GPS/lnertial Mapping (GIM) System for Real Time Mapping of Roadways Using WADGPS

Tim Ash, Randy Silva, Alison Brown, and James LaMance

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. A significant problem in the gathering of mapping information using GPS is the gaps in the base map data base caused by satellite shadowing, which may not be discovered until after the survey is complete. Gaps may also exist in the GIS attribute data base because items were missed during the survey. These are costly problems that usually require new surveys to remedy. To address this problem a low-cost, miniaturized GPSnnertial Mapping (GIM) system has been developed that can deliver l-2 meter accuracies in real time even in the event of temporary GPS signal loss. The GIM system combines inertial aided GPS navigation, position synchronized video, and automatic roadway attribute entry, to provide a powerful tool for generating precise, high quality GIS databases. This paper will describe GIS mapping sessions conducted with the GIM system on the roadways of El Paso County, CO. El Paso County offers an ideal geography to test the capabilities of the NAVSYS GIM system because it offers both urban and rural sections where the GPS signals can be blocked by obstructions that vary from buildings to mountain canyons. The paper will include the test data collected during the mapping sessions, and will demonstrate why inertial aiding is an important component for mapping instrumentation. The NAVSYS GIM system incorporates an innovative optimal processing algorithm that enhances the performance of the inertiaYGPS system enabling a low cost Inertial Measurement Unit (IMU) to be employed in combination with a GPS receiver, and the John E. Chance Omnistar wide area 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 tagging, in both video and electronic formats. 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.
Published in:	Proceedings of the 8th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1995) September 12 - 15, 1995 Palm Springs, CA
Pages:	1825 - 1830
Cite this article:	Ash, Tim, Silva, Randy, Brown, Alison, LaMance, James, "GPS/lnertial Mapping (GIM) System for Real Time Mapping of Roadways Using WADGPS," Proceedings of the 8th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1995), Palm Springs, CA, September 1995, pp. 1825-1830.
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