Stator design of a new type of spherical piezoelectric motor.

The stator design of a new type of spherical motor driven by piezoelectric actuators is developed. A curved piezoelectric actuator is designed to attach to the spherical surface. A series of the curved piezoelectric actuators is laid in a line around a spherical surface. By applying an appropriate voltage signal with phase difference on neighboring actuators, a traveling wave is generated on the hemispherical shell. Each set of curved piezoelectric actuators is designed to provide motion with a single degree-of-freedom (DOF). With two or three sets of the piezoelectric actuators constructed to be mutually perpendicular, the motor can provide 2-DOF or 3-DOF motion. Stator design and analysis and experiment for the 1-, 2-, and 3-DOF conditions are presented in this article. Analytical calculation and experiment results of several fundamental characteristics of the stator are in good agreement. Performance evaluation of rotation speed and torque of the stator and some implementation problems are also addressed.