Automatic Measurement System for Satellite Alignment

In order to improve satellite alignment efficiency, an automatic measurement system is designed, which mainly includes a two-dimensional guide rail system, a precision turntable, and an automatic theodolite assisted with a CCD camera. In this system, the theodolite can be automatically moved along the guide rail system by a motor to the theoretical position, so that its telescope optical axis can be perpendicular to the reflective surface of the optical reference on the precision equipment on the satellite. At the same time, the satellite is fixed on a precision turntable and can be turned around the table axis. Therefore, the optical surface on the satellite can be automatically collimated one by one by use of the theodolite. The yaw angle and pitch angle of each mirror normal direction relative to the theodolite coordinate are automatically recorded. Then, all mirror normal vectors can be transferred with respect to a common reference, and the angles between the normals can be calculated. Therefore, the pose matrix composed of the reference plane normals representing the device coordinate system can be obtained. In the system, in order to achieve automatic positioning of the theodolite, it is necessary to know the theoretical position of the measured equipment reference on the satellite and the initial position of the satellite relative to the guide rail. In order to achieve automatic collimation of the theodolite, a set of CCD cameras is installed on the theodolite eyepiece, which can be used to determine whether the theodolite is properly collimated. In the test, a 17-sided polygonal prism with calibration data is measured. The maximum difference between measurements and calibration data is 4.1 ″ and the stand deviation is 3.3″. The system has been employed to align the GF-2 satellite, and the assembly accuracy is guaranteed. It can satisfy the requirements of high precision and high efficiency.