Ride Comfort Analysis of Seated Occupants Based on an Integrated Vehicle-Human Dynamic Model

Low-frequency vibration caused by road roughness while driving is transmitted to the human body through tires, suspension, and seats. Prolonged exposure of the human body to the vibratory environment will have an impact on ride comfort or even health issues. In order to investigate the vibration response of various segments of occupants while driving, a 15-DOF multi-body dynamic model depicting the shanks with feet, thighs, pelvis, torso with arms, and the head of occupants is established in the two-dimensional sagittal plane, which considers the contact between the occupant and the cushion, backrest headrest, and the vehicle floor simultaneously. The biodynamic parameters are obtained by fitting the published vibration experimental data based on an optimization algorithm. The previously proposed half-car model is incorporated into the human model to construct an integrated vehicle-human model for further ride comfort analysis. The bump road and the random road are respectively adopted as the displacement excitation of the model to simulate the vibration response of each segment of occupants. The contact stiffness and damping between the human body and seats are modified and a sensitivity analysis is performed to explore the influence of various seat parameters on ride comfort. By changing the speed of the vehicle, we investigate the discrepancies in ride comfort on a given road at different speeds. This study reveals the vibration characteristics of seated occupants, vehicles, and the integrated vehicle-human system, based on which a method for evaluating the ride comfort of occupants is established.