Planet centroid extraction algorithm for approach phase with sub-pixel accuracy based on DSP

In this paper, a high-precision centroid extraction algorithm based on DSP for the planet approach phase is proposed. For the long-distance approach, the target is a light spot, and a sub-pixel centroid extraction method is proposed. The region centroid extraction method is used to achieve preliminary centroid extraction, and a sub-pixel correction method is performed based on gray value and image gradient to obtain a more accurate centroid position. For short-distance approach, the target is a two-dimensional projection graphic. An ellipse fitting method based on pseudo-edge removal is proposed to realize centroid extraction. To verify the feasibility and effectiveness of the proposed algorithm, this paper takes Mars as an example to perform a semi-physical simulation. The results illustrate that the preliminary extraction accuracy of the light spot is improved by about 40%, proving the effectiveness of the proposed sub-pixel correction algorithm. The Mars centroid extraction accuracy for proximity is better than 0.7 pixels, meeting the accuracy requirements for autonomous navigation information extraction for the approach phase of deep space exploration.