New Application of Shape Memory Alloy Spring Actuator to Calibration Mechanism with Dual-function of Launch Locking and Fail-safe

摘要

Tilting calibration mechanisms have been widely used for on-board calibration of spaceborne imaging sensors. The main objective of this mechanism is to reflect the radiance temperature from the black body to the image sensor. For this, the calibration mechanism is periodically deployed to view the black-body during calibration, and stowed after calibration. Therefore, the calibration mechanism is required to implement a fail-safe function to prevent blocking of the main optical path when the mechanism stops at a certain position during on-orbit calibration. In addition, structural safety of the mechanical driving part of the mechanism under launch environment must be guaranteed. In this study, we proposed a novel application of a shape memory alloy (SMA) spring actuator as a calibration mechanism that provides the dual-function of implementing mechanical constraints on driving part of the mechanism under the launch phase in addition to implementing a fail-safe function under emergency states. The effectiveness and mission capability of the proposed mechanism were verified through functional tests using an engineering model.