Abstract
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.
Highlights
Alt-az telescopes and analogous electro-optical systems are widely utilized for scientific and commercial applications such as optical communication, aerial photography and antenna stabilization.Control systems of telescopes require high-performance pointing precision to achieve accurate target acquisition; good reproducibility and less jitter are essential
Actual LOS directions and corresponding pointing errors of stars were obtained from the alt-az telescope
It was proven that the LOS pointing precision of alt-az telescopes remarkably improved after calibration, and the proposed Allan Variance based Semi-Parametric model (AVSPM) achieved higher precision than the classical mount model
Summary
Alt-az telescopes and analogous electro-optical systems are widely utilized for scientific and commercial applications such as optical communication, aerial photography and antenna stabilization. Various calibration methods were studied by many scholars to estimate and compensate for errors of alt-az telescopes in mechanical processes, which can be roughly divided into two categories. It is not easy to attribute such models to physical error sources Another method is based upon the kinematic analysis of error sources during mechanical processes, which establishes a kinematic mount model by relating pointing errors to axis positions. To improve the pointing performances of physical kinematic model, a new hybrid model is established to compensate for both geometric errors and nonlinear errors of LOS pointing completely. A physical model based on comprehensive analysis of error sources was set up to demonstrate impacts of geometric errors on LOS pointing. An improved hybrid model called Allan Variance based Semi-Parametric model (AVSPM) was proposed to compensate for residual nonlinear errors. The experiment proved that AVSPM significantly improved the LOS pointing precision of alt-az telescopes
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
