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

Star sensor as an independent output of three axis attitude measurement device,has the characteristics of low power consumption,high accuracy and high reliability.It is widely used in celestial navigation system.The star map recognition algorithm directly affects the attitude measurement precision of star sensor.Star sensor can preprocess the star map by capturing the star map through a camera.The star map preprocessing includes star map noise reduction,star point extraction,and star centroid positioning.The star map can be identified after the star map is preprocessed.Star pattern recognition is taken in the star tracker star star and star in the feature library reference point matching characteristics,which are obtained by calculating the attitude information.According to the small field star sensor of single field capture points,star detection sensitivity,magnitude limit sensitive etc.,carried out research on star pattern recognition algorithm.As an important basis for the construction of matching recognition of star image preprocessing and navigation catalogue,directly affect the star map matching success rate,is the key research contents.First of all,combined with the characteristics of small field star sensor,star extraction problem analysis,research mainly includes image denoising,star extraction,centroid algorithm.On the basis of the known noise situation of the star map,the existing filtering algorithms are analyzed and the noise reduction method suitable for the star map is selected.Based on the extraction of star points,the star location algorithm is mainly studied,including the traditional centroid method,the surface fitting method and the improved centroid method.On the basis of the star map simulation technology,the star point error is analyzed and the method of compensation is studied.The simulation and contrast analysis of the centroid extraction error of these algorithms under the condition of small field of view is carried out.Secondly,according to the small field of star magnitude sensitivity limit is high,dark star detection ability and capture characteristics of single field star number is insufficient,determine the magnitude limit in the magnitude of value of the filter.Set up a navigation star library.The first navigation satellite location information stored in the catalog of the right ascension and declination transform,and area are divided into blocks,then respectively in each region is determined in the navigation satellite direction vector,calculate all the stars of the sky in the angular distance between stars,and it is in ascending order.Finally according to the distribution of sky star angular distance between the two stars,choose the appropriate angular distance between the threshold value,and according to the characteristics of the small field of star sensor,the synthesis process of binary system,establish complete navigation star database.Finally,in view of the fact that the existing star sensor star recognition algorithm is unable to take account of the robustness and accuracy of recognition algorithm in the field of view,an improved triangle star recognition algorithm is proposed.And in view of the characteristics of the data of the navigation star feature library,a dichotomy is used to search,which improves the search speed and reduces the time needed for the search in the recognition process.Simulation results show that the improved algorithm has high recognition success rate and robustness in the field of view with fewer star points and star map noise,and it can be applied to the small field of star sensor field effectively.