REQUEST - A New Recursive Algorithm for Attitude Determination

Itzhack Y. Bar-Itzhack

Abstract:	Spacecraft instantaneous attitude determination is based, usually. on vector measurements. The measurements are pairs of components of the same generalized vector, taken in the spacecraft body, and the reference coordinate systems. Attitude is determined by square root fitting of a transformation matrix to the measurements. This method stems from the so called Wahba’s Problem. An algorithm which performs that fitting is called QUEST. It yields the attitude best estimate expressed by a quatemion. QUEST is an efficient algorithm- which provides a least squares fit of the quatemion of rotation to the vector measurements. QUEST, however, is a single time-point (single frame) batch algorithm, thus measurements that were taken at previous time points are discarded. The algorithm presented in this work provides a recursive routine which considers all Past measurements and, like QUEST, yields a quatemion square root fit to all measurements. The development of the recursive algorithm is presented in this paper and illustrated via a numerical example.
Published in:	Proceedings of the 1996 National Technical Meeting of The Institute of Navigation January 22 - 24, 1996 Loews Santa Monica Hotel Santa Monica, CA
Pages:	699 - 706
Cite this article:	Bar-Itzhack, Itzhack Y., "REQUEST - A New Recursive Algorithm for Attitude Determination," Proceedings of the 1996 National Technical Meeting of The Institute of Navigation, Santa Monica, CA, January 1996, pp. 699-706.
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