METHOD OF CONTROLLING ULTRASONIC BRAKE MOTOR

摘要

PURPOSE:To control brake force by varying the amplitude of elastic traveling wave for exciting a vibration body thereby varying the frictional force between a moving body and the vibration body. CONSTITUTION:The rotary shaft 17 of a motor 16 is coupled through a coupler 22 with the rotary shaft 19 of an ultrasonic motor. The amplitude of elastic traveling wave for exciting a vibration body is varied by varying at least one amplitude of two drive voltages to be applied onto a piezoelectric body 21, by varying the phase difference between two voltages from a set value or by varying the frequencies of two voltages. Rotary direction of the motor 16 is detected through a rotary direction detection circuit 24 and the brake force is controlled accurately over a wide range through a controlling circuit 23 for varying the rotary direction of the moving body based on the phase difference between two voltages.