The Technology Of Optical Autonomous Navigation And Visualization In Small Celestial Bodies Exploration

With the implementation of Moon, Mars and small celestial bodies (such as asteroid and comet) exploration, Deep space exploration becomes the hotspot and significant filed of the development for spaceflight technology in the 21st century. Spacecraft autonomous navigation technology is a regarded key technology in the deep exploration fields. The Visualization technology plays an important role in designation and demonstration for the missions of deep Space exploration. With the supports of 863 Program, this dissertation detailed analyzes the autonomous optical navigation and visualization of the small celestial bodies exploration. The main work and innovations are listed as follows:1. An autonomous navigation system scheme for small celestial bodies exploration is proposed based on the theory of photogrammetry and the technology of image processing(1) Based upon the detailed analysis on characteristics of navigation during small celestial body approaching phase, an autonomous navigation system scheme based on the theory of optical measurement is designed. Several visual small features on the surface of small celestial body are extracted from the images taken by the navigation camera, which are also tracked robustly and accurately. The distance from probe to those navigation targets are measured using the laser range finder. And then the navigation parameters are computed on board.(2) An investigation is made on the extraction and tracking method of targets on board on the basis of navigation image processing, technology. The content and flow of navigation image processing is expatiated systemically. An algorithm for on board extraction of navigation targets is put forward based on image decomposition and local gray variance. The tracking of navigation targets is realized by the technology of image matching.(3) The optical measure principle of navigation parameters is founded. The method and process on computation of navigation parameters are investigated according to the observation of navigation camera and laser range finder. Comparisons and discussions on measuring algorithms for relative position and attitude between the probe and the small celestial body are brought forward. The computation method of Impactor Targeting Vector (ITV) in the different phases of navigation is proposed. The precision of our autonomous navigation system scheme and influencing factors are analyzed.2. The main contents and key technologies on the visualization of small celestial body exploration are investigated with the background of small celestial body approaching and impacting.(1) A method of space objects modeling and visualization is put forward based on the graphics hardware. Aiming at the characteristics of graphics hardware, an index mechanism is introduced to optimize the data structure of space objects, which can facilitate the redundant management effectively and improve the .efficiency of visualization dramatically. Real-time rendering of complex space objects is carried out based on the proposed method.(2) The impact result between small celestial body and the impactor probe is simulated vividly by making use of particle system technology. According to the characteristics of multiple passages of GPU, Anew realization of particle system is proposed based on the GPGPU(General-Purpose Computing on Graphics Hardware), which is probable to increase a numerous of particles in the real-time simulation to enhance the reality of the scene. The particle system based on GPU has a great ability in real-time simulation than the ordinary particle systems.(3) By integrating the proposed algorithms, the whole course of small celestial body approaching and impact is simulated visually.