Motion analysis of a point on the stator of a wobbling type ultrasonic motor based on Euler angles

Different from the conventional electromagnetic motor, the rotor of an ultrasonic motor is driven by motion of stator, therefore, study on the motion law of the stator is the foundation of dynamic characteristics of the ultrasonic motor. Circular wobbling motion of the stator head of a wobbling type ultrasonic motor was simplified as revolution of a rigid body about a fixed point by considering the motion and structural characteristics of the stator. The motion equation of a point on the top surface of the stator was deduced by using the theories of Euler angle and coordinate conversion. Furthermore, the calculation formula of the angle between the motion surface and the top surface of the stator was obtained. The results show that the conclusion of this method is consistent with that of traditional methods. In addition, the method laid a theoretical basis for steady-state analysis and transient analysis of similar ultrasonic motors.