N. N. Vasilyuk. Star Tracker Error Model Taking into Account the Calibration Errors of Intrinsic Parameters of the Digital Camera

The error model of the star tracker is presented as a decomposition into fluctuation and systematic components. The fluctuation error, which arises in the calculation of the star digital image brightness center coordinates, is due to the discrete structure of the signal in the matrix photodetector. When star observations are performed through the atmosphere, the fluctuation error has an additional external component associated with the “jitter” of star images caused by atmospheric turbulence. The systematic error follows from the calibration errors of the intrinsic parameters of the digital camera. Linearized analytical expressions and covariance matrices that depend on the configuration of the observed constellation are derived for all components of the attitude error. The error model is easy to rewrite as an observation equation for the errors in estimating the camera intrinsic parameters in a tightly-coupled integrated astronavigation system. The results of the experimental verification of the proposed error model are discussed. The numerical error values obtained in the experiment make clear the need for regular calibration of the intrinsic parameters of the star tracker’s digital camera during operation.

Keywords: star tracker, error model, centroid, star jitter, distortion calibration, observation equation.

 N. N. Vasilyuk. Star Tracker Error Model Taking into Account the Calibration Errors of Intrinsic Parameters of the Digital Camera; / Gyroscopy and Navigation, 2024, Vol. 15, No.1, pp. 39-51.