Identifying the Factors Affecting Automotive Driving Posture and Their Perceived Importance for Seat and Steering Wheel Adjustment

The aim of the present study was to identify the factors affecting the driving posture and their order of importance for the postural prediction when using a digital human modelling tool. An experiment was carried out with 35 volunteers testing 5 different vehicles with a clutch pedal, covering a large range of European drivers and passenger vehicle types. The seat and steering wheel positions for each vehicle were first adjusted in a lab condition without riding. Then subjects were asked to drive the vehicle on road for about 5 min. Afterwards, they were asked to fill in a questionnaire in order to know the use of available vehicle interior adjustments and to identify the order of priority of the factors affecting the adjustment of vehicle interior dimensions. Results show that 47 out of 175 person-vehicle combinations (27 %) made at least one re-adjustment during the road driving session, suggesting the stationary lab condition could not fully represent road driving. For 55 of 175 volunteers-vehicle combinations (31.4 %), at least one adjustment was judged too restrictive. As expected, short volunteers complained more frequently than others did. The most important factor considered for adjusting the seat and steering wheel positions was the accessibility of the pedals for all participants. The second most important factor depended on stature group. For tall volunteers, the accessibility of the steering wheel was classified as the second most important, while it was the road visibility for short and average height volunteers. These observations could be helpful not only for identifying possible vehicle interior design issues but also for identifying task priority for driving posture prediction when using a DHM tool.