Actuator Fault-Tolerant Control for Four-Wheel-Drive-by-Wire Electric Vehicle

This article presents an active fault-tolerant control (FTC) approach for four-wheel drive-by-wire (4WDW) electric vehicles (EVs) with unmatched disturbance, whose purpose is to preserve stability and improve the tracking performance under actuator fault. The proposed scheme is divided into four steps. First of all, an unmatched nonlinear disturbance observer (NDOB) is established based on the 4WDW EV model to estimate the equal disturbance and compensate for the modeling error. Then, a state tracker with estimated unmatched nonlinear disturbance is designed. Followed by the design of a novel adaptive sliding mode fault-tolerant control (ASM-FTC) strategy based on NDOB. Finally, control efforts allocate according to the degree of motor failure. On the one hand, controller parameters are capable of self-adaptively reconfiguring such that a faster convergence can be realized. On the other hand, better tracking performance is guaranteed with the application of estimated disturbance information in the control law. Hardware-in-the-loop (HIL) simulation results illustrate the validity of the proposed method in various driving scenarios.