Research On Key Technologies Of All-time Astronomical Navigation System

The astronomical navigation system is a navigation system that determines the attitude by detecting the position of celestial bodies.The star sensor is the navigation device with the highest accuracy and the strongest anti-interference in all astronomical navigation systems.Domestic star sensors have been widely used in space and near-ground night missions,but under near-ground daytime conditions,strong sky background radiation will affect the normal operation of star sensors.With the continuous development of our military strength,the near-ground weapons and equipment have put forward higher requirements for the measurement accuracy and anti-interference ability of the navigation system,which makes the application of near-ground all-time star sensors more urgent.Therefore,all-time star sensor is the key and difficult problem that needs to be solved urgently in the field of domestic star sensor research.Aiming at the practical needs of improving the measurement accuracy and anti-interference ability of all-time star sensor,the daytime attitude measurement method,the nighttime attitude optimization method and the blurred star image restoration method of the all-time star sensor are researched.The main research contents are summarized as follows:(1)Aiming at the problem that star sensor cannot perform attitude measurement under daytime conditions,after the research on the star image superposition algorithm,the mapping relationship of the pixels in the consecutive images are analyzed,and the traditional star image superposition algorithm is improved.A star image superposition algorithm based on attitude-correlated frames is proposed,which improves the signal-to-noise ratio of stars in the image,then the attitude measurement method based on the proposed algorithm is used to measure the attitude of the star sensor in the daytime.(2)Aiming at the problem that the attitude of star sensor cannot be measured by the method of star detection when the stars are blocked by clouds in the daytime,after the research on the attitude measurement method based on sun centroid,a fitting algorithm of the sun centroid is proposed and the measurement method based on the proposed algorithm is used to roughly measure the optical axis direction of star sensor during the daytime,whichs improves the attitude measurement robustness of the star sensor in the daytime.(3)Aiming at the problem that the attitude measurement of star sensor at night is disturbed by the measurement noise,after the research on the attitude filtering method of star sensor,a linear system model of the star sensor is established and based on the model an attitude filtering algorithm based on Kalman filter is proposed,which improves the measurement accuracy during the attitude measurement of the star sensor.(4)Aiming at the slow recognition speed of new stars in the field of view of star sensor during star tracking,after the research on the partition method of the star catalog,a star catalog partition method based on regular polyhedron is adopted,based on which,a fast star identification algorithm of star sensor during star tracking is proposed to improve the recognition speed of new stars in the process of star tracking.(5)Aiming at the problem that the stars in image are blurred when all-time star sensor works under dynamic conditions,the motion of star centroid in blurred star image is analyzed and the restoration function of blurred star image is solved.A curvature filter algorithm based on energy function and termination criterion of LR algorithm are proposed to improve the LR restored algorithm,which solves the problem that the poor robustness to noise and no iteration termination criterion of LR restored algorithm.(6)The electronic system of all-time star sensor is designed and the principle prototype of the all-time star sensor is developed.The main technical parameters of the all-time star sensor are calibrated,and based on the calibrated parameters,the accuracy of the all-time star sensor is gotten through theoretical calculation and experimental calibration,respectively.The star observation experiment of the all-time star sensor is carried out,and the research achievement of the key technologies and the performance of all-time star sensor is verified by the star observation experiment during night and daytime,respectively.