Improved sliding mode extension control of vehicle active front wheel steering based on extended state observer

Abstract

In order to improve the handling stability of electric vehicles, a new active front-wheel steering (AFS) control method was proposed. Firstly, parametric uncertainty and external interference in vehicle dynamics are summarized as a nonlinear interference term in vehicle model. An extended state observer (ESO) is designed to observe and compensate the nonlinear interference terms in real time, so as to improve the accuracy and control effect of the model. Secondly, in order to further increase the convergence speed and effectively suppress the chattering phenomenon in sliding mode control without affecting its robustness and reaching speed, an integral exponential fast terminal sliding mode controller (IEFTSMC) based on fast exponential reaching law (FERL) is designed. The problem that the control effect of some regions becomes worse when a single control algorithm is used for global region control in traditional AFS control is addressed. By combining extension theory with sliding mode control method, an improved sliding mode extension control is designed to improve the effect of AFS global control. Finally, comparative simulation tests are carried out on the CarSim/Simulink co-simulation platform. The results show that compared with the traditional FTSMC, the improved sliding mode extension control method based on ESO can not only suppress chattering more effectively, but also smoother the response curve. It also has good control effect when there is external disturbance. The effectiveness and robustness of the control strategy are verified.