Development of Solar Paddle Actuators for Small Satellites Using Shape Memory Alloy

Abstract

We developed two solar paddle actuators for a small satellite using six shape memory alloy (SMA) springs. These actuators can orient the solar paddle alone toward the sun, and are equipped with a counterweight to compensate for the rotating motion of the small satellite in microgravity. One actuator is a prototype that was used in experiments conducted in microgravity and in vacuum. The prototype measures 100 mm in diameter and 127 mm in height, and weighs approximately 660 g including the counterweight (340 g). The counterweight is effective for compensating for the rotating motion of the small satellite in microgravity. Motion repetition experiments in vacuum were conducted to investigate the degradation properties of the SMA. We found that the prototype required the following improvements: (1) to avoid the shadow of the satellite itself, the SMA springs should be located as far from the satellite as possible, (2) offset angle and speed-up gears are required, and (3) some floating or flexible parts should be fixed so that they will not be affected by launch vibration. To this end, a modified actuator was developed. We introduce the modified actuator and show some results of motion experiments.