A New GNSS-PPP/INS Data Fusion for Global Infrastructure-less Safe Train Positioning

Manuel Cunha, François Fund, Stéphane Meyer, Romain Legros, Denis Laurichesse, Nadie Karouche, Antoine Barré

Abstract:	In France, 33 000 kilometers of tracks are used daily by 15 000 trains, inducing extraordinary maintenance costs. A new approach for train localization is mandatory by railway operators as part of European standardization European Rail Traffic Management System. Physical railway signaling has to be removed and capacity of existing lines has to be increased by reducing the distance between the trains. That objectives require the right identification of the railway track and the capacity to localize the train with an along-track accuracy of less than 5m, with a high level of safety. The NRTK technique provides an accurate positioning but has several drawbacks to answer to the other requirements. Mainly, it is based on a high number of CORS and a complex bidirectional process inducing a problem of certification. Geoflex is a new operator of global real-time and post-processed corrections based on the PPP CNES technology. It can provide positions with a horizontal accuracy up to 4cm (95% confidence level) everywhere in the world, and without any nearby infrastructure. To ensure accuracy and availability of train positioning, the Geoflex/CNES PPP technology has been coupled with an ATLANS INS designed by iXblue. A test bed conducted in operational conditions demonstrated that PPP/INS solution can provide positions with an accuracy of 24cm and 87cm at the 68% and 95% confidence levels, respectively. In addition, the Geoflex/CNES PPP engine has been able to re-converge in a few seconds after a significant GNSS outage. Such results are very promising to well-identify the railway track. Next steps are to improve the solution to reach a global error ratio less than 10-9 per hour, this criterion being mandatory for the development of future train generations. This work is conducted by iXblue, Geoflex, CNES, and SCNF in the 3-years Loc4Rail project started in September 2019.
Published in:	Proceedings of the 32nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2019) September 16 - 20, 2019 Hyatt Regency Miami Miami, Florida
Pages:	1265 - 1271
Cite this article:	Cunha, Manuel, Fund, François, Meyer, Stéphane, Legros, Romain, Laurichesse, Denis, Karouche, Nadie, Barré, Antoine, "A New GNSS-PPP/INS Data Fusion for Global Infrastructure-less Safe Train Positioning," Proceedings of the 32nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2019), Miami, Florida, September 2019, pp. 1265-1271. https://doi.org/10.33012/2019.17122
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