Sensitivity of Preferred Driving Postures and Determination of Core Seat Track Adjustment Ranges

With advances in virtual prototyping, accurate digital modeling of driving posture is regarded as a fundamental step in the design of ergonomic driver-seat-cabin systems. Extensive work on driving postures has been carried out focusing on the measurement and prediction of driving postures and the determination of comfortable joint angle ranges. However, studies on postural sensitivity are scarce. The current study investigated whether a driver-selected posture actually represents the most preferred one, by comparing the former with ratings of postures selected at 20 predefined places around the original hip joint center (HJC). An experiment was undertaken in a lab setting, using two distinctive driving package geometries: one for a sedan and the other for an SUV. The 20 postural ratings were compared with that of the initial user-selected position. Alternative HJC locations for each gender, age and stature groups were identified where a postural rating was close to, and sometimes even higher than, the initial score. Using these ratings, equal comfort contour maps with respect to HJC were drawn for each group. In addition, SAE recommended practices related to the positioning of HJC as well as eyes and ball of foot (BOF) were evaluated.