Research on a cryogenic micro-displacement piezoelectric actuator for the radio telescope panels

Based on the merits of ultrasonic motors, a micro-displacement actuator driven by an ultrasonic motor for the radio telescope panels is presented. The whole system includes mechanical structure and motion control unit. In the mechanical structure, the traveling wave rotary ultrasonic motor is used to drive the actuator. The transmission part adopts a differential thread shaft to converts the rotational displacement of the motor into the linear micro-displacement of the driving end and improve the accuracy of micro-displacement. The whole structure is sealed with metal foils so that no humid air could come into the structure inside. The core of the motion control is the DSP and ultrasonic motor driving circuit. Environmental simulation experiments are carried out and the results show that the stepping precision of the actuator can reach 1μm at both room temperature and minus 40 degrees Celsius. The prototype shows good characteristics when working in humid air and under low temperature. The presented actuator can work properly in the environment of Antarctic.