Effects of Vehicle Interior Geometry and Anthropometric Variables on Automobile Driving Posture

Abstract

The effects of vehicle package, seat, and anthropometric variables on posture were studied in a laboratory vehicle mockup. Participants (68 men and women) selected their preferred driving postures in 18 combinations of seat height, fore-aft steering wheel position, and seat cushion angle. Two seats differing in stiffness and seat back contour were used in testing. Driving postures were recorded using a sonic digitizer to measure the 3D locations of body landmarks. All test variables had significant independent effects on driving posture. Drivers were found to adapt to changes in the vehicle geometry primarily by changes in limb posture, whereas torso posture remained relatively constant. Stature accounts for most of the anthropometrically related variability in driving posture, and gender differences appear to be explained by body size variation. Large intersubject differences in torso posture, which are fairly stable across different seat and package conditions, are not closely related to standard anthropometric measures. The findings can be used to predict the effects of changes in vehicle and seat design on driving postures for populations with a wide range of anthropometric characteristics.

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Matthew P. Reed is an assistant research scientist in the Biosciences Division of the University of Michigan Transportation Research Institute. He received a Ph.D. in industrial and operations engineering from the University of Michigan in 1998.

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Miriam A. Manary is a senior research associate in the Biosciences Division of the University of Michigan Transportation Research Institute. She received an M.S.E. in bioengineering from the University of Michigan in 1994.

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Carol A. C. Flannagan in an assistant research scientist in the Biosciences Division of the University of Michigan Transportation Research Institute. She received a Ph.D. in psychology from the University of Michigan in 1993.

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Lawrence W. Schneider is a senior research scientist and head of the Biosciences Division of the University of Michigan Transportation Research Institute. He received a Ph.D. in bioengineering from the University of Michigan in 1973.