Research On Star Identification Algorithm Based On Dynamic Angle

With the increasing number of space missions,the precision of attitude control is required more and more.As the autonomous measuring device with the highest attitude measurement accuracy,star sensor has gradually become an important part of spacecraft.The star sensor realizes the attitude measurement through the recognition of stars.The star pattern recognition algorithm is the most important thing in the star sensor,which determines the performance of the star sensor’s attitude positioning.The research on star pattern recognition algorithms has always been a hot spot.Experts and scholars have successively proposed various types of star pattern recognition algorithms and achieved good results.However,some existing algorithms still have certain deficiencies in terms of robustness to noise and tolerance to image distortion.In response to the above problems,this article mainly does the following work:(1)Along the entire working process of the star sensor,first understand the conversion relationship between the various coordinate systems,the mathematical model of star map imaging and the process of generating digital star maps,and provide support for subsequent research through the generated analog star maps;Secondly,the technology of image denoising,star point extraction and centroid positioning before the recognition algorithm is introduced;finally,the navigation star database is constructed and the general process of the recognition algorithm has a deeper understanding.(2)Some star pattern recognition algorithms use the nearest neighbor as the starting star.In the case of large star point extraction errors,the wrong choice of starting star will directly lead to the failure of recognition.Aiming at this problem,this section using the angle between the adjacent and the distance between the adjacent and observation star as a dynamic angle characteristics,using the characteristics as the starting point for subsequent matches,through the cumulative angle and distance of validation method and the matching degree between each navigation star,finally get the highest star matching degree as the recognition result.Compared with other methods,the proposed method has a higher recognition accuracy,while still maintaining a higher recognition accuracy rate under the influence of positional noise,pseudo-star,and stellar noise.(3)Common star pattern recognition algorithms are susceptible to image distortion,focal length changes,etc.,resulting in failure to complete recognition.Aiming at this problem,combined with distortion,focus on the analysis of the star imaging effect,in the dynamic matching algorithm based on the Angle,distance characteristics of the previous promotion for the ratio between the distance characteristics,combined with dynamic ratio calculation method,makes the algorithm with distortion,especially for the change of the focal length has a stronger ability to adapt,to further improve the robustness of the algorithm.(4)Affected by image distortion and other factors,the number of star points that can be recognized by the star pattern recognition algorithm is greatly reduced compared to the ideal situation.In response to this situation,combined with the recognition process of the recognition algorithm in this paper,and with the help of the position relationship between the recognized star point and the neighboring star,the asterisk of the neighboring star is directly supplemented,which significantly improves the recognizability when the normal method cannot be recognized.The number of star points makes full use of the information between each star point and provides support for image distortion correction.