Fault-Tolerant Control for 4WID/4WIS Electric Vehicles

The passive fault-tolerant approach for four-wheel independently driven and steered (4WID/4WIS) electric vehicles has been investigated in this study. An adaptive control based passive fault-tolerant controller is designed to improve vehicle safety, performance and maneuverability when an actuator fault happens. The proposed fault tolerant control method consists of the following three parts: 1) a fault detection and diagnosis (FDD) module that monitors vehicle driving condition, detects and diagnoses actuator failures with the inequality constraints; 2) a motion controller that computes the generalized forces/moments to track the desired vehicle motion using Model Predictive Control (MPC); 3) a reconfigurable control allocator that redistributes the generalized forces/moments to four wheels with equality constrained optimization. The FTC approach is based on the reconfigurable control allocation which reallocates the generalized forces/moments among healthy actuators once the actuator failures is detected. If one or more in-wheel motors lose efficacy, the FDD module diagnoses the actuator failures first. Then the reconfigurable control allocator accommodates faulty in-wheel motors and reconfigures the control allocation law of the healthy motors to achieve the desired vehicle motion to the greatest extent. Numerical simulations have been conducted to verify the proposed algorithm. It has been shown that the FTC controller prevents the fault further expands, and displays the effectiveness of the proposed fault tolerant control approaches in various driving scenarios.