INTEGRAIL Details
System Design -- Background and Motivation
In railway traffic, three main areas of application of telematics systems (i.e. position/status determination and communication link) have to be distinguished:
- train and signaling control
- passenger information
- fleet management
While passenger information and fleet management show moderate requirements concerning accuracy, reliability, availability, and integrity, high requirements are to be met in train and signaling control.
Low requirements can mostly be fulfilled with "simple" systems using GPS L1 receivers and standard communication links (GSM)
The high demands in signaling and train control can only be fulfilled with hybrid positioning systems using
- GPS (L1+L2) and EGNOS, inertial measurement sensors, odometers, digital track maps, and Kalman filters for sensor fusion
- flexible communication links ( GSM, GSM-R, GPRS, satcom)
Major Objectives
The INTEGRAIL system shall allow precise train positioning in safety-related applications including the safe discrimination between parallel tracks and track change at switches.
The INTEGRAIL mobile unit shall be a coherent multi-sensor positioning system ('mobile locator') combining GPS and EGNOS (GNSS-1) data with other location and velocity sensor data within a 'hybridized positioning solution'.
The mobile unit shall operate autonomously, i.e. without the need for a permanent human operator, but remote monitoring and control shall be possible.
Electrical power shall be provided by the train.
Perspectives
The INTEGRAIL mobile unit shall represent a train-borne position determination sub-system fulfilling the functionality of train location and velocity as specified by the European Train Control Standard (ETCS).
It shall be compatible to communicate with the locomotive's ERTMS/ETCS onboard system via serial interface.
It shall be able to output a software data stream which is compatible to the ERTMS 'Location data message' (LRBG etc.).
The INTEGRAIL system shall not be designed for train integrity monitoring.
Integration of INTEGRAIL into an ETCS Train
Fig. 1 (click image to enhance) -- Integration of INTEGRAIL into an ETCS Train
INTEGRAIL Prototype System Specifications
System Positioning Accuracy
< 5 m + 5% * distance travelled (95%, along-track)
< 1 m (95%, cross-track)
System Integrity
alarm limit < 20 m
TTA < 6 sec
(EGNOS;
target: < 1 sec)
integrity risk < 10-7 (target: < 10-9)
System Availability/Continuity
> 99,99999% (i.e. unavailability < 10-7) for every 20 sec or 2 km travelled
System Qualification
according to CENELEC standards ('electronic systems on rolling stock'): thermal, EMC, vibration
INTEGRAIL Mobile Unit Prototype Block Diagram
Fig. 2 (click image to enhance) -- INTEGRAIL Mobile Unit Prototype Block Diagram
Fig. 3 (click image to enhance) -- INTEGRAIL Mobile Unit Prototype View
INTEGRAIL Sensor Fusion
Fig. 4 (click image to enhance) -- Structure of INTEGRAIL Sensor Fusion
Communication Architecture
Fig. 5 (click image to enhance) -- INTEGRAIL: Communication Architecture
Central Server
Fig. 6 (click image to enhance) -- Central Server Block Diagram
Central Server Communication
Receive (Rx)
- receives pre-defined status messages from the mobile units per SMS to monitor performance
- any message consists of fixed header + header CRC, variable data + data CRC
- messages can be transmitted periodically or upon 'polling' command
- two messages are defined: configuration status, communication addresses
- contents: GPS position, speed, hybridized position, confidence level, health status, memory capacity, configuration data, ...
Transmit (Tx)
- sends pre-defined commands to the Mobile Unit per SMS for change of configuration parameters
- encoding of SMS is realized by communication backend software (header, data, CRC)
- three commands are defined: change communication address, change configuration parameters (archiving intervals, transmission intervals), poll configuration status
Visualization
- Apache webserver running script language PHP version 4
- Incoming messages are retrieved from the data base, outgoing commands are forwarded to data base (no direct link between webserver and communication backend)
- Graphical user interface (GUI), accessible via LAN and internet (TCP/IP) for remote users
- Different users with variable access rights are definable for each Mobile ID
Central Server with Interactive GUI for Remote Control
Fig. 7 (click image to enhance) -- Central Server with Interactive GUI for Remote Control
Selected Tests
In case you want to take a closer look at the data acquired during
several test runs, feel free to
send mail to the INTEGRAIL project manager,