Research Of The Star Identification Algorithm Based On Narrow FOV Star Sensor

As a kind of attitude measuring device which can output three-axis attitude independently,star sensor is widely used in astronomy navigation system because of its low power consumption,high precision and high reliability.Star recognition and attitude calculation,the key technologies of star sensor are closely related to the navigation star catalog.The construction of the navigation star catalog and the star recognition algorithm have a direct impact on the attitude accuracy of star sensor.Star recognition is to identify star points in the star map and the reference star point in the navigation feature database so as to obtain the attitude information of carrier by calculation.The basic process includes the star map pre-processing,the preparation of the navigation star catalog,the establishment of navigation feature database,recognition and other parts.This paper relying on the National Natural Science Foundation(61573113),the city of innovative talent fund(2014RFXJ074),research the star recognition algorithm developed for the small field star sensor,which has fewer star points captured,high detection sensitivity,and large magnitude sensitivity limit.Firstly,the star image preprocessing algorithm is analyzed with the characteristics of small-field star sensor,which mainly includes star image de-noising,star image segmentation and star point location algorithm.Based on the denoising and segmentation of star image,the star centroiding algorithm is mainly studied,including traditional centroid method,square weighted centroid method and Gaussian surface fitting method.Based on the simulation of star map,the centroid extraction errors of the above algorithms are analyzed in the small field of view.Secondly,this paper studies the construction method of the star catalog,and gives the specific process of the selection of the navigation star based on the star-level filtering and the spiral reference point algorithm.In view of the limitations of the application of the spiral reference point algorithm in the small field star sensor,this paper adds the star brightness information,and presents a new method of star catalog construction based on the characteristics of the high sensitivity and high detection capability of the small field star sensor.Star comprehensive performance indicators of the parameter calculation method is introduced,so as to improve the basic algorithm.The simulation results show that the improved algorithm based on the spiral reference point is superior to construct the star catalog in the small star field.Finally,an improved extended star map method is proposed to solve the problem that the star recognition algorithm of small FOV star sensor can not balance the robustness and recognition accuracy of the star recognition algorithm when the FOV is smaller.The improved algorithm combines the traditional grid algorithm with the extended star map method,and introduces the magnitude difference information so that it can be effectively applied in the small field star sensor.The simulation results show that the improved extended star map algorithm still has higher recognition accuracy when the number of star points in the extended field is insufficient,and the robustness to position noise is improved.