针对卫星光学系统在轨工作时机上相机和星敏感器受温度影响其相互间夹角会出现变化而影响相机指向精度的问题, 利用数字摄影测量方法在试验室常温常压环境下对结构件进行了热变形测量试验。通过拍摄组合体结构件上相机和星敏器的特定表面标志点, 计算了坐标值, 拟合了光轴矢量。以相机之一为基准计算法线矢量差和不同工况下矢量差的变化, 即夹角在各工况下的变形量。试验按照试件温度状态分为4个工况、20个子工况。测量结果显示最大变形量为227.9″, 测量精度优于13.9″; 与有限元分析比对, 两者在各子工况的变化趋势一致, 均方值为30.4″。得到的结果表明, 通过用合理选择拍摄位置、剔除粗大误差以及将编码标志点作为公共点进行坐标系转换等方法, 可以提高数字摄影测量系统的测量精度, 满足卫星结构件热变形测量的需求。

As the angles among the optical systems of cameras and star sensors would be changed when a satellite worked on orbits in space environments, this paper proposed a method to measure the angles to improve the orientation precision of cameras. A thermal deformation test for the changed angles of these structures was performed under air pressures and normal temperatures. The digital photogrammetry was used to take the pictures for signed positions on the cameras and star sensors and to calculate coordinates and fit the given planes. By taking a camera as the scale, the angles and their variations were calculated in different working conditions. Results show that the maximum thermal deformation is 227.9″under 4 working conditions and 20 sub-working conditions with different temperature distributions, and the test precision is better than 13.9″. The result is very close to that of the finite element analysis, and the RMS between them is 30.4″. It suggests that the precision of digital photogrammetry could be improved by choosing proper signed positions in photos, eliminating gross errors and taking coordinate conversion with code targets. The method satisfies test requirements for thermal deformation of the satellite structures.