Trajectory tracking strategy for four-wheel steering vehicles based on MPC and EKF optimization
摘要
In order to achieve accurate and stable control of four-wheel steering electric vehicle under extreme conditions such as high speed and low adhesion. An adaptive model predictive control strategy considering tire force is proposed in this paper: the model predictive controller is designed based on a three degree of freedom(3DOF) dynamic model, and the yaw moment is optimally distributed by means of generalized longitudinal force and friction circle; Considering the robustness of the system, a seven degree of freedom(7DOF) model was established, and the real-time tire lateral force estimation and cornering stiffness correction were carried out by using extended kalman filter. Combining with CarSim-Simulink software platform, the simulation analysis is carried out by using frequency conversion sine, quintic polynomial and tire burst condition to study the tracking performance of the controller; in order to verify the reliability of the proposed scheme, a four-wheel independent steering (4WIS) wire controlled chassis testing platform was further constructed and trajectory tracking experiments were conducted. The results show that the lateral tracking error and the side slip angle of the center of mass are reduced by 18