An analytical approach to star identification reliability
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The problem of real-time, on-board star pattern identification is considered which must precede any spacecraft attitude estimation algorithm based on measured line of sight directions to stars. Following the use of the search-less k-vector method to access feasible candidate stars (detailed in a previous paper) a tiered logical structure is introduced in which inter-star angles for pairs, triples and general elementary star configurations are used to match measured patterns to corresponding patterns in a star catalog. Analytical expressions are developed for the expected frequency of matching an observed star pattern with an incorrect pattern in the star catalog due to measurement error. Such knowledge of erroneous match frequencies can be used to rigorously terminate the star identification process with a virtually certain match, while obviating the need for expensive Monte Carlo simulations. Developments shown are supported with a few simulation results. 2009 Elsevier Ltd. All rights reserved.