METHOD FOR DRIVING ULTRASONIC MOTOR, ULTRASONIC MOTOR, AND ROBOT ARM

摘要

A method for driving an ultrasonic motor includes setting an upper limit rotation speed that is lower than a rotation speed at a resonance frequency at a lowest temperature of a predetermined operating temperature range and a lower limit frequency that is more than or equal to a resonance frequency at a highest temperature of the operating temperature range, and, when the ultrasonic motor starts, a rotation speed of the ultrasonic motor becomes lower than the upper limit rotation speed and the ultrasonic motor is driven with a driving frequency which is higher than the lower limit frequency.