A Star Pattern Recognition Algorithm for Autonomous Attitude Determination
1989; Elsevier BV; Volume: 22; Issue: 7 Linguagem: Inglês
10.1016/s1474-6670(17)53386-8
ISSN2589-3653
Autores Tópico(s)Stellar, planetary, and galactic studies
ResumoA star pattern recognition algorithm is described enabling a state-of-the-art star tracker to quickly and reliably determine its attitude about all three axes without requiring any a-priori attitude knowledge. This device, referred to as a "Full-sky Autonomous Star Tracker (FAST)," can serve as a key sensor in future autonomous attitude control and navigation systems. Having a field of view of 11.5 by 11.5 degrees and an accuracy of 8 arcsec (1 sigma), the redundant, microcomputer equipped ASTROS II star tracker being developed by JPL for use with the Mariner Mark II planetary spacecraft is ideally suited to serve as a FAST. It is shown that an ASTROS II based FAST, integrated with an all-sky database of some 4,100 guide stars, and 810K bytes of memory, can deterrnine its attitude in approximately 1 second with a success rate very close to 100%. Its high speed is due to both the accuracy of the tracker and the efficiency of the algorithm which usually does not require any iterations. In addition to enabling a FAST, the recognition algorithm can also be used for automating the acquisition of celestial targets by astronomy telescopes, for updating the attitude of gyro based attitude control systems autonomously (planned for Mariner Mark II), and for automating ground based attitude reconstruction. Monte Carlo simulations and a much faster, highly accurate quasi-analytical method are used for predicting the success rate of the algorithm as a function of the many parameters required to define the sky, the star catalog from which the guide stars are extracted, the tracker, and the control parameters of the algorithm.
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