Angle Tracking and Fault-Tolerant Control of Steer-by-Wire System with Dual Three-Phase Motor for Autonomous Vehicle

In order to facilitate the application of steer-by-wire system in L3 and higher-level autonomous driving vehicle and overcome the shortcomings of the dual motor steer-by-wire system, such as difficult synchronization control, high mechanical accuracy requirements, and high cost, this paper proposes a steer-by-wire execution control scheme based on dual three-phase permanent magnet synchronous motor (PMSM). Firstly, the models of the dual three-phase PMSM, the steer-by-wire system and 2DOF vehicle are established. Then, an angle tracking strategy based on load torque observer and modified sliding mode control, and a redundancy reconstruction rule for the dual three-phase PMSM faults are designed. Finally, verification was conducted through simulation and hardware in loop (HIL)test bench. Simulation and experimental results show that the proposed angle tracking control strategy has excellent dynamic performance and can effectively reduce high-frequency chattering, while the proposed fault-tolerant control strategy can effectively reduce the fluctuations of motor speed and torque under faults. Therefore, the control strategies proposed in this paper not only can meet the high-performance requirements of lateral control of autonomous vehicles, but also can meet the high-safety requirements of steer-by-wire system in high-level autonomous vehicles.