Controller for ultrasonic motor

Abstract

Abstract PURPOSE:To retain the moving speed of an ultrasonic motor at an objective speed automatically by a method wherein the result of the counting of a counter is changed in accordance with a difference between the objective speed and a moving speed to set a duty ratio based on the result of the counting. CONSTITUTION:Driving signals or a signal A and a signal B are supplied to a driving circuit 16 in accordance with a control pulse CP. According to the supply of the signals A, B, an ultrasonic linear motor is accelerated gradually and a feedback signal is outputted from a linear sensor 17 io accordance with the movement of the motor. When the moving speed of the ultrasonic linear motor is smaller than the objective value, the frequency of the pulse of speed command becomes larger than the frequency of the feedback signal and, therefore, the ultrasonic linear motor is accelerated further. When the speed of the motor has arrived at the objective value, the frequency of the pulse of speed command is equalized to the frequency of the feedback signal whereby the counting result of an U/D counter 23 is kept in a constant value substantially. According to this method, the duty ratio of the control pulse CP is retained in a constant value substantially and the ultrasonic linear motor is driven in a constant speed.

Inventors

• 👤 Masayuki Tanaka
• 👤 正行 田中

Bibliographic Details