Musculoskeletal analysis of driving fatigue: The influence of seat adjustments

Main causes for discomfort experienced by vehicle drivers during driving were
investigated using a rigid-body model originally developed in the AnyBody Modeling System [1]. The interactions between the human body and the car-seat in various combinations of seat-pan/backrest inclinations and the effect of pedal spring stiffness were analyzed using an inverse dynamics approach. To deal with the muscle redundancy problem, (i.e. the problem with the human-body containing more muscles than necessary to drive its degrees of freedom) a
“minimum-fatigue” criterion [2] was utilized. The results show that various seat adjustments (e.g., seat-pan and backrest inclinations) and the pedal spring stiffness have complex influences on the muscle activation and spinal joint forces of the human body. From the results, an optimal adjustment for the car-seat is proposed, i.e. the backrest inclination is 10° and the seat-pan inclination is between 0º to 5 º. This study can in general capture the overall interactions between human body and environment (i.e. the maximum muscle activity and spine forces), which is thought to be the factors of driving fatigue.