Adaptive Control of PMSM Servo System for Steering-by-Wire System With Disturbances Observation

Intelligent driving system requires more precise and reliable steering control, and steering-by-wire (SBW) technology can better adapt to the development of autonomous driving. The permanent magnet synchronous motor (PMSM) servo system is the actuator of the SBW. Aiming at the uncertainties of the PMSM servo system, a new adaptive control method for the PMSM servo system is proposed. Parameter adaptive laws are designed for each slowly varying parameter and unknown parameter, and robust terms are introduced to the adaptive laws for the parameter uncertainties. The convergence speed of the parameter adaptive law proposed can be improved by adjusting the parameters related to the convergence rate. To reduce the scope of disturbance uncertainties, the steering load disturbances are divided into a bounded unknown time-varying part and a predictable time-varying disturbance. Based on the Luenberger observer, the prediction term of the load torque is estimated by the current of PMSM in real time. By introducing boundary estimation and robust term of unknown disturbance into the control law and parameter adaptive law, respectively, the uncertainties of parameters and unknown external disturbance can be compensated. Simulation and hardware-in-the-loop tests are carried out on the SBW platform. Experiments show that the control strategy of the PMSM servo system designed in this article has good tracking accuracy and stability.