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Eight whole fresh-frozen cadavers (6 female, 2 male) that were elderly and/or female were laterally impacted using UMTRI's dual-sled side-impact test facility. Cadavers were not excluded on the basis of old age or bone diseases that affect tolerance. A thinly padded, multi-segment impactor was used that independently measured force histories applied to the shoulder, thorax, abdomen, greater trochanter, iliac wing, and femur of each PMHS. Impactor plates were adjusted vertically and laterally toward the subject so that contact with body regions occurred simultaneously and so that each segment contacted the same region on every subject. This configuration minimized the effects of body shape on load sharing between regions. Prior to all tests, cadavers were CT scanned to check for pre-existing skeletal injuries. Cadavers were excluded if they had pre-existing rib fractures or had undergone CPR.

Lateral impact tests were performed using seven male post-mortem human subjects (PMHS) to characterize the force-deflection response of contacted body regions, including the lower abdomen. All tests were performed using a dual-sled, side-impact test facility. A segmented impactor was mounted on a sled that was pneumatically accelerated into a second, initially stationary sled on which a subject was seated facing perpendicular to the direction of impact. Positions of impactor segments were adjusted for each subject so that forces applied to different anatomic regions, including thorax, abdomen, greater trochanter, iliac wing, and thigh, could be independently measured on each PMHS. The impactor contact surfaces were located in the same vertical plane, except that the abdomen plate was offset 5.1 cm towards the subject.

This paper describes the design and development of a family of surrogate child restraints that are intended for use in developing and testing occupant sensing and classification systems. Detailed measurements were made of the geometry and mass distribution characteristics of 34 commercial child restraints, including infant restraints, convertibles, combination restraints, and boosters. The restraints were installed in three test seats with appropriately sized crash dummies to obtain data on seat-surface pressure patterns and the position and orientation of the restraint with belt loading. The data were used to construct two surrogates with removable components. The convertible surrogate can be used to represent a rear-facing infant restraint with or without a base, a rear-facing convertible, or a forward-facing convertible. The booster surrogate can represent a high-back belt-positioning booster, a backless booster, or a forward-facing-only restraint with a five-point harness.

Late model passenger cars and light trucks incorporate occupant protection systems with airbags and knee restraints. Knee restraints have been designed principally to meet the unbelted portions of FMVSS 208 that require femur load limits of 10-kN to be met in barrier crashes up to 30 mph, +/- 30 degrees utilizing the 50% male Anthropomorphic Test Device (ATD). In addition, knee restraints provide additional lower-torso restraint for belt-restrained occupants in higher-severity crashes. An analysis of frontal crashes in the University of Michigan Crash Injury Research and Engineering Network (UM CIREN) database was performed to determine the influence of vehicle, crash and occupant parameters on knee, thigh, and hip injuries. The data sample consists of drivers and right front passengers involved in frontal crashes who sustained significant injuries (Abbreviated Injury Scale [AIS] ≥ 3 or two or more AIS ≥ 2) to any body region.

Most human figure models used in ergonomic analyses present postural comfort ratings based on joint angles, and present a single comfort score for the whole body or on a joint-by-joint basis. The source data for these ratings is generally derived from laboratory studies that link posture to ratings. Lacking in many of these models is a thorough treatment of the distribution of ratings for the population of users. Information about ratings distributions is necessary to make cost-effective tradeoffs when design changes affect subjective responses. This paper presents experimental and analytic methods used to develop distribution models for incorporating subjective rating data in ergonomic assessments.

Recent research in the ASPECT (Automotive Seat and Package Evaluation and Comparison Tools) program has led to the development of a new method for automobile driver posture prediction, known as the Cascade Model. The Cascade Model uses a sequential series of regression functions and inverse kinematics to predict automobile occupant posture. This paper presents an alternative method for driver posture prediction using data-guided kinematic optimization. The within-subject conditional distributions of joint angles are used to infer the internal cost functions that guide tradeoffs between joints in adapting to different vehicle configurations. The predictions from the two models are compared to in-vehicle driving postures.

A new method of predicting automobile occupant posture is presented. The Cascade Prediction Model approach combines multiple independent predictions of key postural degrees of freedom with inverse kinematics guided by data-based heuristics. The new model, based on posture data collected in laboratory mockups and validated using data from actual vehicles, produces accurate posture predictions for a wide range of passenger car interior geometries. Inputs to the model include vehicle package dimensions, seat characteristics, and occupant anthropometry. The Cascade Prediction Model was developed to provide accurate posture prediction for use with any human CAD model, and is applicable to many vehicle design and safety assessment applications.

The ASPECT (Automotive Seat and Package Evaluation and Comparison Tools) manikin provides new capabilities for vehicle and seat measurement while maintaining continuity with previous practices. This paper describes how the manikin is used in the development of new designs, the audit verification of build, and in benchmarking competitive vehicles and seats. The measurement procedures are discussed in detail, along with the seat and package dimensions that are associated with the new tool.

The primary objective of the ASPECT (Automotive Seat and Package Evaluation and Comparison Tools) program was to develop a new generation of the SAE J826 H-point manikin. The new ASPECT manikin builds on the long-term success of the H-point manikin while adding new measurement capability and improved ease of use. The ASPECT manikin features an articulated torso linkage to measure lumbar support prominence; new contours based on human subject data; a new weighting scheme; lightweight, supplemental thigh, leg, and shoe segments; and a simpler, user-friendly installation procedure. This paper describes the new manikin in detail, including the rationale and motivation for the design features. The ASPECT manikin maintains continuity with the current SAE J826 H-point manikin in important areas while providing substantial new measurement capability.

Recent changes in impact protection requirements have led to increased padding on vehicle interior surfaces. In the areas near the driver's head, thicker padding can reduce the available headspace and may degrade the driver's perception of headroom. A laboratory study of driver headroom perception was conducted to investigate the effects of physical headroom on the subjective evaluation of headroom. Ninety-nine men and women rated a range of headroom conditions in a reconfigurable vehicle mockup. Unexpectedly, driver stature was not closely related to the perception of headroom. Short-statured drivers were as likely as tall drivers to rate a low roof condition as unacceptable. Statistical models were developed from the data to predict the effects of changes in headroom on the percentage of drivers rating the head-room at a specified criterion level.

The ASPECT (Automotive Seat and Package Evaluation and Comparison Tools) program developed a new physical manikin for seat measurement and new techniques for integrating the seat measurements into the vehicle design process. This paper presents an overview of new concepts in vehicle interior design that have resulted from the ASPECT program and other studies of vehicle occupant posture and position conducted at UMTRI. The new methods result from an integration of revised versions of the SAE seat position and eyellipse models with the new tools developed in ASPECT. Measures of seat and vehicle interior geometry are input to statistical posture and position prediction tools that can be applied to any specified user population or individual occupant anthropometry.

SAE Recommended Practice J941 describes the eyellipse, a statistical representation of driver eye locations, that is used to facilitate design decisions regarding vehicle interiors, including the display locations, mirror placement, and headspace requirements. Eye-position data collected recently at University of Michigan Transportation Research Institute (UMTRI) suggest that the SAE J941 practice could be improved. SAE J941 currently uses the SgRP location, seat-track travel (L23), and design seatback angle (L40) as inputs to the eyellipse model. However, UMTRI data show that the characteristics of empirical eyellipses can be predicted more accurately using seat height, steering-wheel position, and seat-track rise. A series of UMTRI studies collected eye-location data from groups of 50 to 120 drivers with statures spanning over 97 percent of the U.S. population. Data were collected in thirty-three vehicles that represent a wide range of vehicle geometry.

Four unembalmed human cadavers were used in eight direct-forearm-airbag-interaction static deployments to assess the relative aggressivity of two different airbag modules. Instrumentation of the forearm bones included triaxial accelerometry, crack detection gages, and film targets. The forearm-fracture predictors, peak and average distal forearm speed (PDFS and ADFS), were evaluated and compared to the incidence of transverse, oblique, and wedge fractures of the radius and ulna. Internal-airbag pressure and axial column loads were also measured. The results of this study support the use of PDFS or ADFS for the prediction of airbag-induced upper-extremity fractures. The results also suggest that there is no direct relationship between internal-airbag pressure and forearm fracture. The less-aggressive system (LAS) examined in this study produced half the number of forearm fracture as the more-aggressive system (MAS), yet exhibited a more aggressive internal-pressure performance.

This paper describes an ongoing effort to develop computer-simulated instrumentation for the UMTRI Driver Interface Research Simulator. The speedometer, tachometer, engine and fuel gauges, along with warning lights are back projected onto a screen in front of the driver. The image is generated by a Macintosh running LabVIEW. Simulated instrumentation (instead of a production cluster) was provided so that new display designs can be rapidly generated and tested. This paper addresses the requirements for prototyping software, the advantages and disadvantages of the packages available, and the UMTRI implementation of the software, and its incorporation into the driving simulator.

Data from the 1990 U.S. Nationwide Personal Transportation Survey were analyzed to determine the distribution of trip durations and sitting times for use in the design of automobile seat comfort studies. Two measures relating to the incidence and prevalence of long-term sitting were calculated and presented for the U.S. population and various subgroups. The information can be used to select an appropriate test duration for comfort studies. The subgroup data allow the test duration to be tailored for specific market segments.

This paper describes the architecture and use of a simulation graphical user interface (SGUI) that uses new (1990's) computer hardware and software concepts to provide an easy-to-use environment for simulating vehicle dynamics. The user interacts with windows, buttons, and pop-up menus, in a multitasking environment such as UNIX, Windows®, or Mac OS®. The SGUI reduces the level of computer expertise required of the user. Most information is shown in a graphic context, and “what if?” options are selected by clicking buttons and selecting from pop-up menus. The SGUI is organized as a data base of vehicles, vehicle parts, vehicle inputs, and simulation results. The organization makes it easy for users to assemble the component data needed to (1) simulate new systems, (2) run simulation programs automatically, and (3) view the results graphically. The SGUI is assembled from low-cost software components.

The objective of this analysis is to evaluate the effectiveness of restraints in preventing injury-producing contacts of specific body regions, such as the head or chest, with specific interior components. In order to make comparisons by restraint use, an injury rate is calculated as the number of injury-producing contacts per hundred involved occupants. Data, including the Occupant Injury Classification (OIC), are from the 1988-92 National Accident Sampling System (NASS) Crashworthiness Data System (CDS). The analysis presented is limited to passenger vehicle drivers in towaway, frontal impacts. Injury-producing contact rates are compared for four restraint configurations: unrestrained, three-point belted, driver airbag alone, and driver airbag plus three-point belt. For each restraint configuration, contact rates are compared by three categories of injury severity, AIS 1, AIS 2, and AIS 3-6, body region injured, and contact area producing the injury.

Tilt-table testing is one means of quantifying the static roll stability of highway vehicles. By this technique, a test vehicle is subjected to a physical situation analogous to that experienced in a steady state turn. Although the analogy is not perfect, the simplicity and fidelity of the method make it an attractive means for estimating static rollover threshold. The NHTSA has suggested the tilt-table method as one means of regulating the roll stability properties of light trucks and utility vehicles. One consideration in evaluating the suitability of any test method for regulatory use is repeatability, both within and among testing facilities. As a first step toward evaluating the repeatability of the tilt-table method, an experimental study examining the sensitivity of tilt-table test results to variables associated with methodology and facility was conducted by UMTRI for the Motor Vehicle Manufacturers Association. This paper reports some of the findings of that study.

The effects of child safety seats have been well documented in the medical literature. Scattered throughout the medical literature are individual case reports of cervical injury to children restrained in child restraint systems. A review of the literature is provided identifying previous documented cases. The authors also provide new case details of children with cervical spine injury without head contact. An overview of the growth of the infant and specific details in the cervical spine that may contribute to significant cervical injury without head impact is presented.

Crash injury reduction via lap-shoulder belt use has been well documented. As any interior car component, lap-shoulder belts may be related to injury in certain crashes. Relatively unknown is the fact that cervical fractures or fracture-dislocations to restrained front seat occupants where, in the crash, no head contact was evidenced by both medical records and car inspection. An extensive review of the available world's literature on car crash injuries revealed more than 100 such cases. A review of the NASS 80-88 was also conducted, revealing more examples. Cases from the author's own files are also detailed.