A visual navigation algorithm for landing based on 3D model of small body

A visual navigation algorithm for landing based on 3D model of small body is propoesd to address the requirements of precise landing in deep space. This approach generates reference image and calculates depth of pixels online according to the guess of lander state as well as 3D model of small body, and estimates lander pose relative to the final landing area through matching landmarks of reference image and realistic image collected from navigation camera. Then, we estimate motion of lander with sequential images by aligning pixel intensity of images between two matching events, to achieve accurate navigation for lander. The approach addresses the challenge of large different scale when lander descends from hundreds of thousands meters to meters, which results in higher landmark match rate and more precise motion estimation. In addition, pixel intensity alignment adopts global constraint of gray image, optimizing the translation and rotation between two images until the residual of intensity is minimized, which is able to overcome local minimum problem of motion estimation and improves the robustness, stability of algorithm. Finally, the simulation results show that this visual navigation method performs well and could attain requirements of high precision landing in deep space probe.