Research on Analysis and Compensation of Telescope Pitch Pointing Error Based on Inclination Sensor and Beidou Differential Positioning System

The pitch pointing error of the telescope is a key factor affecting high-precision observation, characterized by non-linearity and multi-source. Existing correction methods mainly rely on long-term observation data to analyze the influence of different error sources, which limits their application in the early stage of telescope installation and calibration. To solve this problem, in this paper, a pitch pointing error analysis and compensation method based on the inclination sensor and the Beidou differential positioning system is proposed. In the analysis, the pitch pointing error of the telescope at various azimuth and pitch angles is calculated according to the actual pitch angle measured by the inclination sensor and the theoretical pitch angle provided by the encoder firstly. Then, the primary error sources are systematically analyzed and corrected. For the azimuth axis tilt, the Beidou differential positioning system is used to collect the positioning data of the telescope, and the motion trajectory is fitted using the positioning data to determine the tilt attitude. Regarding azimuth bearing defects, the spatial-domain filtering algorithm combining standard deviation thresholding with weighted average correction is employed to detect and correct the abrupt errors in the inclination sensor measurement value. Aiming for the pitch encoder zero offset, the finite element model is used to analyze the mechanical stress on the inclination sensor at different pitch angles, and the difference between sensor and encoder readings at the angle of minimum stress is used to quantify the offset value. To solve the structural gravity deformation, the inclination sensor is used to measure the pointing deviations caused by gravity under different pitch angles, and the polynomial model is used to characterize the error trend. Finally, a sinusoidal error model is designed to correct the residual error that varies with pitch angle. Experimental results demonstrate that the proposed method can effectively analyze and correct the above error sources during the installation and calibration stage, which is of great significance for improving the pitch pointing accuracy of the telescope.