Path tracking control for 4WISV based on kinematic inversion and improved LADRC

Taking the strong coupling characteristic between 4WISV’s lateral and yaw motion and the time-delay characteristic of the steering system into consideration can greatly improve the path-tracking accuracy of the Four-Wheel-Independent-Steering Vehicle (4WISV). However, most conventional control methods failed to fully analyze the kinematic relationship between path points and the vehicle and neglected the effect of the steering time-delay characteristic, which limits the improvement of 4WISV’s path-tracking accuracy. This article designs a kind of hierarchical path-tracking strategy (HPTS) and proposes the steering discrete time-delay model with the relaxation factor to solve the problems above. Specifically, the HPTS includes the tracking-motion control layer and the actuator regulating layer. The first layer introduces “kinematic inversion” in mechanics into path-tracking modeling to solve the desired motion commands by using the MPC controller. The second layer, considering the ramp convergence time-delay characteristic of the steering motor, is proposed to follow the motion commands from the first layer by using the improved LADRC controller. Ultimately, the real-time performance and the effectiveness of the HPTS are verified by the simulation and experimental platform. The results show that the HPTS proposed can improve 4WISV’s path-tracking accuracy (the lateral deviation reduced by 28.5% at least) while ensuring driving stability.