Efficient Attitude Determination Algorithm Using Geometrical Concept: SNUGLAD

C. Kee, J. Jang, Y. Sohn

Abstract:	So far, almost researchers have focused on efficiency of search space to reduce computational load because it needs too big burden to search full search volume for a cold start in real-time. And those algorithms are mainly based on least-square techniques in mathematical aspect. In example, LSAST (Least Squares Ambiguity Search Technique) used three independent satellites information to search in 3D space and sequential leastsquares (R. Hatch). But those O.T.F.(On-The-Fly) algorithms have some problems. Firstly, big computational loads by chi-square threshold test. Secondly, computational loads, success ratio and fixing time have a high sensitivity to number of visible satellites. Finally, in multi-baseline case, computational loads increase in proportional to number of baselines. So we suggest new algorithm (SNUGLAD, Seoul National University GPS Lab Attitude Determination) to resolve the above problems. In this paper, we found a method to solve a cycle ambiguity by using a new approach: ¡°Geometrical concept¡±. It uses just a simple algebra to make a two dimensional search space and uses a comparison method to cut off wrong solutions roughly. As a result, computational efforts were reduced by more than 65% and the sensitivities of computational loads are decreased efficiently. For a multi-baseline case, we could determine full attitude angles with the similar or slightly high computational loads than a single-baseline algorithm. In the case that there were enough visible satellites, the search space of multi-baseline algorithm was almost same with that of single-baseline. We confirmed performance of our algorithm by both the simulation and real-time experiments.
Published in:	Proceedings of the 2003 National Technical Meeting of The Institute of Navigation January 22 - 24, 2003 Disneyland Paradise Pier Hotel Anaheim, CA
Pages:	142 - 151
Cite this article:	Kee, C., Jang, J., Sohn, Y., "Efficient Attitude Determination Algorithm Using Geometrical Concept: SNUGLAD," Proceedings of the 2003 National Technical Meeting of The Institute of Navigation, Anaheim, CA, January 2003, pp. 142-151.
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