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 the bending vibration and longitudinal vibration of the stator, which is designed using the finite element analysis. From the simulated driving characteristics, a control method for the ultrasonic motor is proposed. Following this, the driving characteristics of the motor under both open-loop and closed-loop controls were measured experimentally. The multi-DOF position control of the rotor was achieved successfully using the proposed control method.