Model-based control for ultrasonic motors

A complete model-based control for traveling-wave-type ultrasonic motors is presented. The control scheme consists of inner control loops with respect to the oscillation systems, offering all meaningful degrees of freedom for adjusting the traveling bending wave, and outer control loops for torque and speed. After a brief review on modeling the actuator and presentation of a parameter identification method, the control scheme is developed and verified by measurements on a prototype drive system, several measures for the compensation of nonlinearities and temperature effects are developed, and achieved improvements are discussed with respect to the special properties of this novel actuator. Finally, the developed drive is applied to an "active control stick".