Documentation:FIB book/Anthropomorphic Test Device (ATD)/THOR
Introduction
The Test device for Human Occupant Restraint (THOR) ATD includes expanded instrumentation[1] and enhanced biofidelic features[2] compared to the Hybrid III, the current gold standard ATD used in regulated frontal and frontal oblique crash tests. The National Highway Traffic Safety Administration (NHTSA) of the US Department of Transportation has been supporting the THOR's development program since 1985. Many versions of the THOR have been developed and iterated since then, such as the THOR Alpha (2001), the THOR-NT (2005), and the THOR-K (SAE, 2010).
In 2011, NHTSA contracted Humanetics Innovative Solutions, Inc. (Plymouth, Michigan, USA) to develop a 50th percentile male metric version of the THOR, the THOR-50M. They also created a 5th percentile female version, the THOR-5F. The female version was developed based on the same technology as the THOR-50M but has improved design (more human-like) and overall dummy handling in comparison to the male version.[1]
Although the THOR has yet not replaced the Hybrid III in regulated frontal and frontal oblique crash tests in the US, the THOR's final dimensions and weights are currently undergoing validation processes.[1] Moreover, NHTSA and Humanetics meet regularly to address the THOR's performance and test procedures, and to update its drawing package and spare parts. The European New Car Assessment Programme (Euro NCAP) stated in the Euro NCAP 2020 Roadmap that the THOR-50M ATD will be employed in their updated frontal impact test procedures, which will be available by 2020 to assess improvements in restraint systems and vehicle compatibility.
In this review, we will focus on the THOR-50M and compare it to its predecessor, the Hybrid III (henceforth referred to as HIII-50M) (Figure 1).
Figure 1. The THOR-50M[1] (left) and the HIII-50M[3] (right)
Overview
Technical Specifications
A comprehensive overview of the latest THOR-50M specifications can be found on the manufacturer’s website.[1]
The latest documentation related to the THOR-50M can be found on NHTSA's website.[4]
An overview of the THOR-50M and the HIII-50M structural assemblies can be found in the parts catalogs available on the manufacturer’s website (HIII-50M parts catalog & THOR-50M parts catalog).
Design Parameters
Anthropometry
An important aspect to consider when designing an ATD is to ensure that it has a similar size, shape, weight, and overall external dimensions to a human, which is known as anthropometry. A project was carried out to determine the accurate anthropometry of several individuals in automotive seated postures.[5][6] The design process of the THOR-50M ATD utilized these project outcomes to accurately represent the anthropometry of a mid-sized human (50th percentile male in weight and stature). As the THOR-50M is intended for use in frontal and frontal oblique crashes, the nature of injury in these types of crashes required that the THOR-50M design focused on an anatomically correct neck, shoulder, chest, spine, and pelvis.[7]
Biofidelity
The biofidelity of ATDs is tested by comparing the reaction of the ATD under certain test conditions to the reaction of normalized cadavers or volunteers under these same conditions.[8] Data from cadaveric studies is used to create biofidelity corridors which indicate the bounds that the cadavers performed within during the testing. The ATD test results are overlaid on the relevant biofidelity corridors to compare the reactions of the ATD with those of the cadavers. From this, a Biofidelity Ranking System (BioRank) value can be assigned, which measures how close the ATD response is to that of the mean cadaver. The lower the BioRank score, the more biofidelic the ATD is. Hence, a BioRank of 0.0 implies that the ATD performed exactly the same as the mean cadaver, a BioRank of 1.0 means that the ATD performance is, on average, 1 standard deviation away from the mean cadaver, and so on. The typical variation in biofidelic performance between the mean cadaver and any other tested cadaver is, on average, 2 standard deviations, equivalent to a BioRank 2.0.[9] Therefore, it is especially significant when an ATD achieves a BioRank of 2.0 or below as the dummy is then considered to respond similarly to a tested cadaver.
The biofidelity of ATDs can be further assessed in terms of internal or external biofidelity. The internal biofidelity represents the ability of an ATD to mimic human responses directly correlated to injury prediction. These biofidelity measures are generally captured by the ATD's internal instrumentation or by motion tracking systems that record the deformation on the level of the ATD as a whole. Conversely, the external biofidelity corresponds to how well an ATD represents a human during the interaction with external components of a crash scenario, such as the vehicle or the restraint system. The data required to determine external biofidelity is usually gathered at the test fixture level, e.g. pneumatic ram force or pendulum force.[9]
One study analysed the internal and external biofidelity of THOR-50M and assigned BioRank scores for seven of its body regions (head, neck, thorax, abdomen, knee/thigh/hip, lower extremity, and whole-body). Almost all body regions of THOR-50M had BioRank scores below 2.0, except for the abdomen when externally and the neck when internally assessed (see Table 1). However, all THOR-50M body regions received lower internal and external BioRank scores compared to those of the HIII-50M, indicating an improvement in the THOR-50M biofidelic performance versus its predecessor.[9] NHTSA also conducted a study to determine the biofidelity of the THOR-50M for their New Car Assessment Program (NCAP). Their results also demonstrated that the majority of the BioRank scores assigned for both internal and external THOR-50M structures were below 2.0.[10]
Additional Design Parameters
Other important factors in ATD design are repeatability and reproducibility. ATDs need to be used at several time points when testing different vehicles and their safety features, and the results from these tests must be repeatable. Moreover, ATDs are expensive and should, therefore, be durable enough to be employed in multiple crash tests without damage or degradation. The repeatability and reproducibility of the THOR-50M were considered to be sufficient by NHTSA’s NCAP.[10] This group also carried out tests to determine the durability of the ATD. They performed high-energy qualification tests on the face, head, neck, thorax, abdomen, knee, upper leg, and lower leg, and most of their initial results indicated that the THOR-50M possesses good durability. However, the agency is presently seeking comments on the THOR-50M Durability Report, which is currently not publicly available.[10]
Comparison of the THOR-50M and the HIII-50M
When comparing the THOR-50M and the HIII-50M, there are a number of differences in both the structural assembly of different body regions and the included instrumentation. These differences are summarized in Table 1 and Table 2 respectively.
Table 1. The THOR-50M structural changes in comparison to the HIII-50M and associated BioRank values of both ATDs affected by the change.
| Body Region | THOR-50M Structural Changes | THOR-50M BioRank[9] | HIII-50M BioRank[9] |
| Neck | Improved anatomical biofidelity using cables external to the central column to represent neck musculature and improved biofidelity anterior-posterior (AP) and medial-lateral (ML) responses[11] | Neck
Internal: 2.155 External: 1.677 |
Neck
Internal: 2.185 External: 4.318 |
| Thorax | Shoulder assembly added to improved restraint interaction[3] | Thorax
Internal: 0.917 External: 0.948 |
Thorax
Internal: 1.603 External: 2.070 |
| Spine | Flexible joints added in the thoracic and lumbar spine[1] | Abdomen
Internal: 1.470 External: 2.803 |
Abdomen
Internal: 1.629 External: 3.474 |
| Pelvis | Coupling between femur and pelvis reduced[1] | Knee/Thigh/Hip
Internal: 1.400 External: 1.731 |
Knee/Thigh/Hip
Internal: 3.875 External: 6.667 |
| Femur | Biofidelic axial load response improved[1] | Femur Compression
Internal: 1.400 External: 1.180 |
Femur Compression
Internal: 3.875 External: 12.264 |
Table 2. The THOR-50M instrumentation changes in comparison to the HIII-50M.
| Body Region | Instrumentation Present in both THOR-50M[12] and HIII-50M[13] | Additional Instrumentation Only Present in THOR-50M[12] | Instrumentation Only Present in HIII-50M[13] |
| Head |
|
|
|
| Neck |
|
|
|
| Clavicle |
|
||
| Arm |
|
||
| Spine |
|
|
|
| Thorax |
|
|
|
| Pelvis |
|
|
|
| Abdomen |
|
||
| Femur |
|
||
| Lower Extremities |
|
|
|
| * CG: Center of Gravity
** IR-TRACC: Infra-Red Telescoping Rod for the Assessment of Chest Compression *** ASIS: Advanced side-impact systems - Biaxial Iliac Wing (ASIS) Load Cell, designed to measure the force Fz and moment My in the Iliac Wing area. | |||
As inferred from Table 2, the THOR-50M expands greatly on the instrumentation provided in the HIII-50M. In fact, the THOR-50M has 134 channels of data, 78 more than the HIII-50M.[1] More importantly, the THOR-50M includes abdominal instrumentation, which was not available in HIII-50M. Although neither abdominal injury criteria nor the THOR-50M itself are yet included in the Federal Motor Vehicle Safety Standards 208 - Occupant crash protection (FMVSS 208), quantifying damage to the abdomen is of extreme importance because this area of our body houses several life-sustaining organs and is not protected by any bony structure. Thus, abdominal injury is often linked to highly severe or life-threatening incidents, and therefore may be included in regulated crash tests in the near future.
Interestingly, the THOR-50M has facial instrumentation, despite the fact that injuries to the face are not linked to high mortality nor severity. This addition was influenced by the cultural importance that humans place on facial appearance. Damage to the face can result in the onset of negative psychological and behavioral effects in one’s life[14]. Therefore, the ability to determine facial injury likelihood is another benefit of the THOR-50M in comparison to the HIII-50M.
While THOR-50M has not yet become the new gold standard for regulatory frontal and frontal oblique crash tests[15], the development of this ATD paves the way for even more detailed and accurate crash test results to be obtained. The THOR family of ATDs represents the future of biofidelic crash test results and, thus, offers the potential to achieve increased safety in the automotive industry.
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 "THOR 50th Male (Metric)". Humanetics Innovative Solutions, Inc. Retrieved 6 November 2019.
- ↑ D. L. Albert, S. M. Beeman, and A. 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, vol. 19, no. sup1, 2018.
- ↑ 3.0 3.1 "Hybrid III 50th Male". Humanetics Innovative Solutions, Inc. Retrieved 6 November 2019.
- ↑ "THOR Test Device for Human Occupant Restraint". NHTSA. Retrieved 6 November 2019.
- ↑ Schneider, L. W., ‘‘Development of anthropometrically based design specifications for an advanced adult anthropomorphic dummy family, volume 1. Final report’’ U.S. Department of Transportation, DOT–HS–806–715, 1983.
- ↑ Robbins, D. H., ‘‘Anthropometric specifications for mid-sized male dummy, volume 2, and for small female and large male dummies, volume 3. Final report’’ U.S. Department of Transportation, DOT–HS–806–716 & 717, 1983.
- ↑ NHTSA, “New Car Assessment Program [Docket No. NHTSA–2015–0119],” Fed. Regist., vol. 80, pp. 78521–78591, 2015.
- ↑ H. Rhule, B. Donnelly, K. Moorhouse, and Y. S. Kang, “A METHODOLOGY FOR GENERATING OBJECTIVE TARGETS FOR QUANTITATIVELY ASSESSING THE BIOFIDELITY OF CRASH TEST DUMMIES,” 2013.
- ↑ 9.0 9.1 9.2 9.3 9.4 D. Parent, M. Craig, and K. Moorhouse, “Biofidelity Evaluation of the THOR and Hybrid III 50th Percentile Male Frontal Impact Anthropomorphic Test Devices.,” Stapp Car Crash J., vol. 61, pp. 227–276, Nov. 2017.
- ↑ 10.0 10.1 10.2 “DEPARTMENT OF TRANSPORTATION National Highway Traffic Safety Administration New Car Assessment Program,” 2015.
- ↑ D. L. Albert, S. M. Beeman, and A. R. Kemper, “Evaluation of Hybrid III and THOR-M neck kinetics and injury risk under various restraint conditions during full-scale frontal sled tests,” Traffic Inj. Prev., vol. 19, no. sup2, pp. S40–S47, Mar. 2018.
- ↑ 12.0 12.1 "THOR 50th Male (Metric) - Technical Specifications - Instrumentation". Humanetics Innovative Solutions, Inc. Retrieved 8 November 2019.
- ↑ 13.0 13.1 "Hybrid III 50th Male - Technical Specifications - Instrumentation". Humanetics Innovative Solutions, Inc. Retrieved 8 November 2019.
- ↑ J. A. Gibson, E. Ackling, J. I. Bisson, T. D. Dobbs, and I. S. Whitaker, “The association of affective disorders and facial scarring: Systematic review and meta-analysis,” Journal of Affective Disorders, vol. 239, pp. 1–10, 2018.
- ↑ "Title 49: Transportation PART 571—FEDERAL MOTOR VEHICLE SAFETY STANDARDS Subpart B—Federal Motor Vehicle Safety Standards §571.208 Standard No. 208; Occupant crash protection". Electronic Code of Federal Regulations. Retrieved 6 December 2019.
External Links
Humanetics Innovative Solutions, Plymouth, Michigan, USA- Largest manufacturer of ATDs, includes information such as product catalogs, user manuals, FE models and current versions available, technical specifications, etc.
National Highway Traffic Safety Administration (NHTSA) - THOR Test Device for Human Occupant Restraint- from the United States Department of Transportation, their website contains information about the ATD hardware description, documentation (introducing the latest qualification procedures), papers and reports, and public meetings, which include qualification test videos. Their files are made available to the public without charge and may be used, copied, and distributed.
New Car Assessment Program (NCAP) - Docket NHTSA-2015-0119 - Department of Transportation (DOT). Includes notices, supporting and related materials, public submissions, public hearings, memorandums, etc. related to the NCAP. Also contains the latest THOR-50M Qualification Procedures.