Optimal design on stator of multi-DOF ultrasonic motor

We have developed a multi-DOF ultrasonic motor with a cylinder-shaped stator and a spherical rotor. The motor provides multi-DOF rotation around x, y, and z-axes, which are implemented by two-second order bending modes with orthogonality and first order longitudinal mode of the stator. This paper put forward an optimal design method on the stator. Based on the method, an optimization program is developed in MATLAB environment. From the program, the authors designed and implemented a new prototype multi-DOF ultrasonic motor and its stator with diameter 20 mm, height 67 mm, and mass 157 g. The experimental results show that the stator's modal frequencies and mode shapes measured are consistent with the results obtained by the optimal design program that saves a lot of time.