US Patent 8110967 Spherical rotary piezoelectric motor

A spherical rotary piezoelectric motor comprises a spherical rotor, a hemispherical stator, and a plurality of piezoelectric actuators. The hemispherical stator comprises an inner surface and an outer surface, wherein the inner surface forms a hemispherical hollow portion which substantially corresponds to the spherical rotor so as to contain a portion of the spherical rotor. The plurality of piezoelectric actuators is arranged on the inner surface (or the outer surface) of the hemispherical stator respectively so as to drive the hemispherical stator. The hemispherical stator generates traveling waves with a resultant elliptical motion, so the spherical rotor can be rotated accordingly with at least one degree of freedom.