Musculoskeletal computational analysis of the influence of car-seat design/adjustment on fatigue-induced driving

Main causes for fatigue and discomfort experienced by vehicle drivers during city driving were investigated computationally using a musculoskeletal modeling simulation method. Key adjustments of car seat (i.e., the seat-pan and back-rest inclination) together with various values of accelerator pedal´s spring stiffness were analyzed in the present work. A public-domain rigid-body model of a seat together with the detailed full-body musculoskeletal model was used to study biomechanics of seated drivers. Interactions between the drivers and vehicle in various combinations of seat-pan/back-rest inclinations and 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 muscle than necessary to drive its degrees of freedom) the “minimum-fatigue” criterion was utilized. The results show that seat-pan/back-rest inclinations and pedal spring stiffness have complex influences on the muscle activation and spinal joint forces of the human body. From the result, it may be suggested that a slight backward inclination of the seat-pan (approx. -20deg) and back-rest (approx. -20deg) may reduce the muscle fatigue of a driver. In addition, adding a spring (stiffness around 20Nm/rad) to the accelerator pedal does help in minimizing the muscle activity and spinal joint forces.