Replicating posture control of vehicle occupants using a simplified human model

Recently, in vehicle development, the efficiency of the design process and the reduction of development costs are emphasized. Therefore, the development of a human body model that can perform analysis combining various humans and vehicles is required. In this research, we aimed to investigate the effects on posture control motion of vehicle occupants in response to forward deceleration of a vehicle. First, we used multibody dynamics to make a simplified human model consisting of three rigid body segments: head, chest, and lumbar region. Then we performed motion capture experiments to reproduce the motion of the human body when the vehicle decelerates. After this, we used a two-dimensional body model to perform numerical simulations based on the experimental results obtained by motion capture. Then, we identified the parameters for the numerical simulation and simulated the human motion. Next, we used the parameters to reproduce the experimental results. We verified the validity of the human body model by comparing postural changes in the numerical and experimental results. Finally, we conducted a numerical simulation using the identified parameters and clarified how vehicle occupants move their bodies based on the drive torque response of each body segment under different decelerations.