Enhancing Altitude Accuracy in Automotive Navigation using MEMS Barometric Sensor with GPS

Lionel J. Garin, SaiPradeep Venkatraman, Pramod Gupta, Benjamin J. Kokes, Terry A. Smith

Abstract:	Nemerix has developed a solution that effectively blends the altitude from a GPS receiver with the altitude derived from a MEMS pressure sensor. While solutions that integrate the pressure sensor with dead reckoning systems for vertical accuracy improvements in pedestrian navigation have been previously proposed, the use of a pressure sensor based altitude filter that specifically aims at improving altitude in an automotive navigation solution has not received much attention. The reason for this is not so much the lack of applications for enhanced altitude but the challenges imposed by the effects of environmental changes on the pressure and the difficulties in calibrating the sensor. Nemerix has developed calibration and compensation techniques that overcome these challenges. With the proposed solution, it becomes possible to identify if a vehicle is traveling on the upper level or one of the lower levels in a multi-level or stacked road and enhance turn by turn navigation. Typically, the vertical accuracy that is achieved with GPS is lower than the horizontal accuracy. This effect is further aggravated because the lower road is obstructed by the upper road, and exhibits very high multipath that further degrades the vertical accuracy. By using a low cost MEMS pressure sensor in conjunction with high accuracy navigation solution the vertical performance can be significantly improved to the level where a typical road-to-road vertical distance of 10 meters or more can be unambiguously resolved. This paper provides details of the proposed pressure sensor calibration and altitude filtering techniques and provides results and analyses that highlight the performance improvement.
Published in:	Proceedings of the 2008 National Technical Meeting of The Institute of Navigation January 28 - 30, 2008 The Catamaran Resort Hotel San Diego, CA
Pages:	670 - 679
Cite this article:	Garin, Lionel J., Venkatraman, SaiPradeep, Gupta, Pramod, Kokes, Benjamin J., Smith, Terry A., "Enhancing Altitude Accuracy in Automotive Navigation using MEMS Barometric Sensor with GPS," Proceedings of the 2008 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2008, pp. 670-679.
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