Abstract:In order to improve dynamical properties of the inwheel motor drive vehicle, a direct yawmoment control strategy with a hierarchical model was proposed. The upper layer of the strategy combined the feedforward control with the feedback control for motion tracking. More specifically, a feedforward controller based on wheel angle was designed to adjust the steadystate gain of yaw rate. Besides, the sliding mode condition integral controller was designed for feedback control, so that the yaw rate can track its expected value. The lower layer focused on the torque optimal distribution. According to the stability priority principle, the optimization function aiming at reducing the tire load rate of the vehicle was established, and the issue of torque optimal allocation was transformed into a quadratic programming problem to be solved. Based on a prototype of the 8×8 inwheel motor drive armored vehicle, a series of experiments were conducted. The experimental results showed that the proposed strategy can reduce the maximum error of yaw rate to less than 6% and 9% of the ideal yaw rate under continuous steering and double lane shifting conditions, respectively. Additionally, the proposed strategy was capable of achieving the decrease in tire load rate and the differential torque distribution of each inwheel motor. Thus the control effect was able to satisfy the requirements of continuous steering on high adhesion road and double shifting on low adhesion road. In conclusion, the proposed direct yaw moment control strategy with a hierarchical model was feasible to be applied to inwheel motor drive vehicles, and it can effectively improve the tracking ability and handling stability of the vehicle under various driving conditions.