Design of Low Speed Controller for Traveling Wave Ultrasonic Motor

Different from traditional electromagnetic motor, traveling wave ultrasonic motor (TWUSM) has the advantages of low speed, large torque, fast action response and so on. In this paper, an approximate second-order linear mathematical model which conforms to the input-output characteristics of the motor is established by non-parametric modeling identification method. Based on the model, a composite fuzzy-PI controller is designed for the motor at low speed, which makes it possible to use different control methods under different conditions. The model and controller are evaluated by simulation and experiments show that the motor reaches the speed target and achieves stable and continuous operation at low speed.