\142\ This methodology statistically compares the dummy
response to the average PMHS/volunteer response (typically a time-
series but sometimes a point estimate). A BioRank value of 0.0
indicates an ATD response identical to the average PMHS/volunteer
response; a value of 1.0 indicates an ATD response that is on average
one standard deviation \143\ away from the average PMHS/volunteer
response; a value of 2.0 indicates an ATD that is on average two
standard deviations away from the average PMHS/volunteer response; and
so on. Therefore, the lower the BioRank value, the better the
biofidelity. We computed BioRank scores for both the THOR-50M and the
HIII-50M.
---------------------------------------------------------------------------
\140\ Rhule, H., Maltese, M., Donnelly, B., Eppinger, R.,
Brunner, J., Bolte, J. (2002) Development of a New Biofidelity
Ranking System for Anthropomorphic Test Devices. Stapp Car Crash
Journal 46: 477-512.
\141\ Rhule, H., Moorhouse, K., Donnelly, B., Stricklin, J.
(2009) Comparison of WorldSID and ES-2RE Biofidelity Using Updated
Biofidelity Ranking System. 21st ESV Conference, Paper No.09-0563.
\142\ The analysis using Biorank described here mirrors (with
some exceptions) the approach used in the assessment of the WorldSID
50th ATD. See, e.g., 80 FR 78522, 78538 (Dec. 16, 2015) (New Car
Assessment Program Request for Comments); 71 FR 75304 (Dec. 14,
2006) (final rule for ES-2re Side Impact Crash Test Dummy 50th
Percentile Adult Male); 71 FR 7534 (Dec. 14, 2006) (final rule for
SID-IIs Side Impact Crash Test Dummy 5th Percentile Adult Female).
\143\ The standard deviation is a statistic that measures the
dispersion of a dataset relative to its mean.
---------------------------------------------------------------------------
For each body region, we calculated two BioRank scores: one for
external biofidelity (the extent to which the ATD represents a human
surrogate to the vehicle or restraint system); and one for internal
biofidelity (the ability of the ATD to represent the human responses
that relate to prediction of injury). External biofidelity measures are
generally those recorded at the test fixture level, such as pendulum
force or belt force; internal biofidelity measures are generally those
recorded by the internal instrumentation of the ATD or test equipment
such as motion tracking that records subject excursion.
NHTSA considered two other methods of quantifying biofidelity. One
is the International Standards Organization (ISO) 9790 Biofidelity
Classification System. ISO 9790 defines the analysis process, response
corridors, and weighting factors for the quantitative assessment of
biofidelity of side impact ATDs. Because the ISO 9790 response
corridors and weighting factors are specific to side-impact ATDs, it
could not be directly applied to a frontal impact ATD such as the THOR-
50M, and we are not aware of a corollary ISO standard for assessment of
frontal impact ATD biofidelity. While a method similar to that
described in ISO 9790 could be developed to assess frontal impact ATD
biofidelity, we believe such a method may introduce subjective bias
because it contains many subjective features, including weighting
[[Page 61917]]
of test conditions and body regions.\144\ The BioRank system was
developed to minimize subjectivity in the areas of corridor
development, weighting, and scoring. Another method NHTSA considered is
correlation and analysis (CORA), which may be a useful tool to carry
out quantitative analysis.\145\ However, the vast array of tunable
parameters in the software can result in unintentional subjectivity and
poor reproducibility. Further, there are no known and accepted
relationships between CORA scores and biofidelity classifications.
Accordingly, we evaluated biofidelity using BioRank.
---------------------------------------------------------------------------
\144\ Rhule, D., Rhule, H., Donnelly, B. (2005) The Process of
Evaluation and Documentation of Crash Test Dummies for Part 572 of
the Code of Federal Regulations. 19th ESV Conference, Paper No. 05-
0284, pp. 9-10.
\145\ Gehre C, Gades H, Wernicke P (2009) Objective rating of
signals using test and simulation responses, The 21st International
Technical Conference for the Enhanced Safety of Vehicles, Paper No.
09-0407, 2009.
---------------------------------------------------------------------------
We note that because many of the biofidelity test conditions
utilize specialized instrumentation or test equipment, they are not
intended to be carried out as certification or qualification tests
conducted between crash tests or sets of crash tests to confirm that
specified ATD response requirements are met. Instead, due to its
relative complexity, biofidelity testing is carried out at the ATD
design stage to assess the biofidelity of the design. Simplified and
standardized versions of the biofidelity test conditions have been
developed as qualification procedures for some body regions. Because
the qualification response requirements are based on the expected
variation in response of the ATD, not the underlying human response,
the qualification requirements specify a much smaller allowable range
in response than the biomechanical design targets. Therefore, it is
expected that all THOR-50M units that meet the specifications of the
qualification procedures would demonstrate similar biofidelity. The
proposed qualification response requirements are discussed in Section
V.
A full description of NHTSA's biofidelity testing and analysis can
be found in the docketed biofidelity report.\146\ We note that there
are no separate discussions in the report for the shoulder, spine, or
pelvis. Impact biofidelity of the spine and pelvis, as well as the
dynamic biofidelity of the shoulder, are intrinsically evaluated as
part of the whole-body biofidelity sled test series.\147\ Shoulder
biofidelity has also been assessed quasi-statically and found to be
more similar to the human volunteer corridors than existing ATDs. NHTSA
is finalizing a report on the alternate shoulder design, which includes
the biofidelity evaluation described here; once complete, this report
will be published to the research docket.
---------------------------------------------------------------------------
\146\ Parent, D., Craig, M., Moorhouse, K. 2017. Biofidelity
Evaluation of the THOR and Hybrid III 50th Percentile Male Frontal
Impact Anthropomorphic Test Devices. Stapp Car Crash Journal, 61,
227-276, available at: https://www.regulations.gov/document/NHTSA-2019-0106-0004.
\147\ The qualitative biofidelity of the shoulder is also
discussed in the Biofidelity Report, where the role of the shoulder
in belt retention (or lack thereof) is discussed qualitatively. See
p. 272-273.
---------------------------------------------------------------------------
NHTSA believes that the THOR-50M is sufficiently biofidelic for
incorporation into Part 572. The biofidelity report shows that the
THOR-50M exhibits overall internal and external BioRank scores of below
2.0. See Table 7. Both internal and external BioRank scores are lower
than those of the HIII-50M, which is defined in Part 572 (Subpart E)
and used in regulatory and consumer information frontal impact crash
testing. At the body region level, the internal and external BioRank
scores for THOR-50M are all below 2.0 except for neck internal
biofidelity and abdomen external biofidelity. The THOR-50M BioRank
score for the neck and abdomen external biofidelity are, however, lower
(better) than those for the HIII-50M. Overall, the internal BioRank
scores for the THOR-50M were lower than those of HIII-50M in 5 of the 7
body regions evaluated, and THOR-50M external BioRank scores were lower
than those of HIII-50M in 6 of the 7 body regions evaluated. Thus, the
THOR-50M has generally improved biofidelity in the individual body
region tests, which improves the accuracy of injury predictions. The
THOR-50M and the HIII-50M have comparable quantitative biofidelity in
the whole-body sled test conditions.\148\
---------------------------------------------------------------------------
\148\ This finding has been confirmed by independent research; a
2018 study showed that the HIII-50M and THOR-50M demonstrated
similar biofidelity scores in a sled test environment representing a
production vehicle. See Albert, Devon L., Stephanie M. Beeman, and
Andrew R. Kemper. ``Occupant kinematics of the Hybrid III, THOR-M,
and postmortem human surrogates under various restraint conditions
in full-scale frontal sled tests.'' Traffic Injury Prevention
19.sup1 (2018): S50-S58.
Table 7--Body Region Internal and External BioRank Summary
----------------------------------------------------------------------------------------------------------------
THOR-50M HIII-50M
Body region ---------------------------------------------------------------
Internal External Internal External
----------------------------------------------------------------------------------------------------------------
Head............................................ 0.155 1.143 0.013 6.640
Neck............................................ 2.155 1.677 2.185 4.318
Thorax.......................................... 0.917 0.948 1.603 2.070
Abdomen......................................... 1.470 2.803 1.629 3.474
KTH............................................. 1.400 1.731 3.875 6.667
Lower Extremity................................. 1.349 0.871 0.832 1.108
Whole-body...................................... 1.472 1.989 1.576 1.780
---------------------------------------------------------------
Overall..................................... 1.274 1.594 1.673 3.722
----------------------------------------------------------------------------------------------------------------
Since a majority of the test conditions involved pure frontal
loading, and several involved oblique and lateral loading (neck lateral
flexion, neck torsion, lower thorax oblique, Gold Standard 3, and Far
Side Oblique test conditions), these findings are expected to extend to
frontal and frontal oblique crash test conditions. The findings may
not, however, extend to other loading conditions (such as pure lateral
or rear impacts) without further research.
V. Qualification Tests
This NPRM proposes qualification tests (also referred to as
qualification procedures) for THOR-50M. The qualification procedures
describe a series of impact tests performed on a fully-assembled dummy
or dummy sub-assembly. The tests assess the components that play a key
role in the dummy's performance in the intended application of frontal
and frontal oblique crashes. We propose
[[Page 61918]]
qualification tests for the head, face, neck, upper thorax, lower
thorax, abdomen, upper leg, knee, and lower leg. For some body regions
(such as the face) we propose a single test condition (also referred to
as a test mode), while for other body regions (for example, the neck)
we propose a series of different test conditions.
Each qualification test condition consists of test procedures, test
parameters, and acceptance intervals. The test procedures describe a
detailed series of steps that must be carried out to perform the test.
Test parameters describe specific aspects of the dummy's response.
Acceptance intervals (or qualification targets) are specified for each
test parameter. Acceptance intervals are a typically pair of numeric
values (a minimum value and maximum value) within which the dummy
response must fall in order to pass, but can also represent a minimum
or maximum value of the response. For instance, one of the tests
involves striking the head with an impactor and measuring the head's
acceleration, which must be within the acceptance interval 117 11.7 Gs.
The qualification tests mirror the dummy loading patterns observed
in frontal crash tests, including full frontal, oblique, and offset
modes. For the neck assembly, we have specified separate requirements
in flexion, extension, and lateral flexion. These bending modes have
all been observed in crash testing. Additionally, a torsion test is
prescribed for the neck since it also twists along its long axis to
some degree. For the feet and ankles, tests in inversion, eversion,
dorsiflexion, and axial loading through the tibia are specified to
account for the various injurious loads that have been observed in
crash tests. For the head, face, upper and lower thorax, abdomen, upper
legs, and knees, we have only prescribed impact tests to anterior
aspects since injurious loads pass primarily through those aspects
during crash testing. The impact speeds and probe masses have been
selected to demonstrate that the various body segments work properly at
energy levels at or near those associated with high injury risks. For
measurements not associated with an injury criterion, energy levels are
chosen to exercise the dummy approaching its functionality limits, but
without causing damage.
The qualification tests ensure that the dummy is functioning
properly. There are a few inter-related aspects to this. One is that
qualification tests ensure that dummy components and sensors are
properly assembled and functioning. Qualification tests monitor the
response of components that may have become loosened or misaligned
since initial assembly. For each test, certain dummy sensors and signal
characteristics (such as the magnitude and timing) have been specified
as qualification targets. Loose or misaligned parts may become evident
when a signal does not conform to the prescribed signal
characteristics. By monitoring these sensors, the qualification tests
ensure that the dummy is functioning properly. The tests also ensure
that the sensors themselves are working properly. Another aspect is
that qualification tests help identify components that have
deteriorated over time, preventing the dummy from meeting the
qualification targets; such parts need to be replaced or refurbished.
Many of the qualification test protocols are very similar to the
dynamic tests used to assess biofidelity. This helps to ensure that a
qualified dummy is also a biofidelic dummy. Finally, they ensure that
the dummy or particular sub-assembly is responding in a uniform and
expected manner; if it is not, certain dummy components might need to
be tuned or adjusted to obtain a response within the qualification
targets.
NHTSA's experience has shown that the impact tests on body segments
are needed to ensure uniformity of dummy responses in a subsequent
vehicle crash test. In other words, full conformance to part and
assembly specifications (in accordance with the drawings and PADI) is
not enough to guarantee a uniform dummy response in a crash test.\149\
Qualification tests have proven reliable and sound in qualifying
NHTSA's other test dummies. Moreover, some of the proposed
qualification tests use the same test equipment as other ATDs, thus
minimizing the amount of new qualification equipment needed by test
laboratories that may already have such equipment in place for
qualifying other ATDs. Meeting the qualification tests helps ensure
that the dummy is capable of responding properly in a compliance or
research test. This in turn helps to ensure that the dummy is an
objective test device suitable for the assessment of occupant safety in
compliance tests specified in Federal Motor Vehicle Safety Standards,
and for other testing purposes.
---------------------------------------------------------------------------
\149\ At the same time, conformance to a qualification
requirement is not a substitute for parts that do not conform to
drawing specifications.
---------------------------------------------------------------------------
NHTSA proposes setting the qualification targets at
10% of the mean response for each qualification parameter as reported
in the qualification test R&R study (discussed in Section VI). In that
study we subjected multiple dummies to repeated tests in each test
condition at multiple test laboratories. The repeatability testing and
analysis for the qualification tests is described in more detail in
Section VI.A. We believe that 10% is wide enough to account for normal
variations in ATD and laboratory differences, and narrow enough to
ensure consistent and repeatable measurements in standardized testing
with the ATD. This is also consistent with the qualification limits for
the other Part 572 ATDs. For example, for the Hybrid III 10-year-old
child dummy, the acceptance intervals are, on average, set at 9.9% from the nominal midpoint, with a low of 8.4% (neck rotation
in the neck extension test) and a high of 10.8% (in the neck moment in
the extension test and chest deflection in the thorax impact
test).\150\ For all Part 572 ATDs, the average acceptance interval is
11%.
---------------------------------------------------------------------------
\150\ HIII-10C, Subpart T.
---------------------------------------------------------------------------
We also considered setting the qualification targets at plus or
minus two standard deviations from the mean response observed in the
testing reported in the repeatability and reproducibility study. This
would have narrowed the acceptance interval for almost all responses,
some of which would have been unreasonably narrow. For instance, the
head impact test results in the repeatability and reproducibility study
were very uniform, with a CV for peak force of 0.9%. If the acceptance
interval for peak force were set to plus or minus two standard
deviations (1.8%), 24 of the 26 trials would have resulted
in a pass; if it were set to 2.5%, all 26 trials would have
resulted in a pass. This result may have been a function of using only
three THOR-50M units in the test series, all of which were brand new
when we tested them. Therefore, we propose a greater allowance of
10% for all qualification requirements to account for
slight variations that may arise from equipment and testing variations
at different test labs as well as a future population of THOR-50M units
from dummy manufacturers in which lot-to-lot differences in the
fabrication of parts from the same manufacturer may exist. It also
allows for slight changes to individual THOR-50M units over time,
either due to aging of polymeric components or wear and tear under
normal use. Table 8 summarizes the proposed THOR-50M qualification
requirements.
[[Page 61919]]
Table 8--Proposed THOR-50M Qualification Requirements
----------------------------------------------------------------------------------------------------------------
Acceptance
Test Measurement Units Nominal target interval
----------------------------------------------------------------------------------------------------------------
1. Head Impact.................. Peak Probe Force....... N................. 5580 5022-6138
Peak Head CG Resultant G................. 117.0 105.3-128.7
Acceleration.
2. Face Impact.................. Peak Probe Force....... N................. 7098 6378-7796
Peak Head CG Resultant G................. 138 124-152
Acceleration.
3. Neck Flexion................. Peak Upper Neck My..... N-m............... 31.0 27.9-34.1
Upper Neck Fz Most N................. 860 774-946
Positive Value Prior
to 40 ms.
Peak Head Angular deg/sec........... 1975 1777-2172
Velocity vy (relative
to earth).
Peak Head Rotation deg............... 64.5 58.1-71.0
(relative to pendulum).
4. Neck Extension............... Peak Upper Neck My..... N-m............... 23.0 20.7-25.3
Peak Upper Neck Fz..... N................. 2918 2626-3210
Peak Head Angular deg/sec........... 2061 1855-2267
Velocity vy (relative
to earth).
Peak Head Rotation deg............... 65.0 58.5-71.5
(relative to pendulum).
5. Neck Lateral................. Upper Neck Mx first N-m............... 49.7 44.8-54.7
peak after 40.0 ms.
First Peak Head Angular deg/sec........... 1362 1226-1498
Velocity vx (relative
to earth).
Peak Head Rotation deg............... 41.7 37.6-45.9
(relative to pendulum).
6. Neck Torsion................. Peak Upper Neck Mz..... N-m............... 41.4 37.3-45.6
First Peak Upper Neck deg/sec........... 1390 1251-1529
Angular Velocity vz
(relative to earth).
Peak Neck Fixture deg............... 47.9 43.1-52.7
Rotation.
7. Upper Thorax................. Peak Probe Force....... N................. 3039 0-3039
Peak Upper Resultant mm................ 53.6 48.3-59.0
Deflection.
Difference Between Peak mm................ 0 -5 to 5
Left & Right Resultant
Deflections.
Force at Peak Resultant N................. 2677 2409-2944
Deflection.
8. Lower Thorax................. Peak Probe Force....... N................. 3484 3136-3832
Resultant Deflection at mm................ 50.9 45.8-56.0
Peak Force.
9. Lower Abdomen................ Peak Probe Force....... N................. 2918 2626-3210
Lower Abdomen X-axis N................. 83.0 74.7-91.3
Deflection at Time of
Peak Force.
Difference Between Peak mm................ 0 -8 to 8
Left & Right X-axis
Deflections.
10. Upper Leg................... Peak Probe Force....... N................. 8333 7500-9166
Peak Femur Force, Fz... N................. 4920 4428-5412
Peak Resultant N................. 2738 2464-3012
Acetabulum Force.
11. Knee........................ Peak Femur Z-axis Force N................. 6506 5855-7156
Knee Deflection at Peak mm................ 20.2 18.2-22.2
Femur Force.
12. Ankle Inversion............. Peak Lower Tibia Fz.... N................. 505 454-555
Peak Ankle Resistive N-m............... 39.1 35.2-43.0
Moment.
Peak Ankle X-axis deg............... 34.5 31.0-37.9
Rotation.
13. Ankle Eversion.............. Peak Lower Tibia Fz.... N................. 571 514-629
Peak Ankle Resistive N-m............... 43.0 38.7-47.3
Moment.
Peak Ankle X-axis deg............... 29.6 26.6-32.5
Rotation.
14. Ball of Foot................ Peak Lower Tibia Fz.... N................. 3170 2853-3487
Peak Ankle Resistive N-m............... 55.3 49.8-60.8
Moment.
Peak Ankle Y-axis deg............... 33.8 30.4-37.2
Rotation (in
dorsiflexion).
15. Heel........................ Peak Lower Tibia Fz.... N................. 3162 2846-3478
----------------------------------------------------------------------------------------------------------------
Note: For comparison purposes, unless otherwise noted, only positive values are shown for the Nominal Target and
Acceptance Range. Some targets, such as Neck Flexion Angular Velocity ([omega]y = -1362 deg/sec), are defined
by negative values.
The proposed qualification requirements are the same as the 2018
version except for the upper leg; this is discussed in the section
below for the upper leg.
Euro NCAP TB026 explicitly adopts NHTSA's 2018 qualification
procedures \151\ with a couple of differences. First, there are a few
differences between the proposal and TB026 with respect to the tests or
test parameters. TB026 specifies somewhat different qualification
metrics for the upper thorax test and does not include a face impact
test. TB026 prescribes the upper leg test described in NHTSA's 2018
qualification procedures, which we are proposing to update. And,
because TB026 specifies the HIII-50M lower extremities, the
corresponding qualification tests are not the same as those proposed.
Second, although TB026 adopts the rest of the 2018 qualification test
procedures and test parameters, it specifies acceptance intervals that
differ from the proposed acceptance intervals with respect to both the
width and midpoint of the interval. While the proposed acceptance
intervals are 10% around the mean (as calculated from our
R&R testing), the width of the acceptance intervals specified in TB026
range from 1% to 10%, with many of them less than 10%. In addition, the
midpoint of these intervals differs from the means NHTSA calculated
based on its R&R testing. For nine of the parameters, the TB026
specifications are fully contained within the proposed acceptance
intervals. Of the remaining parameters, there is a minimum of 82%
overlap between the Euro NCAP specifications and the proposed
acceptance intervals. Therefore, it is feasible, but not guaranteed,
for a THOR-50M which meets the Euro NCAP acceptance intervals to also
meet the proposed acceptance intervals. NHTSA has tentatively decided
not to adopt narrower acceptance intervals, such as those specified in
TB026, for the reasons given above. Moreover, NHTSA is unaware of the
data on which the Euro NCAP specifications are based, whereas the
proposed specifications are based on NHTSA's carefully-controlled
study. The differences between the proposed
[[Page 61920]]
qualification tests and those specified in TB026 are discussed in more
detail in the relevant sub-sections below. In addition, the proposed
qualification test parameters and acceptance intervals and the
corresponding TB026 values are summarized in Appendix G.
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\151\ Sec. 2.1.
---------------------------------------------------------------------------
We propose to set out the qualification procedures in a separate
document that would be incorporated by reference into Part 572. See
Section XI, Incorporation by reference. This would be a departure from
the other ATDs currently specified in Part 572, for which the
qualification tests are set out in full in the regulatory text in each
of the relevant paragraphs (corresponding to that ATD) in part 572. We
are proposing a separate qualification procedures document for THOR-50M
because the THOR-50M qualification procedures contain many photographs
and diagrams that are not amenable to publication in the CFR; we
believe this extra level of detail will be helpful for end users who
are attempting to qualify the ATD.
NHTSA seeks comment on the proposed qualification tests. NHTSA also
seeks any qualification data commenters are able to provide, as long as
the data are from THOR-50M ATDs conforming to the 2023 drawing package
and were collected following the April 2023 Qualification Procedures
Based on any comments and data received, NHTSA might consider changing
the qualification targets to reflect the larger population of THOR-50M
units in the field. However, before doing so we would assess the effect
that any change could have on the biofidelity of the dummy and the
applicability of injury risk functions. We also seek comment on whether
we should incorporate the qualification procedures by reference, or
whether it would be preferable to locate a much-simplified set of
qualification procedures directly in Part 572 and put additional detail
and documentation in the Office of Vehicle Safety Compliance (OVSC)
laboratory test manual or similar document that would not be
incorporated by reference but instead provided as guidance to DOT
contractors and other ATD end users.
A. Head Impact
The head qualification test is identical to the whole-body head
impact biofidelity assessment, where a fully-assembled THOR-50M is
seated on a table and impacted on the forehead with a 23.36 kg rigid
impactor at 2.00 0.05 m/s. This test serves as a surrogate
for the isolated head drop test used by other ATDs; due to the
construction of the head and neck of the THOR-50M ATD (specifically,
the integration of the neck spring cables into the skull), separation
of the head from the neck is not feasible. The test assesses the
performance of the head skin and CG accelerometers, which are used to
calculate HIC15.\152\ The probe force and the head CG
resultant acceleration are measured and would have to be within the
proposed acceptance intervals.
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\152\ Craig, M., Parent, D., Lee, E., Rudd, R., Takhounts, E.,
Hasija, V. (2020). Injury Criteria for the THOR 50th Male ATD.
Regulations.gov Docket ID NHTSA-2019-0106-0008, available at:
https://www.regulations.gov/document/NHTSA-2019-0106-0008.
---------------------------------------------------------------------------
B. Face Impact
The face qualification test is identical to the face rigid disk
impact biofidelity assessment, where a fully-assembled THOR-50M is
seated on a table and impacted on the face with a 13 kg rigid impactor
with a 152.4 mm diameter flat disk impact surface at 6.73
0.05 m/s. This test assesses the impact response of the face, which is
driven primarily by the face foam insert (Part No. 472-1401).
Additionally, as this test is more severe than the head impact test, it
assesses the head CG accelerometers (which are used to calculate
HIC15) at a level of severity closer to that expected from
vehicle crash tests. FMVSS No. 208 specifies a maximum calculated
HIC15 value of 700 for the HIII-50M, and the average
HIC15 measurement from a set of 29 vehicle crash tests in
either the full frontal rigid barrier or OMDB crash test modes was
285.\153\ The head impact test, however, results in an average
HIC15 of 157 (probability of AIS 3+ injury of 0.05%), while
the face impact is more severe, with an average HIC15 of
around 450 (probability of AIS 3+ injury of 3.5%). Therefore, compared
to the head impact test, the face impact test is a better assessment of
the head response at a severity level expected from vehicle crash
tests, as it results in a HIC15 that is closer to the
current FMVSS No. 208 injury assessment reference value. During these
tests, the probe force and the head center of gravity (CG) resultant
acceleration are measured and would have to be within the proposed
response corridors.
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\153\ The range was 104-1262 and the standard deviation was 210.
---------------------------------------------------------------------------
C. Neck
The proposed neck qualification test series, in which the entire
head-neck assembly is removed from the ATD and affixed to the
conventional Part 572 swinging pendulum to apply a prescribed impulse
to the neck, includes six tests: flexion, extension, left lateral
flexion, right lateral flexion, left torsion, and right torsion. The
swinging pendulum apparatus serves as a surrogate for the more complex
neck biofidelity assessment, which is carried out in a sled test
configuration. The neck qualification tests assess the collective
performance of the molded neck column, the occipital condyle cam and
associated bump stops, and the neck spring towers. In the process, the
neck qualification tests assess the performance of the upper neck load
cell, from which the Z-axis force and Y-axis moment are used to
calculate Nij.\154\ The neck axial force, neck moment about the
relevant axis, and neck rotation about the relevant axis are measured
and would have to be within the proposed acceptance intervals. The neck
flexion and extension qualification tests are similar to those
specified for the HIII-50M \155\ in that they use the same pendulum and
similar deceleration specifications.
---------------------------------------------------------------------------
\154\ Craig et al (2020), Injury Criteria for the THOR 50th Male
ATD.
\155\ 49 CFR 572.33 Neck.
---------------------------------------------------------------------------
D. Upper Thorax
This test involves impacting the chest of a fully-assembled THOR-
50M seated on a table with a rigid impactor. The upper thorax
qualification test is configured similarly to that carried out on the
HIII-50M,\156\ using the same pendulum (23.36 kg, 152.40 mm diameter)
to impact the mid-sternum, but at a lower impact velocity of 4.3 meters
per second. This test assesses the dynamic thoracic response to sternal
impact as well as the functionality of the upper left and upper right
thoracic deflection instrumentation. This test condition is identical
to the associated biofidelity assessment, though the qualification test
uses only internal deflection measurements so that motion tracking or
other external instrumentation is not required. Several measurements
must be within the proposed acceptance intervals: the peak overall
probe force, the peak upper left and upper right resultant deflections,
the difference between the peak left and right resultant deflections,
and the probe force at the peak left and right resultant deflections.
---------------------------------------------------------------------------
\156\ 49 CFR 572.34 Thorax.
---------------------------------------------------------------------------
In the 2016 qualification procedures, the upper thorax
qualification required individual X-axis and Z-axis deflection
specifications for both the upper left and upper right thorax. This was
revised in the 2018 qualification procedures by specifying the peak
resultant deflection instead, which better aligns with the peak
resultant deflection measure used to evaluate thoracic injury
risk.\157\
[[Page 61921]]
Applying specifications on the resultant deflection instead of two
individual components allows for a reduction in the overall number of
required measurements, while still capturing the physical response of
the dummy since the X-axis and Z-axis deflections are the primary
components of the resultant deflection in this test condition.
---------------------------------------------------------------------------
\157\ Craig et al (2020), Injury Criteria for the THOR 50th Male
ATD.
---------------------------------------------------------------------------
The Euro NCAP qualification response requirements differ from the
proposal in three ways. First, they include an additional parameter:
the ratio of Z-axis to X-axis deflection. Second, they do not require a
maximum difference between left and right peak resultant deflection,
whereas the proposed qualification targets limit the left-to-right
difference to 5 millimeters. Using the Euro NCAP targets, the
difference between the left and right peak resultant deflections could
be as high as 7.2 millimeters. Third, as noted above, the qualification
targets are narrower than the proposed qualification targets.
NHTSA has tentatively decided not to specify the ratio of Z-axis to
X-axis deflection because doing so would effectively revert to the 2016
approach of individual X-axis and Z-axis deflection requirements, which
would increase the difficulty in meeting the qualification
specification without a direct link to injury prediction, as the peak
resultant deflection specification is of primary importance because it
is the metric used in the calculation of thoracic injury risk.
NHTSA is aware that the upper thorax qualification specification
has been a topic of frequent discussion within the International
Standards Organization (ISO) working groups (particularly ISO/TC 22/SC
36, Safety and impact testing, Working Groups 5, Anthropomorphic Test
Devices, and 6, Performance criteria expressed in biomechanical terms).
NHTSA understands that those discussions have focused on potential
modifications to the drawing package to meet the upper thorax
qualification response requirements (in the context of testing related
to Euro NCAP). Those modifications--specifically, the shorter rib
guide, the individual rib performance test, and changes in the area of
the coracoid process--have been discussed as describe in Section III,
Design, Construction, and Instrumentation.\158\ NHTSA does not believe
the modifications are necessary to meet the proposed upper thorax
qualification requirements because NHTSA's repeatability and
reproducibility testing showed that those requirements were achieved by
three different THOR-50M units at three different test labs. See
Section VI, Repeatability and Reproducibility. Moreover, it is not
clear whether these changes would preclude a THOR-50M from meeting the
proposed qualification requirements, though since the Euro NCAP
specifications are narrower, any variation caused by these changes may
be within the NHTSA's proposed acceptance intervals. Before
implementing any of these design changes, the performance of the
prototype parts would need to be evaluated.
---------------------------------------------------------------------------
\158\ In addition, some members of Working Group 5 have observed
variations in the ATD responses in the upper thorax qualification
tests that have led to difficulties in meeting the Euro NCAP
qualification specifications, and have suggested that this may
result from variation in the spine flex joint, potentially due to
material that was not as hard as the specification called for.
---------------------------------------------------------------------------
In an effort to further investigate these contemplated changes to
THOR-50M, NHTSA analyzed its upper thorax qualification test data.
NHTSA's limited analysis suggests that the difficulty meeting the Euro
NCAP upper thorax qualification requirements might stem not from the
dummy design, but from the smaller allowable range of peak resultant
deflection and the addition of the deflection ratio corridor specified
in TB026. However, it would be necessary to know how the Euro NCAP
upper thorax qualification requirements were determined to carry out a
complete analysis. This preliminary analysis is discussed in more
detail in Appendix A.
E. Lower Thorax
The lower thorax qualification test is unique to the THOR-50M. This
test involves impacting the lower thorax of a fully-assembled THOR-50M
seated on a table with a rigid impactor. It is similar to the upper
thorax qualification test, as it uses the same pendulum (23.36 kg,
152.40 mm diameter) at the same impact velocity (4.3 meters per
second). The test assesses the dynamic impact response of the lower
torso, to which the rib cage and the upper and lower abdomen assemblies
contribute, while at the same time assessing the functionality of the
lower left and upper right thoracic deflection instrumentation. The
lower thorax qualification test is a simplification of the lower
ribcage oblique impact biofidelity condition. In the biofidelity
condition, the torso is rotated by 15 degrees and a chestband is used
to measure external deflection. In the qualification condition, the
torso is not rotated, but instead offset relative to the line of travel
of the pendulum such that the pendulum is centered on the lower left or
lower right anterior attachment point of the thoracic deflection
instrumentation. As in the upper thorax condition, the lower thorax
qualification mode uses internal deflection measurements so that motion
tracking or other external instrumentation is not required. During this
test, the peak overall probe force and the peak resultant thoracic
deflection at the time of peak probe force are measured and would have
to be within the proposed acceptance intervals.
F. Abdomen
This test (which is unique to the THOR-50M) impacts the lower
abdomen of a fully-assembled THOR-50M with a 177.8 mm by 50.8 mm rigid
rectangular face impactor, weighing 32.00 kg, at 3.30 m/s. It was
originally based on the lower abdomen rigid bar biofidelity condition,
though several modifications were made over time to increase its
objectivity and improve its utility as a qualification test. This test
assesses the dynamic response of the lower abdomen, including the
jacket, lower abdomen foam inserts, and lower abdomen bag, as well as
the functionality of the abdominal deflection instrumentation. The peak
overall probe force, the peak left and right X-axis abdomen deflection
at the time of peak probe force, and the difference between the left
and right X-axis deflection at the time of peak probe force are
measured and would have to be within the proposed acceptance intervals.
G. Upper Leg
The upper leg qualification test assesses the dynamic impact
performance of the knee flesh, knee flesh insert, and femur compression
element, while evaluating the functionality of the femur and acetabulum
load cells. The full THOR-50M is seated on a table with a posterior
restraint adjacent to the pelvis flesh and impacted at the knee by a
12.00 kg impactor with a 76.2 mm diameter rigid disk impact surface at
3.3 0.05 m/s parallel to the femur. The peak probe force,
peak femur Z-axis force, and peak resultant acetabulum force would have
to be within the proposed acceptance intervals.
This differs from the test procedure in the 2018 Qualification
Procedures Manual in the THOR-50M research docket. The 2018 draft
qualification test procedures for impacting the knee specifies the use
of a 5.0 kg impactor at 2.6 m/s. NHTSA's repeatability and
reproducibility testing of the qualification procedures, however--which
used the 2018 draft procedures--resulted in coefficients of variation
[[Page 61922]]
(CVs) \159\ above 10%, particularly for the peak resultant acetabulum
force. NHTSA therefore conducted a detailed review of the qualification
test procedure.\160\ This review led NHTSA to conclude that the impact
energy was unrealistically low, leading to two problems. First, the low
test energy did not load the acetabulum at a magnitude similar to that
produced in vehicle crash tests or associated with a meaningful injury
risk. This is particularly important because the upper leg test mode is
the only qualification test that assesses the acetabulum load cells,
and peak resultant acetabulum force is used in calculating the
acetabulum injury risk. Second, and relatedly, the measurement values
were so low, it was difficult to distinguish the signal from the noise.
---------------------------------------------------------------------------
\159\ See infra Section VI.A.
\160\ Millis, W. (2021). An Improvement to the THOR-50M Upper
Leg Qualification Test Methodology. 2021 SAE Government-Industry
Digital Summit, available at: https://www.nhtsa.gov/node/103666.
---------------------------------------------------------------------------
Accordingly, NHTSA revised the test parameters by increasing the
impactor mass and velocity and installing a backer plate behind the
pelvis to prevent any rearward motion during the test. These are the
parameters that we are proposing and for which data is presented (and
acceptance intervals calculated) in the qualification repeatability and
reproducibility study. As we explain in Section VI.A, the revised test
procedures resulted in repeatability and reproducibility CVs of 5% or
lower for all test measurements including peak resultant acetabulum
force. Additionally, the average acetabulum force recorded in the
improved upper leg qualification is more representative of the forces
recorded in frontal rigid barrier and OMDB vehicle crash tests, and
represents a non-negligible injury risk.
H. Knee and Lower Leg
NHTSA is also proposing qualification tests for the knee and lower
leg (ankle, ball of foot, and heel).
The knee qualification test is a simplification of the knee shear
biofidelity condition. The test assesses the response of the anterior-
posterior translation of the tibia with respect to the femur at the
knee joint, the translational resistance of the knee slider and the
stiffness of the stop assembly, and the functionality of the knee
slider string potentiometer. To conduct the knee impact test, the left
or right knee assembly (detached at the base of the femur load cell) is
removed from the ATD and mounted to a rigid surface, and a load
distribution bracket is attached to the knee slider assembly. The load
distribution bracket is impacted with a 12.00 kg impactor with a 76.2
mm diameter rigid disk impact surface at 2.20 0.05 m/s.
Unlike the HIII-50M knee slider test, no foam pad is used on the impact
surface for this test. During these tests, the femur Z-axis force and
knee slider deflection at peak femur force are measured and would have
to be within the proposed acceptance intervals.
We propose four different qualification tests to assess the lower
leg responses: ankle inversion, ankle eversion, ball of foot impact,
and heel impact. All four test setups are similar. In each, the lower
legs are removed from the dummy and each leg is tested separately. The
leg is affixed to a rigid fixture and struck by a pendulum parallel to
the tibia. The alignment of the pendulum differs for each test: for the
heel impact, it is in-line with the tibia; for the ball of foot impact,
it produces dorsiflexion of the foot; for the inversion impact; it is
offset medially from the tibia; for the eversion impact, it is offset
laterally from the tibia. For the inversion and eversion impacts, the
shoe is removed and replaced with a special striker plate that
interfaces with the pendulum.
Euro NCAP TB026 specifies different qualification requirements for
the knee and lower leg because TB026 specifies that the THOR-50M be
fitted with the HIII-50M knee and lower leg.
VI. Repeatability and Reproducibility
Any ATD that is to be used for Federal regulatory testing must have
an acceptable level of repeatability and reproducibility to ensure
confidence in the responses provided by the dummy. In the context of
dummy evaluation, repeatability refers to the similarity of responses
from a single dummy when repeatedly subjected to a particular test
condition. Reproducibility refers to the similarity of the responses
from multiple dummies repeatedly subjected to a particular test
condition. NHTSA also evaluated the repeatability and reproducibility
of the qualification tests themselves, in addition to the dummy. To
evaluate whether the THOR-50M ATD yields consistent results, NHTSA
undertook an extensive series of testing.
NHTSA systematically investigated the repeatability and
reproducibility (R&R) of the THOR-50M by conducting an extensive series
of qualification and sled tests. Qualification test measurements are
especially useful for evaluating dummy R&R because they are relatively
simple tests on individual dummy components that can be tightly
controlled so that variability in the test measurements is more likely
to come from the dummy than from other potential sources of
variability, such as the test procedures or vehicle structures and
materials. Sled testing is useful because it offers insight into the
dummy's performance as a complete system in an environment similar to
that of an actual vehicle--e.g., the consistency of its kinematics, its
impact response as an assembly, and the integrity of the dummy's
structure. Sled tests are therefore more challenging for the dummy,
while at the same time much more tightly controlled than a vehicle
test, which does not provide a desirable environment for R&R testing
due to the uncontrollable variation in vehicle structural materials and
manufacturing variability. Qualification and sled tests together
provide a basis for assessing whether the dummy will yield consistent
results when it is ultimately used in full-scale vehicle tests. NHTSA's
R&R testing also served several other important functions, such as
developing the qualification corridors and further validating the
usability and durability of the dummy.
NHTSA's R&R analysis of qualification and sled testing is briefly
summarized in the next two sections. For more detailed information, the
reader is referred to the docketed report ``THOR-50M Repeatability and
Reproducibility of Qualification Tests'' (R&R Report).\161\
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\161\ National Highway Traffic Safety Administration (2022).
THOR-50M Repeatability and Reproducibility of Qualification Tests,
May 2021, available at https://downloads.regulations.gov/NHTSA-2019-0106-0009/attachment_2.pdf. We note that for the sled test R&R
analysis, there are no previously-published reports that provide
this analysis. However, this analysis is provided in the paragraphs
below on sled testing (and in the relevant appendices) and the
underlying data is available in the NHTSA crash test database in
either the biomechanics or vehicle paragraphs (the specific location
is provided in the relevant discussion below).
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A note about dummy reproducibility: At the time NHTSA conducted
this R&R testing (both qualification tests and sled tests) it only
owned--and tested--THOR-50M units manufactured by Humanetics.
Therefore, the reproducibility analyses reported here concerned dummy
reproducibility (same lab, different dummies) and test reproducibility
(same dummy, different labs).\162\ However, another aspect of
reproducibility is whether dummies fabricated by different
manufacturers perform in a uniform manner. To this end, NHTSA has
purchased THOR-50M units from JASTI, Cellbond, and Kistler,
[[Page 61923]]
and may test with these units prior to the final rule.
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\162\ NHTSA did not examine lab-to-lab reproducibility of the
sled tests.
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A. Qualification Tests
NHTSA has completed an R&R study of the qualification tests. This
study has three main purposes. One is to assess the repeatability and
reproducibility of the dummy. Another is to determine the acceptance
intervals for the qualification tests. Third, is to assess the R&R of
the qualification tests themselves. Assessing the R&R of the
qualification tests is important for at least two reasons: it aids in
determining whether the variation in measurements are attributable to
the dummy, the test procedures, or the testing practices of different
laboratories, and it helps ensure that the qualification test
procedures themselves are as consistent and replicable as possible so
that, ultimately, the test measurements obtained in a compliance test
are uniform across dummies and test laboratories. In addition to these
main purposes, the qualification R&R testing also helped NHTSA to
identify and resolve potential issues with the qualification
procedures; reveal and resolve potential issues with, and functional
limitations of, the dummy.
Below, we first summarize our methodology for the qualification R&R
analysis, and then proceed to briefly summarize the results of the R&R
assessment for each THOR-50M body region.
Methodology
The proposed qualification tests were carried out on three THOR-50M
ATDs manufactured by Humanetics. The ATDs conformed to the proposed
drawing package. Every ATD was subjected to five repeat tests in each
qualification test condition at NHTSA's Vehicle Research and Test
Center (VRTC) and one of the three dummies was tested at two other
labs, Humanetics and Calspan (with some exceptions as described in the
following paragraphs). All tests were used in development of the
proposed qualification acceptance intervals, with some exceptions as
explained below where the input velocity did not meet the
specification. For qualification test conditions where one ATD
component is tested in both the left and the right direction, only the
left direction is included in the analysis, as the dummy design is
symmetric and not expected to differ between the two sides. For
qualification test conditions in which multiple ATD components are
tested, data from the left and right tests or measurements are
combined.
We evaluated R&R of both the dummy and the qualification tests
using a statistical analysis of variance referred to as the coefficient
of variation (CV). The CV approach was first introduced by NHTSA as a
means for evaluating dummy repeatability when the original subpart B
Hybrid II 50th percentile male ATD was proposed.\163\ Since then, the
agency has used this approach for other Part 572 rulemakings.\164\ The
CV is a measure of variability expressed as a percentage of the mean.
It is defined as the percentage of the sample standard deviation
divided by the mean of the data set:
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\163\ 40 FR 33466 (Aug. 8, 1975).
\164\ See, e.g., 85 FR 69898, 69904-69905 (Nov. 3, 2020) (final
rule for Q3s ATD).
[GRAPHIC] [TIFF OMITTED] TP07SE23.019
In the qualification test series, the data points of each trial are
considered on their own and not as being representative of a large
population. Thus, the sample-based standard deviation is applied in
which s is an estimate of the standard deviation based on a
sample.\165\ It is computed using the following formula, where x is the
average value of the trials (sample mean) and n is the number of trials
(sample size).
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\165\ The population-based standard deviation, which is always
lower than the sample-based standard deviation, is not appropriate
because only a limited number of NHTSA-owned THOR-50M units were
tested, and the tests were carried out at a limited number of test
facilities.
[GRAPHIC] [TIFF OMITTED] TP07SE23.020
For each qualification test parameter (e.g., head impact peak probe
force) specified for each test condition (e.g., head impact), we
computed the mean, standard deviation, and coefficient of variation.
More specifically, to investigate dummy repeatability and test
repeatability, we calculated these summary statistics for the five
tests of each test condition performed on each of the three dummies at
VRTC. To investigate dummy reproducibility, we pooled the data for the
three dummies tested at VRTC. Finally, to investigate test
reproducibility, we pooled the data for the dummy that was tested at
VRTC, Calspan, and Humanetics.
We used the following approach to assess R&R:
CV <5%: No further investigation. We believe that a set of
responses with a CV below 5% indicates a highly repeatable and
reproducible condition.
5% >= CV <= 10%: sources of variability investigated.
CV >10%: Test procedure thoroughly reviewed and dummy(ies)
inspected.
When the CV was greater than or equal to 5%, we investigated the
source of the variability. In all cases, we were able to determine the
source of the variation with reasonable confidence. Once NHTSA had
refined the qualification test procedures it only obtained a CV greater
than 10% in two instances--repeatability of the face foam, and test
reproducibility in one measurement in the neck extension mode. Prior to
refining the test procedures, NHTSA obtained a CV greater than 10% for
the upper leg test. A full investigation led to a new and improved test
procedure. That new test procedure is reflected in the R&R report, and
the resulting CVs all less than 10%. Table 9 and Table 10 summarize the
CVs that we calculated for each test parameter for each qualification
test condition. Table 11 summarizes the variability sources and
resolutions seen in the qualification R&R test series.
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Table 11--Summary of Qualification Test Variability Sources and
Resolutions
------------------------------------------------------------------------
Test mode Source of varibility; control solution
------------------------------------------------------------------------
Head......................... None.
Face......................... Face foam degradation occurs cumulatively
with successive impacts; monitor and
swap out foam as needed.
Neck Extension............... The inverse relationship between My and
Fz may be balanced by adjusting the
input pulse through the selection of the
pendulum's honeycomb cell configuraton.
Neck Flexion................. For a new molded neck, My and Fz may be
elevated in initial test only. Also, the
pendulum's honeycomb cell configuration
may need attention to control input
pulse.
Neck Lateral................. None.
Neck Torsion................. None.
Upper Thorax................. None.
Lower Thorax................. The asymmetric test setup requires a high
level of diligence from operator in
aligning the dummy with the probe.
Abdomen...................... Operator diligence is needed to ensure a
symmetric test setup. Otherwise, right
vs. left discrepancies in force and
deflection measurements will occur.
Upper Leg.................... If a high femur Fz occurs, a test lab may
need to experiment with set-ups and
dummy positioning (within allowable
tolerances).
Knee......................... Low femur Fz measurements may be resolved
at the test labs by experimenting with
setups and dummy positioning.
Ankle Inversion.............. Ankle inversion and eversion tests are
Ankle Eversion............... run on the same apparatus and are nearly
identical. The ankle moment, tibia Fz,
and ankle rotation may be slightly low
in an initial qualification test if
there has been an extended period of non-
use of the Ensolite pad on the test
fixture. This is only a concern if the
tibia force and moment are just below
the upper qualification limits, since
subsequent tests may be expected to
produce slightly higher moments and
forces (which might be out of the
qualification range). Labs can simply
perform an additional test to confirm
that the response of the ankle is within
the requirements.
Ball of Foot................. Test labs may need to adjust their set-
ups and fixtures (within allowable
tolerances) to attain a reponse within
10% of the target for ankle moment.
Heel......................... In cases where passing qualification
results cannot be achieved, a test lab
may need to replace the molded shoe
assembly (472-7800-1 (left) or -
2(right)) and/or the upper tibia
complaint bushing assembly (472-7315) in
order to attain a peak lower tibia Fz
within 10% of the target.
------------------------------------------------------------------------
Our investigation of the sources of variability also gives us
additional confidence that the proposed acceptance intervals ( 10% of the mean response reported in the R&R study) are both
achievable and sufficient to ensure that the dummy is providing uniform
responses. In NHTSA's testing, when the CV was below 5%, the responses
in all the tests were always within the proposed acceptance intervals.
When the CV exceeded 5%, however, we observed a response outside the
proposed acceptance interval in at least one test. When the CV exceeded
10%, several tests were outside the qualification corridor.
NHTSA seeks comment on this methodology. Although the qualification
R&R study utilizes only NHTSA's test data, NHTSA is open to considering
qualification data provided by commenters in the finalization of the
qualification specifications, provided that the data are from THOR-50M
ATDs conforming to the 2023 drawing package and collected following the
proposed Qualification Procedures.
Head Impact
In the head impact qualification test mode, all CVs for
repeatability and reproducibility were below 5%, and the responses in
all the tests were within the proposed qualification acceptance
intervals.
Face Impact
We used a slightly different approach to evaluating the R&R of the
face than we did for the other qualification tests. Our approach was
motivated by two characteristics of the THOR-50M face.
First was the response of the face foam. The impact response of the
face is driven primarily by the face foam insert, which is constructed
of a memory foam that necessitates an extensive recovery period after a
dynamic impact; the THOR-50M Qualification Procedures specifies at
least 24 hours of recovery between tests. Even with this extended
recovery period, however, the foam progressively degrades after each
impact so that the peak probe force and peak head resultant
acceleration increases with each test. We were able to conduct eight to
nine tests with a new face foam insert before the face fell outside the
upper bound of the face rigid disc impact biofidelity corridor (4,400 N
to 8,200 N).
Second, because the face foam degrades, any variations in the dummy
response are likely to be masked by the significant variations caused
by the foam. That is, most of the observed variation in the face
qualification test is essentially due to the face foam response; any
contributions of other components or lab-to-lab differences were
negligible.\166\
---------------------------------------------------------------------------
\166\ This is seen in the head impact test series, in which the
headskins were found to be repeatable and reproducible, with
repeated impacts to the head yielding nearly identical responses.
---------------------------------------------------------------------------
In light of these characteristics, we modified the R&R test
methodology for the face impact tests. Our testing consisted of
evaluating one dummy (DO9799) at VRTC, using three different new,
unused, face foams (as opposed to testing three different ATDs); we
deemed it unnecessary to test multiple ATDs because the variation in
response was predominantly due to the face foam, not the ATD. We also
did not test lab-to-lab variability (test reproducibility), because
this would require testing the same face foam successively at multiple
laboratories, which the degradation of the face foam prevented us from
doing. We allowed 24 hours between tests as specified in the
Qualifications Procedures. We tested each dummy until the peak probe
force
[[Page 61930]]
fell out of the biofidelity corridor (until the peak probe force
exceeded 8,200 N). Only those tests which fell within the peak probe
force biofidelity corridor were then included in the repeatability
analysis and used to set the qualification targets. This gave us eight-
to-nine tests for each of the three face foams we tested.
For two of the face foam inserts tested, repeatability CVs were
below 10%. The third face foam insert resulted in CVs for peak probe
force and peak head CG resultant acceleration of 10.1% and 12.1%.
Though not reported in the R&R paper, CVs for the HIC15
values associated with the head resultant accelerations recorded in the
face impact test are within 1% of the CVs for peak resultant head CG
acceleration. However, in practice, we would likely not observe this
level of variability because in several of the tests used to calculate
CV, the peak probe force was outside of the qualification targets
(either too high or too low) and so the dummy would have been further
adjusted before being used in a compliance (or research) test. We
observed that when the response of a new face foam insert is too low,
it likely indicates the need for an additional ``break in'' test, in
which case the face impact test would be repeated. If the response is
too high, it likely indicates that the face foam needs to be replaced,
in which case a new face foam insert will be installed and the face
impact test repeated. Therefore, we believe that the face impact test
is sufficiently repeatable. Moreover, although we did not test at
multiple labs to evaluate reproducibility due to face foam degradation,
we also believe that the face impact test is reproducible. The head
impact test uses essentially the same test apparatus and a similar
impact condition as the face impact test. Because the test
reproducibility was very good in the head impact test, we expect that
there will be acceptable levels of lab-to-lab variability for the face
impact test as well.
Neck
For the neck qualification tests, the entire head-neck assembly is
removed from the THOR-50M, so the serial numbers listed in Table 9 are
those of the individual head-neck assemblies and not the ATD itself.
With respect to repeatability, across all four neck test modes
(flexion, extension, lateral flexion, and torsion), CVs for
repeatability were below 10% for all qualification test parameters and
for all necks, and were below 5% except in the neck flexion test mode
for two of the necks: peak upper neck Y-axis moment (5.8%) and peak
upper neck Z-axis force (6.0%) for neck EB6007, and peak upper neck Y-
axis moment for neck EB6006 (5.1%). For both of these necks, the first
test resulted in a peak upper neck Y-axis moment higher than the
resulting qualification targets; thus this first test would have been
re-run in practice. If this first test were discarded, the resulting
repeatability CVs would be at or below 5% for all necks. Labs may find
that while the first neck flexion test performed on a new neck produces
a Y-axis moment greater than the qualification targets, subsequent
tests result in lower values within the acceptance interval. Also, labs
may need to adjust the input pulse by experimenting with honeycomb cell
configurations to achieve the target response.
Reproducibility CVs were below 5%, except in four instances, two
for the neck flexion test mode, and two for the neck extension test
mode.
In the neck flexion test mode, the dummy reproducibility CV for
peak upper neck Y-axis moment was 5.4%. This likely results from the
same break-in issue described above. Also in the neck flexion test
mode, the test reproducibility CV for peak upper neck Z-axis force was
7.5%. In this case, there were two tests each at Calspan and Humanetics
that would not have met the resulting qualification
specifications,\167\ though discarding these tests would still result
in a reproducibility CV of 6.4% for peak upper neck Z-axis force.
However, we believe that this variance is not likely to lead to
inconsistent compliance test outcomes because the average peak upper
neck Z-axis force (860 N) represents a very low probability of injury
(0.7% risk of AIS 3+ injury). Although NHTSA has not yet established
injury assessment reference values (IARVs) for the THOR, when it does
(NHTSA anticipates rulemaking in the near future to add the THOR-50M to
FMVSS No. 208 as an optional test device) an IARV for neck flexion
would almost certainly be specified to correspond to a risk of AIS 3+
injury much higher than 0.7%, i.e., corresponding to a much higher Z-
axis force than 860 N.\168\
---------------------------------------------------------------------------
\167\ R&R Report, Table 6-14.
\168\ Upper neck Fz is currently specified in FMVSS
NO. 208 as an injury criterion for the HIII-50M and is also a
component of THOR-specific Nij criterion.
---------------------------------------------------------------------------
In the neck extension test mode, two test reproducibility CVs were
above 5%: peak upper neck Y-axis moment (5.6%) and peak upper neck Z-
axis force (12.2%). These elevated CVs result from the tests on neck
EB6007 at Calspan, for which the first four tests resulted in peak
upper neck Z-axis forces lower in magnitude than the resulting
qualification targets, while the last test resulted in a peak upper
neck Y-axis moment higher in magnitude than the resulting qualification
targets, and at Humanetics, for which four of the five tests resulted
in peak upper neck Z-axis forces higher in magnitude than the
qualification targets, though by not more than 32 N.\169\ However,
since all of the remaining tests on neck EB6007 at VRTC (15 tests)
would have met the qualification targets, and the associated test
reproducibility CVs would be below 3% for all test parameters except
for the Calspan observations, this finding likely results from either
an issue with test execution at Calspan, or an issue specific to neck
EB6007, such as damage or unintended adjustment of the neck spring
cables after it was tested at both VRTC and Humanetics.
---------------------------------------------------------------------------
\169\ R&R Report, Table 7-16.
---------------------------------------------------------------------------
While the input parameters for the tests conducted on EB6007 were
all within the qualification specifications, the pendulum velocity at
20 and 30 milliseconds after T-zero was notably higher at Calspan
compared to VRTC and Humanetics, which may explain the differences in
results. As such, it may be worth considering narrower specifications
on the pendulum velocity input parameters. On the other hand, if the
differing results at Calspan resulted from issues with the neck itself,
then the fact that the qualification specifications were not met
indicates that the qualification tests successfully identified a
damaged or improperly configured neck.
Upper Thorax
In the upper thorax qualification test mode, all CVs for
repeatability and reproducibility were below 5%, which indicates that
the qualification specifications were achievable by three different
THOR-50M ATDs and at three different test labs. Further, as all CVs
were below 3.7%, this indicates that all tests were within the 10% target.
Lower Thorax
In the lower thorax qualification test mode, all but one of the CVs
for repeatability were below 5%. One repeatability assessment, peak
resultant deflection at peak probe force for ATD DO9798, had a CV of
5.2%. For this ATD, peak resultant deflections on the right side were
closer to the upper end of the corridor, while those on the left side
were closer to the lower end of the corridor. CVs for dummy
reproducibility were below 5%. Test
[[Page 61931]]
reproducibility CVs were slightly above 5%. Here, one of the tests at
Humanetics would not have met the resulting peak probe force
qualification specifications, while four of the tests at Calspan would
not have met the resultant deflection at peak force specification.\170\
If the tests that would not fall within the qualification
specifications were excluded, as would be done in practice,
reproducibility CVs would be below 5%. Overall, the lower thorax
qualification specifications were achievable by three different THOR-
50M ATDs and at three different test labs.
---------------------------------------------------------------------------
\170\ R&R Report, Table 11-9.
---------------------------------------------------------------------------
Abdomen
When the abdomen qualification repeatability and reproducibility
testing was conducted, all three THOR-50M ATDs were not available.
As an alternative, three different abdomen assemblies were tested
on the same ATD. We believe this modification is acceptable because the
abdomen foam inserts and the structure of the abdomen bag are
responsible for a majority of the variation in the lower abdomen
qualification test, whereas the remainder of the THOR-50M is
essentially a ballast.
All of the CVs for repeatability and reproducibility of peak probe
force were below 5%. All of the CVs for repeatability and
reproducibility of the peak left and right X-axis deflection at the
time of peak force were between 5% and 6%. Of these tests, three at
Calspan resulted in right abdomen X-axis deflections lower in magnitude
than the qualification specifications. While not included in the CV
calculation, the difference between left and right X-axis deflection
measurement highlighted the fact that all tests at VRTC had a positive
difference of at least 6.8 millimeters, indicating that the magnitude
of right X-axis deflection was greater than the magnitude of left X-
axis deflection in all tests. The opposite was true at Calspan, where
three of the tests showed notably higher magnitude deflections on the
left side. In total, six of the abdomen qualification tests (five at
VRTC and one at Calspan) were beyond the 8 millimeter difference
specified by the qualification specifications. Further examination of
the test setup at VRTC showed that the ATD was consistently rotated
slightly about the Z-axis, resulting in the right side of the abdomen
being closer to the probe than the left side, and subsequently
recording more deflection. The test configuration at VRTC has since
been corrected. This issue is not expected to introduce variability in
test results in the future because such tests outside the qualification
targets would necessitate dummy adjustment and re-running the test. If
only tests that were within the maximum difference in left-to-right
deflection specification were included, both the dummy and test
reproducibility CVs would be 5.0% or below.
Upper Leg
As we explained earlier (Section VI, Qualification Tests), the
proposed upper leg qualification test procedure reflects revisions to
the 2018 Qualification Test Procedures that we made in light of our R&R
testing. The CVs for repeatability and reproducibility for the revised
test procedure for all three measurements were at or below 5%,
demonstrating that the upper leg qualification specifications can be
met by three different THOR-50M ATDs at three different test labs.
Knee
For the knee qualification test, all CVs for repeatability were
below 5%. For dummy reproducibility, CVs were 5.0% and below for both
measures. For test reproducibility, the CV for knee deflection at peak
femur Z-axis force was below 5%, while the CV for peak femur Z-axis
force was 5.9%. This elevated CV appears to result from the tests at
Calspan, which were all generally lower in magnitude than at VRTC and
Humanetics, and three of the tests resulted in peak femur Z-axis force
lower than the qualification specification. As the three tests that
were outside of the qualification specifications were the first or
second tests in the series, it is possible that the lower forces
resulted from misalignment of the load distribution plate or other
slack in the system that was corrected in the remaining tests. In light
of this, we believe that the knee qualification repeatability and
reproducibility test series demonstrated that the qualification
specifications could be achieved by six different THOR-50M knees at
three different test labs.
Lower Leg
As used by VRTC, the lower legs are considered modular, and are
typically assigned to a THOR-50M on deployment and not necessarily tied
to a specific THOR-50Ms serial number. As such, the repeatability and
reproducibility qualification study was carried out by testing three
different lower legs at VRTC, followed by testing two of those legs at
both Humanetics and Calspan. This resulted in a total of 15 tests for
the dummy reproducibility assessment, and 30 tests for the
reproducibility assessment (although several of the tests at Calspan
were not included because they did not meet the test velocity input
specifications).
For all the lower leg test modes, repeatability CVs were all below
5%, indicating that the qualification specifications are achievable by
three different THOR-50M ATDs. There were, however, a few test mode/
parameters for which reproducibility CVs were above 5%.
In the ankle inversion test mode, test reproducibility for the peak
lower tibia Z-axis force measurement was 5.3%. The source of this
elevated CV appears to be the first test of leg DL5405 at VRTC, where
the peak lower tibia Z-axis force was -451 N, which was just outside
the acceptance interval (-454 to -555 N). In practice, this test would
have been re-run, and all the remaining tests on this leg would have
met the qualification targets. Removing this test from the CV
calculation would result in a test reproducibility CV of 4.9%.
In the ankle eversion test mode, dummy reproducibility was above 5%
for the peak lower tibia Z-axis force (5.7%), and test reproducibility
was above 5% for lower tibia Z-axis force (6.0%) and peak ankle
resistive moment (5.1%). These elevated CVs appear to result from the
first tests on DL0202 at VRTC, where the peak lower tibia Z-axis force
(-512 N) was just outside the acceptance interval (-514 N to -629 N),
and at Calspan, where the peak lower tibia Z-axis force (-454 N) and
the peak angle resistive moment (35.6 Nm) were both below the lower end
of the associated qualification specifications (-514 N and 38.7 Nm,
respectively). In practice, these tests would have been re-run, and all
the remaining tests on this leg at both labs would have met the
qualification specification. Removing these two tests from the CV
calculation would result in reproducibility CVs all below 5%, which
demonstrates that the ankle eversion qualification specifications can
be met by six different legs at three different test labs.
In the ball-of-foot test mode, which assesses both the impact
response of the ball-of-foot portion of the molded shoe and the
dorsiflexion response of the ankle, the only CV above 5% was the test
reproducibility of the peak ankle resistive moment (6.9%). In the tests
at Calspan, only two of the five tests on the left leg (DL0202) met the
qualification specification for input velocity. The three tests that
did not meet the qualification specification were considered invalid
tests and therefore were not included in the test
[[Page 61932]]
reproducibility assessment, so only seven tests from Calspan were
included as opposed to 10 tests from each of the other labs. Of the
tests run by Calspan on the right leg (DL5404), four of the five
resulted in peak ankle resistive moments of 61.3 to 61.8 Nm, just above
the upper end of the qualification specification (60.8 Nm). As the
tests at Calspan were consistently higher in peak ankle resistive
moment than those at VRTC and Humanetics, it is possible that this
finding results from either an issue with test execution at Calspan, or
an issue specific to leg DL5404, such as damage or unintended
adjustment of the Achilles spring cables after it was tested at both
VRTC and Humanetics. Reviewing the time-history data for ankle
resistive moment from exemplar tests from Calspan, VRTC, and Humanetics
(Figure 1), there are some differences early in the event (note the
large positive moment before 10 milliseconds in the Calspan test) that
suggest differences in test setup and/or impactor hardware.
[GRAPHIC] [TIFF OMITTED] TP07SE23.028
In the heel impact test, which assesses both the impact response of
the heel portion of the molded shoe and the tibia compliant element,
the repeatability CVs were all under 5%, but both the dummy (6.4%) and
test (5.9%) reproducibility CVs were over 5%. If the test CVs are
calculated independently for the left and right legs, the resulting CVs
are much lower (2.1% and 3.0%, respectively). This suggests that the
test itself is repeatable (as all repeatability CVs were 1.6% or below)
and reproducible, but that there is some ATD-to-ATD (in this case, leg-
to-leg) variation. Nonetheless, the qualification specifications for
the heel impact test can be met using three different legs in at least
two different test labs.
Additional Qualification Test Lab
We performed a variety of vehicle tests (discussed in Section VIII,
Overall Usability and Performance) where multiple dummies were
qualified at two different labs, including a lab (Applus+ IDIADA KARCO
Engineering LLC) that was not one of the laboratories used to develop
the qualification specifications, and it was possible to qualify the
dummies. This qualitative information gives us further confidence that
the qualification tests are reproducible. Therefore, NHTSA tentatively
concludes that there is a sufficiently high degree of uniformity in the
construction of the dummy components being tested and in the procedures
followed by the labs for that test requirement for the THOR-50M to be
incorporated into Part 572.
B. Sled Tests
THOR-50M repeatability was also assessed through sled tests
representing several different vehicle crash environments, including
unbelted, standard, and load-limited three-point belt configurations at
different speeds for both the driver and right front passenger seating
positions, as well as several restraint configurations in the rear
seat. NHTSA's sled test repeatability analysis is based on data from
three different sled test series that NHTSA ran in the course of
developing THOR-50M. One is a sled test series conducted to develop
thoracic injury criteria for the THOR-50M. Another is a sled test
series conducted to assess the performance of THOR-50M in low-speed
belted crashes. The third is a sled test series conducted to assess
THOR-50M's performance in low-speed unbelted crashes.
In summary, while there were several cases where the variation from
test to test of the same THOR-50M ATD was greater than 10%, these cases
can be explained by either differences in physical interactions (e.g.,
contact of the head with the arm in the rear seat sled test), which can
be addressed by careful pre-test positioning of the ATD, or by the low
magnitude of the measurements, as demonstrated through the use of
normalized CV to identify cases where the variation occurs at a much
lower level than would be associated with a risk of injury.
This is discussed in more detail in the sections that follow. We
begin by explaining our methodology, and then proceed to discuss the
three different test series.
1. Methodology
As with the qualification R&R analysis, we assessed repeatability
using the coefficient of variation. The CVs were calculated for each of
the injury criteria described in the THOR-50M injury criteria report,
as well as for peak
[[Page 61933]]
values from a few other key data channels: \171\ lap belt, upper
shoulder belt, and lower shoulder belt.
---------------------------------------------------------------------------
\171\ The low-speed sled tests have fewer metrics than the
thoracic injury criteria set (11 vs. 12) because lower shoulder belt
loads were not recorded in the low-speed sled tests.
---------------------------------------------------------------------------
The CV analysis was the same as in the qualification test R&R
study, with two modifications. As with the qualification test R&R
study, CVs below 5% were considered to require no further
investigation; for CVs between 5% and 10% we reviewed the results for
outliers; and for CVs greater than 10% we thoroughly investigated the
sources of variability in the test procedure and the ATD. However, our
assessment differed in two ways from the CV assessment in the
qualification R&R study.
First, we used the population standard deviation instead of the
sample standard deviation to calculate the CV because these test series
are the only sled test series that have been run.\172\ Accordingly,
---------------------------------------------------------------------------
\172\ This differs from the qualification tests, for which it is
known that the data set is a sample of a larger population (because
NHTSA and other test labs have run the qualification tests on other
THOR-50M ATDs).
[GRAPHIC] [TIFF OMITTED] TP07SE23.029
Second, in addition to the CVs we also considered the normalized
CVs. A potential limitation of the CV calculation is that when the
magnitude of a given measurement is relatively low, as is the case with
off-axis sensor channels, the standard deviation can be high relative
to the mean, leading to CVs over 10%. However, this result is not
necessarily meaningful: although the amount of variation might be high
relative to the mean, it might not be high with respect to say, a
critical value of the measurement being evaluated (e.g., in the context
of a compliance test involving an ATD, it might not be high with
respect to the IARV). This was generally not an issue in the
qualification test R&R analysis because the qualification modes, test
parameters, and targets were all selected because they are meaningful
to the test mode and/or are in the primary load path, so that the
resulting measurements were generally of sufficient magnitude for a
reliable CV calculation. In sled and vehicle crash tests, on the other
hand, it is not known in advance which sensor channels will be of
sufficient magnitude for a reliable CV assessment. For this reason,
researchers often disregard high CV values when the magnitude of the
measurement is relatively low. However, determining the level of the
measurement below which CV is not reliable is inherently subjective.
Accordingly, for CVs above 10% we also considered normalized CVs.
To calculate normalized CV, the mean ([mu]) in the CV calculation (Eqn.
1) is replaced with a meaningful, pre-determined reference value. Such
a reference value could be an IARV or a measurement value that
corresponds to an injury risk similar to the risk that would correspond
to an IARV. Because IARVs for the THOR-50M have not yet been finalized,
in most cases we calculated the normalized CV using the value
associated with a 50% risk of AIS 3+ (above the pelvis) or AIS 2+
(below the pelvis) injury as the reference value.\173\ However, there
is not a known risk function that relates belt forces to risk of
injury, so for this metric we normalized using the average shoulder
belt force from the thoracic injury criteria development data set, for
which just over 50% of the subjects sustained AIS 3+ thoracic injuries
(a denominator of 5,000 N).\174\ The normalization denominators used
for each of the measurements are shown in Table 12.
---------------------------------------------------------------------------
\173\ Fifty percent risk of a given injury severity is a widely-
used tolerance level in ATD research. IARVs specified in the FMVSS
may or may not correspond to a 50% risk.
\174\ We used the shoulder belt force to normalize the lap belt
force because there was not meaningful lap belt force data in some
of the thoracic injury criteria development test conditions.
Table 12--Normalization Denominators for Calculation of Normalized CV
----------------------------------------------------------------------------------------------------------------
Metric Normalization factor Normalization rationale
----------------------------------------------------------------------------------------------------------------
HIC15................................... 1724................................ 50% risk of AIS 3+ injury.
BrIC.................................... 0.96................................
Neck Tension............................ 4,662 N............................. 50% risk of AIS 3+ injury when
used in Nij risk function.
Neck Compression........................ -5,017 N............................
Nij..................................... 1.11................................ 50% risk of AIS 3+ injury.
Chest Peak Res. Defl.................... 51.4 mm.............................
Left Femur Axial Force.................. 10,577 N............................ 50% risk of AIS 2+ injury.
Right Femur Axial Force................. 10,577 N............................
Peak Femur Axial Force.................. 10,577 N............................
Lap Belt Force.......................... 5,000 N............................. Average from thoracic injury
criteria development data set.
Upper Shoulder Belt Force............... 5,000 N.............................
Lower Shoulder Belt Force............... 5,000 N.............................
----------------------------------------------------------------------------------------------------------------
As an example, consider a repeated test with peak femur forces of
500 N, 1,000 N, and 1,500 N. For these tests, the calculated CV would
be 41% (standard deviation of 408 N divided by average of 1000 N),
which would require a thorough investigation of the test procedure and
ATD. However, these femur forces are all well below 10,577 N, the force
at which 50% risk of AIS 2+ injury occurs. Thus, calculating a
normalized CV may provide a more meaningful assessment. In this case,
the normalized CV would be 4% (standard deviation of 408 N divided by
50% risk of AIS 2+ injury of 10,577 N), which would require no further
investigation.
2. Thoracic Injury Criteria Development Sled Tests
One source of data NHTSA looked at to further assess repeatability
is a sled test series conducted to develop thoracic injury criteria for
the THOR-50M. This involved conducting matched-pair tests of PMHS and a
THOR-50M ATD in a variety of sled
[[Page 61934]]
test conditions.\175\ This series tested the same THOR-50M unit in
three to four repeat tests in each of six different test conditions:
Gold Standard 1, 2, and 3; Rear Standard; Rear Load-limited (Rear LL);
and Rear Inflatable (Table 13).\176\
---------------------------------------------------------------------------
\175\ Craig, M., Parent, D., Lee, E., Rudd, R., Takhounts, E.,
Hasija, V. (2020). Injury Criteria for the THOR 50th Male ATD.
Docket ID NHTSA-2019-0106-0008, available at: https://www.regulations.gov/document/NHTSA-2019-0106-0008.
\176\ Our testing included a seventh test condition: Far-Side
Oblique (representing the right front passenger in an oblique moving
deformable barrier crash test). The THOR-50M setup and positioning,
however, differed in each of these tests. These tests were not valid
for the purposes of the repeatability analysis, because the
differences in setup and positioning is expected to--and in fact
did--lead to a wider variation in results. Specifically, the CVs for
8 of the 15 measurements exceeded 10%, with most of these over 20%,
and some as high as 72%.
Table 13--THOR-50M Thoracic Injury Criteria Development Test Matrix
----------------------------------------------------------------------------------------------------------------
Nominal test
TSTNO TSTREF speed (km/h) Test condition name, description
----------------------------------------------------------------------------------------------------------------
11117...................................... S0156 40 Gold Standard 1: flat rigid seat,
11118...................................... S0157 standard lap and shoulder belts,
11119...................................... S0158 knees restrained, right front
passenger restraint geometry.
11120...................................... S0159 30 Gold Standard 2: flat rigid seat,
11121...................................... S0160 force-limited shoulder belt and
11122...................................... S0161 standard lap belt, knees
restrained, right front passenger
restraint geometry..
11514...................................... UVAS0309 30 Gold Standard 3: flat rigid seat
11515...................................... UVAS0310 angled 30 degrees
11516...................................... UVAS0311 counterclockwise, force-limited
11517...................................... UVAS0312 shoulder belt and standard lap
belt, knees restrained, right
front passenger restraint
geometry.
11143...................................... S0199 48 Rear Standard: rear passenger in
11144...................................... S0200 2004 Ford Taurus buck; 3-point
11145...................................... S0201 standard belt.
11140...................................... S0196 48 Rear LL: rear passenger in 2004
11141...................................... S0197 Ford Taurus buck; 3-point load-
11142...................................... S0198 limited belt with pretensioner.
11137...................................... S0193 48 Rear Inflatable: rear passenger in
11138...................................... S0194 2004 Ford Taurus buck; 3-point
11139...................................... S0195 inflatable force-limited belt with
pretensioner.
----------------------------------------------------------------------------------------------------------------
Notes: All tests were on THOR-50M S/N 9207. These tests are available in the NHTSA biomechanics database.
We calculated CVs and normalized CVs for each of the injury
criteria described in the THOR-50M injury criteria report, as well as a
few other key data channels, for a total of 12 metrics for each of the
six test conditions. See Table 14 (CVs) and Table 12 (normalization
denominators). Sixty-five of the seventy-two CVs calculated were below
10%, while seven CVs were 10% or above.
BILLING CODE 4910-59-P
[[Page 61935]]
[GRAPHIC] [TIFF OMITTED] TP07SE23.030
BILLING CODE 4910-59-C
We believe that this data supports our tentative conclusion that
the THOR-50M is sufficiently objective for inclusion in Part 572.
Almost all the CVs were below 10%, and many were at or below 5%. For
the seven CVs at or above 10%, we believe that these do not indicate
that the dummy does not yield repeatable results. These seven
measurements with CVs above 10% were: Gold Standard 1 condition for
neck compression, Nij, and lap belt load; rear-seat standard belt
condition neck tension; rear-seat load-limited condition for BrIC and
neck compression; and rear-seat inflatable belt condition for
HIC15). When normalized, however, none of these CVs were
above 10%. This suggests that the variability in these measurements
would not likely lead to variability in actual testing outcomes. The
variability in these measurements is much lower than the magnitudes of
these measurements that would be used as an IARV specified in FMVSS No.
208.
For instance, the individual measurements for neck compression in
the Gold Standard 1 tests were -394 N, -427 N, and -328 N. These have
an average of -383 N and a standard deviation of 41 N, resulting in an
unadjusted CV of 11%. While this is greater than 10%--potentially
suggesting that the source of this variability needs investigation--
these measurements are all much lower in
[[Page 61936]]
magnitude than the compression force that would result in a 50% risk of
AIS 3+ injury (-5017 N). When the standard deviation is compared to
this compression force instead of the average neck compression, we
obtain a normalized CV of 0.8%. This suggests that the magnitudes of
the neck compression measurements are low compared to the magnitude of
compression that corresponds to a meaningful injury risk.
There was one measurement for which the unadjusted CV was below 10%
but the normalized CV was above 10%: the peak lap belt force in the
rear-seat inflatable belt condition, which had a normalized CV of
11.7%. In this instance, the average lap belt load (6,701 N) was higher
than the normalizing denominator (5,000 N), resulting in an inflated
normalized CV. As stated earlier, there is not a known risk function
that relates belt forces to risk of injury, so this elevated normalized
CV is not of particular concern.
Otherwise, the highest normalized CV occurred in the BrIC
measurement in the rear seat load-limited and pretensioned condition
(9.6%). This appears to result from inconsistent initial positioning of
the left arm, which is more of a test procedure concern than a THOR-50M
concern.
3. Low-Speed Belted Sled Tests
Another source of data NHTSA looked at to assess repeatability is a
sled test series conducted to assess the performance of THOR-50M in
low-speed belted conditions. These tests were based on the rigid
barrier, perpendicular impact belted crash test specified in FMVSS No.
208 for the HIII-50M. Sled tests were conducted at crash pulses
representing three frontal rigid barrier impact velocities (24, 32, and
40 km/h) (15, 20, and 25 mph). This range of speeds was selected
because FMVSS No. 208 specifies a speed of up to 56 km/h (35 mph) for
this crash test, and air bag deployment thresholds are typically around
24 km/h (15 mph); we spanned the 24-40 km/h (15-25 mph) range and
selected a mid-point of 32 km/h (20 mph) to conduct a crash test and
get a crash pulse. In each test, the THOR-50M was seated in either the
driver or right front passenger seating locations of a buck
representing a mid-sized passenger car.\177\ Three tests were conducted
at each impact velocity, for a total of 9 tests. The test buck was
created from an actual vehicle, and included seat belts, front air
bags, knee-bolsters, and pretensioners. The test matrix and additional
information about the test setup is provided in Appendix D.
---------------------------------------------------------------------------
\177\ A HIII-50M was seated in the other front outboard seat.
---------------------------------------------------------------------------
As with the thoracic injury criteria development test series, both
CVs and normalized CVs (Table 15) were calculated for each of the
relevant injury metrics described in the THOR-50M Injury Criteria
Report, as well as femur and seat belt loads, for 11 metrics for each
of the six test conditions. Of these 66 CVs, 31 were under 5%, 17 were
between 5% and 10%, and 18 were above 10%.
We believe that this data supports our tentative conclusion that
THOR-50M is sufficiently objective to include in Part 572. Most of the
CVs were under 10% and many were under 5%. None of the 18 measurements
for which the CV was above 10% had a normalized CV over 10%, and only
five were above 5%. This is not surprising, as the low-speed belted
test condition presents a low likelihood of injury. Thus, while there
may be variations in the injury metrics, these variations are small
relative to the values that would represent a meaningful injury risk.
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4. Low-Speed Unbelted Sled Tests
Another source of data NHTSA looked at to assess repeatability is a
sled test series conducted to assess the performance of THOR-50M in a
low-speed unbelted condition. Sled tests were conducted at crash pulses
representing two frontal rigid barrier impact velocities, 32 km/h (20
mph) and 40 km/h (25 mph), with the THOR-50M in both the driver and
right front passenger seating locations of a test buck. Three tests
were conducted at each impact velocity. The test buck was identical to
that used in the low-speed belted tests except for some minor
modifications. The test matrix and additional information about the
test setup is provided in Appendix E.
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As with the thoracic injury criteria development and belted test
series, CVs and normalized CVs were calculated for each of the relevant
injury metrics described in the THOR-50M Injury Criteria Report, as
well as femur loads, for nine metrics for each of the two crash pulses.
Of these 36 CVs, 12 were less than 5%, 20 were between 5% and 10%, and
four were above 10% (Table 16).
We believe this supports our tentative conclusion that the THOR-50M
is objective. Almost all the CVs were under 10%, and many were under
5%. Three of the four measurements with a CV over 10% had a normalized
CV under 10% (neck tension for driver 32 km/h and RFP 40km/h, and
HIC15 for RFP 40 km/h), suggesting that the variation is
small relative to the values that would represent a meaningful injury
risk. The low magnitudes of neck tension occur because there is no
torso restraint in these unbelted tests, so that the tension force
acting on the neck due to the deceleration of the torso is minimal
(below 500 N). The HIC15 measurements were relatively low
because the frontal air bags minimized the contact of the head with
hard surfaces or at least decelerated the head before contact. The
highest average HIC15 (360) occurred in the right front
passenger 40 km/h condition, where individual measurements of 309, 349,
and 423 resulted in a standard deviation of 47.3 and a CV of 13.1.
Only one of those four measurements that had a CV over 10% also had
a normalized CV over 10% (BrIC in the Driver 40 km/h condition, 14%).
NHTSA's analysis of the test procedure and ATD revealed that the
variation in this case appears to result from a difference in head
interaction with the sun visor and underlying roof structure, brought
about by small differences in the timing and/or position of the head at
the time of contact. This variation could be brought on by initial
position differences, differences in interaction of the pelvis and
thighs with the seat cushion during initial forward translation, or
differences in knee interaction with the knee bolster and/or knee
bolster air bag. For additional information on this analysis, see
Appendix E.
There was one measurement with a relatively low CV, but an
associated normalized CV above 10%. This occurred for the Nij
measurement in the
[[Page 61939]]
driver 40 km/h condition, where the CV was 4.7% and the normalized CV
was 10.7%. Because we normalized by the value of Nij associated with a
50% injury risk, this indicates that the average value of Nij from the
three tests in the driver 40 km/h condition were above an Nij
associated with 50% risk of injury. Closer inspection of the data
revealed several peaks that cannot be explained by the interaction of
the dummy with the restraint system and vehicle interior. This suggests
possible damage to a load cell or cabling. For additional information
on this analysis, see Appendix E.
VII. Overall Usability and Performance
NHTSA's extensive testing with the THOR-50M has also enabled it to
assess THOR-50M's overall usability and performance. This includes
durability, ease and frequency of maintenance, and how the ATD fits and
responds in the vehicle environment. We discuss these issues in the
sections that follow.
A. Assembly and Qualification
Based on NHTSA's experience with the dummy at VRTC, assembling the
THOR-50M following the instructions in the PADI takes roughly 80 hours,
as detailed in Table 17.
We note that NHTSA treats its THOR-50M units not so much as a
serialized dummy, but as a set of serialized parts and sub-assemblies.
NHTSA's THOR-50M units typically undergo a routine breakdown and
inspection after each application; when the dummy is reassembled,
different parts may be introduced (for example, if a part needed to be
refurbished before it could be used again). In addition, parts or sub-
assemblies may be taken out of service at regular intervals and set
aside to await preventative maintenance. For example, a head and neck
sub-assembly (both of which are serialized) may be taken out of service
at regular intervals and set aside to await preventative maintenance;
once clear, the head and neck sub-assembly may end up in another
serialized dummy. Therefore, a serialized dummy does not typically
define the dummy well because different parts are constantly being
interchanged. The parts and assemblies which are serialized, either by
the manufacturer or by NHTSA upon delivery of a new ATD or part, are
listed in Appendix C.
Table 17--Estimated Time To Carry Out Assembly and Associated Procedures
Described in the THOR-50M PADI
------------------------------------------------------------------------
PADI assembly time
-------------------------------------------------------------------------
Time
Body region or procedure (hrs)
------------------------------------------------------------------------
Head......................................................... 4
Neck......................................................... 8
Spine........................................................ 4
Thorax....................................................... 8
Shoulder..................................................... 4
Upper Abdomen................................................ 4
Lower Abdomen................................................ 4
Pelvis....................................................... 8
Upper Leg.................................................... 4
Lower Extremity.............................................. 8
Arm.......................................................... 4
Jacket and Clothing.......................................... 4
Bundling Cables.............................................. 4
Polarity Check............................................... 4
Documentation................................................ 8
----------
Total.................................................... 80
------------------------------------------------------------------------
Based on NHTSA's experience at VRTC, a complete qualification test
series of 24 tests takes roughly 80 hours, assuming that the
qualification specifications are met (Table 18). If the qualification
specifications are not met, it may take additional time to inspect,
replace parts where necessary, and re-test. Table 19 describes the
equipment required to carry out the THOR-50M qualification tests, along
with the associated setup procedures. Some of this equipment is the
same or similar to the equipment required for qualification of ATDs
currently defined in Part 572. For example, the THOR-50M qualification
procedures for the neck and the upper thorax use the same equipment as
used in qualification of the HIII-50M. For equipment not currently
defined in Part 572, the necessary drawings are included in the THOR-
50M drawing package with two exceptions: the impactors for the face
qualification test and upper leg and knee qualification tests. We
believe that existing impactors (such as the knee impact probe for the
HIII-5F \178\) can be modified or ballasted to achieve the required
mass.
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\178\ 49 CFR 572.137(b).
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Table 19--Equipment Required for Qualification Tests
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Test fixture description [0.02 kg, 0.25 mm] Reference Section(s) Title
----------------------------------------------------------------------------------------------------------------
Rigid disk impactor 23.36 kg, 152.4 mm CFR Title 49, Sec. 4, 7, 8 Head, Upper Thorax, Lower
diameter disk. 572.36(a); DL500-325. Thorax.
Rigid disk impactor 13.0 kg, 152.4 mm THOR-50M Qualification 5 Face.
diameter disk. Procedures, Section 5.2.
Neck pendulum.......................... Figure A-2; CFR Title 49, 6.6, 6.7, 6.8, Neck Torsion, Neck
Sec. 572.33(c)3. 6.9 Frontal Flexion, Neck
Extension, Neck Lateral
Flexion.
THOR neck twist fixture................ DL472-1000............... 6.6 Neck Torsion.
Lower abdomen probe face assembly...... DL472-3000............... 9 Abdomen.
Rigid disk impactor 12.0 kg, 76.2 mm THOR-50M Qualification 11 Upper Leg, Knee.
diameter disk. Procedures, Section 11.2.
Dynamic impactor....................... TLX-9000-013............. 12, 13, 14 Ankle Inversion and
Eversion, Ball of Foot,
Heel.
External positioning bracket........... TLX-9000-016M............ 12, 14 Ankle Inversion and
Eversion, Heel.
Dynamic inversion/eversion bracket..... TLX-9000-015............. 12 Ankle Inversion and
Eversion.
Lower leg mounting bracket assembly.... DL472-4100............... 12, 13 Ankle Inversion and
Eversion, Ball of Foot
Lower leg zero bracket................. DL472-3500............... 3.4 Ankle Rotary
Potentiometer Zeroing
Procedure.
Achilles fixture complete assembly..... DL472-4000............... 3.5 Achilles Cable Adjustment
Procedure.
Load cell mounting assembly............ DL472-4200............... 3.5 Achilles Cable Adjustment
Procedure.
Knee slider load distribution bracket DL472-5000............... 11 Knee.
assembly.
Tibia adaptor.......................... DL472-4300............... 14 Heel.
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B. Durability and Maintenance
In previous sections of the NPRM, we have discussed NHTSA's
biofidelity testing, qualification testing, and sled tests. In this
testing, we generally observed that THOR-50M stood up well during
testing and required maintenance consistent with existing Part 572
ATDs. In addition to that testing, NHTSA has conducted a variety of
other tests over the last several years as development of THOR-50M has
progressed. With respect to evaluating THOR's durability and
maintenance needs, three series of tests are especially useful because
they subject the THOR-50M to more severe or challenging crashes:
elevated energy qualification tests; OMDB testing; and unbelted FMVSS
No. 208 tests. We discuss this testing in the sections that follow.
1. Elevated Energy Qualification Test Series
In order to assess THOR-50M's durability, NHTSA conducted an
additional series of qualification tests at elevated energy levels (for
example, impactor velocities that exceeded the levels specified in the
qualification test procedures).\179\ A series of five tests was
conducted for each of the qualification test modes (except, as
explained below, the abdomen). The first test in each set was a
baseline test performed according to the qualification, except that if
the response measurement did not either represent at least a 50% risk
of injury or have a magnitude greater than the mean plus one standard
deviation of the same measurement in a set of 18 oblique vehicle crash
tests,\180\ the test speed was increased until either of those targets
were met; this was then considered the baseline speed. There were two
test modes where the test speed specified in the qualification
procedures did not reach either of these targets: upper leg impact and
heel impact.\181\ The next three tests were at speeds corresponding to
energy level increases of 10 percent, 20 percent, and 30 percent. A
final baseline test was then performed at the prescribed qualification
test velocity. The results were considered to show acceptable
durability if the final baseline test demonstrated a response similar
to the initial baseline test and within the qualification targets, and
visual inspection revealed no damage to any of the dummy components.
For a majority of the qualification test modes, durability was found to
be acceptable. No visible damage was observed in any of the tested
components after the series of five tests. Two exceptions to these
findings occurred in the face and the abdomen qualification test modes.
---------------------------------------------------------------------------
\179\ National Highway Traffic Safety Administration (2020).
THOR-50M Durability Report. Regulations.gov Docket ID NHTSA-2019-
0106-0003, available at: https://www.regulations.gov/document/NHTSA-2019-0106-0003.
\180\ Saunders, J., Parent, D., Ames, E., 2015. NHTSA oblique
crash test results: vehicle performance and occupant injury risk
assessment in vehicles with small overlap countermeasures. In:
Proceedings of the 24th International Technical Conference for the
Enhanced Safety of Vehicles (No. 15-0108). Available at https://downloads.regulations.gov/NHTSA-2019-0106-0008/attachment_1.pdf.
\181\ The increase in energy of the upper leg impact test was
later implemented in the revised qualification procedure.
---------------------------------------------------------------------------
In the face impact test, the final baseline peak probe force and
peak head CG resultant acceleration were higher than the qualification
specifications. This is consistent with the results of the
qualification R&R study (Section VI.A). While not ideal, we believe
that, because this is now a known issue, it can be managed with the
replacement of a face foam insert when the face qualification test
results are higher in magnitude than the qualification specification.
Moreover, the deterioration in the face foam insert probably would not
meaningfully affect crash test results because, in a vehicle test, more
energy will likely be absorbed by a vehicle interior component and/or
restraint system compared to the rigid qualification impact probe.
However, NHTSA would consider specifying a different face foam material
or design that had improved durability, as long as the material or
design does not introduce unintended consequences such as negatively
impacting biofidelity, changes to the inertial properties of the head,
degradation of repeatability and reproducibility, overall usability, or
other concerns.
We did not conduct elevated-energy tests for the abdomen because
the qualification test already demonstrates a higher energy condition
than a vehicle crash test. Accordingly, impacts at a
[[Page 61942]]
higher energy level could cause damage due to exhausting the stroke of
the abdomen instrumentation. Moreover, this would not be meaningful as
it would represent a loading condition not representative of the front
seat vehicle crash test environment. However, we do recognize that our
testing has shown that damage to the abdomen deflection instrumentation
can occur in vehicle crash test environments where submarining is
possible, such as reclined rear seats. For example, several rear seat
sled tests were conducted at VRTC in 2015 in which the IR-TRACCs
installed in the abdomen experienced dislodged internal retaining rings
and damage including pinched cables. These issues are believed to have
resulted from interaction of the IR-TRACC tubes with the foam inserts
inside of the lower abdomen bag. To address this, the lower abdomen
sewing assembly (472-4763) was redesigned in late 2015, and an
inspection procedure was added to the drawing package (472-8320) to
ensure that the lower abdomen foam inserts remain aligned once
installed in the assembled lower abdomen bag.
We seek comment on these issues, especially on alternative
equivalent face foams.
2. Oblique OMDB Test Series
In developing THOR-50M, NHTSA ran a series of full-vehicle oblique
tests with a moving deformable test barrier (OMDB).\182\ Three crash
tests were conducted on the same make/model vehicle (a 2016 Mazda CX-5)
at three different test facilities. ATDs were seated in both front
outboard seats and were fully qualified. Two THOR-50M ATDs were
successfully implemented in a total of nine vehicle crash tests, with
qualification tests before and after each set of three tests. In this
test condition, there were no signs of damage beyond normal wear and
tear, and there were no sensor failures that were critical to the
calculation of injury risk. The dummies were inspected after each test.
---------------------------------------------------------------------------
\182\ Saunders, J., & Parent, D. (2018). Repeatability and
reproducibility of oblique moving deformable barrier test procedure
(No. 2018-01-1055). SAE Technical Paper, available at https://www.regulations.gov/document/NHTSA-2019-0106-0005. The discussion
here briefly summarizes some of the relevant results from this
report. This testing is not being considered as an evaluation of the
ATD's repeatability and reproducibility because in order to provide
a meaningful ATD R&R analysis, control of the test conditions must
be exercised. Component tests, such as the qualification tests, are
more readily controlled and thus may be expected to provide the best
estimates of a dummy's R&R. Sled testing provides an efficient
alternative to vehicle crash testing and offers insight into the
dummy's performance as a complete system. In full-vehicle crash
testing, however, the variation contributed by the vehicle (e.g.,
variation in structural materials) and the overall test procedure
make it difficult to identify the variability attributable to the
dummy itself. Additionally, the severity of the test conditions
utilized for R&R assessment must also be considered. For example, if
the test conditions are so severe that the responses are near or
beyond the dummy's mechanical limits or electronic capacity, then
the corresponding R&R analysis may not be meaningful. See generally
Rhule et al (2005).
---------------------------------------------------------------------------
There were no signs of damage beyond normal wear and tear, and no
part replacements were necessary. We did observe some sensor anomalies
or failures to sensors, but almost all the sensors that failed were
non-critical--for example off-axis channels (e.g., right femur X-axis
force) or sensors not used in the calculation of injury criteria (e.g.,
lower neck load cell, foot accelerometers). See Appendix F. Such sensor
anomalies can also occur in other Part 572 ATDs, such as the HIII-50M
and HIII-05F used in Frontal NCAP testing. In the past six years of
Frontal NCAP testing, there was an average of one failed ATD sensor
channel per crash test (0.68 1.08), with five of those
instances occurring in a critical channel.
Many of these anomalies were the results of loose Amphenol pins.
These are the electrical contacts inside of the connectors used to
interface the THOR-50M umbilical cables with the specific data
acquisition system of the test facility. These connectors are used to
prevent the need for cutting wires and attaching lab-specific
connectors each time an ATD is sent to a new facility with a different
data acquisition system. In practice, ATDs sent to test facilities for
the execution of regulation or consumer information testing will often
remain on-site for an extended period of time, which makes laboratory-
specific connectors more feasible. Such issues would not exist for
THOR-50M ATDs with in-dummy data acquisition systems. Many of the
sensor failures that occurred were in non-critical instrumentation, for
example off-axis channels or sensors not used in the calculation of
injury criteria. For research tests, a larger number of sensors are
recorded for the sake of completeness and post-test investigation; in a
regulatory or consumer information testing environment, these channels
may not be recorded. If the user does want to record such sensors, they
would need to be repaired or replaced before pre-test qualification for
the next vehicle crash test.
The only sensor anomalies related to the calculation of injury
criteria were in the chest and abdomen, but, once linearized, scaled,
filtered, and converted to three-dimensional resultant deflection local
spine coordinate system, these ``blips'' were no longer evident; thus
they would not influence the calculation of injury risk for this
occupant. These voltage drops are characteristic of the abrupt
decreases in the IR-TRACC voltage time-history described in Section
III.E.2. See Appendix F.
3. FMVSS No. 208 Unbelted Vehicle Crash Tests
NHTSA performed a series of unbelted vehicle crash tests required
in FMVSS No. 208. The results are briefly summarized in this section
and are discussed in more detail in the referenced paper.\183\ FMVSS
No. 208 specifies a frontal crash test into a rigid barrier with the
barrier angle at 0 degrees to 30 degrees at between 20 mph
(32 km/h) and 25 mph (40 km/h), inclusive, with an unbelted 50th
percentile male dummy seated at either front outboard seat.\184\
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\183\ Saunders, J., Parent, D., Martin, P., 2023. THOR-50M
Fitness Assessment In FMVSS No. 208 Unbelted Crash Tests. In:
Proceedings of the 24th International Technical Conference for the
Enhanced Safety of Vehicles (No. 23-0339). Available at: https://www-esv.nhtsa.dot.gov/Proceedings/27/27ESV-000339.pdf.
\184\ S14.5.2; S5.1.2(b).
---------------------------------------------------------------------------
NHTSA ran two sets of tests. First, we ran this test at the highest
regulatory speed of 40 km/h (25 mph) for crash geometries of 30 degrees
to the left, 30 degrees to the right, and perpendicular (12 tests).
Second, we ran a modified version of this test, with an elevated speed
of 48 km/h (30 mph) for crash geometries of 30 degrees to the left and
right (six tests). We tested with two different THOR-50M ATDs, both
manufactured by Humanetics and built to the 2018 drawing package
(except that one ATD (EG2595) was fitted with the proposed optional in-
dummy DAS). For these tests, the laboratory test procedures for FMVSS
No. 208 \185\ were followed, with the exception of the seating
procedure, for which the Revised THOR 50th Percentile Male Dummy
Seating Procedure \186\ was followed. The ATD was instrumented so that
all injury criteria defined for the HIII-50M in FMVSS No. 208 and in
the THOR-50M Injury Criteria Report could be calculated. A total of 19
tests were run on four different vehicle models
[[Page 61943]]
(the Honda Accord, Mazda CX-5, Chevrolet Equinox, and Ford Escape).
---------------------------------------------------------------------------
\185\ National Highway Traffic Safety Administration (2008).
Laboratory Test Procedure for FMVSS 208, Occupant Crash Protection,
TP208-14.
\186\ National Highway Traffic Safety Administration (2020).
Revised THOR 50th Percentile Male Dummy Seating Procedure, June
2019. Regulations.gov Docket ID NHTSA-2019-0106-0006, available at
https://www.regulations.gov/document/NHTSA-2019-0106-0006.
---------------------------------------------------------------------------
This study showed that the THOR-50M, when exercised in unbelted
frontal rigid barrier testing, experienced only minor issues. We
performed a full set of qualification tests before the test series, a
partial qualification test series \187\ after each test, and a full
qualification test series halfway through the test series. In all
cases, the THOR-50Ms met the qualification specifications without need
for part replacement or other refurbishment. In addition, each ATD was
inspected after each test for damage and to investigate sensor
anomalies. While no parts were found to be in need of replacement,
there were some sensor anomalies and damage. One of the ATDs did not
experience any sensor anomalies or damage during testing, while the
other ATD experienced some sensor anomalies that were repairable, while
others were not. The sensors that were not repaired were non-critical
channels (for example, the left tibia mid-shaft X-axis accelerometer),
thus a decision was made to continue testing instead of repairing or
replacing the sensors, which would have caused delays in the test
schedule. The quantity and severity of sensor anomalies were similar to
those experienced in testing with the HIII-50M, especially considering
increased sensor count and level of complexity of the THOR-50M. Aside
from minor wear and tear (e.g., scrapes on the top of the head skin of
one ATD were noted after one test) there was no damage to either ATD
and both met all qualification specifications.
---------------------------------------------------------------------------
\187\ To maximize efficiency, the partial qualification test
series only included the tests that did not require any disassembly
of dummy components: head, upper thorax, lower thorax, lower
abdomen, and left/right upper leg. The face impact test was not
included because direct impact to the face was not expected during
this test series.
---------------------------------------------------------------------------
Based on these observations, NHTSA tentatively concludes that THOR-
50M is sufficiently durable for use in FMVSS No. 208 unbelted testing,
even at an elevated closing speed. Overall, this unbelted test series
provides additional assurance that the THOR-50M units are durable and
stand up well under testing, with the amount of wear and tear normal
for our test dummies, and that NHTSA's THOR-50M design specifications
have resulted in highly uniform and durable units.
C. Sensitivity to Restraint System Performance
NHTSA's testing with the THOR-50M has also highlighted its ability
to detect differences in restraint system performance. One example of
this occurred in the Oblique OMDB testing described above in Section
VII.B.2.\188\ This testing involved vehicles of the same model and
model year with a THOR-50M seated in each front outboard seat. In one
series of tests which included three Oblique OMDB crash tests of the
same vehicle make and model, the THOR-50Ms seated in the right front
passenger seat showed a much wider variation in injury assessment
values related to head injury risk than the THOR-50Ms seated in the
driver's seat. A thorough investigation of the test data, including
inspection of the high-speed video, revealed that the right front
passenger air bag did not function consistently to manage the ride-down
of the occupant: the high-speed images revealed differences in air bag
deployment, interaction between the head and the air bag, and contact
between the head and the instrument panel. Inspection of the air bag
revealed tears in the air bags in two of the three tests, with the
largest tears associated with the highest injury assessment
values.\189\ This is one example of how the innovative features of the
THOR-50M can help lead to improved vehicle safety.
---------------------------------------------------------------------------
\188\ Saunders, J., & Parent, D. (2018). Repeatability and
reproducibility of oblique moving deformable barrier test procedure
(No. 2018-01-1055).
\189\ These results were shared with the vehicle manufacturer,
which instituted a series of modifications. In a later test of the
vehicle, there were no passenger air bag tears evident, and the head
injury criteria were similar to those measured in the previous tests
that did not appear to result in air bag tears.
---------------------------------------------------------------------------
VIII. Intellectual Property
While there is no specific prohibition on specifying a patented
component, copyrighted design, or name-brand product in Part 572, NHTSA
has been mindful of the legislative history of the Safety Act and its
own responsibility under statute to make all information, patents, and
developments related to a research and development activity available
to the public where it makes more than a minimal contribution to the
activity.\190\ This understanding has guided dummy development at NHTSA
for many years and explains why NHTSA has not incorporated into final
rules materials owned by third parties except in rare cases (discussed
below). The legislative history of the Safety Act shows that while
Congress explicitly declined to include a provision preventing use of
patents by the agency in standards, Congress did ``assume[ ] that the
Secretary is not likely to adopt a standard which can be met only by
using a single patented device, and that the Secretary would, before
doing so, take steps to obtain an understanding from the patent holder
that he would supply the item or grant licenses on reasonable terms.''
\191\ In addition, NHTSA itself plays a significant role in the
testing, evaluation and performance verification of dummies and
provides a substantial amount of information to the public to identify
the basis for improvement in testing devices to ensure the
repeatability and reproducibility of results. The outcome of the
agency's involvement has been an interest in making sure the test
device is available for use without restriction to the public.
---------------------------------------------------------------------------
\190\ 49 U.S.C. 30182(f).
\191\ S. Rep. No. 89-1301, at 15, reprinted in U.S.C.C.A.N.
2709, 2723.
---------------------------------------------------------------------------
To be clear, there are also several potential concerns with
specifying proprietary components. They may be modified by the
proprietary source such that original is no longer available, and the
new part no longer fits. The proprietary source may alter the part in
ways that change the response of the dummy, such that dummies with the
newer part do not provide the same response as dummies with the older
part. Components produced by only one manufacturer are not subject to
competitive sales pressures. And the manufacturer of a sole-source part
may simply cease manufacturing the part.
For these reasons, NHTSA has generally avoided specifying in Part
572 patented components or copyrighted designs without either securing
agreement from the rights-holder for the free use of the item or to
license it on reasonable terms \192\ or developing an alternative
unencumbered by any rights claims.\193\
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\192\ See, e.g., 38 FR 8455 (Apr. 2, 1973) (NPRM for the initial
50th percentile male dummy) (``To the knowledge of this agency, the
only patent on a component of the specified dummy is one on the knee
held by Alderson, and that company has stated to the NHTSA that it
will license production under its patent for a reasonable
royalty.'')
\193\ See, e.g., 65 FR 17180, 17187 (Mar. 31, 2000) (final rule
for twelve-month-old child dummy) (declining to incorporate a
copyrighted PADI developed by an ATD manufacturer and instead
incorporating a NHTSA-authored PADI).
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As noted earlier in the preamble (Section III), we are specifying
some patented parts but not without specifying suitable alternates
where no intellectual property claims apply. We briefly discuss these
below.
Shoulder
As explained earlier, we are proposing to include two alternative
shoulder specifications: the SD-3 shoulder and the alternate shoulder.
Humanetics has two patents on the SD-3 shoulder: one describes a
mechanical shoulder joint assembly and the other describes an upper arm
[[Page 61944]]
assembly with a load cell.\194\ The shoulder joint is formed using a
pivot connected to a spring element inside of a housing, which has an
adjustable element to control the friction of the joint. Humanetics is
currently the sole manufacturer of the SD-3 shoulder in the United
States.
---------------------------------------------------------------------------
\194\ U.S. Patent Nos. 9,514,659 (upper arm assembly) and
9,799,234 (shoulder joint assembly).
---------------------------------------------------------------------------
In order to avoid potential concerns with specifying a patented
part as the sole specification, NHTSA has developed an alternative to
the SD-3 shoulder. The alternate shoulder does not include the
adjustable friction element, and does not use a coil, clock, or watch
spring mechanism. Instead, the alternate shoulder design uses a molded
rubber cylinder acting as a torsion bar. The response of the rubber
cylinder can be tuned by both changes in material and changes in
geometry, such as removal of material to create voids of different
sizes and shapes. This lack of a friction adjustment in the alternate
shoulder is a change in the functional aspect of the design.
Accordingly, with the significant differences noted, we are proposing
to specify the use of either the alternate shoulder or the SD-3
shoulder.
Chest Instrumentation
NHTSA is proposing the IR-TRACC and the S-Track as permissible
alternate instrumentation. While NHTSA is not aware of any patent
protection on the IR-TRACC, it is manufactured only by Humanetics.
There is a patent on the S-Track, and NHTSA's understanding is that the
S-Track is currently manufactured only by ATD-LabTech, which was
recently acquired by Humanetics.
We believe that specifying the design such that either the IR-TRACC
or the S-Track could be used would be sufficient to ensure
instrumentation availability to dummy users. We seek comment on this.
IX. Consideration of Alternatives
NHTSA is not aware of a 50th percentile male ATD intended for use
in frontal or frontal oblique crash tests and more advanced than the
HIII-50M, other than the THOR-50M. Throughout this document we have
discussed various alternative configurations, specifications, and tests
that we have considered in developing the proposal and on which we are
seeking comment.
As discussed in more detail in the rulemaking analyses section,
Executive Order 13609 provides that international regulatory
cooperation can reduce, eliminate, or prevent unnecessary differences
in regulatory requirements. Similarly, Sec. 24211 of the
Infrastructure, Investment, and Jobs Act \195\ instructs DOT to
harmonize the FMVSS with global regulations to the maximum extent
practicable (for example, to the extent that harmonization would be
consistent with the Safety Act).
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\195\ H.R. 3684 (117th Congress) (2021).
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The only regulatory authority or consumer ratings program we are
aware of that currently uses the THOR-50M is Euro NCAP. Euro NCAP TB026
references the August 2018 drawing package,\196\ the September 2018
Qualification Procedures,\197\ and the August 2018 PADI.\198\ Although
TB026 largely follows these documents, it does depart from them in
several ways. Those differences have been identified and discussed in
the relevant sections of the preamble and are summarized in Table 20.
The tentative reasons for those differences are explained in detail in
the relevant section of the preamble. In general, we believe that those
differences are justified given NHTSA's experience testing with the
THOR-50M in frontal rigid barrier and frontal oblique vehicle crash
test modes, and the necessity of ensuring that a dummy specified for
use in regulatory compliance testing be objectively specified.
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\196\ Sec. 1.1.
\197\ Sec. 2.1.
\198\ Sec. 3.1.
Table 20--Summary of Differences Between the THOR-50M as Proposed and as
Specified for Use in Euro NCAP
------------------------------------------------------------------------
Issue Proposal Euro NCAP
------------------------------------------------------------------------
Design & Construction:
Split shoulder pad.......... Not proposed...... Under
consideration.
Spine....................... Spine Pitch Change Four-Position
Joint. Spine Box.
Lower Leg................... THOR-specific HIII-50M lower
lower leg. leg.
Instrumentation:
S-Track/IR-TRACC............ IR-TRACC or S- IR-TRACC, S-Track,
Track. or KIR-TRACC
Does not specify
the systems part-
by-part with
engineering
drawings.
In-dummy DAS................ Permitted as TB026 requires an
optional in-dummy DAS.
configuration TB029 currently
with part-by-part does not specify
engineering any specific in-
drawings dummy DAS,
compatible with although earlier
the SLICE6 and versions of TB029
any other did specify a few
similarly- different
configured system. approved in-dummy
DAS systems.
Does not specify
the systems part-
by-part with
engineering
drawings.
Qualification Tests:
Acceptance interval midpoint Based on R&R test Basis not
data. identified in
TB026.
Acceptance interval width... 10% Varies from 1% to 10%.
Upper thorax................ Ratio of Z-axis to Specifies ratio of
X-axis deflection Z-axis to X-axis
not specified as deflection as
test parameter. test parameter.
Face impact test............ Specified......... Not specified.
Knee slider................. Specified......... Certified to SAE
J2876.
Lower legs...................... Ankle inversion/ Certified to Annex
eversion; Ball of 10 of ECE
foot; heel. Regulation No.
94.
------------------------------------------------------------------------
[[Page 61945]]
X. Lead Time
Since this rulemaking action itself would not impose requirements
on anyone, we are proposing that the final rule would be effective on
publication in the Federal Register.
XI. Incorporation by Reference
Under regulations issued by the Office of the Federal Register (1
CFR 51.5(a)), an agency, as part of a final rule that includes material
incorporated by reference, must summarize in the preamble of the final
rule the material it incorporates by reference and discuss the ways the
material is reasonably available to interested parties or how the
agency worked to make materials available to interested parties.
In this proposed rule, NHTSA incorporates by reference a technical
data package for the THOR-50M. The technical data package consists of
two-dimensional engineering drawings and a parts list; procedures for
assembly, disassembly, and inspection (PADI); and qualification
procedures. Copies of these documents are available in the research
docket identified earlier in this document. Interested persons can
download a copy of the materials or view the materials online by
accessing www.Regulations.gov. The material is also available for
inspection at the Department of Transportation, Docket Operations, Room
W12-140, 1200 New Jersey Avenue SE, Washington, DC Telephone: 202-366-
9826. If the proposed rule is finalized, final versions of these
documents would be placed in a docket that would be readily available
to the public online (via regulations.gov) and in-person at DOT
headquarters.
Although agency-created documents are presumptively ineligible for
incorporation by reference, they may be approved for incorporation by
the Office of the Federal Register if they (among other things) consist
of criteria, specifications, or illustrations; are reasonably available
to the class of persons affected; are easy to handle; and possesses
other unique or highly unusual qualities.\199\
---------------------------------------------------------------------------
\199\ See 1 CFR 51.7(b) (``The Director will assume that a
publication produced by the same agency that is seeking its approval
is inappropriate for incorporation by reference. A publication
produced by the agency may be approved, if, in the judgment of the
Director, it meets the requirements of paragraph (a) and possesses
other unique or highly unusual qualities. A publication may be
approved if it cannot be printed using the Federal Register/Code of
Federal Regulations printing system.''); (a)(2)(i)(``published data,
criteria, standards, specifications, techniques, illustrations, or
similar material''); (a)(3)(``reasonably available to and usable by
the class of persons affected''); (a)(3)(i)(``The completeness and
ease of handling of the publication'').
---------------------------------------------------------------------------
We believe these documents (which were created by NHTSA) meet these
criteria. Except for the qualification procedures, NHTSA typically
incorporates these elements of the technical data package by reference.
NHTSA has not typically incorporated the qualification procedures by
reference. Doing so is a departure from the other ATDs currently
specified in Part 572, for which the qualification tests are set out in
full in the regulatory text in each of the relevant paragraphs
(corresponding to that ATD) in part 572. We are proposing a separate
qualification procedures document for the THOR-50M because the THOR-50M
qualification procedures involve procedures that are made clearer by
photographs and diagrams that are not amenable to publication in the
CFR.\200\ We believe this extra level of detail will be helpful for end
users who are attempting to qualify the ATD. We seek comment on this.
---------------------------------------------------------------------------
\200\ The qualification procedures document states that the
photographs are provided for reference only.
---------------------------------------------------------------------------
XII. Regulatory Analyses
Executive Order (E.O.) 12866, E.O. 13563, E.O. 14094, and DOT
Regulatory Policies and Procedures
NHTSA has considered the impacts of this regulatory action under
Executive Orders 12866, 13563, 14094, and the Department of
Transportation's regulatory policies and procedures.\201\ This
rulemaking action was not reviewed by the Office of Management and
Budget under E.O. 12866. It is also not considered ``of special note to
the Department'' under DOT Order 2100.6A. We have considered the
qualitative costs and benefits of the proposed rule under the
principles of E.O. 12866.
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\201\ 49 CFR, Part 5, Subpart B; Department of Transportation
Order 2100.6A, Rulemaking and Guidance Procedures, June 7, 2021.
---------------------------------------------------------------------------
This document would amend 49 CFR part 572 by adding design and
performance specifications for an advanced test dummy representative of
a 50th percentile adult male that the agency would possibly use in
FMVSS No. 208 front crash tests and for research purposes. This Part
572 proposed rule would not impose any requirements on anyone.
Businesses are affected only if they choose to manufacture or test with
the dummy.
There are benefits associated with this rulemaking but they are not
readily quantifiable. The THOR-50M is an advanced dummy with advantages
over existing dummies with respect to biofidelity, instrumentation,
injury prediction, and evaluation of vehicle performance. The dummy is
currently used for testing by Euro NCAP, and may be incorporated in ECE
R137. It is also likely being used by vehicle and restraint
manufacturers for testing, research, and development.
Accordingly, NHTSA is considering a proposal to incorporate the
THOR-50M into FMVSS No. 208, ``Occupant crash protection,'' for use in
frontal crash compliance testing at the manufacturers' option.\202\
This contemplated rulemaking action would permit manufacturers to
direct NHTSA to use the THOR-50M in belted and unbelted barrier crash
testing of the vehicles they produce instead of the HIII-50M ATD in
NHTSA's compliance tests. Incorporating the dummy in Part 572 will
enable manufacturers and others to streamline testing, choosing to use
THOR-50M in place of the HIII-50M, potentially reducing the number of
tests they run, and leveraging the value of the tests they do run.
---------------------------------------------------------------------------
\202\ FMVSS No. 208 THOR-50M Compliance Option (RIN 2127-AM21),
Fall 2023 Unified Agenda of Regulatory and Deregulatory Actions;
Department of Transportation, available at https://www.reginfo.gov/public/do/eAgendaViewRule?pubId=202304&RIN=2127-AM21.
---------------------------------------------------------------------------
Incorporating the THOR-50M into Part 572 would also have other
benefits beyond use in NHTSA's compliance testing. The ability of the
THOR-50M to potentially monitor additional injury modes and its
improved biofidelity may facilitate the development and introduction of
innovative occupant crash protection features. While the purpose of
Part 572 is to ``describe the anthropomorphic test devices that are to
be used for compliance testing of motor vehicles and motor vehicle
equipment with motor vehicle safety standards,'' it also serves as a
definition of the ATD for other purposes as well, such as consumer
information crash testing, standards and regulations in other
transportation modes, and research. As such, it would be to the benefit
of government, academia, and the multi-modal transportation industry to
include a definition of the THOR-50M ATD in Part 572. In addition, the
availability of this dummy in a regulated format would be beneficial by
providing a suitable, stabilized, and objective test tool to the safety
community for use in better protecting occupants in frontal impacts.
The costs associated with the THOR-50M only affect those who choose
to use the THOR-50M. This rule would not impose any requirements on
anyone. If incorporated into FMVSS No. 208, NHTSA would use the dummy
in its compliance testing of the requirements
[[Page 61946]]
at the option of a regulated entity, but regulated entities are not
required to use the dummy or assess the performance of their products
in the manner specified in the FMVSSs.
NHTSA has found that the cost of a THOR-50M corresponding to the
2023 drawing package has been approximately $550,000 to $750,000
depending on whether an in-dummy DAS is installed and the level of
instrumentation. The minimum set of instrumentation needed for
qualification testing includes 66 channels. If the S-Track were used
instead of the IR-TRACC, the total cost would be roughly the same.
In addition to these costs, as with any ATD, dummy refurbishments
and part replacements are an inherent part of ATD testing. Various
parts will likely have to be refurbished or replaced, but we generally
do not know which parts are likely to be worked on the most. As we note
in the NPRM, however, the face foam appears to need more frequent
replacement but this should not add appreciably to the overall cost.
Because the dummies are designed to be reusable, costs of the dummies
and of parts can be amortized over a number of tests. While the
expected maintenance costs for the THOR-50M are expected to be higher
than those for less complex dummies such as the HIII-50M, these costs
are expected to be similar to advanced dummies such as the WorldSID.
There are minor costs associated with conducting the qualification
tests. Most of the qualification fixtures are common with those used to
qualify other Part 572 dummies (including the neck pendulum and the
probes used in the head, upper thorax and lower thorax tests). Some
additional equipment unique to the THOR-50M may be fabricated from
drawings within the technical data package, for an estimated cost of
about $50,000. This includes the cost to fabricate the torsion fixture
for the neck torsion test, the lower abdomen probe face assembly,
impact probes not used for other Part 572 dummies (or weighted collars
to achieve the specified mass), and test apparatus for the lower leg
tests (including the dynamic impactor, external positioning bracket,
dynamic inversion/eversion bracket, lower leg mounting bracket, lower
leg zero bracket, Achilles fixture, load cell mounting assembly, knee
slider load distribution bracket, and tibia adapter). The costs of the
instrumentation equipment needed to perform the qualification tests
amounts to about an additional $4,400 (two angular rate sensors, $850
apiece; two test probe accelerometers, $800 apiece; one rotary
potentiometer, $1,100).
Regulatory Flexibility Act
Pursuant to the Regulatory Flexibility Act (5 U.S.C. 601 et seq.,
as amended by the Small Business Regulatory Enforcement Fairness Act
(SBREFA) of 1996), whenever an agency is required to publish a proposed
or final rule, it must prepare and make available for public comment a
regulatory flexibility analysis that describes the effect of the rule
on small entities (i.e., small businesses, small organizations, and
small governmental jurisdictions), unless the head of the agency
certifies the rule will not have a significant economic impact on a
substantial number of small entities. The Small Business
Administration's regulations at 13 CFR part 121 define a small
business, in part, as a business entity ``which operates primarily
within the United States.'' (13 CFR 121.105(a)).
We have considered the effects of this rulemaking under the
Regulatory Flexibility Act. I hereby certify that this rulemaking
action would not have a significant economic impact on a substantial
number of small entities. This action would not have a significant
economic impact on a substantial number of small entities because the
addition of the test dummy to Part 572 would not impose any
requirements on anyone. This NPRM only proposes to include the dummy in
NHTSA's regulation for crash test dummies; it does not propose NHTSA's
use of the ATD in agency testing or require anyone to manufacture the
dummy or to test motor vehicles or motor vehicle equipment with it.
National Environmental Policy Act
NHTSA has analyzed this proposed rule for the purposes of the
National Environmental Policy Act and determined that it would not have
any significant impact on the quality of the human environment.
Executive Order 13045 and 13132 (Federalism)
Executive Order 13045 (62 FR 19885, April 23, 1997) applies to any
rule that: (1) is determined to be ``economically significant'' as
defined under E.O. 12866, and (2) concerns an environmental, health, or
safety risk that NHTSA has reason to believe may have a
disproportionate effect on children. If the regulatory action meets
both criteria, we must evaluate the environmental health or safety
effects of the planned rule on children and explain why the planned
regulation is preferable to other potentially effective and reasonably
feasible alternatives considered by us.
This proposed rule is not subject to the Executive Order because it
is not economically significant as defined in E.O. 12866.
NHTSA has examined this proposed rule pursuant to Executive Order
13132 (64 FR 43255, August 10, 1999) and concluded that no additional
consultation with States, local governments or their representatives is
mandated beyond the rulemaking process. The agency has concluded that
the proposed rule would not have federalism implications because the
proposed rule would not have ``substantial direct effects on the
States, on the relationship between the national government and the
States, or on the distribution of power and responsibilities among the
various levels of government.'' This proposed rule would not impose any
requirements on anyone. Businesses will be affected only if they choose
to manufacture or test with the dummy.
Further, no consultation is needed to discuss the preemptive effect
of this proposed rule. While NHTSA's safety standards can have
preemptive effect, the proposed rule would amend 49 CFR part 572 and is
not a safety standard. This Part 572 proposed rule would not impose any
requirements on anyone.
Civil Justice Reform
With respect to the review of the promulgation of a new regulation,
section 3(b) of Executive Order 12988, ``Civil Justice Reform'' (61 FR
4729, February 7, 1996) requires that Executive agencies make every
reasonable effort to ensure that the regulation: (1) Clearly specifies
the preemptive effect; (2) clearly specifies the effect on existing
Federal law or regulation; (3) provides a clear legal standard for
affected conduct, while promoting simplification and burden reduction;
(4) clearly specifies the retroactive effect, if any; (5) adequately
defines key terms; and (6) addresses other important issues affecting
clarity and general draftsmanship under any guidelines issued by the
Attorney General. This document is consistent with that requirement.
Pursuant to this Order, NHTSA notes as follows.
The issue of preemption is discussed above in connection with E.O.
13132. NHTSA notes further that there is no requirement that
individuals submit a petition for reconsideration or pursue other
administrative proceeding before they may file suit in court.
[[Page 61947]]
Paperwork Reduction Act
Under the Paperwork Reduction Act of 1995, a person is not required
to respond to a collection of information by a Federal agency unless
the collection displays a valid control number from the Office of
Management and Budget (OMB). This proposed rule would not have any
requirements that are considered to be information collection
requirements as defined by the OMB in 5 CFR part 1320.
National Technology Transfer and Advancement Act
Section 12(d) of the National Technology Transfer and Advancement
Act of 1995 (NTTAA), Public Law 104-113, section 12(d) (15 U.S.C. 272)
directs NHTSA to use voluntary consensus standards in its regulatory
activities unless doing so would be inconsistent with applicable law or
otherwise impractical. Voluntary consensus standards are technical
standards (e.g., materials specifications, test methods, sampling
procedures, and business practices) that are developed or adopted by
voluntary consensus standards bodies. The NTTAA directs NHTSA to
provide Congress, through OMB, explanations when the agency decides not
to use available and applicable voluntary consensus standards.
The following voluntary consensus standards have been used in
developing the THOR-50M:
SAE J211-1, Instrumentation for impact test--Part 1:
Electronic Instrumentation, Version 2014-03-31
SAE J1733, Sign Convention for Vehicle Crash Testing,
Version 2007-11-02.
SAE J2570, Performance specifications for anthropomorphic
test device transducers, Version 2009-08-12.
SAE J2876, Low Speed Knee Slider Test Procedure for the
Hybrid III 50th Male Dummy, Version 2015-05-07.
ISO-MME Task Force, 2015-04-15 proposed mnemonic codes for
the THOR-50M.
Unfunded Mandates Reform Act
The Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4) (UMRA)
requires agencies to prepare a written assessment of the costs,
benefits, and other effects of proposed or final rules that include a
Federal mandate likely to result in the expenditures by States, local
or tribal governments, in the aggregate, or by the private sector, of
$100 million or more (adjusted annually for inflation with base year of
1995) in any one year. Adjusting this amount by the implicit gross
domestic product price deflator for 2022 results in $177 million
(111.416/75.324 = 1.48). The assessment may be included in conjunction
with other assessments, as it is here. UMRA requires the agency to
select the ``least costly, most cost-effective or least burdensome
alternative that achieves the objectives of the rule.''
This proposed rule would not impose any unfunded mandates under the
UMRA. This proposed rule does not meet the definition of a Federal
mandate because it does not impose requirements on anyone. It amends 49
CFR part 572 by adding design and performance specifications for a 50th
percentile adult male frontal crash test dummy that the agency could
use in FMVSS No. 208 and for research purposes. This proposed rule
would affect only those businesses that choose to manufacture or test
with the dummy. It would not result in costs of $100 million or more
(adjusted for inflation) to either State, local, or tribal governments,
in the aggregate, or to the private sector.
Plain Language
Executive Order 12866 and E.O. 13563 require each agency to write
all rules in plain language. Application of the principles of plain
language includes consideration of the following questions:
Have we organized the material to suit the public's needs?
Are the requirements in the rule clearly stated?
Does the rule contain technical language or jargon that
isn't clear?
Would a different format (grouping and order of sections,
use of headings, paragraphing) make the rule easier to understand?
Would more (but shorter) sections be better?
Could we improve clarity by adding tables, lists, or
diagrams?
What else could we do to make the rule easier to
understand?
If you have any responses to these questions, please include them
in your comments on this proposal.
Regulation Identifier Number
The Department of Transportation assigns a regulation identifier
number (RIN) to each regulatory action listed in the Unified Agenda of
Federal Regulations. The Regulatory Information Service Center
publishes the Unified Agenda in April and October of each year. You may
use the RIN contained in the heading at the beginning of this document
to find this action in the Unified Agenda.
Privacy Act
In accordance with 5 U.S.C. 553(c), DOT solicits comments from the
public to better inform its rulemaking process. DOT posts these
comments, without edit, to www.regulations.gov, as described in the
system of records notice, DOT/ALL-14 FDMS, accessible through
www.dot.gov/privacy. In order to facilitate comment tracking and
response, we encourage commenters to provide their name, or the name of
their organization; however, submission of names is completely
optional. Anyone is able to search the electronic form of all comments
received into any of our dockets by the name of the individual
submitting the comment (or signing the comment, if submitted on behalf
of an association, business, labor union, etc.). You may review DOT's
complete Privacy Act Statement in the Federal Register published on
April 11, 2000 (Volume 65, Number 70; Pages 19477-78).
XIII. Public Participation
How do I prepare and submit comments?
Your comments must be written and in English. To ensure that your
comments are correctly filed in the Docket, please include the agency
name and the docket number or Regulatory Identification Number (RIN) in
your comments.
Your comments must not be more than 15 pages long. (49 CFR 553.21).
We established this limit to encourage you to write your primary
comments in a concise fashion. However, you may attach necessary
additional documents to your comments. There is no limit on the length
of the attachments.
If you are submitting comments electronically as a PDF (Adobe)
file, NHTSA asks that the documents be submitted using the Optical
Character Recognition (OCR) process, thus allowing NHTSA to search and
copy certain portions of your submissions.
Please note that pursuant to the Data Quality Act, in order for
substantive data to be relied upon and used by the agency, it must meet
the information quality standards set forth in the OMB and DOT Data
Quality Act guidelines. Accordingly, we encourage you to consult the
guidelines in preparing your comments. OMB's guidelines may be accessed
at https://www.transportation.gov/regulations/dot-information-dissemination-quality-guidelines.
[[Page 61948]]
How can I be sure that my comments were received?
If you wish the Docket to notify you upon its receipt of your
comments, enclose a self-addressed, stamped postcard in the envelope
containing your comments. Upon receiving your comments, the Docket will
return the postcard by mail.
How do I submit confidential business information?
You should submit a redacted ``public version'' of your comment
(including redacted versions of any additional documents or
attachments) to the docket using any of the methods identified under
ADDRESSES. This ``public version'' of your comment should contain only
the portions for which no claim of confidential treatment is made and
from which those portions for which confidential treatment is claimed
has been redacted. See below for further instructions on how to do
this.
You also need to submit a request for confidential treatment
directly to the Office of Chief Counsel. Requests for confidential
treatment are governed by 49 CFR part 512. Your request must set forth
the information specified in Part 512. This includes the materials for
which confidentiality is being requested (as explained in more detail
below); supporting information, pursuant to Part 512.8; and a
certificate, pursuant to Part 512.4(b) and Part 512, Appendix A.
You are required to submit to the Office of Chief Counsel one
unredacted ``confidential version'' of the information for which you
are seeking confidential treatment. Pursuant to Part 512.6, the words
``ENTIRE PAGE CONFIDENTIAL BUSINESS INFORMATION'' or ``CONFIDENTIAL
BUSINESS INFORMATION CONTAINED WITHIN BRACKETS'' (as applicable) must
appear at the top of each page containing information claimed to be
confidential. In the latter situation, where not all information on the
page is claimed to be confidential, identify each item of information
for which confidentiality is requested within brackets: ``[ ].''
You are also required to submit to the Office of Chief Counsel one
redacted ``public version'' of the information for which you are
seeking confidential treatment. Pursuant to Part 512.5(a)(2), the
redacted ``public version'' should include redactions of any
information for which you are seeking confidential treatment (i.e., the
only information that should be unredacted is information for which you
are not seeking confidential treatment).
NHTSA is currently treating electronic submission as an acceptable
method for submitting confidential business information to the agency
under Part 512. Please do not send a hardcopy of a request for
confidential treatment to NHTSA's headquarters. The request should be
sent to Dan Rabinovitz in the Office of the Chief Counsel at
[email protected]. You may either submit your request via email
or request a secure file transfer link. If you are submitting the
request via email, please also email a courtesy copy of the request to
John Piazza at [email protected].
Will the agency consider late comments?
We will consider all comments received before the close of business
on the comment closing date indicated above under DATES. To the extent
possible, we will also consider comments that the docket receives after
that date. If the docket receives a comment too late for us to consider
in developing a final rule (assuming that one is issued), we will
consider that comment as an informal suggestion for future rulemaking
action.
How can I read the comments submitted by other people?
You may read the comments received by the docket at the address
given above under ADDRESSES. The hours of the docket are indicated
above in the same location. You may also see the comments on the
internet. To read the comments on the internet, go to https://www.regulations.gov. Follow the online instructions for accessing the
dockets.
Please note that even after the comment closing date, we will
continue to file relevant information in the docket as it becomes
available. Further, some people may submit late comments. Accordingly,
we recommend that you periodically check the Docket for new material.
You can arrange with the docket to be notified when others file
comments in the docket. See www.regulations.gov for more information.
List of Subjects in 49 CFR Part 572
Motor vehicle safety, Incorporation by reference.
Proposed Regulatory Text
In consideration of the foregoing, NHTSA proposes to amend 49 CFR
part 572 as follows:
PART 572--ANTHROPOMORPHIC TEST DEVICES
0
1. The authority citation for part 572 continues to read as follows:
Authority: 49 U.S.C. 322, 30111, 30115, 30117 and 30166;
delegation of authority at 49 CFR 1.95.
0
2. Add Subpart X, consisting of Sec. Sec. 572.220 through 572.221, to
read as follows:
Subpart X--THOR-50M 50th Percentile Male Frontal Impact Test Dummy
Secs.
572.220 Incorporation by reference.
572.221 General description.
Subpart X--THOR-50M 50th Percentile Male Frontal Impact Test Dummy
Sec. 572.220 Incorporation by reference.
Certain material is incorporated by reference (IBR) into this part
with the approval of the Director of the Federal Register under 5
U.S.C. 552(a) and 1 CFR part 51. To enforce any edition other than that
specified in this section, NHTSA must publish a document in the Federal
Register and the material must be available to the public. This
material is available for inspection at the Department of
Transportation, the National Archives and Records Administration
(NARA), and in electronic format through regulations.gov. Contact DOT
at: Department of Transportation, Docket Operations, Room W12-140, 1200
New Jersey Avenue SE, Washington DC 20590, telephone 202-366-9826. For
information on the availability of this material at NARA, email
[email protected] or go to www.archives.gov/federal-register/cfr/ibr-locations. To locate the material on regulations.gov, search for
Docket No. NHTSA-202X-XXXX. The material may be obtained from the
source:
(a) NHTSA Technical Information Services, 1200 New Jersey Ave. SE,
Washington, DC 20590, telephone 202-366-5965.
(1) A drawing package entitled, ``THOR-50th Percentile Male with
Alternate Shoulders Frontal Crash Test Dummy (THOR-50M Male w/Alt.
Shoulders) Drawings, External Dimensions, and Mass Properties,'' dated
(and revised) January 2023 (Drawings and Specifications); IBR approved
for Sec. 572.221.
(2) A parts list entitled, ``Parts List, THOR-50th Percentile Male
Frontal Crash Test Dummy with Alternate Shoulders (THOR-50M w/Alt.
Shoulders)'' dated (and revised) January 2023 (Parts List); IBR
approved for Sec. 572.221.
(3) A procedures document entitled ``THOR 50th Percentile Male
(THOR-50M) Procedures for Assembly, Disassembly, and Inspection
(PADI)'' dated (and revised) June 2023 (PADI); IBR approved for Sec.
572.221.
[[Page 61949]]
(4) A procedures document entitled ``THOR 50th Percentile Male
(THOR-50M) Qualification Procedures and Requirements'' dated (and
revised) April 2023 (Qualification Procedures); IBR approved for Sec.
572.221.
Sec. 572.221 General description.
(a) The THOR-50M 50th percentile male test dummy is defined by the
following materials:
(1) The Drawings and Specifications (incorporated by reference, see
Sec. 572.220);
(2) The Parts List (incorporated by reference, see Sec. 572.220);
(3) The PADI (incorporated by reference, see Sec. 572.220);
(4) The Qualification Procedures (incorporated by reference, see
Sec. 572.220).
Issued under authority delegated in 49 CFR 1.95, 501.4, and 501.
Ann Carlson,
Acting Administrator.
[FR Doc. 2023-19008 Filed 9-6-23; 8:45 am]
BILLING CODE 4910-59-P
