Improved GPS Positioning for Motor Vehicles Through Map Matching

Craig Scott

Abstract:	Absolute positioning systems, especially the Global Po- sitioning System (GPS), are playing an increasing role in the tracking of motor vehicles. Such systems, however were not designed to specifically track motor vehicles. Apart from the start and finish of journeys, motor vehi- cles are restricted to the road network, a fact not reflected by the position measurements. Techniques exist for cor- recting the measurements according to a map of the net- work but a mathematical framework for this correction process is lacking. The author has developed such a framework resulting in a map-aided estimation process that takes into account the measurement noise statistics to optimally translate the raw position measurements onto the road network. The theoretical performance of this es- timator is derived and compared with that achieved using GPS measurements. The effect that Selective Availabil- ity (SA) has on the map-aided estimator is analysed and a technique for reducing the effect of SA is demonstrated. In addition to the accuracy improvements, the map-aided positioning framework also provides a means for readily incorporating other sources of positioning information. Driver behaviour, road type, and vehicle dynamics can be used to make further improvements in positioning ac- curacy and road identification.
Published in:	Proceedings of the 7th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1994) September 20 - 23, 1994 Salt Palace Convention Center Salt Lake City, UT
Pages:	1391 - 1400
Cite this article:	Scott, Craig, "Improved GPS Positioning for Motor Vehicles Through Map Matching," Proceedings of the 7th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1994), Salt Lake City, UT, September 1994, pp. 1391-1400.
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