A geometric star identification algorithm based on triple triangle pattern

Abstract

Star trackers have been widely studied in the three past decades due to their high accuracies as well as, their capabilities in attitude determination as per 3 main axis in the real time. Star identification(star-ID) algorithms are of the most effective software parts in the devices of aid navigation in the performance of star trackers. In this research presents a star-ID algorithm which has four stars in the field of view (FOV). Having these stars, it finds the parameters of separating angles, areas and polar moment between the formed triangles and compares them with the information stored in the memory of star tracker to achieve the unique response. In this research, the triangular patterns have been prevented from being formed between all stars of research catalogue for reducing the volume of the data stored in the memory. Therefore, only the triangles created between the central star and its near three stars are formed and stored. In order to make the feature lists, each star of the catalogue is considered once as the central star. The suggested algorithm has been compared with pyramid, composite and Liebe's algorithms. This algorithm has a speed nearly twice that of pyramid algorithm due to the reducing of stored data volume as well as using the K-vector searching method. The simulation has been performed in the MATLAB software in the M-file format. The results for accuracy and speed of the algorithms are obtained from repeating 50 times for each algorithm. It should be mentioned that the HYG catalogue has been used as the reference star catalogue for simulation.