Method for Controlling Multi-DOF Ultrasonic Motor Using Neural Network

A multi-DOF ultrasonic motor developed by the authors can generate multi-DOF rotation of a spherical rotor using three orthogonal natural vibrations of a bar-shaped stator. The ultrasonic motor is suitable for making small, lightweight and simple multi-DOF motion unit. In the present paper, a control methodology for the multi-DOF ultrasonic motor is proposed and a motion control test using the method is conducted. First, we develop an inverse model of the multi-DOF ultrasonic motor using our prior knowledge of ultrasonic motors and neural network technique in order to deal with the redundancy and non-linearity of the driving characteristics. Second, we propose a novel control method using the inverse model. Then, numerical simulation and motion control test are conducted to confirm the ability of the proposed control method. The results confirm that the rotor can be rotated around arbitrary rotational axis using the inverse model, and that the proposed control method does work successfully.