Position Control of Robot Manipulators with Ultrasonic Motors using Pulse Width Modulation and Fuzzy Controllers.

Abstract

A traveling wave-type ultrasonic motor is one of the promising actuators for robot manipulators, since it has a simple structure, a high response, and large torque at low speed. The rotational direction of the rotor can be changed easily by reversing the direction of the traveling wave. We propose position control using a fuzzy controller and a rotational speed control method, such as pulse width modulation (PWM), by changing the duty ratio of the reverse-direction duration, which we proposed in a previous paper. The basic characteristics of the ultrasonic motor using this position control are examined experimentally. It is confirmed that exact position control of the manipulator can be achieved through an adjusting motion, such as with a pulse motor, in addition to position control using a fuzzy controller.