Joint Estimation of Stellar Atmospheric Refraction and Star Tracker Attitude

A star tracker operating inside the atmosphere requires stellar atmospheric refraction (SAR) correction with rapidness, autonomy, and accuracy to promote its attitude determination. To meet this demand, a joint estimation of the SAR and star tracker attitude (STA) is proposed in this article. An SAR model involving the equivalent refractive coefficient (ERC) and the true zenith distances (TZDs) of stars is established. A reprojection error feedback (REF) iteration is proposed to implement the joint estimation of the SAR and STA. Different from existing correction methods, the proposed method avoids the limitations of theoretical atmospheric models and the corresponding empirical formulas. The REF mechanism guarantees the sensitivity and rapidness of the joint estimation. Experimental results show that the SAR correction of a single measurement can converge in only a few loops, and the results are consistent with the established model. The average reprojection error (ARE) of continuous measurements in different groups with SAR correction decreases by 80.06%, which is significantly improved compared to the traditional method and demonstrates the efficiency of the proposed method.