Influence of tire inflation pressure on vehicle dynamics and compensation control on FWID electric vehicles

This paper presents a comprehensive study revealing the influences of tire pressure variations and their distribution among four tires on vehicle dynamics performance and driver's steering workload for a four wheel independent drive electric vehicle (FWID EV). Then a direct yaw-moment control (DYC) strategy employing an unbiased adaptive model predictive control (MPC) algorithm is proposed to compensate for the influences. An unbiased estimation strategy is developed to update the time-variant prediction model for the adaptive MPC system. An extended magic formula (MF) tire model and a modified Unitire model involving tire inflation pressure are employed to describe the tire longitudinal and lateral forces, respectively. Various tire pressure variations are simulated in CarSim to exhibit the influences of tire inflation pressure, including all four tires at same and different pressures. The unbiased estimation results and compensation effects of the DYC strategy are also verified through simulations. A vehicle dynamics and lateral motion stability index, and driver's steering workload are proposed to quantify the influence of tire pressure variations and distributions. Analyses on the simulation results indicate that: pressure reduction on a front tire and rear tire induces a large steering angle and a large vehicle sideslip angle, respectively; all-tire inflation pressure decrease will increase driver's steering workload. The proposed DYC strategy can achieve satisfactory compensation effects through significantly decreasing the vehicle sideslip angle, steering wheel angle and reducing driver's steering workload by up to 90%.