Gore/Seam Cable Actuated Shape Control of Inflated Precision Gossamer Reflectors - Assessment Study

This investigation explores the feasibility of utilizing an active gore/seam cable based control system to reduce global RMS figure errors due to thermal loading and inflation effects (W-error) in large gossamer inflatable membrane reflectors. Analysis is performed on an inflated spherical membrane with PVDF actuated radial cables, where the cable lengths and attachment points are designed via a Genetic Algorithm optimization. It is found that through proper tailoring of cable lengths and attachment points, significant global RMS figure error reduction is achieved. Specifically, RMS errors due to on-orbit thermal loading were reduced by approximately 75% with a 104 cable active gore/seam cable control system which has a mass equal to 15% the original reflector. Similarly, W-errors were be reduced by approximately 95% with a 104 cable active gore/seam cable control system with a mass ratio of 12%. Finally, to deal with simultaneous W-error and thermal loading conditions, a hybrid gore/seam cable control configuration based on a combination of the optimized thermal and W-error cable patterns is considered. Due to the relatively lightweight designs and shape control effectiveness, the gore/seam cable based shape control concept seems promising for future gossamer reflector applications.

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