A High-Precision Dynamic Six Degree-of-Freedom Pose Measurement of the Subreflectors of Large Antennas Based on a Position Sensitive Detector and Laser Array

Abstract

Subreflector misalignment of a large steerable radio telescope induces a pointing error and reduces the gain of the antenna system. To improve the antenna’s operational efficiency, it is necessary to measure and adjust the position and attitude of the subreflector in real time. In this paper, a method based on a position sensitive detector (PSD) and laser array without an optical system is proposed to measure the six degree-of-freedom (DOF) poses of the subreflector. The laser emitted by the laser module array ensures that the PSD can be covered as it moves with the subreflector, and the PSD can obtain more than three laser beams. These ensure the measurement of all attitude changes of a large-aperture antenna subreflector. The two-dimensional coordinates of the centroids of three laser spots are extracted using the PSD, and then the bursa model is established to complete the coordinate transformation. Finally, the 6-DOF attitude information of the antenna subreflector is obtained. The results of a 6.05 m measurement simulation show that it can obtain high 6-DOF PSD attitude information. The experimental results show that the 6-DOF position and attitude information of the subreflector at a distance of 5.78 m can be obtained within seconds. Moreover, the error of the translation is within 0.014 mm and the error of the rotation is within 0.37^°. This method can meet the pose measurement requirements of the subreflector.