Design and control of an ultrasonic motor capable of generating multi-DOF motion

A multi-degree-of-freedom (DOF) ultrasonic motor consisting of a bar-shaped stator and a spherical rotor was developed. It can generate 3-DOF rotation of the rotor around perpendicular axes using bending vibrations and a longitudinal vibration of the stator, which was designed using finite element analysis. From the simulated driving characteristics, a control method for the ultrasonic motor was proposed. Following this, the driving characteristics of the motor under open-loop control and closed-loop control were measured experimentally. Mufti-DOF position control of the rotor was achieved successfully using the proposed control method.