Research On Fine Guidance Sensor Attitude Determination Technology For Space Telescope

To get high quality astronomy images,the light of sight must be keep stable in long time when the space telescope takes deep space exploration.As the space telescope is affected by many outside disturbance all the time,designing the high stability and precision image stabilization system is needed.As a key part of large aperture space telescope,fine guidance sensor provides high precision attitude measurement information to keep light of sight stable.It detects light of sight's error to output relative attitude information,which forms detection unit of precision image stabilization control system.And with star identification and attitude determination,it outputs high precision absolute attitude to ensure the attitude control system of space telescope work normally.Based on this background for exploratory study and feasibility verification in advance,investigating challenges in developing fine guidance sensor for the precision image stabilization system in our country's space telescope.Put emphasis on long focal length and small field of view and the magnitude within 10 to 14,study fast attitude determination technology with more star points,and research on how to get high accuracy attitude with level in arcsecond.In the paper,deep study about research status and development history is made on fine guidance sensor of space telescope at home and aboard,and much concern on development history of high accuracy and high rate attitude determination technology.The main technical specifications of fine guidance sensor and difficulties need to be overcome are analyzed.The basic system structure and research plan are made.According to the requirements of fine guidance sensor attitude determination,star identification algorithms are studied,and new fast identification algorithm is proposed with long focal length and small field of view.After simulated and compared the traditional attitude determination technology,the improved algorithm is proposed that is useful for fine guidance sensor.Combined with Cubature Kalman filter with excellent performance,two improved algorithms are proposed based on it.Finally,semi-physical experiment is performed to verify the attitude determination algorithm under laboratory environment.The paper fulfills the advanced and foresighted research work for fine guidance sensor attitude determination.The paper has following innovations:For the attitude determination key technology demands in fine guidance sensor,based on UCAC4 catalogue with magnitude range from 10 to 14,quick searching navigation feature table is built with the method of k-vector search,the improved fast star identification algorithm based on star feature unchanged theory is proposed.The simulations present the algorithm is validated to prove its feasibility for star identification with large star catalogue,and its identification rate can reach 97%.Improved ESOQ2 algorithm is proposed for fine guidance sensor after simulated and compared,with respect to attitude determination accuracy,speed and robustness for the classical attitude determination algorithms under multi-stars condition.The new algorithm can satisfy the requirement of accuracy and speed for fine guidance sensor.It can guarantee the accuracy and avoid the attitude update rate slow down.The Cubature Kalman filter attitude estimation algorithm is improved and fuzzy logic adaptive Cubature Kalman filter quaternion attitude estimation method is proposed.The Method is simulated and validated,the results prove that the new method can recover to stable trace state compared to the traditional one.Another improved method,SVD aided Cubature Kalman filter quaternion attitude estimation method is proposed,which also has better performance compared the traditional one.Algorithm verification software with Qt is designed and can be transplanted in other platforms.Anafocus' s Lince5M181 focal plane camera is designed and captures images successfully,combined with Ti corporation's Multi-core DSP evaluation board TMDSEVM6678 LE,the laboratory validation platform is built.Attitude determination algorithm is optimized and experiments are performed based on it.The processing time for multi-stars attitude determination can be kept 24 ms which satisfy the real time requirement.Static and dynamic experiment results present that algorithms proposed satisfy the requirements of fine guidance sensor and prove that the theoretic work is rationally.