Quick and Precise Position Control of Ultrasonic Motors Using Hybrid Control

Abstract

The ultrasonic motor has an excellent performance and many useful features, which electromagnetic type motors do not possess, such as high torque, low speed, compactness in size, no electromagnetic interferences and so on. Particularly, this motor has a large holding torque and a high response characteristic. So, it has been expected to use as position servomotor. The driving principle of ultrasonic motors is, however, different from those of electromagnetic type motors and its mathematical model has not been developed yet. Moreover, its speed characteristics vary with the driving conditions. Therefore, it is difficult to control ultrasonic motors with high performance. In this paper, the position control method of this motor by adaptive control is proposed. The usefulness and validity of proposed control method is examined in experiment.