Uncoupled spatial biodynamic model for seated humans exposed to vibration-development and validation

Abstract

Human body is sensitive to whole body vibration and ride discomfort due to vibration has brought lots of concerns in recent years due to requirement of better ride comfort performance for newly developed vehicles. Vehicle ride discomfort has a direct effect on driver's performance and will result in overall customer satisfaction. This paper presents an uncoupled spatial seated human multi-body dynamic model with 48 degrees of freedom based on Chinese occupants' characteristic to evaluate vehicle ride discomfort. The model is composed of feet, legs, thighs, trunk, head, and neck and it includes the uncoupled longitudinal, lateral and vertical translational motions and pitch, roll and yaw rotational motions for whole body vibration. Based on the vibration transmissibility from the seat to head as the evaluation index of human dynamic response, the low-frequency three directional vibration test of human body is carried out with eight subjects. The acceleration responses of human head are recorded and then the seat to head vibration transmissibility is obtained. The genetic algorithm (GA) is implemented to identify the parameters for the uncoupled spatial biodynamic model and the objective function is defined by minimizing the square sum of the difference between the test value and the simulation value of the vibration transmissibility from the seat to head. The goodness of fit is used as the index to evaluate the effect of model. The results show that the model can well capture the seat to head vibration transmissibility response for whole body vibration. The uncoupled spatial biodynamic model can be used to guide the design of better ride comfort vehicles.