GPS-Based Relative Positioning Test Platform for Automotive Active Safety Systems

C. Basnayake, C.C. Kellum, J. Sinko, J. Strus

Abstract:	Driver Assistance Systems (DAS) are designed to aid drivers with normal driving scenarios in day-to-day driving. This paper discusses the results of a recent GPS relative positioning test platform development effort by General Motors Research and Development for automotive DAS. This GPS-based system does not require additional GPS infrastructure and is intended for use with positioning and communication systems built into vehicles. The test platform was used to evaluate several grades of GPS receivers, with the objective of identifying hardware that can deliver the accuracy and latency required for different DAS applications, while fulfilling the cost constraints of mass deployment. The test system is implemented in several cars equipped with 802.11-based communication capability. The vehicles broadcast messages containing GPS and other vehicle data at regular intervals. Each vehicle DAS uses these broadcasts from neighboring vehicles to aid drivers with different functionalities, ranging from warnings to automated evasive action when the driver did not respond to an imminent collision. The GPS test platform consists of two modules: Receiver Manager (RM) and GPS Solution Generator (GSG). The RM acts as the interface between all GPS receivers and the GSG and contains GPS relative positioning algorithms. Two high-end receivers are installed on each vehicle to provide a fixed baseline truth reference, which greatly increases reliability of the single-epoch Real-Time Kinematic (RTK) solutions generated by the GSG. The relative positioning solution for low-cost receivers uses a Kalman filter approach to estimate the float ambiguities, which yields around 0.5 meter accuracy. This accuracy is sufficient for lane-level applications. System performance was tested in environments ranging from freeways with open skies to heavily foliated suburban areas. System availability ranging from 80–99% was observed in most test routes, with least availability in heavily foliated environments. In open sky routes, the low-cost system produced relative horizontal position accuracy of better than 0.25 meters 98% of the time. On more obscured routes, 96% of verifiable measurements were within 0.5 meters of the truth system, limited by the time duration when the truth system was able to provide a solution.
Published in:	Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006) September 26 - 29, 2006 Fort Worth Convention Center Fort Worth, TX
Pages:	1457 - 1467
Cite this article:	Basnayake, C., Kellum, C.C., Sinko, J., Strus, J., "GPS-Based Relative Positioning Test Platform for Automotive Active Safety Systems," Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006), Fort Worth, TX, September 2006, pp. 1457-1467.
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