Multibody Biomechanical Modelling of Human Body Response to Vibrations in an Automobile

Vehicle drivers experiencing long sitting posture suffer from muscle fatigue and various problems in spine like herniated discs and low back pain. In order to design a seat to improve their comfort, it is necessary to choose a modeling method of appropriate level of complexity - one that allows the interaction of all major parts of the body to be captured but is simple enough so that effect of contact of separate parts of the body with the seat can be estimated. A 26 degree of freedom multibody biomechanical model reported in this paper is an attempt in this direction. The restraining effect on the upper part of the torso due to contact of hands with steering wheel has been included in the model - an effect which has been ignored by most researchers. Sixty-five model parameters have been identified by using genetic algorithm to minimize the sum squared error between seat to head transmissibility and apparent mass of the model and experimental results. A parameter sensitivity study revealed that a seat design which targets vertical compression at pelvis is likely to be the most effective followed by the ability to restrain horizontal motion at thigh.