A piezoelectric spherical motor with two degree-of-freedom

A novel ultrasonic spherical motor is presented in this paper. With only a single moving part (rotor), the spherical motor is capable of providing two -DOF (degree-of-freedom) motions required for micro-satellite and space rob ot actuation. The operating principle of the motor is elaborated and an ini tial prototype was fabricated and tested. The elliptical trajectories of th e rotor tip were demonstrated by making use of two MTI Fotonic 2000 displac ement probes. The feasibility of the operating principle was verified using a normal ball bearing held on to the top of the rotor, and a fast spinning of the ball-bearing occurs at resonance frequencies of 10.67, 18.9 and 29. 9 kHz, respectively. Finally, further improvement issues of the motor are b riefly discussed. (C) 2001 Elsevier Science B.V. All rights reserved.