Test Results of the NAVSYS GPS/lnertial Mapping (GIM) System

Timothy Ash, Josef Coetsee, Randy Silva, and Alison Brown

Abstract:	Geographic Information Systems (GIS) constitute a multi- billion dollar market for geographic data, and GPS offers a quick and accurate method to meet the demand for this data. However, a significant and costly problem in the gathering of location information using GPS is voids in the data base caused by satellite shadowing, voids which may not be discovered until after the survey is complete. To address this problem, a low-cost, miniaturized GPS/Inertial Mapping (GIM) system has been developed by NAVSYS Corporation. The system can deliver 1-2 meter accuracies in real time even in the event of temporary GPS signal loss. This paper describes the NAVSYS GIM system, and the results obtained with the system during recent road mapping sessions. The NAVSYS GIM system incorporates an innovative optimal processing algorithm that enhances the performance of the inertial/GPS system enabling a low cost Inertial Measurement Unit (IMU) to be employed in combination with a GPS receiver, and a differential GPS correction system to provide an accurate, real time position and attitude reference. The overall process is controlled by an intelligent data management system capable of recording feature and attribute information in real time, with associated time tagging for exact location. The GIM system is packaged into a portable, modular architecture that is suited for various vehicles such as cars, four wheel drives, watercraft or railroad cars, allowing quick and accurate surveys to be performed in a wide variety of geographies. Recent results obtained from roadway surveys demonstrate that the system is capable of maintaining 1-2 meter accuracy while driving over several different types of terrain with varying degrees of GPS coverage, and while operating at highway speeds.
Published in:	Proceedings of the 51st Annual Meeting of The Institute of Navigation (1995) June 5 - 7, 1995 Antlers Doubletree Hotel Colorado Springs, CO
Pages:	155 - 171
Cite this article:	Ash, Timothy, Coetsee, Josef, Silva, Randy, Brown, Alison, "Test Results of the NAVSYS GPS/lnertial Mapping (GIM) System," Proceedings of the 51st Annual Meeting of The Institute of Navigation (1995), Colorado Springs, CO, June 1995, pp. 155-171.
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