Adaptive fault-tolerant control based on linear matrix inequalities for actuator failures in steer-by-wire system

Aiming at the vehicle stability and safety problems caused by the actuator failure of Steer-By-Wire (SBW) system, a two-layer control strategy combining the Performance-Preserving Robust Control (PPRC) and Adaptive Fault-Tolerant Control (AFTC) using the Linear Matrix Inequality (LMI) processing is proposed. The PPRC of the SBW system by tracking the ideal reference model is the first layer of control, the vehicle is robust to speed and low failure rate defects of the SBW system actuator within the performance range of the SBW system, and the side slip angle (beta) and yaw rate (omega) of the vehicle can approach optimal values; The second layer of control: AFTC is added to the above PPRC based on the online estimation of the final failure, when a high failure rate failure in the actuator of the SBW system occurs and the performance limit of the PPRC is exceeded, this allows the vehicle state in the high failure rate failure mode of the actuator to still track the specified ideal reference state. Compared with the traditional Fault-Tolerant Control (FTC) that requires Fault Detection and Isolation (FDI), the control method used in this paper does not require accurate fault information, but only uses the system state change generated by the fault as the information to automatically adjust the control input, which can still achieve the purpose of stabilizing the whole SBW system when the actuator fails.