Path Tracking and Direct Yaw Moment Integrated Control for Autonomous Vehicles with Steer-by-Wire Based on LMI and Terminal Sliding Mode

This paper proposes a path-tracking and direct yaw moment integrated control strategy based on linear matrix inequality (LMI) and terminal sliding mode for autonomous distributed drive electric vehicles (A-DDEVs) equipped with a steer-by-wire (SBW) system. This strategy effectively attenuates the effects of external disturbances and parameter uncertainties on path tracking, thereby enhancing vehicle safety. The control-oriented vehicle model accounts for roll effects, with the system state matrix incorporating mismatched norm bounded uncertainties. Firstly, for overall vehicle motion control, an LMI-based integral sliding mode controller (ISMC) is designed to generate desired front wheel steering angle and additional yaw moment. This aims to converge path-tracking errors and ensure vehicle stability. A sufficient condition for the existence of a sliding surface ensuring asymptotic stability of the sliding mode dynamics is provided, along with a demonstration of the attainability of the ISMC. Secondly, for the steer-by-wire steering system, a front wheel steering angle tracking controller has been designed based on the nonsingular terminal sliding mode control method. It is proven that the tracking error of the closed-loop system converges to the sliding surface in finite time and converges along the sliding surface to the origin. Additionally, a torque vector controller based on constrained optimization method is designed to allocate longitudinal driving forces and additional yaw moments. Finally, the effectiveness of the control strategy is validated through high-fidelity Carsim-Matlab simulations. Results demonstrate that the proposed control strategy robustly ensures the accuracy of vehicle path tracking and yaw stability. The results indicate that the proposed control strategy has excellent performance in improving the vehicle path-tracking accuracy and ensuring the vehicle stability.