Position control of robot manipulators with ultrasonic motors using pulse width modulation

This paper proposes position control of robot manipulators using ultrasonic motors under a fuzzy controller and a rotational speed control method, such as pulse width modulation (PWM), by changing the duty ratio of the forward direction duration, which we proposed in a previous paper. From the experiments, it was confirmed that exact position control of the manipulator was achieved through an adjusting motion, such as with a pulse motor, besides the position control using a fuzzy controller for instance. The ultrasonic motor is hardly affected by the friction in the position control since the rotor can approach a desired position with the jitters by PWM.