Design and simulation of a novel APS star tracker

Star trackers determine attitude by identifying stars imaged on the image sensor via an optical system whose performance is required to meet the star identification algorithm. The method to determine parameters of the optical system is proposed based on the identification algorithm. These parameters include focal length, aperture, and field of view (FOV). Aberration correction requirements are also analyzed. Pyramid identification algorithm utilized in this paper is investigated. Some improved approaches are presented for star map processing, onboard catalog organization and star identification. A link table construction is designed to save brightness from the programmed APS sensor which decreases data effectively and enhances the ability to calculate star positions in star maps. A method is developed to organize the onboard catalog which avoids searching and comparing similar star pairs but makes for rapid and unique identification. When performing star identification with Pyramid identification algorithm, only X brightest stars are chosen from star maps to acquire high signal to noise ratio and decrease spikes. Star number statistics is fulfilled all over the sky with any orientations by varying FOV and limited magnitude. Base on the requirement of the identification algorithm, parameters of the optical system are determined with the given STAR1000 APS sensor by analyzing their feasibility in optical design. According to these determined parameters, a star camera is designed. An onboard catalog on which star identification relies is produced. Star identification simulation is implemented. Simulation result proves that the designed system gets a satisfactory performance.