Robust angle regulation for ultrasonic motor using CLF-based controller

This paper describes a robust controller for a constant angle regulation problem of a travelling wave ultrasonic motor. Generally, control problems of ultrasonic motors are difficult because the motors have various nonlinearities. Further, construction problems of physical models of ultrasonic motros are also difficult. In this paper, we propose an approximate model of the travelling wave ultrasonic motor taking the nonlinearities into consideration. Then, we design a CLF (control Lyapunov function) based controller, which has robustnesses for modeling errors and friction forces. Finally, by experiments, we show that our control model is useful for constant angle regulation problems of the ultrasonic motor.