Optimal design of the stator of a three-DOF ultrasonic motor

This paper introduces an optimization design method for a three-degree of freedom (three-DOF) ultrasonic motor stator using constrained variable metric algorithm (CVMA). It is a circular cylindrical stator with a spherical rotor attached at its end. A mathematical model of the stator is established with combining the finite element method (FEM) and the optimal analysis method. Based on the model, the authors code an optimal program, which is implemented with MATLAB. The object is to optimize the characteristic length L1, and L2 of the stator in order to satisfy its vibration and contained conditions. According the optimization results, the stator is manufactured and tested. The experiments show that the stator's mode frequencies and shapes agree well with those predicted by the program. The program is easy to operate, and that is time saving.