Speed Control of Ultrasonic Motor Based on Sliding Mode Control

Ultrasonic motor (USM) has the advantages of low speed and high torque, no interference from electromagnetic field, power off self-locking and so on. However, due to the special operating mechanism based on friction, the operating state of ultrasonic motor has obvious nonlinear characteristics. Therefore, the traditional analytical method is too complicated to construct the mathematical model of USM. In this paper, the second order model of USM is established by using system identification method based on Hammerstein model. In order to improve the speed stability of the USM, to overcome the speed fluctuations caused by temperature changes and frequency changes, the sliding mode control algorithm is applied to the design of the controller to improve the speed regulation performance and operation robustness of the USM. The control algorithm is designed based on the second-order mathematical model of the motor, and the robustness of the sliding mode control algorithm is verified by simulation. Design experiment based on DSP TMS320F28069 to observe the speed regulation performance of the proposed control algorithm. Experiments show that the algorithm has good control effect.