Accuracy Improving Deformation Measurement System for Large Components in Thermal Vacuum Using Close-Range Photogrammetry

摘要

The structure deformation of the spacecraft due to the variation of temperature in space has a significant effect on the performance and stability of the spacecraft. Therefore, a system with high accuracy to identify the deformation is proposed in this study for large components in thermal vacuum using close-range photogrammetry. A novel thermal vacuum deformation measurement platform is firstly presented to provide a space simulation chamber in where not only temperature of specimen are available from - 170 to + 140 degrees C, but also coordinates of measurement points of component can be efficiently measured by using close-photogrammetry. In addition, an improved deformation computation method based on coordinate optimization registration is proposed. In this method, through combining random sample consensus with singular value decomposition, partial global points whose variations are relatively small can be selected for coordinate registration. Finally, the deformation measurement for the main reflector of a Cassegrain antenna in thermal vacuum is selected as an example to validate the effectiveness of the proposed platform and method. The experimental results show that the platform and method are practical and will provide a foundation for further applications.