Low-cost PND Dead Reckoning using Automotive Diagnostic Links

Jefferey L. Wilson

Abstract:	Factory installed Navigation and Telematics solutions have used Dead-Reckoning Algorithms coupled with Vehicle Sensors to augment their GPS solutions for more than a decade, but the adoption of similar Dead- Reckoning solutions in the Personal Navigation Device category has been limited by the cost and complexity of tying into the vehicle’s sensor infrastructure. This paper will show a low-cost approach that couples Absolute Heading (i.e. a multi-axis compass sensor), a low-cost 3-axis MEMS Accelerometer, and a Automotive Diagnostic Link connection to provide a Dead-Reckoning solution in a PND-style device. Current Dead-Reckoning solutions for PND devices are limited by the portable nature of the device and the complexity of tying the PND device into the vehicle bus. Manually splicing into a car’s vehicle harness to implement a Dead-Reckoning solution is not acceptable in today’s marketplace. Using the vehicle’s mandated OBD-II Interface (available in 1996 and newer vehicles in the U.S.) allows for a simplified connection to the vehicle that provides velocity information which can augment current Dead-Reckoning solutions, however a simple retrofit of OBD-II velocity data into current Dead- Reckoning solutions is not necessarily optimal. Since a successful Dead-Reckoning solution for PND devices must also work with a variety of installations (i.e. Wind-shield Mount, Vent-Mount, Cup-holder Mount, et cetera), this can put severe constraints on the current Gyro plus Odometer based Dead-Reckoning solution in terms of its Gyro response (especially in highly-inclined centerconsole mountings where the angle of the Gyro to the horizontal plane can exceed 45 degrees or more and be angled to an axis that is not inline with the vehicle’s yaw axis). Trial runs of the proposed system are shown in magnetically-adverse environments such as Chicago’s Wabash Avenue (underneath Chicago’s Elevated Train) and Chicago’s Upper Wacker Drive (under girded by steel support girders). A data comparison between current Dead-Reckoning solutions and the proposed solution is presented and evaluated.
Published in:	Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007) September 25 - 28, 2007 Fort Worth Convention Center Fort Worth, TX
Pages:	2066 - 2074
Cite this article:	Wilson, Jefferey L., "Low-cost PND Dead Reckoning using Automotive Diagnostic Links," Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007), Fort Worth, TX, September 2007, pp. 2066-2074.
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