Piezoelectric motor for cryogenic applications

Expanding the capabilities that are used in the NASA's exploration of planetary bodies in our solar system would require mechanisms and actuators that can operate at cryogenic temperatures (-240 degrees C to -60 degrees C) in dusty environments. These applications include the exploration of lunar surface environments with temperatures that are below -100 degrees C. For this purpose, the authors are working on developing piezoelectric motors capable of operating at such extreme conditions. Novel piezoelectric motors were conceived and are being investigated to enable precision deployment and motion mechanisms that can be used for potential actuation of antennas and solar arrays, lower power robot arms, and percussive drills. This motor technology is intended to be integrated in a testbed developed at NASA to demonstrate its capabilities once it has been characterized at room temperature. These motors are being developed as game changers for enabling rotational drive mechanisms (rovers, robots, gimbals, drills, etc.) in extremely cold and dusty environments. These drive systems will be operated without the use of heaters or atmospheric control chambers (which eliminates grease lubrication) to raise the actuator's temperature. Further, these motors will enable actuation of very high precision mechanisms having lower power motion without gears or gear lubrication, backlash, or power consumption to hold position. These actuators contain piezoelectrically-excited fixtures that are vibrated out of phase such that they sequentially push the rotor to produce continuous rotation. A proof-of-concept linear actuator that uses fixtures with flexure-preloaded piezoelectric stacks and operates in an inch-worm configuration at low frequency has been developed and demonstrated. Further, a proof-ofconcept rotary actuator is currently being developed that uses a V-shaped piezoelectric fixture driven in resonance that generates an elliptical motion at the horn tip to drive a rotor. In this paper, the latest progress will be presented.