1,720,975 research outputs found
The Perspective of Adopting the GNSS for the Evolution of the European Train Control System (ERTMS): A Roadmap for a Standardized and Certifiable Platform
No full textDespite several GNSS based solution have been proposed, to modernize the ERTMS-ETCS European Train Control System, till now a certifiable solution compliant with the CELENEC SIL-4 requirements and accepted by the rail stake-holders does not exist. In this paper we present a roadmap for the the development of GNSS applications as a contribution to the validation and certification process. The achievement of a certifiable solution that can be used in the rail domain in the shortest time as possible will have to re-use the expertise of the aviation sector for safety of life applications. A pillar of our roadmap is the Rail Test Range deployed in the Sardinia Island, in Italy, in the framework of the ERSAT project. Considering the importance of the performance assessment in the certification process, particular attention is devoted in the paper to the analytical evaluation of the impact of the SIS hazards on the estimation error of the train separation distance, and then on Integrity (in terms of Protection Levels and Tolerable Hazard Rate) and Availability, when a variable block length management is introduced. Previous models considered just one train at time
Track Constrained RTK-like Positioning for Railway Applications
Get PDFHere, we investigate PVT solutions based on multi-constellation receivers and dedicated augmentation networks allowing to determine the track on which a train is operating with a very high safety Integrity level. Because the time needed to accomplish this task has a relevant impact on the rail traffic management performance and, therefore, it is considered a key performance indicator by rail infrastructure managers, a double frequency solution is investigated. Particularly, we focus our attention on the advantages of relative positioning solutions, based on Double-Difference Wide-Laning Carrier Phase measurement combination, exploiting the fact that the train location is completely determined by its mileage due to the track constraint, to speed up track discrimination. No ambiguity fix is required at this scope. Here, a detailed description of the overall processing and achievable performance is given. Performance assessment is provided by means of Monte Carlo simulations based on observations recorded on field campaigns. © 2018 The Authors. Navigation published by Wiley Periodicals, Inc. on behalf of Institute of Navigation
High Integrity Two-tiers Augmentation Systems for Train Control Systems
No full textThis paper deals with high integrity systems based on a two-tiers Augmentation system architecture. The Augmentation System is based on a regional system and a local system. This work intends to define a Formal mathematical approach to improve the performance in terms of Integrity of a Local Area Augmentation and Integrity Monitoring Network. Such model is due to the stringent requirements in railways application that are described by SIL-4 (Integrity Risk < 10-9 during 1 hour). The Integrity Monitoring is performed on three different levels: Reference Station, Satellite, Constellation. For each of them the fault identification and exclusion algorithms are defined and analyzed. The novelty of this work is the integration of Local Area Augmentation Networks with single regional SBAS Systems in order to develop a 2-tiers High Accuracy and High Integrity Augmentation Systems able to reach the above Integrity requirements. At this aim the false alarm probability has been rigorously defined including 2-tiers Reference Stations fault probabilities. Simulation framework has been developed to assess both satellite and Reference Station faults and evaluate relevant 2-tier Augmentation Systems performances
GNSS Integrity Monitoring for Rail Applications: 2-tiers method
No full textThe paper presents an innovative GNSS fault detection and exclusion approach for the adoption of satellite localization in the rail sector. Current global integrity monitoring systems cannot guarantee the safety level needed for such applications as train control where Tolerable Hazard Rate in the order of 10 is required. A new method, named 2-tiers, enabling to integrate local augmentation systems and global augmentation infrastructures, is presented. It is based on the comparison of single differences residuals among satellites for detecting signal in space faults and double difference residuals among local augmentation stations and SBAS RIMS for detecting reference stations faults. GPS SIS faults described in literature and real GNSS raw data recorded on a train are taken into account. The present work reports the performance analysis for the 2-tiers approach carried out during relevant European projects. A Test-Bed architecture has been developed through the implementation of the algorithm in real-time on a local augmentation operational centre. Relevant performances have been tested on a rail track for validating the algorithm in real operative conditions. Significant results of the analysis are reported for SIS integrity assessment only
A GNSS based solution for supporting virtual block operations in train control systems
No full textThis paper deals with the adoption of GNSS (Global Navigation Satellite System) applications for the evolution of ERTMS (European Railway Traffic Management System) system. We have studied a solution to monitor the train integrity and to accurately locate the position where the last coach of the train is stopped when a failure causes the split of the train into two sections. Train integrity is mandatory for the introduction of the moving block functionality foreseen by ETCS (European Train Control System) Level 3 that will bring major long-term benefits in terms of maintenance and operational capacity. The novelty of our approach lies in the exploitation of the multi-constellation capability to fast detect the train split with the shortest distance between the departed train sections compatible with the highest safety conditions set by the ETCS standard. The results are presented in a parametric form by varying the number of constellations and the probability of false detection and missed detection
Performance of Indoor Positioning based on TDOA over OFDM-like Signals in Multipath Environments
No full textIonospheric incremental delay models in railway applications
No full textThe paper focuses on the introduction of the GNSS technology into the frame of the train control system. The goal of this work is to analyse and compare the existing ionospheric incremental delay models influence on accuracy of On Board Unit (OBU) position to verify the achievable performance by adopting them during the estimation procedure. The performance results will be shown, based on a campaign test acquired on a ring-shaped highway (named Grande Raccordo Anulare (GRA)) around Rome (Italy) to simulate movement of a train on a generic track
A multiple satellite fault detection approach for railway environment
No full textThe aim of this work is related to railway sector and particularly with the introduction of the GNSS (Global Navigation Satellite System) into that environment. More in details, our aim is to evaluate system performance in terms of integrity of the navigation data. In the train control system, the integrity is one of the most challenge feature to achieve. Under that assumption, an algorithm that is able to exclude multiple SIS (Signal in Space) faults has been designed. In the design of the approach a multi-constellation framework has been taken into account. Simulation results highlighted promising outcomes both in terms of detection probability and in terms of false alarm rate
Indoor Vehicle Localization Based on Wi-Fi Navigation Beacons for Multi-Modal Transportation Applications
No full textTrack constrained RTK for railway applications1
No full textAt the start of missions trains compliant with the European ERTMS/ETCS standard have to run in Staff Responsible Mode (SRM) until the track where the train is lying on is identified by the Control Center (i.e., the Radio Block Center). Since SRM implies very low average speeds, this procedure produces a waste of time, and then money, every time a service starts. Thus, rail infrastructure managers are starting to ask for GNSS based solutions, able to determine which is the track occupied by the train in a very short time. Thus, in this paper we investigate PVT solutions based on multiconstellation receivers and dedicated augmentation networks that allow to determine the unknown track at the start of mission with the required safety Integrity level (SIL- 4). Particularly we focus our attention on RTK solutions that benefit of the constraint represented by the track for the train location, in order to speed up convergence. Considering that the saved money strictly depends on the time needed to solve phase ambiguities, a double frequency solution has been considered. In this contribution a detailed description of the overall processing and achievable performance is given. Assessment of the performance is provided by means of Monte Carlo simulations making use of observations recorded in the framework of the European Union Horizon 2020 Galileo-2014-1 ERSAT EAV Project
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