Embedded GNSS-receiver for Multi-Constellation Localization in Railway Applications

Jiaying Lin, Jan-Jöran Gehrt, Thomas Konrad, Michael Breuer, Dirk Abel, Rene Zweigel

Abstract: This publication presents the implementations of a tightly-coupled navigation filter on an embedded GNSS receiver, especially designed for railway applications. The tightly-coupled navigation filter processes the measurements of an Inertial Measurement Unit (IMU) and signals of a Global Navigation Satellite System (GNSS). Different methods to correct the pseudo-ranges of the satellite measurements have been implemented, such as the use of two frequencies for each satellite (dual-frequency), differentially corrected GPS (DGPS) and Klobuchar, [1], [2]. To select the most suitable correction mode with respect to current reception conditions, the navigation filter is extended by a state machine. Furthermore, the implementation of the navigation filter on an embedded system is presented. The used hardware and implemented software architecture are introduced. The synchronization of different sensors is achieved via a Pulse per Second (PPS) signal using the GNSS time. In order to implement the navigation filter, which is a combination of event-triggered signal preprocessing and time-based multirate extended Kalman filter, in a single-core processor with limited calculation capacity, a multi-threading framework has been proposed. The performance of the navigation filter in the embedded GNSS receiver is validated in two real world scenarios: rail track between two railway stations in Bayern, Germany, and a shunting railway station in Wustermark, Germany. Different conditions are encountered and the corresponding results are analyzed. In the rail track scenario with harsh environmental conditions such as wooded surroundings, signal damping due to heavy snow and multi-path effects due to snow covered ground and trees are encountered. A 2D accuracy of approximately 2-4 meter was achieved based on multi-constellation with the dual-frequency correction method. On the other hand, the shunting scenario was characterized by an adequate satellite reception and mobile radio, which was used to receive DGPS correction data. Under these conditions, an average 2D accuracy with less than 0.4 meter has been achieved, which has guaranteed a track-accurate localization as basis for autonomous shunting within the joint-research project Galileo Online: GO!.
Published in: Proceedings of the 31st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2018)
September 24 - 28, 2018
Hyatt Regency Miami
Miami, Florida
Pages: 2007 - 2017
Cite this article: Lin, Jiaying, Gehrt, Jan-Jöran, Konrad, Thomas, Breuer, Michael, Abel, Dirk, Zweigel, Rene, "Embedded GNSS-receiver for Multi-Constellation Localization in Railway Applications," Proceedings of the 31st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2018), Miami, Florida, September 2018, pp. 2007-2017.
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