IRESA - Intelligent Redundant Spacecraft Actuator, Generation II

The main objective of the IRESA-project is the development and production of an actuator for space applications that is based on the shape memory technology. Apparent advantages, like a high force-to-mass-ratio, a compact design as well as a low power consumption predestine it for the usage in small satellites. Both generations of IRESA are designed to serve as drives for one-unit cubesats. A translational and a rotational output movement ensure a use in hold-down and release mechanisms as well as pointing and tracking applications. Thus, it is possible to adjust and hold antennas or solar arrays in accordance with the position of the satellite. The modular construction allows a rather simple assembly and testing and additionally enables a possible use in terrestrial scenarios. Beside the installation of exclusively space-compliant materials, IRESA is equipped with one redundant shape memory wire. During the usual operation only one of both wires is activated. After a potential failure, the second element comes into action and guarantees an ongoing service. In this paper the design and the test results of the second generation are presented. While in the first one the conversion of the translational output into a rotation was realized by a cam disk, the second generation uses a rack in combination with a pinion. The test results prove a more stable and reliable functionality in the second generation. Combined with comprehensive data analysis, the paper concludes with a comparison of both generations as well as tasks for a future improvement.