Methods for Characterizing the Reliability of Deployable Modules for Large Optical Reflectors

The In-Space Telescope Assembly Robotics (ISTAR) project has proposed an architecture for a large robotically-assembled telescope in space, comprised of many deployable truss modules. The truss modules are based on the Pactruss deployment scheme and are equipped with Rolamite tape spring hinges. Fabrication and assembly errors that arise from bulk manufacturing the modules may make the deployment unreliable. A simulation toolkit has been developed to characterize the deployment behavior of the module in the presence of such errors. This paper first outlines the details of the toolkit, including the truss model, the Rolamite hinge model, and the simulation methodology. It then describes the experiment designed to validate the toolkit. A module was constructed and deployed while tracking the displacements of a select node and the rotations of the Rolamite hinges. The measured shape of this module was recreated in the simulation model and the same parameters were obtained. It was found that the experimental and simulated nodal displacements matched within 10%. The experimental hinge behavior was generally captured in the simulation, with some discrepancies in the latching of one hinge. The possible causes for the discrepancies and ongoing work to improve the results are discussed in the paper.