Performance Comparison of Kinematic GPS Integrated with Different Tactical Level IMUs

H.T. Zhang, M.G. Petovello and M.E. Cannon

Abstract:	Improvements from the integration of GPS and a tactical- grade inertial navigation system (INS) have previously been investigated using the Honeywell HG1700 for highaccuracy vehicular applications. However, side-by-side testing of other tactical-grade inertial measurement units (IMUs) has not been done to assess whether the same improvements can be achieved. In this paper, a Honeywell HG1700 IMU and a Litton LN200 IMU are independently integrated with a NovAtel OEM4 dualfrequency GPS receiver in the same test vehicle for highaccuracy positioning using GPS carrier phase observables. The improvements from the integration of GPS and these two tactical-grade INS’s using different integration strategies are investigated. The performance in the position domain is measured through the system accuracy during complete GPS data outages. The time to fix carrier phase integer ambiguities after complete data outages is then used to measure the improvement in the ambiguity domain to determine how INS aiding affects the ambiguity resolution process, relative to the GPS-only solution. Results from field testing show that the integrated systems are both capable of providing 2-4 centimeter accuracy under good GPS coverage. Furthermore, the estimated accuracy of the free-inertial solution as good as or better than 1.8 meters, which is the estimated accuracy of differential GPS for the data analyzed, for data outages lasting up to about 26 s and 40 s for HG1700 and LN200 respectively. In the ambiguity domain, instantaneous L1 integer ambiguity resolution was found to be possible using either tight or loose coupling strategies after up to 2 and 4 seconds of complete GPS data outages for the HG1700 and LN200 systems respectively. Furthermore, a quantitative relationship between the free-inertial positioning accuracy after a GPS outage and the respective ambiguity resolution improvements with the aiding of inertial data is given in this paper.
Published in:	Proceedings of the 2005 National Technical Meeting of The Institute of Navigation January 24 - 26, 2005 The Catamaran Resort Hotel San Diego, CA
Pages:	243 - 254
Cite this article:	Zhang, H.T., Petovello, M.G., Cannon, M.E., "Performance Comparison of Kinematic GPS Integrated with Different Tactical Level IMUs," Proceedings of the 2005 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2005, pp. 243-254.
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