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Technical Paper

Modeling Vehicle Ingress and Egress Using the Human Motion Simulation Framework

2008-06-17
2008-01-1896
The ease of getting into and out of passenger cars and light trucks is a critical component of customer acceptance and product differentiation. In commercial vehicles, the health and safety of drivers is affected by the design of the steps and handholds they use to get into and out of the cab. Ingress/egress assessment appears to represent a substantial application opportunity for digital human models. The complexity of the design space and the range of possible biomechanical and subjective measures of interest mean that developing useful empirical models is difficult, requiring large-scale subject testing with physical mockups. Yet, ingress and egress motions are complex and strongly affected by the geometric constraints and driver attributes, posing substantial challenges in creating meaningful simulations using figure models.
Technical Paper

Geometric Visibility of Mirror Mounted Turn Signals

2005-04-11
2005-01-0449
Turn signals mounted on exterior rearview mirrors are increasingly being used as original equipment on passenger cars and light trucks. The potential for mirror-mounted turn signals (MMTS) to improve the geometric visibility of turn signals is examined in this paper. A survey of U.S. and UN-ECE regulations showed that the turn signals of a vehicle that is minimally compliant with U.S. regulations are not visible to a driver of a nearby vehicle in an adjacent lane. Measurements of mirror location and window geometry were made on 74 passenger cars and light trucks, including 38 vehicles with fender-mounted turn signals (FMTS). These data were combined with data on driver eye locations from two previous studies to assess the relative visibility of MMTS and conventional signals. Simulations were conducted to examine the potential for signals to be obstructed when a driver looks laterally through the passenger-side window.
Technical Paper

A Method for Measuring the Field of View in Vehicle Mirrors

2003-03-03
2003-01-0297
A new method is presented for physically measuring drivers' field of view in rearview mirrors. A portable coordinate measurement apparatus (FARO Arm) is used to measure the mirror locations, contours, and curvature. Measurements of the driver's head and eye locations while looking into each mirror are also made. Raytracing is used to map the two- or three-dimensional field of view in each mirror. The method differentiates between monocular, binocular, and ambinocular fields of view, and can account for head movements. This method has been applied to passenger cars, light trucks, and heavy trucks to document how drivers aim their mirrors during normal use.
Technical Paper

Knee, Thigh and Hip Injury Patterns for Drivers and Right Front Passengers in Frontal Impacts

2003-03-03
2003-01-0164
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.
Technical Paper

Computer Synthesis of Light Truck Ride Using a PC Based Simulation Program

1999-05-17
1999-01-1796
An easy-to-use computer program for ride analysis was recently developed. The result of this effort-RideSim- predicts time history responses, power spectral density (PSD) functions, and a driver oriented measure of ride comfort. RideSim employs a graphical user interface (called SGUI, for simulation graphical user interface) to control data preparation, simulation execution, animation, and data analysis. The SGUI allows the user to operate the program by pointing and clicking with a mouse, rather than by using cumbersome text commands. It also manages the vehicle dynamics parameters, the resulting simulation output, and results of post-processing analyses (i.e., PSD analysis). The vehicle dynamics model was generated with the AUTOSIM multibody dynamics program. This program uses Kane’s Method and computer algebra to create a parametric dynamics simulation that can be easily linked to the SGUI.
Technical Paper

Development of an Improved Driver Eye Position Model

1998-02-23
980012
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.
Technical Paper

Effects of Large-Radius Convex Rearview Mirrors on Driver Perception

1997-02-24
970910
The U.S. currently requires that reai-view mirrors installed as original equipment in the center and driver-side positions be flat. There has recently been interest in using nonplanar mirrors in those positions, including possibly mirrors with large radii (over 2 m). This has provided additional motivation to understand the effects of mirror curvature on drivers' perceptions of distance and speed. This paper addresses this issue by (1) reviewing the concepts from perceptual theory that are most relevant to predicting and understanding how drivers judge distance in nonplanar rearview mirrors, and (2) reviewing the past empirical studies that have manipulated mirror curvature and measured some aspect of distance perception. The effects of mirror curvature on cues for distance perception do not lead to simple predictions. The most obvious model is one based on visual angle, according to which convex mirrors should generally lead to overestimation of distances.
Technical Paper

Driver Perceptual Adaptation to Nonplanar Rearview Mirrors

1996-02-01
960791
This study examined perceptual adaptation to nonplanar (spherical convex and aspheric) rearview mirrors. Subjects made magnitude estimates of the distance to a car seen in a rearview mirror. Three different mirrors were used: plane, aspheric (with a large spherical section having a radius of 1400 mm), and simple convex (with a radius of 1000 mm). Previous research relevant to perceptual adaptation to nonplanar mirrors was reviewed. It was argued that, in spite of some cases of explicit interest in the process of learning to use nonplanar mirrors, previous research has not adequately addressed the possibility of perceptual adaptation. The present experiment involved three phases: (1) a pretest phase in which subjects made distance judgments but received no feedback, (2) a training phase in which they made judgments and did receive feedback, and (3) a posttest phase with the same procedure as the pretest phase.
Technical Paper

On-the-Road Visual Performance with Electrochromic Rearview Mirrors

1995-02-01
950600
This study was part of a series of studies on variable-reflectance rearview mirrors. Previous work included laboratory studies of human visual performance, field collection of photometric data, and mathematical modeling of the visual benefits of variable-reflectance mirrors. We extended that work in this study by collecting photometric and human-performance data while subjects drove in actual traffic. Three mirror conditions were investigated: (1) fixed-reflectance mirrors in the center and driver-side positions, (2) a variable-reflectance mirror in the center with a fixed-reflectance mirror on the driver side, and (3) variable-reflectance mirrors in both positions. The fixed and variable reflectivities were produced by the same mirrors by overriding the circuitry that normally controlled reflectance in the variable mode.
Technical Paper

Repeatability of the Tilt-Table Test Method

1993-03-01
930832
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.
Technical Paper

Rearward Vision, Driver Confidence, and Discomfort Glare Using an Electrochromic Rearview Mirror

1991-02-01
910822
Electrochromic rearview mirrors can provide continuous levels of reflectivity and unobtrusive, automatic control. The availability of this technology has increased the importance of understanding how to select the best level of reflectivity for a given set of lighting conditions. For night driving with glare from following headlights, the best reflectivity level will always depend on a tradeoff among several variables. This study was designed to help clarify what variables are important and how they should be quantified. Twenty subjects, 10 younger and 10 older, performed a number of visual tasks while viewing stimuli through an electrochromic rearview mirror. Subjects were seated in an automobile mockup in a laboratory, and the reflectivity level of the mirror was changed before each of a series of discrete trials. On each trial, subjects saw reflected in the mirror a visual-acuity stimulus and a glare source of varying intensity.
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