Moving Track of the Surface Particle and Torque for the Ultrasonic Motor Using the Traveling Wave in the Plane

A friction model of the ultrasonic motor using the traveling wave in the plane is proposed. The dynamic passing mechanism of the ultrasonic motor using the traveling wave in the plane is investigated, and the optimal working point for the motor is derived. Combining the efficiency and torque of the motor with the displacement along the normal direction and tangential direction of the motor stator and pre-pressure, it was suggested that the vertical displacement of the surface particles coincides with the circular motion direction of the particles in the rotator contact zone, so as to realize big torque and efficiency of the motor. Besides, it was suggested to have the ratio of the tangential displacement to the normal displacement of the stator particles as big as possible, and the optimal ratio should be determined by taking into account the pre-pressure between the stator and the rotator, so that the motor worked at a maximum stiction. Moreover, the method was verified by finite element method.