On-orbit calibration of star sensor based on a new lens distortion model

A new lens distortion model is built to eliminate the adverse effect of lens distortion on star sensors, and an on-orbit calibration algorithm which is based on the new model is proposed. In view of the conventional lens distortion model\´s defects, that are the conventional model doesn\´t tolerate the variation of temperature and it\´s based on the over-simplified pin-hole camera model, the new lens distortion model is built by simulating and analyzing the image data of a wide-field and large-aperture star sensor lens. There are several distortion coefficients in this new distortion model, which include the thermal coefficients that can be used to describe the effect of thermal environment\´s change on lens distortion. Afterward an on-orbit EKF algorithm is created to calibrate these distortion coefficients. And the simulation\´s results reveal that the precision of star sensor has been improved to 0.279" by this EKF algorithm, therefore the new lens distortion model and the new calibration algorithm are effective to eliminate the adverse effect of lens distortion on star sensors.