Name : Chengming Jin Supervisor : Allison Kealy GNSS-based Positioning Scheme & Application in Safety-critical Systems of Rail Transport
CONTENT I ntroduction 1 Challenges 2 Solutions 3
Introduction How Modern Railway Signal Works? 1
Introduction Signalling System: Track Circuit 2
Introduction History of Signalling Systems 3 Diversity of European ATP systems ETRMS/ETCS Cockpit
Introduction Train Control Systems: Positioning Scheme Signalman Token one engine in steam Driver A token being offered by a signalman on the Keighley 4 and Worth Valley Railway (from Wikipedia)
Introduction Train Control Systems: Positioning Scheme speed, location speed, location Accumulated error Calibration 5
Introduction Train control systems: Balise 2.5 km More in station Expensive difficult to maintain 6
Introduction Signalling System: Fixed Block & Moving Block A B C D E Mainstream Signalling System Signalling System in the Future 7 *THE DEVELOPMENT AND PRINCIPLES OF UK SIGNALLING
Introduction Next-Generation Train Control System No track circuit Ability to determine train integrity on board No or less balise Trains find their position themselves Full radio-based train spacing Moving Block 8
Introduction GNSS Location info. with high accuracy Time info. in all weather conditions Short messages(BDS) anywhere on or near the Earth Cost-efficient available 24/7/365 9
Introduction GNSS-based train control systems GPS-based PTC (Positive Train EC and European Railway Agency Control) had been equipped in (ERA) launched many projects to ATLAS 400, an European GPS- the US and China (Qinghai-Tibet promote the progress of GNSS- based train control system Line) based railway applications GLONASS SDCM 2014 Shift2Rail WAAS GALI LEO EGNOS 2012 3InSat SATLOC MSAS GPS WAAS BDS QZSS 2010 GRail Ⅱ GAGAN 2005 GRail Non-safety 2004 GEORAIL applications ECORAIL Locoprol 2001 InteGRail Gaderos RUNE GNSS is a worldwide, cost-efficient approach to locate the target, Europe GNSS-based railway which makes GNSS-based positioning become one of the most promising applications projects positioning solutions for the next-generation train control system. 10
CONTENT I ntroduction 1 Challenges 2 Solutions 3
Challenges GNSS was refused by railway: Policy issue ETCS (European Train Control System) 、 CTCS (Chinese Train Control System) have been standardized in the last two decades. Balise and STM (Specific Transmission Module) are necessary in ETCS-1,2. ERTMS/ETCS reference architecture* *SUBSET-026 ERTMS/ETCS System Requirements 11 Specification issue:3.0.0
Challenges GNSS was refused by railway: Masked sky Accuracy & multipath 34% Accuracy of distances measured on-board: ± + (5 m 5% ) S Accuracy of distinguishing parallel tracks: 1.5m Masked sky & multipath 3-5m ERTMS/ETCS reference architecture* *SUBSET-026 ERTMS/ETCS System Requirements 12 Specification issue:3.0.0
Challenges GNSS was refused by railway: There is a wall!! RAMS Railway applications must meet the requirements for Reliability, Availability, Maintainability, and Safety GNSS performance parameters, which are derived from aviation, are SIS Relation between GNSS and Railway Signalling Availability, Integrity, Continuity QoS Properties* Safety: According to CCS TSI 2012/88/EU, for the hazard `exceeding speed and/or distance limits advised to ERTMS/ETCS' the tolerable rate (THR) is 10 -9 /h for random failure, for on-board ERTMS/ETCS and for track-side, and < 10 -9 positioning unit is just one of many subsystems. ? *Debiao Lu, “GNSS for Train Localisation Performance 13 Evaluation and Verification”, Dissertation, 2014.
CONTENT I ntroduction 1 Challenges 2 Solutions 3
Solutions Solutions: Potentially SPS Pseudorange-based High Accuracy GNSS DGNSS High Availability RTK Carrier-phase-based GNSS High Safety PPP SPS: Standard Positioning Service DGNSS: Differential GNSS RTK: Real Time Kinematic PPP: Precise Point Positioning 14
Solutions Solutions: Why PPP? Station movements that result from geophysical phenomena such as tectonic plate motion, Earth Differential solutions tides and ocean loading enter the PPP solution in ϕ = ρ + ε full, as do observation errors resulting from the i i i troposphere and ionosphere. − ϕ = − ρ − ε Relevant satellite specific errors are satellite clocks, satellite antenna phase center offset, group j j j delay differential, relativity and satellite antenna phase wind-up error. PPP solutions Receiver specific errors are receiver antenna ϕ = ρ + ε phase center offset and receiver antenna phase k k k wind-up. In comparison with DGNSS, PPP has higher accuracy(centimetre to decimetre level*) Compared with RTK, PPP requires fewer reference stations globally distributed. PPP gives a highly redundant and robust position solution * M.D. Laínez Samper et al, Multisystem real time precise-point-positioning, Coordinates, Volume VII, Issue 2, February 2011 15
Solutions Solutions: PPP-based multi-sensor fusion δψ δ δ b b , b n , v p a g nb eb b b f Navigation Corrected Position, ib IMU ω Processor Velocity, Attitude b ib n n p , v − I I + n v O ODO EKF + δ K n n p , v G G Integrity Integrity PPP Monitoring Information IMU: Inertial Measurement Unit ODO: odometer 16 EKF: Extended Kalman Filter
Solutions Scenarios GNSS/PPP IMU ODO not converged Scenario 1 available available available available available available Scenario 2 converged unavailable Scenario 3 available available 16
Solutions On-site test GNSS/INS Kalman Filter compares with GNSS position 10 6 2.8956 2.8954 2.8952 2.895 2.8948 ECEF y axis (unit:m) 2.8946 2.8944 2.8942 2.894 Kalman Filter Solution 2.8938 GNSS Position Info. 2.8936 -4.1299 -4.1298 -4.1297 -4.1296 -4.1295 -4.1294 -4.1293 -4.1292 -4.1291 ECEF x axis (unit:m) 10 6 Trajectory of On-site Test Position Error 17
Solutions Simulation test 10 6 INS Navi. Solution Compares with Real Trajectory 4.3882 INS Navi. Solution 4.38815 Real Trajectory 4.3881 ECEF y axis (unit:m) 4.38805 4.388 4.38795 4.3879 4.38785 -2.1723 -2.1722 -2.1721 -2.172 -2.1719 ECEF x axis (unit:m) 10 6 SPIRENT Simulator Navigation Trajectory 17
Solutions Solutions: PPP-based multi-sensor fusion INS Navigation Error INS/ODO Kalman Filter Position Error 15 1 North error 0.5 East error Down error 10 0 INS/ODO Navigtaion error(unit:m) -0.5 5 Navigation Error(unit:m) -1 0 -1.5 -2 -5 North Error East Error -2.5 Down Error -3 -10 0 1000 2000 3000 4000 5000 6000 0 1000 2000 3000 4000 5000 6000 Num of Navigation Solution Num of Navigation Solution INS/ODO Kalman Filter Navigation Error INS Navigation Error *GNSS position error ~ N(0,1); GNSS velocity error ~ N(0,0.01); ODO velocity error ~ N(0,0.01) 17
Solutions Solutions: PPP-based multi-sensor fusion GNSS/INS/ODO Kalman Filter position error GNSS/INS Kalman Filter Position Error 0.6 1.2 North error North error 1 East error East error 0.4 Down error Down error 0.8 GNSS/INS Kalman Filter Navigation Error(unit:m) 0.2 0.6 GNSS/INS/ODO Navigation Error(unit:m) 0.4 0 0.2 -0.2 0 -0.2 -0.4 -0.4 -0.6 -0.6 -0.8 -0.8 0 1000 2000 3000 4000 5000 6000 0 1000 2000 3000 4000 5000 6000 Num of Navigation Solution (Sample frequency: 100 Hz) Num of Navigation Solution (Sample frequency: 100 Hz) GNSS/INS Kalman Filter Navigation Error GNSS/INS/ODO Kalman Filter Navigation Error *GNSS position error ~ N(0,1); GNSS velocity error ~ N(0,0.01); ODO velocity error ~ N(0,0.01) 18
Solutions Quality Control: Detection, Identification and Adaptation(DIA) − T 1 v Q v = k v k t k Based on consistency check of innovations k m k *Quality control and integrity, Delft school 19
Solutions Quality Control: Detection, Identification and Adaptation(DIA) Bias (unit: m/s) Detected Missed Detection Success Rate 0 1000 20 98.04% 0.1 134 886 13.13% 0.5 1000 20 98.04% 1 1020 0 100% Bias (unit: degree) Detected Missed Detection Success Rate 0 1000 20 98.04% 0.0000001 77 943 7.54% 0.000001 1000 20 98.04% 0.1 1000 20 98.04% 0.5 1000 20 98.04% 10 1020 0 100% 20
Solutions Threshold THR <= 10 -9 /h 0.12 Chi-square Noncentral Chi-square 0.1 Threshold 0.08 0.06 0.04 0.02 0 0 5 10 15 20 25 30 35 40 45 50 20
Solutions Further Research DIA global test Track maps aided PPP integrity monitoring scheme 21
Thank You Lhasa
Recommend
More recommend
