Numerical analyses on multi-DOF ultrasonic motor-development of analysis method and results

A multi-DOF ultrasonic motor has significant potentials for dexterous actuation. The ultrasonic motor provides multi-DOF rotation of a spherical rotor using three natural vibrations of a bar-shaped stator. In this paper, numerical analyses on the multi-DOF ultrasonic motor are conducted. First, a forward model of multi-DOF ultrasonic motor is developed considering the frictional condition between the rotor/stator. Using the forward model, driving state of the multi-DOF ultrasonic motor under arbitrary combination of vibrations is clarified. Second, an inverse model of the multi-DOF ultrasonic motor is also developed. The inverse model is constructed using experienced knowledge about ultrasonic motor and neural network technique. An appropriate input for the multi-DOF ultrasonic motor with regard to arbitrary rotational axis is estimated using the inverse model. The proposed models are available not only for our motor but for all multi-DOF ultrasonic motors