Demonstration of a New, Tightly-Coupled GPS/INS

Donald T. Knight, Allen W. Osborne, Robert W. Snow, Don G. Kim

Abstract:	A system architecture has been developed that accomplishes tightly-coupled GPS/INSintegration, while at the same time simplifying the task of bringing compo- nents together and verifying their integration. The simplified integration can be expected to make the systems affordable and available to a wider range of users than is currently possible. The objective of the work reported here was to prove out the integration concept, and to validate the major hardware and soft- ware components, by demonstrating an actual prototype. An Allen Osborne Associates, Inc. (AOA)TurboRogue GPS receiver was optimally integrated with an Inertial Science, Inc. (ISI) inertial navigation system using the integration concept and GPS/INS integration software developed by Don Knight. GPS/INS van testing was conducted, resulting in a verification of functionality and accuracy of the prototype. Test methods and results are described. Akey aspect of the prototype verification was the availability of a full GPS constellation. In two hours of van testing, with the van in motion, with an average of 6.7 satellites in track, and with an atomic clock in the van, the actual, measured differential delta ranges converged on a solution for van speed and heading with an RMS accuracy of 2 mm/set, or about 0.004 mph (four one thousandths of a mile per hour), The quantity and quality of GPS data enabled rapid calibration and alignment of the INS, using a Kalman fdter, and provid- ed an extremely accurate truth reference. That, in turn, allowed integration testing to be completed quickly, and it avoided having to resort to some other system, such as a laser ranging system, to serve as truth reference. What has not beenaccomplished at this time is demonstration of the whole system executing in real-time, and the use of INS-derived estimates of GPS Doppler in order to improve the receiver’s noise rejection, and to improve the reacquisition of signals that have been interrupted. The significance of this work is that tightly-coupled GPS/INS systems may becomemuch easier to build, and that, in turn, would benefit both users and suppliers by expanding thenumber and diversity of optimal GPS/INS systems in use.
Published in:	Proceedings of the 6th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1993) September 22 - 24, 1993 Salt Palace Convention Center Salt Lake City, UT
Pages:	205 - 214
Cite this article:	Knight, Donald T., Osborne, Allen W., Snow, Robert W., Kim, Don G., "Demonstration of a New, Tightly-Coupled GPS/INS," Proceedings of the 6th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1993), Salt Lake City, UT, September 1993, pp. 205-214.
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