In-space Shape Measurement of Large Planar Structures

A measurement and integration scheme is proposed to estimate the shape of a large planar structure in space. Lightweight sun sensors distributed on the structure measure the local angles relative to the sun. A reconstruction technique is introduced to estimate the shape of the satellite through a decomposition on a function basis. The estimated shape is determined by the coefficients associated with the basis functions which are calculated from the measurements. A trade-off study to analyze the influence of different reconstruction schemes and the position of the sensors is presented. An optimization scheme minimizes the RMS error between the estimated and true shape. An experiment was conducted to show the feasibility and performance of the proposed system at the lab scale. Finally, a simulation of the accuracy of the presented solution on a 60 m space solar power module is performed. The expected error is 0.7 mm RMS using sensors every 30 cm.