Abstract: Aiming to address the problem of shape center and optical center extraction of small bodies in deep space autonomous optical navigation, the concept of asteroid irregularity degree (AID) is proposed and defined in this paper. The AID is an index for evaluating the irregularity in shape and luminance of small bodies and can be used as the selection criteria for centroid extraction algorithms. The criteria for selecting centroid extraction algorithms based on AID are proposed. Furthermore, for asteroids with a large AID, an algorithm for extracting the shape center of irregular asteroids based on minimum enclosing graphics (MEG) is proposed. The selection method and centroid extraction algorithm based on AID are simulated, and the results demonstrate that selection criteria can effectively identify the most suitable algorithm for achieving high precision centroid extraction of asteroids. In addition, the MEG algorithm improves the precision of centroid extraction for irregularly shaped asteroids. As a result, the estimation accuracy of navigation system can be improved.

Key words: Asteroid irregularity degree, Centroid extraction; Optical navigation, Image processing