Integrated Path-Following and Fault-Tolerant Control for Four-Wheel Independent-Driving Electric Vehicles

Autonomous vehicles are prone to instability when the motors of the four-wheel independent-driving electric vehicles fail at high driving speed on low-adhesion roads. To improve the vehicle tracking performance in the expected path and ensure vehicle stability when the motor fails, this paper designs an integrated path-following and passive fault-tolerant controller. The path-following controller is designed to improve the vehicle path-following performance based on model predictive control (MPC), while the passive fault-tolerant controller is used to ensure vehicle stability when the motor fails. First, a vehicle dynamic model is established and simplified, and an MPC controller based on a state-space equation is designed. Then, taking the motor fault as a fault factor, a first-order sliding mode fault-tolerant controller is developed. The first-order sliding mode fault-tolerant controller takes the vehicle's yaw rate and sideslip angle into account. Furthermore, to address the chattering problem of the traditional first-order sliding mode fault-tolerant controller, a second-order sliding mode fault-tolerant controller with a disturbance observer is developed. Finally, the developed controller is tested using the Simulink/Carsim platform and applied to a Raspberry Pi 4B for controller hardware-in-the-loop experiment. Simulation and experiment results show the practicability and effectiveness of the proposed integrated control strategy.