Subjects representative of the mid-sized automobile market segment in the United States drove a four-door 1995 Chevrolet Lumina on three highway trips. We measured their posture, seat position, muscle activity, pressure distribution and comfort under highway driving conditions. Two identical vehicles were instrumented with video cameras to measure anatomical joint center positions (including H-point and D-point in the pelvis) in three-dimensional space, pressure distribution in the cushion and back, and an on-board PC equipped with an A-to-D board that was used to digitize signals from EMG electrodes on the driver's back and all seat position transducers. The seat was a six-way power seat with a power recline and a four-way lumbar support. A technician sat in the back seat operating all measurement equipment and conducting a brief comfort interview at prescribed intervals during the drive. The subjects, obtained from the general population in mid-Michigan, were selected to drive the vehicle without prejudice for halo or marketing effects. This report describes how these subjects used the 12-way power seat in the vehicle to achieve a comfortable or occupant-preferred seat position while operating the vehicle on the highway.
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