Note: Descriptions are shown in the official language in which they were submitted.
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Equipment for a secondary rail detection system and signalization system
integrating such equipment
The present invention relates to equipment for a secondary rail detection
system of
an interlocking system for a signalization system.
The present invention more particularly relates to an automatic train control
architecture for trains traveling on a railroad network. Such an architecture
is referred to
as Automatic Train Control (ATC).
In a known manner, an ATC architecture comprises different systems cooperating
with each other to allow trains to travel safely on the network.
Different ATC architectures exist; however, the present invention more
specifically
relates to an ATC architecture of the "communication-based train control"
(CBTC) type. A
CBTC architecture is diagrammatically illustrated in figure 1.
A CBTC architecture is based on the presence of computers onboard the trains.
The computer 26 of a train determines a certain number of operating parameters
and
communicates with various systems on the ground to allow the train to perform
its
assigned mission safely. This computer on the one hand covers the functional
needs of
the train, i.e., for example the stations to be served, and on the other hand
controls safety
points, i.e., for instance verifies that the train is not traveling at an
excessive speed. The
computer 26 of a train is at least connected to an onboard radio communication
unit 27,
able to establish a radio link with base stations 25 of a communication
infrastructure,
which in turn is connected to a communication network 29 of the CBTC
architecture.
On the ground, the CBTC architecture comprises a zone controller (ZC)
referenced
by figure 50 in figure 1. This zone controller 50 is in particular responsible
on the one hand
for monitoring the presence of the trains on the railroad network, and on the
other hand, in
a centralized architecture, for providing movement authorizations to the
trains that are of a
nature to guarantee their safe movement, i.e., for example not to give a train
a movement
authorization that would cause it to go past the train preceding it.
The CTC architecture is part of an overall system, called signaling system (SS
in
figure 1), that is also able to command a plurality of pieces of equipment on
the track.
The signaling system comprises an automatic train supervision (ATS) system.
The
ATS system is implemented in an operational unit and comprises man / machine
interfaces, allowing operators to intervene on the various systems of the
signaling system
and, in particular, the trackside equipment. For example, the operator can
remotely control
closing of the signal (turning a light red) from the ATS.
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The signaling system also comprises an interlocking system. Such an
interlocking
system is able to manage the trackside equipment, such as signal lights,
switching
actuators, etc., that trackside equipment allowing the trains to move safely
and avoiding
conflicting movements between them. Once based on electromechanical relays,
today the
interlocking system is computerized by suitable computers able to command the
trackside
equipment. Such an interlocking computer is referenced by number 19 in figure
1.
The railroad network is made up of railroad track sections, each track section
being subdivided into zones. In figure 1, three successive zones 14A, 14B and
14C are
shown.
The occupancy of a zone of a track section is a key piece of information for
railroad security. The determination of that information will now be
described.
The zone controller receives information on the one hand from a primary
detection
system, and on the other hand from a secondary detection system.
The primary detection system makes it possible to determine the zone occupied
by
a train based on the instantaneous position of the train determined by the
train itself. More
specifically, the zone controller receives the instantaneous position of a
train from each
computer 26 onboard that train 16. This position is determined by the onboard
computer
from the detection of beacons 24 placed along the track 12 and whose
geographical
positions are known, and from odometry means equipping the train and allowing
the
computer 26 to determine the distance traveled by the train since the last
beacon crossed.
In another embodiment, the train uses other means to determine its position:
for example,
an accelerometer (in place of the odometer) or a GPS (in place of the
beacons). From the
instantaneous position of the train, the zone controller uses a geographical
map of the
network, on which each zone is uniquely identified, to deduce the zone in
which the train
is currently located. A first state El of the zone in which the train is
located then assumes
the "occupied" value.
It should be noted that for safety reasons, according to the primary detection
system, not only is the zone in which the train is located in the "occupied"
state, but the
adjacent zones before and after that central zone are as well, so as to define
a safety area
around the train. That additional area covers the maximum distance that the
train can
travel between the time when it calculates the position that it will send to
the zone
controller and the time when that zone controller receives the information.
Furthermore, as long as no other position information is received by the zone
controller, the latter continues to extrapolate the position of the train to
cover its potential
movements.
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The first state El of the zones in which no train is located at the current
moment
assumes the "free" value.
In this way, a first piece of occupancy information for each zone is
determined by
the zone controller.
The secondary detection system is able to back up the primary detection
system;
for instance, in the event the radio communication unit 27 of a train 16 is no
longer
working, the zone controller 50 cannot obtain the instantaneous position of
the train. It is
important to note that a "purely" CBTC system can operate with only the
primary
detection. The secondary system is, however, important on the one hand to
cover the
failure modes of the CBTC communication, and on the other hand to allow trains
not
equipped with CBTC to travel on the same railroad network.
Using suitable track equipment, positioned alongside the track, the secondary
detection system is able to detect the presence of a train in a given zone.
In a first embodiment, the secondary detection system is based on counting the
number of axles of a vehicle passing in front of an axle sensor situated at
each end of the
considered zone. This system is referred to as an "Axle Counter". Thus, when a
vehicle
enters a zone, the entry sensor, situated at the entry of that zone, allows
the
incrementation of a state counter associated with that zone, each time the
passage of an
axle of the vehicle is detected. When the vehicle leaves the considered zone,
the exit
sensor, situated at the exit from that zone, makes it possible to decrement
the same state
counter by one unit, each time the passage of an axle of the vehicle is
detected. Thus, the
zone is in the "free" state when the state counter associated with that zone
is equal to
zero. Otherwise, the zone is in the "occupied" state.
In a second embodiment, the secondary detection system comprises a sensor of
the track circuit type. This sensor makes it possible to detect the presence
of a short-
circuit when each line of rails of the considered zone is powered on. In fact,
if a vehicle is
present in that zone, the axle of the vehicle electrically connects the two
rail lines and
creates a short-circuit. Thus, detecting a short-circuit makes it possible to
place a binary
state counter at the unit value corresponding to the "occupied" state of the
zone.
Otherwise, the state counter assumes the zero value and the zone is in the
"free" state.
In these two embodiments, the secondary detection system comprises, aside from
a plurality of tracks sensors, a plurality of intermediate equipment items
making it possible
to use analog measurement signals at the output of the sensors to generate
occupancy
information for the track that can be sent to the interlocking system. Thus,
the interface
between the tracks sensors and the interlocking system can be broken down into
two
parts:
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- an "upstream" part, which connects the tracks sensors to a piece of
detection
equipment. This part is made up of a cable connecting the sensors to the
detection equipment, which in turn is made up of electromechanical relays
making it possible to acquire analog signals at the output of the sensors, and
allowing the implementation of occupancy state sensors for the corresponding
zones by controlled switches;
- a "downstream" part, which connects the detection equipment to the
interlocking system. This part is able to emit a read signal of the occupancy
state sensor of a zone of the detection equipment, generate a suitable
message comprising the occupancy information, and send it to the interlocking
system. In the state of the art, this downstream part is also made up of
pieces
of equipment composed of electromechanical relays and electronic boards for
interfaces with the interlocking system.
In general, these intermediate pieces of equipment are installed in a
technical site
arranged to that end at the edge of the railroad track.
The secondary detection system of the state of the art has a certain number of
drawbacks.
In particular, the intermediate equipment of the secondary detection system is
expensive, bulky and difficult to install and maintain. In particular, the
second so-called
"downstream" part for interfacing with the interlocking system is complex.
The present invention aims to resolve the aforementioned problems. It in
particular
aims to propose an interface between sensors and an interlocking system for a
secondary
ground detection system that is more compact, less expensive, easier to
install and easy
to maintain. The present invention aims to simplify the second so-called
"downstream"
part of such an interface by drastically decreasing the necessary number of
components.
This simplification involves modifying the detection equipment of the so-
called "upstream"
part of that interface.
To that end, the invention relates to a piece of detection equipment for a
secondary rail detection system of an automatic railroad traffic control
architecture on a
railroad track, said railroad track being subdivided into a plurality of
zones, said equipment
being associated with at least one particular zone, and being able to generate
release
information for said particular zone that by a vehicle traveling on the track,
from at least
one measurement signal received from at least one sensor of the secondary
detection
system connected to said equipment, wherein said equipment is a computer,
comprising:
- a hardware layer, comprising:
= computation means;
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= storage means;
= an input interface comprising: a connector, to connect said at least one
sensor to said equipment, and digitization means, to produce a digital
signal from the measurement signal delivered by said at least one
5 sensor;
= a communication board, to connect the equipment to a communication
network and allow direct two-way communication between the
equipment and an interlocking system of a signaling system to which
said automatic traffic control architecture belongs, said interlocking
system being connected to the communication network;
- a hardware layer, comprising:
= application software, able to acquire the digital signal of the entry
interface and generate release information for said particular zone;
= pilot software, able to generate a data message from said release
information of said particular zone, the data message respecting a
secure communication protocol, and to pass the data message to the
communication board so that it sends that data message over the
communication network to the interlocking system.
According to other advantageous aspects of the invention, the equipment
comprises one or more of the following features, considered alone or according
to all
technically possible combinations:
- said sensor of the secondary detection system is a track circuit sensor,
said
connector and said application software being adapted to that sensor;
- said sensor of the secondary detection system is an axle sensor, said
connector
and said application software being adapted to that sensor;
- said communication board is a communication board of the ETHERNET type;
- said secure communication protocol is the protocol defined by standard
FSFB2;
- said pilot software is able to command a reset of the release information
for said
particular zone from a reset message coming from said interlocking system and
received
by said communication board.
The invention also relates to a signalization system for a railroad track
comprising:
a communication network, preferably of the ETHERNET type; an interlocking
system for
controlling the traffic of the vehicles traveling on the track; and an
automatic control
architecture for the railroad traffic on the track, the architecture being of
the type based on
control of the vehicles by onboard computers, said railroad track being
subdivided into a
plurality of zones, said architecture comprising:
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- a primary detection system, to detect the presence of a vehicle on at least
one
particular zone from a determination of the position of the vehicle done by a
computer
onboard said vehicle, the primary detection system being able to generate a
first piece of
release information; and
- a secondary track detection system, to detect the presence of a vehicle on
at
least one particular zone of the track, comprising a sensor situated along the
track,
associated with said particular zone and able to generate a measurement
signal, said
secondary detection system being able to generate a second piece of release
information
and communicate it to the interlocking system, the secondary detection system
being
independent from the primary detection system,
wherein the secondary detection system comprises a piece of equipment
according to any one of the preceding claims, the entry interface of which is
connected to
said at least one sensor and the communication board of which is directly
connected to
the interlocking system, via the communication network.
The invention will be better understood using the following description,
provided
solely as a non-limiting example and done in reference to the appended
drawings, in
which:
- figure 1 is a diagrammatic view of an automatic railroad traffic control
architecture
on a railroad track according to the invention and a vehicle traveling on that
railroad track;
- figure 2 is a diagrammatic view of a piece of equipment of the secondary
track
detection system of the architecture of figure 1.
The signalization system 10 for a railroad track 12 is illustrated in figure
1.
The railroad track 12 is divided into a plurality of sections, each section
being
subdivided into a plurality of zones on which the railroad traffic is
monitored. Figure 1
illustrates a section of the railroad track 12, which is subdivided into three
zones
designated by reference is 14A, 14B and 140.
Each zone 14A, 14B or 140 comprises an identifier making it possible to
distinguish it uniquely and certainly from the set of zones of the track 12.
Figure 1 further illustrates a vehicle 16 traveling on that railroad track 12.
The
vehicle is illustrated at the time when it enters the zone 14B: it crosses a
first border 18A,
situated between the zones 14A and 14B and making up an entry border for the
zone
14B, and moves toward a second order 18B, situated between the zones 14B and
140
and constituting an exit border for the zone 14B.
"Vehicle" refers to any vehicle able to travel on the railroad track 12.
The vehicle 16 comprises a plurality of axles, at least one wheel for each
line of
rails of the railroad track 12 being mounted on each axle to allow the vehicle
16 to move
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along the railroad track. The axles and the wheels are made from an
electrically
conductive material. In figure 1, the vehicle 16 comprises four axles
designated by
references 17A, 17B, 170 and 17D.
The signalization system 10 comprises an interlocking system 19 to control the
travel of the vehicles traveling on the railroad track 12, and in particular
that of the vehicle
16. Such an interlocking system of the railroad track 12 is also referred to
in the state of
the art as interlocking.
The interlocking system 19 is able to drive the operation of a plurality of
pieces of
equipment distributed along the track 12, only one piece of detection
equipment 20,
described in more detail below, being shown in figure 1. Thus, for example,
such pieces of
equipment assume the form of switching actuators, signalization lights or
other
electromechanical devices known in themselves in the state of the art.
The interlocking system 19 for example comprises a plurality of computers able
to
analyze and control the railroad traffic on the railroad track automatically
or semi-
automatically. The interlocking system 19 is situated away from the equipment
of the
railroad track 12 and is connected thereto by a suitable communication network
22,
preferably of the ETHERNET type.
The signalization system 10 comprises an automatic traffic control
architecture for
trains on the track, which is an architecture of the communication-based train
control
(CBTC) type.
This architecture comprises a zone controller 50 able to reconcile the
occupancy
information of the track from a primary detection system and a secondary
detection
system.
This architecture thus comprises a primary detection system SPD using beacons
24A, 24B or 240. The latter are respectively situated in zones 14A, 14B and
140 and are
able to send their precise geographical position to a computer 26 onboard the
vehicle 16.
The instantaneous position is computed by the computer 26, from the
geographical
position of the last beacon crossed, which is updated with the measurement of
the path
traveled by the vehicle since the last beacon crossed, obtained using odometer
means
equipping the vehicle 16.
The vehicle 16 further comprises onboard radio communication units 27, able to
send and receive wireless signals with base stations 25 positioned on the
ground along
the track 12. These base stations 25 are connected to a communication network
29 of the
system 10.
The units 27 allow communication to the zone controller 50 of a message
comprising the instantaneous position and an identifier of the vehicle 16,
making it
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possible to distinguish it uniquely and certainly from other vehicles
traveling on the track
12.
Based on the track layout plan, i.e., the subdivision into geographically
identified
zones of the track 12, and the instantaneous position of the vehicle 16, the
zone computer
50 determines the identifier of the zone in which the vehicle is located. It
associates the
"occupied" state with that zone.
In order to offset a failure of the primary detection system SPD or to allow
the
travel of trains not equipped with CBTC on the same railroad network, the
primary
detection system SPD is backed up by a secondary detection system SSD, which
is able
to detect the occupancy state of the zones of the track 12 through a direct
measurement
of the presence of the vehicle in each zone.
The architecture thus comprises a secondary detection system SSD to detect the
presence or absence of a vehicle in the zones 14A, 14B and 140 of the railroad
track 12.
The secondary detection system SSD generates a second piece of occupancy
information
that is communicated to the zone computer 50.
The secondary detection system SSD comprises a plurality of sensors and a
plurality of pieces of detection equipment 20.
In a first embodiment shown in figure 1, the secondary detection system SSD
comprises axle sensors. In order to determine the occupancy state of the zone
14B, an
entry sensor 28A and an exit sensor 28B are placed along the track at the
first border 18A
and the second border 18B of the zone 14B, respectively. Each sensor 28A or
28B is a
counting head able to send a measurement signal when an axle crosses the
border 18A
or 18B, respectively. The measurement signal is for example a short-lasting
pulse.
Each zone of the track 12 is associated with an entry sensor and an exit
sensor.
Advantageously, to reduce costs, the exit sensor of the zone is also the entry
sensor of
the next zone.
It should be noted that in figure 1, a zone is a track portion with two ends,
but it
could be a zone comprising several entry and/or exit ends, such as a zone
corresponding
to a switch.
The two sensors of a zone are connected to the input of a piece of detection
equipment 20. More particularly, for the case of the zone 14B, the sensors 28A
and 28B
are directly connected to the detection equipment 20 by wired connections.
In the example embodiment shown here in detail, the detection equipment is
dedicated to one zone. It is therefore associated with a pair of sensors.
Alternatively, a
piece of detection equipment is shared by a plurality of zones that are
geographically
adjacent to one another. The sensors of each of the zones are connected to the
input of
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the detection equipment, which measures the occupancy state of each of those
zones at
each moment.
The detection equipment 20 is also directly connected to the interlocking
system
19, via a communication network 22.
The detection equipment 20 is able to acquire the measurement signals coming
from a pair of sensors, and process them so as to determine an occupancy state
of the
corresponding zone and send the occupancy information to the interlocking
system 19 via
the communication network 22.
The interlocking system 19 relays this information and sends it to the zone
controller 50, via the communication network 29 of the system 10.
The equipment 20 is illustrated in more detail in figure 2.
Thus, as illustrated in this figure 2, the equipment 20 is a computer 40
comprising
a hardware layer 42 and a software layer 44.
The hardware layer 42 comprises a computation means 51 and a storage means
53. The storage means 53 is for example a memory able to store the
instructions for a
plurality of software programs. The computation means 51 is for example a
processor
able to execute the software stored in the storage means 53.
The hardware layer 42 further comprises an input interface 55. The input
interface
comprises a plurality of connectors 57, each connector 57 making it possible
to connect
the equipment 20 to a sensor, such as the sensors 28A and 28B. The input
interface
comprises digitization means 59 to produce a digital signal from an analog
measurement
signal coming from a sensor 28A or 28B.
The hardware layer 42 further comprises a communication board 61 of the
ETHERNET type to connect the equipment 20 to the communication network 22.
This
communication board 61 thus allows direct two-way communication between the
detection
equipment 20 and the interlocking system 19, through the communication network
22.
In the prior art, the hardware means for connecting the detection equipment to
the
interlocking system is not a communication board, but a digital/analog
conversion board
able to generate a digital/analog signal that is sent, through a plurality of
pieces of wired
intermediate equipment (such as relays able to perform an impedance
adaptation), to
intermediate input equipment on the interlocking system. This input equipment
comprises
input boards connected by a communication network to the interlocking system.
Thus, the
present detection equipment eliminates the many intermediate layers between
the
sensors and the interlocking system 19.
The software layer 44 comprises an application software program 63 stored in
the
storage means 53. When it is executed, the application software 63 is able to
acquire the
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digital signals provided at the output of the digitization means 59, and from
the signals, for
each zone of the track with which the equipment 20 is associated, to keep a
state counter
up to date and generate occupancy information as a function of the current
value of that
state counter.
5 The
state counter of a zone for example assumes the form of an integer variable
64, associated with that zone and stored in the storage means 53. The
application
software 63 is able to increment or decrement the value of that variable 64 as
a function of
the measurement signals coming from the sensors associated with that zone or a
reset
message MR coming from the interlocking system 19 via the communication
network 22.
10 For
security reasons, the occupancy information is in reality done in the form of
its
inverse state, i.e., release information. The release information is a binary
property
assuming a "false" value when the state counter is different from zero, the
corresponding
zone being in the "occupied" state, and a "true" value when the state counter
is equal to
zero, the corresponding zone being in the "free" state.
The software layer 44 further comprises a pilot software program 65 stored in
the
storage means 63 and able to generate a data message MD from the release
information
generated by the application software 63 and the identifier of the
corresponding zone.
The data message MD is generated by the pilot software so as to respect a
secure
communication protocol, for example the FSFB2 (Fail Safe Field Bus 2nd
generation)
protocol. This protocol in particular makes it possible to send the data
message MD, via
the communication network 22, with a requisite security level for railroad
applications.
The pilot software 65 is able to pass the data message MD to the communication
board 61 so that the latter sends it to the interlocking system 19 via the
communication
network 22.
The pilot software 65 is also able to reset the state counter of a zone, i.e.,
to reset
the corresponding variable 64, from a reset message MR sent by the
interlocking system
19 and received via the communication network 22 and the communication board
61.
The operation of the equipment 20 according to the first embodiment of the
invention will now be explained.
Initially, no vehicle traveling in the zone 14B of the railroad track 12, the
state
counter associated with that zone is equal to zero, corresponding to the
initialization
value. The zone 14B is therefore in the "free" state.
When the vehicle 16 enters the zone 14B by crossing the first border 18A, the
entry sensor 28A detects the first axle 17A and sends a measurement signal
corresponding to the detection of an axle to the input interface 55 of the
equipment 20.
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This measurement signal is next converted into a digital signal by the
digitization
means 59 and is processed by the application software 63 executed by the
computation
means 51.
Thus, the application software 63 increments the variable 64 by one unit. The
state
sensor being non-zero, the occupancy state switches to the "occupied" state.
If the variable 64 is different from zero, the pilot software 65 generates a
data
message MD comprising the "false" release information indicating the
"occupied" state of
the zone 14B and the identifier of the zone 14B. It next sends that message MD
to the
interlocking system 19.
Similarly, upon each passage of one of the axles 17B, 170 or 17D, the variable
64
is incremented by one unit. Thus, in the embodiment of figure 1, after the
passage of all of
the axles of the vehicle 16, the variable 64 is equal to "4".
When the first axle 17A of the vehicle 18 crosses the second border 18B of the
zone 14B, the exit sensor 28B sends a measurement signal to the input
interface 55 of the
equipment 20.
This measurement signal is next converted into a digital signal that is
processed by
the application software 63. Once it is received, the application software 63
decrements
the variable 64 by one unit.
Similarly, upon each passage of an axle 17B, 170 or 17D, the variable 64 is
decremented by one unit.
Whenever that variable is once again equal to zero, the pilot software 65
generates a data message MD comprising the "true" release information,
indicating that
the occupancy state of the zone 14B is "free", and the identifier of the zone
14B. This
message MD is sent to the interlocking system 19.
The zone 14B is considered by the interlocking system 19 to be free until a
message MD is received indicating that the state is "occupied".
If the equipment 20 receives a reset message MR from that interlocking system
19, the variable 64 is reset to its initialization value, i.e., zero. The
message MR thus
comprises the identifier of the zone whose status counter must be reset.
According to a second embodiment (not illustrated), the operation of the
secondary
detection system SSD to detect the presence of the vehicle in a zone is based
on a track
circuit associated with that zone, also known in the state of the art as a
Track Circuit.
In this embodiment, the lines of rails of the railroad track are connected to
each
other by electrical conductors placed at the entry and exit borders of a zone
to obtain an
electric circuit forming a loop.
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The secondary detection circuit SSD comprises a sensor making it possible,
when
that loop is turned on, to detect the presence of a short-circuit in that loop
created by an
axle of a vehicle.
The measurement signal sent by that sensor to the input interface of the
equipment, once digitized, is processed appropriately by the application
software.
That measurement signal for example corresponds to the impedance value of the
electric circuit. Thus, a variation of that value allows the application
software to determine
the occupancy state of that zone.
More particularly, if that variation is outside a predetermined interval for
the
corresponding zone, the pilot software generates a data message comprising the
"false"
release information, indicating that the occupancy state of the zone is
"occupied", and the
identifier of the zone. That message is sent to the interlocking system. When
that variation
is again situated in the predetermined interval, the pilot software generates
a data
message comprising the "true" release information, indicating that the
occupancy state of
the zone is "free", and the identifier of the zone, to send that message to
the interlocking
system.
The particular advantage of the detection equipment and its interfacing with
the
interlocking system lies in its smaller dimensions relative to those of the
various
component equipment items of a secondary detection system of the state of the
art.
Furthermore, the equipment, as well as its interfacing with the interlocking
system, can be
installed easily and is particularly simple to maintain. The associated
manufacturing cost
and the operating cost are particularly low. This equipment may further be
easily adapted
to different communication protocols and different control architectures
through a simple
modification of its software layer.
