Ellipse declining angle and the contact angle of a cylinder type multi-DOF ultrasonic motor

It is important to generate ellipse motion on the stator driving-surface of ultrasonic motor in order to drive the motor. The characteristics of the ellipse motion affect the properties of the motor directly. The ellipse motion of the driving points for cylinder type multi-DOF ultrasonic motor and its characteristics were outlined firstly. Then the formula of the ellipse declining angle was put forward. The relation between the ellipse declining angle and the contact angle was analyzed, and the optimum contact angle was obtained. The methods of satisfying the optimum contact angle were suggested. Finally, the output properties of the motor, affected by the contact angle, were analyzed through experiments.