Fast Star Pattern Recognition Using Planar Triangles

A new method for star identification based on using planar triangles is developed and compared to a standard angle method approach. The angle method creates angles between stars within the field of view of a star tracker and matches them to angles in a catalog to determine which stars make them up. The new method creates triangles from the stars within the field of view of a star tracker, determines their area and polar moment, then matches the triangles to a catalog of triangles in a way that is faster and more successful than the angle method. Simulation results are provided that show the performance of the new method as well as its robustness with respect to including false stars. Introduction Star Identification Methods A very important device on any spacecraft is the one that determines the attitude of a spacecraft. There are many different methods by which attitude can be determined, but one of the mostly widely used is the star tracker. Other methods for determining attitude exist, including sun sensors and magnetometers, but cannot report attitude with the precision a star tracker can. Oftentimes, on high-budget missions, these other sensors will complement or back-up a star tracker. On missions with tight attitude knowledge requirements, the primary means to determine attitude is the star tracker. Before an attitude can be determined, the ∗ACS Engineer, Space Systems Group, Orbital Sciences Corporation, Dulles, VA 20166. Email: [email protected], Member AIAA. †Associate Professor, Department of Mechanical & Aerospace Engineering, University at Buffalo, State University of New York, Amherst, NY 14260-4400. Email: [email protected]. Associate Fellow AIAA.