Proposal of Space-use SMA Actuator System Model and Primary Experiments

Abstract

This study aims at improving the actuator which has hold-down and releases mechanism using Shape Memory Alloy (SMA). The SMA actuator, which is discussed in this study, consists of an SMA tube, a restraint, and a heater. These kinds of actuators can achieve high power density; however, their force generation trajectories are affected by the environmental temperature variation because of their huge heat capacity. This paper discusses the method to track the required force trajectories for drive timing improvement. First, previous studies are introduced. Then, this paper points out the problems in previous research and describes the details of the modeling to improve simulation accuracy. The hysteresis model of SMA is introduced and the system identification method used in this study is shown. Finally, the experiment is performed to identify the hysteresis characteristics of SMA. The result was consistent with the trend of the detailed model. Moreover, the constraints for the system identification were derived from the experiment results.