Adaptive terminal sliding mode trajectory tracking control with fixed-time prescribed performance considering rollover stability of autonomous vehicles

In the face of external disturbances, the autonomous vehicle with a high center of gravity is exposed to the risk of roll instability during trajectory tracking. To this end, this paper aims to propose a vector-extended-state-observer (VESO)-based adaptive fixed-time terminal sliding mode prescribed performance control strategy, which coordinates the front wheel steering angle and external roll moment to ensure the roll stability of the high center of gravity autonomous vehicle while improving the tracking dynamic and steady state performances. The VESO for estimating the external disturbance is designed to enhance the robustness outside the sliding mode surface, based on which the adaptive updating laws compensate the estimation errors to provide the control system's dynamic performance. A fixed-time sliding mode control with prescribed performance is proposed, which combines a fixed-time prescribed performance control method to further improve the transient performance and steady-state accuracy. The double lane-changing reference trajectory tracking conditions under different vehicle driving speeds and initial errors settings are verified by simulation in MATLAB/Simulink environment, and the results show that the proposed control strategy can ensure the rolling stability of the vehicle, can track the reference trajectory accurately and quickly, and has strong robustness.