Abstract
We developed the ultrasonic motor of a thin model to realize high torque and high efficiency. This motor was designed to have the appropriate shape to be driven by mixture of the two oscillation mode, the first longitudinal vibration and the second flexural vibration. The mixture of this two modes cause an ellipse vibration. We can get the driving power from the rotor, which is driven by the frictional force between the rotor and the oscillator. The main problem we had to solve, was to reduce the fluctuation of the resonance frequency caused by a disturbance. We tried to sweep the control frequency and cover the fluctuation. Thus, we established the controlling method of the motor.
