The human body exposition to vibration and to mechanical shocks may cause discomfort and physiologic alterations. Researches have been developed for at last 30 years, with the objective to find the human body behavior and the collateral effects caused when submitted to vibration. This is a present-day topic and worries the scientific community. Clinical investigations shows that vehicle drivers and industrial workers exposed to vibration and shock exhibit reduction of vertebral discs thickness [1] and epidemiologic evidences aim the human body exposition to vibration to be the principal cause of low back pain (LBP) [2, 3]. A four DOF model of the system composed of a seat and a person on it is considered, to describe the measured experimental curves of transmissibility in urban buses drivers. The model was adjusted to describe the measured transmissibility between the bus's ground and the seat, and between the seat and the driver's shoulder. The seat is represented by one stiffness-mass system degree of freedom and the human body by the three others. The experimental data used had been measured in a previous work. The identification of the parameters was made with a routine of adjustment of curves developed to minimize the transmissibility difference between the experimental data and the result of the model for the analyzed behavior. The range of the mass, stiffness and damping used in the optimization function had been defined through anthropometric and biomechanical data. The development of a model capable to represent the biodynamic behavior of the seated human body will be useful in the development of seat vehicle, aiming to protect the health and to provide greater user's comfort.
