Spacecraft Attitude Determination And Its Semi-physical Simulation Technology Research

Star sensor is a kind of high-precision attitude sensor, which gain attitude information by observing stars, it can obtain higher precision attitude information of spacecraft in inertial coordinate system, providing exterior azimuth elements for three-dimensional mapping without ground control points. Spacecraft attitude determination semi-physical simulation system can offer the basic platform for research on space attitude independently determination technology based on star sensor. This paper outspread closely around the main line that build the spacecraft attitude determination semi-physical simulation system to, technologies involved in spacecraft attitude determination semi-physical simulation system was depthly studied. The main work and innovations of the thesis are listed as follows:1. Making full use of the parallel computing characteristics ,high-precision floating-point computing power and other features of GPU, designed and implemented a rapid simulation method of the star map, which can real-time accurately calculate the position of each star, taking proper motions into account, this method can rapidly simulate the star maps used all star table including more than 200 million stars data information , can meet the large field, wide range of star magnitude, short sampling period and other requirements.2. Ly operator used in the photogrammetric was used to determine center of mass of star maps and considering the characteristics of star maps, Ly operator was improved by traditional centroid algorithm. The result of final experiments show that the centroid algorithm for star image based on improved Ly operator is better than other methods in the instance of low SNR and big star image. Compared with traditional centroid algorithm, the rate is faster, fixed position accuracy is more precise, and noise restraining ability is stronger. Compared with centroid algorithm with threshold, when fixed position accuracy is same, the rate is faster.3. Compared a large number of star pattern recognition methods, the voting method of star pattern recognition was depthly studied, based on this method of voting, the most critical navigation star database search method was improved by the mapping table mechanism. Finally, The result of final experiments validated many advantages of the voting method and the improved voting method; also introduced the basic idea of QUEST algorithm which is most popular, and validated the method by experiments.4. Worked over the work principium of the whole semi-physical simulation system, and detailedly designed each module, finally built the spacecraft attitude determination semi-physical simulation system, calibrated the system ,gived the general experimental program, completed the static-state and dynamic experiments. the system can offer the basic platform for research on space attitude independently determination technology based on star sensor. The platform can service for a variety of purposes, such as verification of three-dimensional mapping project without ground control points, validation of the accuracy of star simulation maps, camera calibration, validation of attitude determination program and so on.