Optical Navigation Method Based On Shape Model During Descending Phase In Small Body Exploration

Autonomous navigation and guidance technology is the key to the mission of planetary exploration,which directly affects the precise landing of the lander and the implementation of scientific investigations on the ground.With the deepening of deep space exploration missions,traditional autonomous navigation methods have been unable to meet the accuracy requirements of planetary landing missions and subsequent patrol roaming navigation missions.Visual information can provide the absolute position and attitude information of the detectors,which improves the navigation accuracy and accuracy of planetary exploration missions.Task flexibility is of great significance.In this paper,with the background of the descending segment of the deep sky detection of small celestial bodies,the visual navigation scheme based on the fixed feature library is first designed based on the traditional visual navigation scheme,and the navigation accuracy and existing deficiencies of the image data of the "Falcon 2" mission are used.Analyzed and evaluated.Aiming at the difficulty of feature matching caused by changes in image scale and other factors during the descent of the detector,this paper studies a visual navigation scheme based on the three-dimensional model of celestial bodies.This solution replaces the traditional two-dimensional navigation map carried by the detector with the threedimensional terrain of the landing area.During the landing process of small celestial bodies,the navigation system generates online reference images based on the estimated pose of the detector and the real navigation images in the descent stage for feature extraction and matching,The difference between the posture and scale of the navigation reference image and the real navigation image is small,so the difficulty of extracting and matching navigation features can be greatly reduced.Finally,this paper takes the position and pose estimation of visual navigation as the observation measurement,designs the navigation filter to fuse state recursion information,and evaluates the accuracy of the visual navigation scheme.