Spacecraft angular velocity estimation method using optical flow of stars

Abstract

Angular velocity is a crucial parameter for spacecraft navigation, which, at present, is mainly obtained by using gyroscopes. Several studies have been performed on angular velocity estimation using star sensors when data from gyroscopes are not available. Most of the previous angular velocity estimation methods using star sensors are based on information on the attitude or star vector measurements. In this paper, an angular velocity estimation method using the optical flow (OF) directly from the star images is proposed, which, unlike the previous methods, requires star coordinates in two consecutive images only. Because the procedure of star identification is eliminated, the corresponding high computation requirement is reduced. Simulations demonstrate that the proposed method has a robust performance in terms of computational cost and the number of stars in the field of view (FOV) compared with the previous methods. Finally, certain affecting factors are analyzed, including lens distortion, star senor instantaneous FOV (IFOV), star number, and accuracy of the star sensor.