In this paper, a new model called Allan variance based semi-parameter model is put forward to improve the pointing precision for alt-az telescopes. As for electro-optical tracking systems, the precision of line-of-sight (LOS) pointing is seriously influenced by both geometric and nonlinear error sources. In modeling part of the parameter model, a simplified mount model is set up to demonstrate impacts of geometric errors that are caused by imprecision during mechanical processes on LOS pointing, according to values of encoders and miss distances in charge-coupled-device (CCD) cameras. Considering the limitations of mount models, an improved hybrid model called the Allan variance based semi-parameter model is introduced to compensate for residual nonlinear errors in the calibration portion. Compared with the classical mount model, the Allan variance based semi-parameter model removes both geometric errors and nonlinear errors, and the LOS pointing precision has been remarkably improved after calibration of the proposed model.

This paper proposes a new optimized parameter model that enhances the pointing accuracy of moving-platform electro-optical telescopes (MPEOTs). The study begins by comprehensively analyzing the error sources, including the telescope and the platform navigation system. Next, a linear pointing correction model is established based on the target positioning process. To eliminate multicollinearity, stepwise regression is applied to obtain the optimized parameter model. The experimental results show that the MPEOT corrected by this model outperforms the mount model, with pointing errors of less than 50 arcsec for approximately 23 h. In the three tests conducted, the modified azimuth error(s) (RMS) were 14.07″, 12.71″, and 28.93″, and the elevation error(s) (RMS) were 12.94″, 12.73″, and 28.30″, respectively.

Pointing accuracy, as one of the important indexes to measure the performance of optical tele-scope products, is directly related to the observation quality and efficiency of the telescope, but affected by a variety of complex factors, the timeliness problem of pointing correction affects the smooth progress of the work. In this study, this paper focuses on the error modelling of optical telescope pointing system under limited observation conditions. In this paper, we first explore the changing law of each parameter and the unknown system error. On this basis, assuming that the system is in a stable state, a digital twin modelling model applied to the pointing system of an electro-optical telescope is proposed, which significantly improves the accuracy of the local pointing error correction by means of a limited observing condition: one newly captured star, and simulates and evaluates the feasibility of the twin model by using the experimental data from the external field, which provides the conditions for the evaluation of the maintenance status of the equipment.