Fast Ambiguity Resolution by a Combined System of Multiple-Baseline Equations

T. Kashiwayanagi, Y. Koura, K. Ogawa, H. Suzuki, M. Nakamura

Abstract:	GNSS-INS attitude determination systems for marine navigation rely on precise relative positioning applying carrier phase measurements. The precise relative positioning requires resolution of integer ambiguities; for xample, the integer ambiguities are resolved by the Least-squares AMBiguity Decorrelation Adjustment (LAMBDA) method. General systems with a single baseline between two antennas determine the heading and the pitch angles or the heading and the roll angles. In contrast, systems with three baselines among three antennas determine all the heading, the pitch and the roll angles. The three-antenna systems require resolving ambiguities to two baselines. If the LAMBDA method is applied for the resolution, each baseline system of equations needs to be solved separately; with single-frequency receivers, it takes a few minutes to resolve the ambiguities. We have devised a new integer ambiguity resolution algorithm for GNSS-INS attitude determination systems with three baselines. We call the algorithm the Non- Linear Ambiguity Resolution (NLAR) algorithm. The NLAR algorithm resolves all the integer ambiguities simultaneously from a combined nonlinear system of equations for the two baseline vectors with geometric relations among the known three baselines. Consequently, the NLAR algorithm considerably improves reliability of resolved integer ambiguity vectors even with short time observation data. We show the fast resolution and the high reliability of the NLAR algorithm from results of simulation and field experiments. In normal environment with relatively less multipath, the NLAR algorithm shows correct ambiguity resolution above 99% for only one-epoch even with single-frequency receivers. Furthermore the NLAR algorithm shows reliable ambiguity resolution even with fewer available satellites or in bad environment with larger multipath.
Published in:	Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006) September 26 - 29, 2006 Fort Worth Convention Center Fort Worth, TX
Pages:	286 - 291
Cite this article:	Kashiwayanagi, T., Koura, Y., Ogawa, K., Suzuki, H., Nakamura, M., "Fast Ambiguity Resolution by a Combined System of Multiple-Baseline Equations," Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006), Fort Worth, TX, September 2006, pp. 286-291.
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