GPS/INS - A Very Different Way

Frank van Graas and James L. Farrell

Abstract:	Test results are presented for a tightly coupled GPS/INS implementation that differs radically from all other approaches reported up to this time. The method combines, for the first time, the following three desirable features: 1) really low-cost (less than $5k IMU); 2) cm/s velocity accuracy despite high dynamics; 3) no need whatsoever for carrier phase cycle ambiguity resolution. Reporting of results is unusually extensive, including a plan view of paths and time histories for all of the following: altitude; roll, pitch and heading angles; Kalman filter verticality and heading corrections; position residuals; and carrier phase residuals. Descriptions are included for data collection procedures and, since data synchronization played a major role, also for interfacing and preprocessing. Knowledge gained from these techniques will clearly benefit future applications, not only in test but in operation as well. Not only the GPS data processing approach is very different; other facets of this experience also run counter to prevailing wisdom (e.g., coning and sculling had a very minor role for this land-mobile application). The approach, results, and completeness of data sets, and procedures described herein are sufficiently unique to suggest wide applicability to future systems, with important ramifications for economy as well as performance. As micro electro-mechanical sensors (MEMS) availability moves increasingly toward widespread deployment, characteristics of the approach used in this paper (“quick-react” capability combined with full utilization of partial information) is envisioned as a sure complement to the low-cost instrument development.
Published in:	Proceedings of the 57th Annual Meeting of The Institute of Navigation (2001) June 11 - 13, 2001 Albuquerque, NM
Pages:	715 - 721
Cite this article:	van Graas, Frank, Farrell, James L., "GPS/INS - A Very Different Way," Proceedings of the 57th Annual Meeting of The Institute of Navigation (2001), Albuquerque, NM, June 2001, pp. 715-721.
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