Structural parameter calibration method for multiple field of view star tracker

Based on rotation-invariant star-pair angular distances, a calibration algorithm was proposed to calibrate structural parameters of multiple field of view (FOV) star tracker. With the rotation relationships of each subfield of view were described by three Euler angels, the calibration scheme and objective function were generated by some starlight vectors of star pairs, which were obtained from the image coordinates and the corresponding celestial coordinates of observed star points. Levenberg-Marquardt (L-M) algorithm optimized the objective function and provided the relative Euler angles of each sub FOV. External attitude-measurement devices are not necessary, and the method can be used for on-obit and ground calibrations. Several attitudes were randomly selected to create star images used for calibration in the celestial sphere, then the inter star-angle statistical residual was chosen as an evaluation standard for accuracy calibration. The results show that this method is effective to calculate the accurate structural parameters. Under the positional noise level of 0.1 pixel, the inter star-angle statistical residual can reach 1.3 arc sec on average, and it can reach 6.4 arc sec on average when the method is used in outdoor experiments.