Multi-Step Predictive Position Control of Ultrasonic Motor with Nonlinear Inverse

Background: Ultrasonic motor is a typical nonlinear system with significant time-varying characteristics. In this paper, the position control of ultrasonic motor is comprehensively studied. Method: Firstly, a Hammerstein model is established to obtain the characteristic form of the motor operation, followed by the establishment of an inverse control model aiming to handle the nonlinear characteristic of the ultrasonic motor. By canceling the nonlinear component, the motor is modeled as a linear system and the controller is also designed linearly. The direct multi-step predictive control strategy is then designed and used to realize the precise position control on the basis of stable motor operation. Conclusion: The experimental results show that the proposed control algorithm has superior tracking behavior and small steady-state error when the structure or parameters of the controlled object change.