| Summary: | The performances of spacecraft payloads and platforms on orbit are influenced by dimensional stability of spacecraft structure. This article had researched the test method of structure thermal deformation in the vacuum thermal environment simulated on the ground to improve measurement and verification method of the space structure deformation on orbit.It presented a single-camera and multistation photogrammetric measurement scheme,based on the analysis of related test methods and typical measurement systems. Then a camera protection system and a two-dimensional motion mechanism was developed. The camera can complete the image acquisition at different stations in a arc surface through the arc shaped guide of the motion mechanism in the vacuum thermal environment,and satisfy the measurement requirement of multistation. The influence on the camera calibration due to the optical window of the camera protection system had been discussed. Besides,the effect of the scene depth,the contrast of circular feature points and scale factor on the measurement accuracy was verified by the simulation and experiment,then a multi-exposure image processing method was proposed,which selecting the best circle center extraction and recognition results from circular feature point images taken from different exposures to fusion computation,ensuring better contrast and brightness images were obtained. Finally,the structure thermal deformation measurement method in the vacuum thermal environment proposed in this article was test and verified through a typical test piece,the test results all reached a measuring accuracy of 0. 043 mm,and it proved that this method can effectively meet the needs of thermal deformation measurement for the spacecraft structure in the future.
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