Adjustable Compliant Motion of Ultrasonic Motor
Atsuo Kato*, Koji Ito**, and Masami Ito***
*Department of Electronic Engineering, Aichi Institute of Technology, 1247 Yagusa-cho, Toyota, 470-03 Japan
**Department of Information and Computer Sciences, Toyohashi University of Technology, Toyohashi, 441 Japan
***Department of Information Engineering, Nagoya University, Nagoya, 464-01 Japan
As actuators for a prosthetic arm, we used traveling wave ultrasonic motors. The arm must move in compliance with the environmental force around every joint of it as in the human arm. In order to realize the compliant arm, it is desired that the actuator have an adjustable compliance and damping characteristics without interaction force control. However, the traveling wave ultrasonic motors have no compliant characteristic in itself. Then, we developed an adjustable compliance and damping system. for the motor. The system was realized by a phase difference control loop of two-phase driving signals of the motor within the PD control loop of the shaft angle. This system acts much like an adjustable spring with an adjustable damper.