CA3100131A1 - High-integrity autonomous system for locating a train in a railway network reference system - Google Patents
High-integrity autonomous system for locating a train in a railway network reference system Download PDFInfo
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- CA3100131A1 CA3100131A1 CA3100131A CA3100131A CA3100131A1 CA 3100131 A1 CA3100131 A1 CA 3100131A1 CA 3100131 A CA3100131 A CA 3100131A CA 3100131 A CA3100131 A CA 3100131A CA 3100131 A1 CA3100131 A1 CA 3100131A1
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- 238000000034 method Methods 0.000 description 11
- 238000004364 calculation method Methods 0.000 description 6
- 230000008859 change Effects 0.000 description 6
- 230000007704 transition Effects 0.000 description 4
- 238000012545 processing Methods 0.000 description 3
- 230000008901 benefit Effects 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B61—RAILWAYS
- B61L—GUIDING RAILWAY TRAFFIC; ENSURING THE SAFETY OF RAILWAY TRAFFIC
- B61L15/00—Indicators provided on the vehicle or train for signalling purposes
- B61L15/0092—Memory means reproducing during the running of the vehicle or vehicle train, e.g. smart cards
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B61—RAILWAYS
- B61L—GUIDING RAILWAY TRAFFIC; ENSURING THE SAFETY OF RAILWAY TRAFFIC
- B61L25/00—Recording or indicating positions or identities of vehicles or trains or setting of track apparatus
- B61L25/02—Indicating or recording positions or identities of vehicles or trains
- B61L25/021—Measuring and recording of train speed
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B61—RAILWAYS
- B61L—GUIDING RAILWAY TRAFFIC; ENSURING THE SAFETY OF RAILWAY TRAFFIC
- B61L25/00—Recording or indicating positions or identities of vehicles or trains or setting of track apparatus
- B61L25/02—Indicating or recording positions or identities of vehicles or trains
- B61L25/025—Absolute localisation, e.g. providing geodetic coordinates
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B61—RAILWAYS
- B61L—GUIDING RAILWAY TRAFFIC; ENSURING THE SAFETY OF RAILWAY TRAFFIC
- B61L2205/00—Communication or navigation systems for railway traffic
- B61L2205/04—Satellite based navigation systems, e.g. global positioning system [GPS]
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Train Traffic Observation, Control, And Security (AREA)
Abstract
Disclosed is a high-integrity autonomous system for locating a train in a railway network reference system, comprising:
- a high-integrity geographical locating device (1); - a high-integrity map database (2) of the railway network; and - a device (3) for tracking the train.
- a high-integrity geographical locating device (1); - a high-integrity map database (2) of the railway network; and - a device (3) for tracking the train.
Description
I
High-integrity autonomous system for locating a train in a railway network reference system The present invention relates to a high-integrity autonomous location system for locating a train in a rail network reference frame.
Systems for locating a train in a rail network using dedicated ground infrastructures are known, these guaranteeing the integrity of the location, that is to say that the risk of the train not being on the indicated section is smaller than an acceptable limit. This limit is linked to the risk of a serious event, such as a collision or derailment, and to the capacity of the rail traffic control system. These devices are very expensive.
Non-autonomous solutions require ground infrastructures that have a high maintenance cost. The cost of ETCS L2 track signaling is around Ã200K per km of track, and its deployment is therefore limited to high-traffic lines. The present solution has a far lower cost depending on the intended level of integrity, thereby making it possible to fit lines of the secondary network at a lower cost.
High-integrity autonomous geographical location devices also exist. Geographical location is understood to mean the location of a moving object in a reference frame linked to the Earth, such as longitude, latitude and altitude; high-integrity is understood to mean association, with the location, of an integrity protection interval or error ellipsoid and an alarm signal (the risk of the indicated position being outside the ellipsoid, without an alarm being raised, is smaller than an acceptable limit); and autonomous is understood to mean the lack of use of dedicated infrastructures.
A device based on a GNSS receiver and an inertial measurement unit IMU is one example of this type of high-integrity autonomous geographical location device. For example, European patent EP 301844761.
High-integrity autonomous system for locating a train in a railway network reference system The present invention relates to a high-integrity autonomous location system for locating a train in a rail network reference frame.
Systems for locating a train in a rail network using dedicated ground infrastructures are known, these guaranteeing the integrity of the location, that is to say that the risk of the train not being on the indicated section is smaller than an acceptable limit. This limit is linked to the risk of a serious event, such as a collision or derailment, and to the capacity of the rail traffic control system. These devices are very expensive.
Non-autonomous solutions require ground infrastructures that have a high maintenance cost. The cost of ETCS L2 track signaling is around Ã200K per km of track, and its deployment is therefore limited to high-traffic lines. The present solution has a far lower cost depending on the intended level of integrity, thereby making it possible to fit lines of the secondary network at a lower cost.
High-integrity autonomous geographical location devices also exist. Geographical location is understood to mean the location of a moving object in a reference frame linked to the Earth, such as longitude, latitude and altitude; high-integrity is understood to mean association, with the location, of an integrity protection interval or error ellipsoid and an alarm signal (the risk of the indicated position being outside the ellipsoid, without an alarm being raised, is smaller than an acceptable limit); and autonomous is understood to mean the lack of use of dedicated infrastructures.
A device based on a GNSS receiver and an inertial measurement unit IMU is one example of this type of high-integrity autonomous geographical location device. For example, European patent EP 301844761.
2 For this type of device, the service that is provided does not locate the train with a guarantee of integrity: as soon as the error ellipsoid is greater than half the distance between the railway tracks, it is no longer possible to reliably locate the train in the rail network.
One aim of the invention is to overcome the abovementioned problems.
What is proposed, according to one aspect of the invention, is a high-integrity autonomous location system for locating a train in a rail network reference frame, comprising:
- a high-integrity geographical location device (1) for high-integrity geographical location in a global geographical reference frame, comprising an inertial unit, a GNSS receiver, and a hybridization module for hybridizing the measurements provided by the inertial unit and the GNSS receiver, configured so as to provide the three position coordinates, the three speed components, and the heading angle of the train in the global geographical reference frame as well as their respective integrity protection intervals with respect to critical events that may affect the high-integrity geographical location device, so that the probability of the position or the speed or the heading angle being outside the integrity protection intervals is less than once every million hours;
- a high-integrity map database (2) of the rail network, configured so as to provide data geographically representing the rail network in the form of segments; and information representative of areas of the surroundings of the railway track exhibiting a risk of reflected GNSS
paths in order to maintain the integrity of the geographical location device; and - a tracking device (3) for tracking the train, configured so as to autonomously determine an identifier of the rail network segment on which the train is located, a high-integrity position of the train on this segment in the rail network reference frame, and the protection interval associated with the position of the train on the segment based on data
One aim of the invention is to overcome the abovementioned problems.
What is proposed, according to one aspect of the invention, is a high-integrity autonomous location system for locating a train in a rail network reference frame, comprising:
- a high-integrity geographical location device (1) for high-integrity geographical location in a global geographical reference frame, comprising an inertial unit, a GNSS receiver, and a hybridization module for hybridizing the measurements provided by the inertial unit and the GNSS receiver, configured so as to provide the three position coordinates, the three speed components, and the heading angle of the train in the global geographical reference frame as well as their respective integrity protection intervals with respect to critical events that may affect the high-integrity geographical location device, so that the probability of the position or the speed or the heading angle being outside the integrity protection intervals is less than once every million hours;
- a high-integrity map database (2) of the rail network, configured so as to provide data geographically representing the rail network in the form of segments; and information representative of areas of the surroundings of the railway track exhibiting a risk of reflected GNSS
paths in order to maintain the integrity of the geographical location device; and - a tracking device (3) for tracking the train, configured so as to autonomously determine an identifier of the rail network segment on which the train is located, a high-integrity position of the train on this segment in the rail network reference frame, and the protection interval associated with the position of the train on the segment based on data
3 provided by the high-integrity map database and the positions, speeds, headings and integrity protections provided by the high-integrity geographical location device, by resolving ambiguities of candidate segments, such that the probability of the train not being at the indicated location of the rail network is less than once every million hours, the tracking device being configured so as to retroactively provide said information representative of areas of the surroundings of the railway track exhibiting a risk of reflected GNSS paths to the high-integrity geographical location device during the movement of the train;
the high-integrity geographical location device being configured so as either to use only GNSS satellites for which the direction of the line of sight does not exhibit a risk of reflected paths at the location of the train, or to modify the weighting given to the various GNSS satellites used at the location of the train.
Such a system provides the high-integrity location service in the reference frame of interest, and not in the initial geographical reference frame. It thus makes it possible to inexpensively enhance devices based on IMU and GNSS, which provide a high-integrity service in a geographical reference frame, and to have excellent availability of the system regardless of climatic conditions.
Thus, if the geographical location device uses one or more sensors whose measurements are liable to be corrupted by the surroundings of the railway track, feedback makes it possible to reduce this risk. For example, for a GNSS sensor, the measurements, coming from satellites for which the geometric configuration of objects close to the track exhibits a risk of alteration, may be ignored a priori, so as not to compromise the integrity of the geographical location device.
In one embodiment, the tracking device is configured so as to retroactively provide high-integrity measurements of lateral deviation and heading deviation of the train with respect to the railway track of the rail network to the high-integrity geographical location device, the hybridization module being configured so as to take said measurements into account.
the high-integrity geographical location device being configured so as either to use only GNSS satellites for which the direction of the line of sight does not exhibit a risk of reflected paths at the location of the train, or to modify the weighting given to the various GNSS satellites used at the location of the train.
Such a system provides the high-integrity location service in the reference frame of interest, and not in the initial geographical reference frame. It thus makes it possible to inexpensively enhance devices based on IMU and GNSS, which provide a high-integrity service in a geographical reference frame, and to have excellent availability of the system regardless of climatic conditions.
Thus, if the geographical location device uses one or more sensors whose measurements are liable to be corrupted by the surroundings of the railway track, feedback makes it possible to reduce this risk. For example, for a GNSS sensor, the measurements, coming from satellites for which the geometric configuration of objects close to the track exhibits a risk of alteration, may be ignored a priori, so as not to compromise the integrity of the geographical location device.
In one embodiment, the tracking device is configured so as to retroactively provide high-integrity measurements of lateral deviation and heading deviation of the train with respect to the railway track of the rail network to the high-integrity geographical location device, the hybridization module being configured so as to take said measurements into account.
4 The geographical location device may thus benefit from additional measurements, which are liable to improve its performance, without compromising its integrity.
In one embodiment, the tracking device is configured so as to:
- eliminate the candidate segments not contained at least partly within the protection intervals provided by the high-integrity geographical location device, - compare the heading angle provided by the high-integrity geographical location device and the heading angle of the segments from the database that are compatible with the chaining of the rail network, and - select the segments compatible with the protection interval of the heading angle provided by the high-integrity geographical location device, and for which the following segment or the previous segment, depending on the direction of travel, has already been a candidate segment.
The device is thus capable of safely reducing the number of candidate segments, until discriminating the one true segment on which the train is located.
Candidate segment is the name given to a segment that has already been selected by the tracking device using one of the abovementioned methods. The set of candidate segments is stored from one calculation cycle to another in order to determine the candidate segments in the next calculation cycle that depend on the candidate segments in the previous calculation cycle and on the new data provided by the high-integrity geographical location device, as described further below.
According to one embodiment, the tracking device is configured so as to perform a correlation along the curvilinear abscissa between the successive heading angles provided by the high-integrity geographical
In one embodiment, the tracking device is configured so as to:
- eliminate the candidate segments not contained at least partly within the protection intervals provided by the high-integrity geographical location device, - compare the heading angle provided by the high-integrity geographical location device and the heading angle of the segments from the database that are compatible with the chaining of the rail network, and - select the segments compatible with the protection interval of the heading angle provided by the high-integrity geographical location device, and for which the following segment or the previous segment, depending on the direction of travel, has already been a candidate segment.
The device is thus capable of safely reducing the number of candidate segments, until discriminating the one true segment on which the train is located.
Candidate segment is the name given to a segment that has already been selected by the tracking device using one of the abovementioned methods. The set of candidate segments is stored from one calculation cycle to another in order to determine the candidate segments in the next calculation cycle that depend on the candidate segments in the previous calculation cycle and on the new data provided by the high-integrity geographical location device, as described further below.
According to one embodiment, the tracking device is configured so as to perform a correlation along the curvilinear abscissa between the successive heading angles provided by the high-integrity geographical
5 location device and the successive headings taken by each of the candidate segments, so as to select a single segment.
The tracking device is thus capable of discriminating the true segment from the other candidate segments when these follow paths having different headings.
In one embodiment, the tracking device is configured so as to determine a high-integrity speed and direction of movement of the train, by projecting, onto the direction of the current segment, the speed and its protection interval as provided by the high-integrity location device.
The tracking device thus provides additional information in addition to the positioning information. Reliability of the speed and direction of movement information is essential for controlling the train and managing traffic.
According to one embodiment, said data representing the rail network in the form of segments comprise, for each segment, the position coordinates and the heading angle of the initial point of the segment in the global geographical reference frame, the length of the segment, the value of a parameter representative of the curvature and its variation, and the value of parameters for chaining the segment with other segments, and the values of the limits in terms of the position error and the heading error of this segment.
A small number of parameters thus makes it possible to represent a significant length of the rail network. The chosen representation makes it possible notably to accurately calculate the geographical position coordinates and the heading angle of any point belonging to the segment, based on its curvilinear abscissa.
The tracking device is thus capable of discriminating the true segment from the other candidate segments when these follow paths having different headings.
In one embodiment, the tracking device is configured so as to determine a high-integrity speed and direction of movement of the train, by projecting, onto the direction of the current segment, the speed and its protection interval as provided by the high-integrity location device.
The tracking device thus provides additional information in addition to the positioning information. Reliability of the speed and direction of movement information is essential for controlling the train and managing traffic.
According to one embodiment, said data representing the rail network in the form of segments comprise, for each segment, the position coordinates and the heading angle of the initial point of the segment in the global geographical reference frame, the length of the segment, the value of a parameter representative of the curvature and its variation, and the value of parameters for chaining the segment with other segments, and the values of the limits in terms of the position error and the heading error of this segment.
A small number of parameters thus makes it possible to represent a significant length of the rail network. The chosen representation makes it possible notably to accurately calculate the geographical position coordinates and the heading angle of any point belonging to the segment, based on its curvilinear abscissa.
6 According to one embodiment, the tracking device comprises, in order to resolve ambiguities of the candidate segments:
- a module configured so as to perform an instantaneous resolution function based on distance; and/or - a module configured so as to perform an instantaneous resolution function based on the heading; and/or - a module configured so as to perform a points resolution function.
All of the geometric characteristics of the railway track are thus utilized to ascertain a bearing.
In one embodiment, the system furthermore comprises:
- an additional high-integrity geographical location device for high-integrity geographical location in a global geographical reference frame, different from the high-integrity geographical location device, configured so as to provide the position, the speed and the heading of the train as well as their respective integrity protections;
- an additional high-integrity map database of the rail network, identical or similar to the high-integrity map database of the rail network, configured so as to provide data representing the rail network in the form of segments;
- an additional tracking device for tracking the train, identical or similar to the tracking device for tracking the train, configured so as to determine a high-integrity autonomous position of the train in the rail network reference frame and a corresponding rail network segment identifier, based on data provided by said additional high-integrity map database and the respective positions, speeds, headings and integrity protections provided by the additional high-integrity geographical location device, by resolving ambiguities of candidate segments; and - a consolidation module for consolidating the integrity protections provided by the tracking device for tracking the train and the additional tracking device for tracking the train, providing a consolidated segment identifier and a consolidated position on the segment, as well as the consolidated protection interval, such that the risk of lack of integrity of
- a module configured so as to perform an instantaneous resolution function based on distance; and/or - a module configured so as to perform an instantaneous resolution function based on the heading; and/or - a module configured so as to perform a points resolution function.
All of the geometric characteristics of the railway track are thus utilized to ascertain a bearing.
In one embodiment, the system furthermore comprises:
- an additional high-integrity geographical location device for high-integrity geographical location in a global geographical reference frame, different from the high-integrity geographical location device, configured so as to provide the position, the speed and the heading of the train as well as their respective integrity protections;
- an additional high-integrity map database of the rail network, identical or similar to the high-integrity map database of the rail network, configured so as to provide data representing the rail network in the form of segments;
- an additional tracking device for tracking the train, identical or similar to the tracking device for tracking the train, configured so as to determine a high-integrity autonomous position of the train in the rail network reference frame and a corresponding rail network segment identifier, based on data provided by said additional high-integrity map database and the respective positions, speeds, headings and integrity protections provided by the additional high-integrity geographical location device, by resolving ambiguities of candidate segments; and - a consolidation module for consolidating the integrity protections provided by the tracking device for tracking the train and the additional tracking device for tracking the train, providing a consolidated segment identifier and a consolidated position on the segment, as well as the consolidated protection interval, such that the risk of lack of integrity of
7 the consolidated outputs is much smaller than the risk of lack of integrity of the outputs of the two devices taken separately, the consolidated position being calculated by weighted barycenter of the position of the main device and of the additional device, and the protection interval being calculated by combining the protection intervals of the main device and of the secondary device.
Identical or similar is understood to mean an element assumed to be identical but produced by two different entities, such as the database that is assumed to be identical but may be produced by two different entities and contain a few inopportune differences.
The invention will be better understood on studying a few embodiments described by way of completely non-limiting example and illustrated by the appended drawings, in which:
- figure 1 schematically illustrates one embodiment of a high-integrity autonomous location system for locating a train in a rail network reference frame, according to one aspect of the invention;
- figures 2 to 4 schematically illustrate how the geographical uncertainty ellipse leads to the existence of a plurality of candidate segments, according to one aspect of the invention;
- figures 5 to 10 schematically illustrate the rules taken into account by the tracking device, according to one aspect of the invention;
- figure 11 schematically illustrates one embodiment of a tracking device, according to one aspect of the invention;
- figures 12 to 20 schematically illustrate the operation of the tracking device, according to one aspect of the invention;
- figure 21 schematically illustrates one embodiment of a high-integrity autonomous location system for locating a train in a rail network reference frame, according to one aspect of the invention.
Throughout the figures, elements having identical references are similar.
Identical or similar is understood to mean an element assumed to be identical but produced by two different entities, such as the database that is assumed to be identical but may be produced by two different entities and contain a few inopportune differences.
The invention will be better understood on studying a few embodiments described by way of completely non-limiting example and illustrated by the appended drawings, in which:
- figure 1 schematically illustrates one embodiment of a high-integrity autonomous location system for locating a train in a rail network reference frame, according to one aspect of the invention;
- figures 2 to 4 schematically illustrate how the geographical uncertainty ellipse leads to the existence of a plurality of candidate segments, according to one aspect of the invention;
- figures 5 to 10 schematically illustrate the rules taken into account by the tracking device, according to one aspect of the invention;
- figure 11 schematically illustrates one embodiment of a tracking device, according to one aspect of the invention;
- figures 12 to 20 schematically illustrate the operation of the tracking device, according to one aspect of the invention;
- figure 21 schematically illustrates one embodiment of a high-integrity autonomous location system for locating a train in a rail network reference frame, according to one aspect of the invention.
Throughout the figures, elements having identical references are similar.
8 In the present description, the embodiments that are described are in no way limiting, and features and functions that are well known to a person skilled in the art are not described in detail.
Figure 1 shows a high-integrity autonomous location system for locating a train in a rail network reference frame, comprising:
- a high-integrity geographical location device 1 for high-integrity geographical location in a global geographical reference frame, configured so as to provide the position, the speed and the heading of the train as well as their respective integrity protections with respect to critical events that may affect the high-integrity geographical location device;
- a high-integrity map database 2 of the rail network, configured so as to provide data geographically representing the rail network in the form of segments; and - a tracking device 3 for tracking the train, configured so as to autonomously determine an identifier of the rail network segment on which the train is located, a high-integrity position of the train on this segment in the rail network reference frame, and the protection interval associated with the position of the train on the segment based on data provided by the high-integrity map database 2 and the positions, speeds, headings and integrity protections provided by the high-integrity geographical location device 1, by resolving segment ambiguities of the rail network.
Using a high-integrity geographical location 1 (geographical position, geographical speed, geographical heading), the system performs tracking 3 that uses a database 2 (describing the rail network) and whose purpose is to provide the user with the identifier of the current segment with a .. guaranteed integrity.
The tracking device 3 may furthermore provide measurements of lateral deviation and heading deviation of the train with respect to the railway track to the geographical location device 1, in order to improve its
Figure 1 shows a high-integrity autonomous location system for locating a train in a rail network reference frame, comprising:
- a high-integrity geographical location device 1 for high-integrity geographical location in a global geographical reference frame, configured so as to provide the position, the speed and the heading of the train as well as their respective integrity protections with respect to critical events that may affect the high-integrity geographical location device;
- a high-integrity map database 2 of the rail network, configured so as to provide data geographically representing the rail network in the form of segments; and - a tracking device 3 for tracking the train, configured so as to autonomously determine an identifier of the rail network segment on which the train is located, a high-integrity position of the train on this segment in the rail network reference frame, and the protection interval associated with the position of the train on the segment based on data provided by the high-integrity map database 2 and the positions, speeds, headings and integrity protections provided by the high-integrity geographical location device 1, by resolving segment ambiguities of the rail network.
Using a high-integrity geographical location 1 (geographical position, geographical speed, geographical heading), the system performs tracking 3 that uses a database 2 (describing the rail network) and whose purpose is to provide the user with the identifier of the current segment with a .. guaranteed integrity.
The tracking device 3 may furthermore provide measurements of lateral deviation and heading deviation of the train with respect to the railway track to the geographical location device 1, in order to improve its
9 performance. These deviation measurements are of high integrity, which is essential, as otherwise these measurements could corrupt the geographical location device 1.
The tracking device 3 may also provide information allowing the geographical location device 1 to maintain the integrity of its measurements, taking into account the surroundings of the railway track. In this operating mode, the map database 2 comprises descriptive elements describing the surroundings of the railway track when said surroundings are liable to corrupt the measurements of the high-integrity location system.
The system also provides the abscissa on the segment, the speed of the train on the segment, and the direction of movement, with high integrity and independently of the tachometric system, based on the observation of the movement of the wheels.
There is therefore a starting point of a high-integrity location, as illustrated in figure 2 and, by virtue of the database 2, a protection uncertainty represented by the short dashed lines in figure 3 is passed.
By virtue of the tracking device 3, positional uncertainty represented by the short dashed lines in figure 4 is passed.
The present invention applies to the railway sector, and in general to all positions and speeds of rail-borne vehicles, such as trains, trams, and other rail-borne construction vehicles.
The high-integrity geographical location device 1 may comprise a GNSS receiver coupled to an inertial measurement unit IMU through high-integrity hybridization, for example described in Thales patent EP 3018447.
The database 2 of the rail network describes the network in the form of segments, and defines the features of each segment through geometric features (such as the coordinates of the start of the segment, the
The tracking device 3 may also provide information allowing the geographical location device 1 to maintain the integrity of its measurements, taking into account the surroundings of the railway track. In this operating mode, the map database 2 comprises descriptive elements describing the surroundings of the railway track when said surroundings are liable to corrupt the measurements of the high-integrity location system.
The system also provides the abscissa on the segment, the speed of the train on the segment, and the direction of movement, with high integrity and independently of the tachometric system, based on the observation of the movement of the wheels.
There is therefore a starting point of a high-integrity location, as illustrated in figure 2 and, by virtue of the database 2, a protection uncertainty represented by the short dashed lines in figure 3 is passed.
By virtue of the tracking device 3, positional uncertainty represented by the short dashed lines in figure 4 is passed.
The present invention applies to the railway sector, and in general to all positions and speeds of rail-borne vehicles, such as trains, trams, and other rail-borne construction vehicles.
The high-integrity geographical location device 1 may comprise a GNSS receiver coupled to an inertial measurement unit IMU through high-integrity hybridization, for example described in Thales patent EP 3018447.
The database 2 of the rail network describes the network in the form of segments, and defines the features of each segment through geometric features (such as the coordinates of the start of the segment, the
10 length of the segment and the value of the clothoid or spline parameters) and the chaining features in the network (for example: identifier of the successor and predecessor segments). In one mode of use, the database 2 may also contain descriptive elements describing the surroundings in the vicinity of the position under consideration.
The tracking device 3 receives the location information provided by the high-integrity geographical location device (geographical position, geographical speed, geographical heading, protection radii at 10-x/h and associated alarms) as input and uses the database to identify the current segment, such that the probability of the train not being located on the indicated segment, without an alarm being raised, is less than 10x/h.
The high-integrity geographical location device 1 produces the following information:
- the geographical position (longitude, latitude, altitude);
- the parameters of the position protection ellipsoid at 10-x/h (North, East, Vertical, North/East, North/Vertical, East/Vertical components);
- the geographical heading angle;
- the interval protecting the heading at 10x/h;
- the geographical speed (North speed, East speed, Vertical speed);
- the parameters of the ellipsoid protecting the speed at 10-x/h; and - the alarm signal (indicating that the integrity is no longer guaranteed).
The geographical location device 1 has high integrity in the sense that the probability (taking into account normal, rare and abnormal events that may affect this data source) of the measurements produced by the location being outside the field of protection advertised by the geographical location device 1, without an alarm being raised, is lower than the specified risk (for example 10-6/h).
Thales patent EP3018447 describes one example of IMU/GNSS
hybridization providing all of this information.
The tracking device 3 receives the location information provided by the high-integrity geographical location device (geographical position, geographical speed, geographical heading, protection radii at 10-x/h and associated alarms) as input and uses the database to identify the current segment, such that the probability of the train not being located on the indicated segment, without an alarm being raised, is less than 10x/h.
The high-integrity geographical location device 1 produces the following information:
- the geographical position (longitude, latitude, altitude);
- the parameters of the position protection ellipsoid at 10-x/h (North, East, Vertical, North/East, North/Vertical, East/Vertical components);
- the geographical heading angle;
- the interval protecting the heading at 10x/h;
- the geographical speed (North speed, East speed, Vertical speed);
- the parameters of the ellipsoid protecting the speed at 10-x/h; and - the alarm signal (indicating that the integrity is no longer guaranteed).
The geographical location device 1 has high integrity in the sense that the probability (taking into account normal, rare and abnormal events that may affect this data source) of the measurements produced by the location being outside the field of protection advertised by the geographical location device 1, without an alarm being raised, is lower than the specified risk (for example 10-6/h).
Thales patent EP3018447 describes one example of IMU/GNSS
hybridization providing all of this information.
11 Generally speaking, an IMU/GNSS hybridization usually produces the position, the speed and the heading angle, but also the roll and pitch angles. In the present invention, the heading plays an important role for the points resolution, but not the roll and pitch angles.
It should be noted that, with the train moving over a locally flat terrain, the protection volume or interval is locally reduced to the intersection of the ellipsoid with this plane (which is an ellipse).
The map database 2 meets the following integrity conditions:
- for each segment of the rail network described in the database, the chaining information is not incorrect (identifier of the segment and of the contiguous segments); and - for each segment described in the database, the positioning information allows the tracking device 3 to calculate the geographical position and the geographical heading of any point of the segment with an error smaller than the error limits indicated in the description of the segment.
More rigorously, these conditions are met with a given risk: for example if the risk of lack of integrity of the database is 10-6/h, and the average number of segments visited by the train is 100 segments/hour, then an error rate of 10-8/segment is tolerated.
In figure 5, the segments correspond to the portions between the crosses.
The branches correspond to the various possible choices when traveling in the network, in this case three branches (of different paths) are shown, involving two junctions (framed cross).
A junction is a segment of zero length that has one entry and two possible exits. The junction exists only in one direction: if the train is traveling in the other direction, the junction does not create an alternative.
It should be noted that, with the train moving over a locally flat terrain, the protection volume or interval is locally reduced to the intersection of the ellipsoid with this plane (which is an ellipse).
The map database 2 meets the following integrity conditions:
- for each segment of the rail network described in the database, the chaining information is not incorrect (identifier of the segment and of the contiguous segments); and - for each segment described in the database, the positioning information allows the tracking device 3 to calculate the geographical position and the geographical heading of any point of the segment with an error smaller than the error limits indicated in the description of the segment.
More rigorously, these conditions are met with a given risk: for example if the risk of lack of integrity of the database is 10-6/h, and the average number of segments visited by the train is 100 segments/hour, then an error rate of 10-8/segment is tolerated.
In figure 5, the segments correspond to the portions between the crosses.
The branches correspond to the various possible choices when traveling in the network, in this case three branches (of different paths) are shown, involving two junctions (framed cross).
A junction is a segment of zero length that has one entry and two possible exits. The junction exists only in one direction: if the train is traveling in the other direction, the junction does not create an alternative.
12 In one embodiment, the database 2 furthermore contains descriptive elements describing the surroundings when said surroundings are liable to corrupt the integrity of the high-integrity geographical location device 1. For example, if one of the sensors used by the high-integrity geographical device 1 is a GNSS receiver, it may be corrupted by the contribution of the surroundings close to the position occupied by the train, notably in an area exhibiting a risk of reflected GNSS paths from surrounding buildings or an area exhibiting a risk of radiofrequency interference (radiofrequency pollution near a telecommunications repeater, or a specific industrial site). The descriptive elements describing an area at risk of reflected paths may for example provide the distance and the height of the buildings with respect to the point under consideration of the railway track, thereby allowing the high-integrity geographical location device 1 to select only the GNSS satellites for which the orientation of the lines of sight does not exhibit a risk, or to modify the weighting given to the various lines of sight in the calculation of the high-integrity position, so as to guarantee that the protection ellipsoid is not underestimated when the train is in the vicinity of the risk area. The descriptive elements describing an area at risk of interference may be limited just to the indication "do not use", so that the high-integrity geographical location source does not use the GNSS measurements in the vicinity of this area.
The tracking device 3 implements rules that express the constraint of the rails, and ambiguity resolution methods that make it possible to reduce the number of possible segments from among all of the segments of the rail network.
The main rules taken into account by the tracking device are as follows:
- R1: the train cannot leave the area of uncertainty provided by the high-integrity location at input. In figure 6, only the short dashed lines are possible for the true position with the given risk of error.
The tracking device 3 implements rules that express the constraint of the rails, and ambiguity resolution methods that make it possible to reduce the number of possible segments from among all of the segments of the rail network.
The main rules taken into account by the tracking device are as follows:
- R1: the train cannot leave the area of uncertainty provided by the high-integrity location at input. In figure 6, only the short dashed lines are possible for the true position with the given risk of error.
13 - R2: the train cannot jump from a current segment to a non-adjacent segment without passing via a junction. This makes it possible to take advantage of the past situation: for example, as illustrated in figure 7, the train was previously on the segment 2, so it cannot now be on the segment 1 even if the uncertainty regarding the geographical position at input allows it to be.
- R3: The train cannot return to a previous segment if its direction of movement has not changed. For example, in figure 8, if the positional uncertainty increases due to a loss of GNSS signal, as illustrated in figure 9, the fact that the train has passed over the top track now becomes plausible unless it is known that the direction of movement has not changed. The change of direction is monitored based on the speed provided by the location source with a given risk.
- R4: The train cannot change branch (set of successive segments) without being subject to a heading variation. If the new branch is parallel to the previous one, the heading variation is momentary (it corresponds to crossing the points). If the new branch is not parallel, the heading change continues. These events are monitored using the heading angle provided by the location source with a given risk.
The main ambiguity resolution methods implemented in the tracking device 3 are as follows:
- instantaneous resolution based on distance: the segments (described in the database 2) whose positions are outside the integrity ellipse provided by the high-integrity geographical location device 1 are discarded. The uncertainty of the high-integrity map database 2 is also taken into account in this decision.
- instantaneous resolution based on heading: the candidate segments whose heading interval does not intersect the heading interval provided by the high-integrity geographical location device 1 are discarded. The
- R3: The train cannot return to a previous segment if its direction of movement has not changed. For example, in figure 8, if the positional uncertainty increases due to a loss of GNSS signal, as illustrated in figure 9, the fact that the train has passed over the top track now becomes plausible unless it is known that the direction of movement has not changed. The change of direction is monitored based on the speed provided by the location source with a given risk.
- R4: The train cannot change branch (set of successive segments) without being subject to a heading variation. If the new branch is parallel to the previous one, the heading variation is momentary (it corresponds to crossing the points). If the new branch is not parallel, the heading change continues. These events are monitored using the heading angle provided by the location source with a given risk.
The main ambiguity resolution methods implemented in the tracking device 3 are as follows:
- instantaneous resolution based on distance: the segments (described in the database 2) whose positions are outside the integrity ellipse provided by the high-integrity geographical location device 1 are discarded. The uncertainty of the high-integrity map database 2 is also taken into account in this decision.
- instantaneous resolution based on heading: the candidate segments whose heading interval does not intersect the heading interval provided by the high-integrity geographical location device 1 are discarded. The
14 uncertainty of the high-integrity map database 2 is also taken into account in this decision.
- points resolution: when the current position and its uncertainty indicate the proximity of points, the points resolution function is activated. This analyzes the successive heading measurements provided by the high-integrity geographical location device 1 and evaluates the correlation of these measurements with the geometrical heading values, along the two candidate trajectories, extracted from the high-integrity map database 2. The length of the movement, on which this analysis is performed, and the decision thresholds are calculated taking into account the position and heading uncertainties produced by the high-integrity geographical location device 1 as well as the uncertainties of the high-integrity map database 2, such that the probability of an incorrect decision is limited. When the points are divergent (that is to say non-parallel tracks at the points exit), the resolution function also analyzes the position deviation with respect to the two candidate trajectories.
The tracking device 3 has a plurality of functions:
- first-level tracking: the inputs of this function are the position, the heading and the associated protections (ellipsoid protecting the position, heading protection interval, alarm), provided by the high-integrity geographical location device 1, as well as the description of the segments of the high-integrity database 2. The first-level tracking identifies the temporal chaining of the segments, and implements the points resolution (see above) whenever necessary. The first-level tracking is activated at a sufficiently high frequency (typically 10 Hz) so as to be able to track the chaining of the segments. The output of the first-level tracking is the list of candidate segments, and the position on each candidate segment. In "normal" mode, this list contains a single segment. Depending on the level of uncertainty of the inputs, the first-level tracking is not always able to identify the current segment: in this case, the list contains a plurality of candidates.
- points resolution: when the current position and its uncertainty indicate the proximity of points, the points resolution function is activated. This analyzes the successive heading measurements provided by the high-integrity geographical location device 1 and evaluates the correlation of these measurements with the geometrical heading values, along the two candidate trajectories, extracted from the high-integrity map database 2. The length of the movement, on which this analysis is performed, and the decision thresholds are calculated taking into account the position and heading uncertainties produced by the high-integrity geographical location device 1 as well as the uncertainties of the high-integrity map database 2, such that the probability of an incorrect decision is limited. When the points are divergent (that is to say non-parallel tracks at the points exit), the resolution function also analyzes the position deviation with respect to the two candidate trajectories.
The tracking device 3 has a plurality of functions:
- first-level tracking: the inputs of this function are the position, the heading and the associated protections (ellipsoid protecting the position, heading protection interval, alarm), provided by the high-integrity geographical location device 1, as well as the description of the segments of the high-integrity database 2. The first-level tracking identifies the temporal chaining of the segments, and implements the points resolution (see above) whenever necessary. The first-level tracking is activated at a sufficiently high frequency (typically 10 Hz) so as to be able to track the chaining of the segments. The output of the first-level tracking is the list of candidate segments, and the position on each candidate segment. In "normal" mode, this list contains a single segment. Depending on the level of uncertainty of the inputs, the first-level tracking is not always able to identify the current segment: in this case, the list contains a plurality of candidates.
15 - second-level tracking: the inputs of this function are the list of candidates provided by the first-level tracking, the position, the speed, the heading and the associated protections, provided by the high-integrity geographical location device 1, as well as the description of the segments of the high-integrity database 2. This function is activated at a lower rate (typically 1 Hz) because the calculation volume may be high. This function analyzes the list of candidates identified by the first-level tracking and compares it with the one constructed from the outputs (position and associated protection) produced by the high-integrity geographical location device 1, in order to detect complex cases (see figure illustrating the outbound points followed by inbound points). Eliminating false candidates implements instantaneous distance-based and heading-based resolutions, as well as speed measurement, which makes it possible to detect changes of direction.
The processing operations that are implemented use the protection information (about the position, about the heading, about the speed, about the content of the database) such that the probability of an incorrect decision is limited. In the case of a cold start, all of the segments of the high-integrity database 2 are candidates.
- producing outputs and associated indicators: this function calculates the operational outputs (segment identifier, abscissa on the segment, protection interval of the abscissa, direction of movement, speed on the segment, protection interval of the speed, alarm, operating mode).
- producing deviation measurements: when the operating mode indicates "nominal", only one segment is a candidate, the position on the segment is known with the associated protection interval, and the geographical heading is known with the associated protection interval.
It is then possible to calculate the lateral deviation between the position produced by the high-integrity geographical device 1 and the track, as well as the deviation between the heading produced by the high-
The processing operations that are implemented use the protection information (about the position, about the heading, about the speed, about the content of the database) such that the probability of an incorrect decision is limited. In the case of a cold start, all of the segments of the high-integrity database 2 are candidates.
- producing outputs and associated indicators: this function calculates the operational outputs (segment identifier, abscissa on the segment, protection interval of the abscissa, direction of movement, speed on the segment, protection interval of the speed, alarm, operating mode).
- producing deviation measurements: when the operating mode indicates "nominal", only one segment is a candidate, the position on the segment is known with the associated protection interval, and the geographical heading is known with the associated protection interval.
It is then possible to calculate the lateral deviation between the position produced by the high-integrity geographical device 1 and the track, as well as the deviation between the heading produced by the high-
16 integrity geographical device 1 and that of the track, as well as the associated uncertainty intervals.
- producing descriptive elements describing the surroundings of the railway track: if the high-integrity database 2 also contains a description of the surrounding elements liable to corrupt the integrity of the high-integrity geographical device 1, the tracking device 3 may provide this information to the high-integrity geographical device 1 when the tracking device 3 is in "nominal" operating mode. Specifically, in this case, knowledge of the segment and of the position on the segment, as well as its associated protection interval, makes it possible to identify, in the high-integrity database 2, the descriptive elements associated with the area centered on the estimated position and of length equal to twice the protection interval. When the operation is not "nominal" (a plurality of segments are possible), these descriptive elements are also provided, but considering the worst contribution offered by the candidate segments in the database.
Figure 10 illustrates one example of a complex situation, in which the possible reversal of the direction of movement of the train should be taken into account in the tracking device.
Figure 11 shows the tracking device 3.
The tracking 3 is divided into two parts: a first-level tracking part 3a and a second-level tracking part 3b. The choice to perform this tracking 3 in two parts is mainly due to the fact that the second-level tracking 3b requires a large number of calculations and that it should be performed at a lower frequency.
The purpose of the first-level tracking 3a is to:
- determine the curvilinear abscissa associated with all of the candidate segments on the basis of the current position resulting from the high-
- producing descriptive elements describing the surroundings of the railway track: if the high-integrity database 2 also contains a description of the surrounding elements liable to corrupt the integrity of the high-integrity geographical device 1, the tracking device 3 may provide this information to the high-integrity geographical device 1 when the tracking device 3 is in "nominal" operating mode. Specifically, in this case, knowledge of the segment and of the position on the segment, as well as its associated protection interval, makes it possible to identify, in the high-integrity database 2, the descriptive elements associated with the area centered on the estimated position and of length equal to twice the protection interval. When the operation is not "nominal" (a plurality of segments are possible), these descriptive elements are also provided, but considering the worst contribution offered by the candidate segments in the database.
Figure 10 illustrates one example of a complex situation, in which the possible reversal of the direction of movement of the train should be taken into account in the tracking device.
Figure 11 shows the tracking device 3.
The tracking 3 is divided into two parts: a first-level tracking part 3a and a second-level tracking part 3b. The choice to perform this tracking 3 in two parts is mainly due to the fact that the second-level tracking 3b requires a large number of calculations and that it should be performed at a lower frequency.
The purpose of the first-level tracking 3a is to:
- determine the curvilinear abscissa associated with all of the candidate segments on the basis of the current position resulting from the high-
17 integrity geographical location and the preceding curvilinear abscissas, - update the set of candidate segments each time a junction is encountered using the database and update the tracking mode (see below), - resolve the points under certain conditions (see below), - work out the deviations between the position and the heading, produced by the geographical location module, and the position and the heading calculated from the database, and provide them to the high-integrity geographical location when a single segment is a candidate, and - provide a set of candidate segments and curvilinear abscissas associated with the second-level tracking 3b.
The purpose of the second-level tracking 3b is to:
- determine the set of possible segments using:
o the uncertainty associated with the high-integrity geographical location position, and o the set of possible segments provided by online tracking, - use the various geographical location parameters and their associated uncertainties to reduce the set of potential candidates in order to resolve potential junctions, - provide the high-integrity geographical location with a geographical position measurement calculated from the database, if the position produced by the tracking device proves to have better uncertainty than the one produced by the high-integrity location module. This is an additional functionality, which offers the option of one-off recalibration of the geographical location device, thereby making it possible to improve its performance, and therefore to improve the future availability of the tracking device, - provide the end user with:
o the set of possible segments and the associated minimum and maximum curvilinear abscissas, o the estimated position,
The purpose of the second-level tracking 3b is to:
- determine the set of possible segments using:
o the uncertainty associated with the high-integrity geographical location position, and o the set of possible segments provided by online tracking, - use the various geographical location parameters and their associated uncertainties to reduce the set of potential candidates in order to resolve potential junctions, - provide the high-integrity geographical location with a geographical position measurement calculated from the database, if the position produced by the tracking device proves to have better uncertainty than the one produced by the high-integrity location module. This is an additional functionality, which offers the option of one-off recalibration of the geographical location device, thereby making it possible to improve its performance, and therefore to improve the future availability of the tracking device, - provide the end user with:
o the set of possible segments and the associated minimum and maximum curvilinear abscissas, o the estimated position,
18 0 the curvilinear abscissa or abscissas estimated on the basis of the tracking mode.
Three modes are distinguished between in tracking:
- a nominal mode in which all of the junctions have been resolved and tracking is capable of providing:
o a single estimated segment and an associated curvilinear abscissa, o an uncertainty expressed by the minimum and maximum curvilinear abscissas on this segment, or by a set of a plurality of segments with their minimum and maximum curvilinear abscissas if the uncertainty extends over a plurality of contiguous segments.
- a "degraded" mode and an "init" mode in which the tracking is capable of providing:
o a plurality of estimated segments and a plurality of associated curvilinear abscissas, o an uncertainty expressed by a set of segments with their minimum and maximum curvilinear abscissas.
The "init" mode is activated when there is no information about the possible candidate segments before searching for the candidate segments of the second-level tracking 3b.
The "init" mode is also activated if the high-integrity geographical location device activates its high-integrity alarm signal.
The first-level tracking 3a starts from "init" mode and is initialized either:
- from an external aid, providing a segment, from an associated curvilinear abscissa and from the uncertainty associated with this abscissa (init), - from the provision of a segment, an abscissa and an associated uncertainty resulting from the search function for the candidate segments. There are
Three modes are distinguished between in tracking:
- a nominal mode in which all of the junctions have been resolved and tracking is capable of providing:
o a single estimated segment and an associated curvilinear abscissa, o an uncertainty expressed by the minimum and maximum curvilinear abscissas on this segment, or by a set of a plurality of segments with their minimum and maximum curvilinear abscissas if the uncertainty extends over a plurality of contiguous segments.
- a "degraded" mode and an "init" mode in which the tracking is capable of providing:
o a plurality of estimated segments and a plurality of associated curvilinear abscissas, o an uncertainty expressed by a set of segments with their minimum and maximum curvilinear abscissas.
The "init" mode is activated when there is no information about the possible candidate segments before searching for the candidate segments of the second-level tracking 3b.
The "init" mode is also activated if the high-integrity geographical location device activates its high-integrity alarm signal.
The first-level tracking 3a starts from "init" mode and is initialized either:
- from an external aid, providing a segment, from an associated curvilinear abscissa and from the uncertainty associated with this abscissa (init), - from the provision of a segment, an abscissa and an associated uncertainty resulting from the search function for the candidate segments. There are
19 various types of segment resolution, as explained below: the resolution used here is the resolution in "init" mode.
At the end of "init" mode, there is a segment, a curvilinear abscissa and an associated uncertainty. Nominal mode is then entered.
The inputs are then the current position P provided by the geographical location solution (position, heading, speed, uncertainties) and the previous segment (or the previous segments), which is provided either by the "init" mode or by the list of candidate segments resulting from the first-level tracking of the previous cycle (these segments being provided with their curvilinear abscissas), to or from which the segments identified by the second-level tracking 3b have been added or removed. From these inputs, the set of possible segments and the curvilinear abscissas associated with the current time are calculated as follows:
Let P be the current position and let a candidate segment resulting from the previous iteration be called id. Let s be the curvilinear abscissa associated with the estimated point P1 of the candidate segment. At P1, the direction vector of the tangent to the segment is calculated. The vector P1P
is projected onto the direction vector calculated above. The value of the scalar product gives an approximation of the deviation of the curvilinear abscissa (As) between the point P1 and the point P projected onto the track.
The value of s is updated with s = s + As in order to recalculate a new point P1. Iteration is performed until the scalar product has become low in order to obtain a new estimated position on the track P2.
Figure 12 shows the rail in short broken lines, P1 is the estimated position on the segment at the previous time, P is the current position sent by the high-integrity geographical location and P2 is the position after iteration.
If the position P2 has a curvilinear abscissa greater than the declared length of the segment id, the high-integrity database 2 is searched for the next segment. If the following segment is not a junction, the new segment with a new curvilinear abscissa is passed over. If the following
At the end of "init" mode, there is a segment, a curvilinear abscissa and an associated uncertainty. Nominal mode is then entered.
The inputs are then the current position P provided by the geographical location solution (position, heading, speed, uncertainties) and the previous segment (or the previous segments), which is provided either by the "init" mode or by the list of candidate segments resulting from the first-level tracking of the previous cycle (these segments being provided with their curvilinear abscissas), to or from which the segments identified by the second-level tracking 3b have been added or removed. From these inputs, the set of possible segments and the curvilinear abscissas associated with the current time are calculated as follows:
Let P be the current position and let a candidate segment resulting from the previous iteration be called id. Let s be the curvilinear abscissa associated with the estimated point P1 of the candidate segment. At P1, the direction vector of the tangent to the segment is calculated. The vector P1P
is projected onto the direction vector calculated above. The value of the scalar product gives an approximation of the deviation of the curvilinear abscissa (As) between the point P1 and the point P projected onto the track.
The value of s is updated with s = s + As in order to recalculate a new point P1. Iteration is performed until the scalar product has become low in order to obtain a new estimated position on the track P2.
Figure 12 shows the rail in short broken lines, P1 is the estimated position on the segment at the previous time, P is the current position sent by the high-integrity geographical location and P2 is the position after iteration.
If the position P2 has a curvilinear abscissa greater than the declared length of the segment id, the high-integrity database 2 is searched for the next segment. If the following segment is not a junction, the new segment with a new curvilinear abscissa is passed over. If the following
20 segment is a junction, a new possible candidate is created and there are two possible segments with two curvilinear abscissas at output.
The points resolution in the online tracking 3a is performed only if:
- working in degraded mode (in nominal mode, there is nothing to resolve and in "init" mode it is the second-level tracking 3b that performs the work), - and if the position and its uncertainty are contained entirely within the candidate segments. Specifically, in the opposite case, it would be possible to reach incorrect conclusions: as in the following example illustrated by figures 13 and 14.
In the example of figures 13 and 14, the segments S20 and S50 are the candidate segments. In the first configuration of figure 13, the points resolution is activated. In the second configuration of figure 14, the points resolution is deactivated because the uncertainty overflows onto the segment S51. In the second configuration, there is a risk of choosing the segment 20 because the true position heading is consistent with the segment 20 and the two candidate segments are the segments 20 and 50.
The points resolution may be performed in three ways:
- through instantaneous comparison of the heading between the heading of the geographical location solution and the heading of the candidate segments at the estimated curvilinear abscissa, - by seeing if a single segment is contained within the confidence ellipse, and - through correlation between the successive headings from the high-integrity geographical location module and the successive headings taken by each of the candidate segments over a given length, this makes it possible to eliminate the heading error linked to the positional uncertainty.
The points resolution in the online tracking 3a is performed only if:
- working in degraded mode (in nominal mode, there is nothing to resolve and in "init" mode it is the second-level tracking 3b that performs the work), - and if the position and its uncertainty are contained entirely within the candidate segments. Specifically, in the opposite case, it would be possible to reach incorrect conclusions: as in the following example illustrated by figures 13 and 14.
In the example of figures 13 and 14, the segments S20 and S50 are the candidate segments. In the first configuration of figure 13, the points resolution is activated. In the second configuration of figure 14, the points resolution is deactivated because the uncertainty overflows onto the segment S51. In the second configuration, there is a risk of choosing the segment 20 because the true position heading is consistent with the segment 20 and the two candidate segments are the segments 20 and 50.
The points resolution may be performed in three ways:
- through instantaneous comparison of the heading between the heading of the geographical location solution and the heading of the candidate segments at the estimated curvilinear abscissa, - by seeing if a single segment is contained within the confidence ellipse, and - through correlation between the successive headings from the high-integrity geographical location module and the successive headings taken by each of the candidate segments over a given length, this makes it possible to eliminate the heading error linked to the positional uncertainty.
21 At the end of the points resolution, a set of candidate segments and their associated curvilinear abscissas are available, which may be transmitted to the second-level tracking.
In nominal mode when the estimated position and the uncertainty are contained within the candidate segment, it is possible to calculate the tracking measurements. This is the lateral deviation with respect to the track and the estimated heading at the estimated curvilinear abscissa. This information is sent to the high-integrity geographical location device with its associated uncertainties. The uncertainty depends on the accuracy of the database and the uncertainty regarding the curvilinear abscissa.
The lateral deviation with respect to the track is calculated as the scalar product between the direction vector perpendicular to the track at the estimated curvilinear abscissa and the vector P2P, where P2 is the estimated position on the track and P is the estimated position sent by the geographical location device.
The detail of the resolution of the candidate segments follows.
The resolution in "init" mode does not make any assumption about the segments that may be candidates.
There is a starting point of a position estimate and its confidence ellipse resulting from the high-integrity location: cross and ellipse in solid lines in figure 15 in the diagram below. For all of the segments of the high-integrity database 2 (all of the segments are potential candidates), those that are contained within the ellipse are sought.
To see whether a segment belongs to an ellipse, the segment is first of all sampled. The sampling distance should be a fraction of the minimum length between the positional uncertainty and the segment length.
Next, for each point, it is checked whether this is contained within the ellipse:
the points contained within an ellipse with major axis a and minor axis b
In nominal mode when the estimated position and the uncertainty are contained within the candidate segment, it is possible to calculate the tracking measurements. This is the lateral deviation with respect to the track and the estimated heading at the estimated curvilinear abscissa. This information is sent to the high-integrity geographical location device with its associated uncertainties. The uncertainty depends on the accuracy of the database and the uncertainty regarding the curvilinear abscissa.
The lateral deviation with respect to the track is calculated as the scalar product between the direction vector perpendicular to the track at the estimated curvilinear abscissa and the vector P2P, where P2 is the estimated position on the track and P is the estimated position sent by the geographical location device.
The detail of the resolution of the candidate segments follows.
The resolution in "init" mode does not make any assumption about the segments that may be candidates.
There is a starting point of a position estimate and its confidence ellipse resulting from the high-integrity location: cross and ellipse in solid lines in figure 15 in the diagram below. For all of the segments of the high-integrity database 2 (all of the segments are potential candidates), those that are contained within the ellipse are sought.
To see whether a segment belongs to an ellipse, the segment is first of all sampled. The sampling distance should be a fraction of the minimum length between the positional uncertainty and the segment length.
Next, for each point, it is checked whether this is contained within the ellipse:
the points contained within an ellipse with major axis a and minor axis b
22 satisfy the equation: u2/a2+v2/b2<=1, u and v being the coordinates of the point of the segment in the reference frame whose center is the estimated position and the X and Y axes correspond to the major axis and minor axis of the confidence ellipse.
If only one branch of segments (and not a single segment) is a candidate, a segment to be provided either to the list of segments of the first-level tracking or to the initialization of the first-level tracking has been found:
transition [A]. A switch to nominal mode is also ordered. The candidate segment to be provided is closest to the estimated position. The curvilinear abscissa associated with the candidate segment will be the abscissa associated with the point of the segment that is closest to the estimated position. For reasons of simplicity, the uncertainty is that of the estimated position provided initially, even if it is seen that a better result could be achieved using geometric considerations.
At the end of this search, it is possible to remove a set of candidate segments as well as the minimum and maximum abscissa per segment of the points contained within the ellipse, which will be called smin, smax. (what is sought is a single branch of segments and not one segment, since the estimate could be at the intersection between two segments).
In the example of figure 16: S2, S3, and S4 are candidates and belong to one and the same branch. It is therefore possible to switch to nominal mode. The segment provided to the online tracking is the segment 2.
This search makes it possible to manage the rule R1.
The second type of resolution, in nominal and degraded mode, is a resolution on a limited number of segments from the list of segments originating from the first-level tracking. This is the most complex part of the algorithm.
If only one branch of segments (and not a single segment) is a candidate, a segment to be provided either to the list of segments of the first-level tracking or to the initialization of the first-level tracking has been found:
transition [A]. A switch to nominal mode is also ordered. The candidate segment to be provided is closest to the estimated position. The curvilinear abscissa associated with the candidate segment will be the abscissa associated with the point of the segment that is closest to the estimated position. For reasons of simplicity, the uncertainty is that of the estimated position provided initially, even if it is seen that a better result could be achieved using geometric considerations.
At the end of this search, it is possible to remove a set of candidate segments as well as the minimum and maximum abscissa per segment of the points contained within the ellipse, which will be called smin, smax. (what is sought is a single branch of segments and not one segment, since the estimate could be at the intersection between two segments).
In the example of figure 16: S2, S3, and S4 are candidates and belong to one and the same branch. It is therefore possible to switch to nominal mode. The segment provided to the online tracking is the segment 2.
This search makes it possible to manage the rule R1.
The second type of resolution, in nominal and degraded mode, is a resolution on a limited number of segments from the list of segments originating from the first-level tracking. This is the most complex part of the algorithm.
23 The search starts from the various segments provided by the first-level tracking. For each segment resulting from the first-level tracking (only one in nominal mode and a plurality in degraded mode), the set of its possible previous and following segments is sought. The set of possible following and previous segments belongs to the confidence ellipse provided by the high-integrity location device 1.
The confidence ellipse has a major axis whose value for the required integrity (10-n/h) is denoted R. This value is derived from the information sent by the high-integrity geographical location by diagonalizing the position covariance matrix. For each segment id, of abscissa s and of length L, provided by the first-level tracking, all of the segments preceding and following the segment id, which are located within a length R (in terms of curvilinear integral) of the abscissa s of the segment id, are considered to be contained within the confidence ellipse. This is an approximation that will be supplemented using another method described later on.
The search for the following segments takes place as follows: For each segment id provided by first-level tracking:
- If s+R>L (in other words if the part of the segment starting from the abscissa s and arriving at the end of the segment id belongs to the confidence ellipse), then the set of segments that directly follow id are sought in the database. The value of R is then updated for the next segments R = R¨(Ls), - For each immediate successor of id denoted id1 of length denoted L1, the same procedure is applied. If R-L1>0, then the immediate successors of id1 are sought in the database and the value of R is further reduced R= R ¨ L1, - The previous operation restarts until R has the value zero.
The confidence ellipse has a major axis whose value for the required integrity (10-n/h) is denoted R. This value is derived from the information sent by the high-integrity geographical location by diagonalizing the position covariance matrix. For each segment id, of abscissa s and of length L, provided by the first-level tracking, all of the segments preceding and following the segment id, which are located within a length R (in terms of curvilinear integral) of the abscissa s of the segment id, are considered to be contained within the confidence ellipse. This is an approximation that will be supplemented using another method described later on.
The search for the following segments takes place as follows: For each segment id provided by first-level tracking:
- If s+R>L (in other words if the part of the segment starting from the abscissa s and arriving at the end of the segment id belongs to the confidence ellipse), then the set of segments that directly follow id are sought in the database. The value of R is then updated for the next segments R = R¨(Ls), - For each immediate successor of id denoted id1 of length denoted L1, the same procedure is applied. If R-L1>0, then the immediate successors of id1 are sought in the database and the value of R is further reduced R= R ¨ L1, - The previous operation restarts until R has the value zero.
24 At the end of the procedure, a list of successor segments is available and a minimum abscissa and a maximum abscissa is associated for each successor segment.
The same operation is performed in the other direction for the predecessor segments.
In fact, a segment of length greater than R may be contained within the confidence ellipse since the segments are not straight lines. The segments and the abscissas found in the previous method are supplemented by searching for segments for which at least one point is contained within the ellipse using the method presented in the "init" mode. Only the segments following and preceding each segment provided by the first-level tracking are retained. The following and previous segments are obtained by running through the database, starting from each segment provided by the online tracking.
The implementation of the two methods described above is more rigorous with respect to integrity data provided by the high-integrity geographical location device 1 than the use based simply on searching for segments within the ellipsoid, since the uncertainty is taken into account depending on the direction of the track.
This search for successor and predecessor segments makes it possible to manage the fact that it is not possible to jump from one segment to another without passing via a junction: rule R2. Specifically, a segment contained within the ellipse, which is neither the successor nor the predecessor of a candidate segment resulting from the search detailed above, is not a candidate.
The direction of travel is then determined. The speed is obtained by projecting the geographical speed vector, produced by the geographical location device, onto the direction of the tangent to the segment. The protection interval of the speed is the interval defined by the intersection of the speed protection ellipse, produced by the geographical location device, with the segment. The direction of movement is reliably identified when the speed modulus is greater than the speed protection half-interval.
The same operation is performed in the other direction for the predecessor segments.
In fact, a segment of length greater than R may be contained within the confidence ellipse since the segments are not straight lines. The segments and the abscissas found in the previous method are supplemented by searching for segments for which at least one point is contained within the ellipse using the method presented in the "init" mode. Only the segments following and preceding each segment provided by the first-level tracking are retained. The following and previous segments are obtained by running through the database, starting from each segment provided by the online tracking.
The implementation of the two methods described above is more rigorous with respect to integrity data provided by the high-integrity geographical location device 1 than the use based simply on searching for segments within the ellipsoid, since the uncertainty is taken into account depending on the direction of the track.
This search for successor and predecessor segments makes it possible to manage the fact that it is not possible to jump from one segment to another without passing via a junction: rule R2. Specifically, a segment contained within the ellipse, which is neither the successor nor the predecessor of a candidate segment resulting from the search detailed above, is not a candidate.
The direction of travel is then determined. The speed is obtained by projecting the geographical speed vector, produced by the geographical location device, onto the direction of the tangent to the segment. The protection interval of the speed is the interval defined by the intersection of the speed protection ellipse, produced by the geographical location device, with the segment. The direction of movement is reliably identified when the speed modulus is greater than the speed protection half-interval.
25 If the direction of travel does not change, segments that are predecessor segments of a successor segment, or segments that are successor segments of a predecessor segment, cannot be candidates.
Otherwise, this would mean that the train has changed direction (see example below): this is rule R3. It is for this reason that these segments are not sought in the method described above.
If the direction of travel changes or if the direction of travel is unknown (rule R3 no longer applies), for each successor segment obtained in the previous part, it is sought, for each successor segment obtained by the processing operation described above, whether its previous segment is declared to be a junction in the high-integrity database 2. If this is the case, all of the segments preceding this junction should be added to the list of candidates of the first-level tracking (transition [B]).
For each predecessor segment obtained through the processing operation described above, it is sought in the same way whether its following segment is a junction. If this is the case, all of the segments following this segment should be added to the list of candidates of the first-level tracking (transition [B]).
If there are too many junctions to resolve, there is a return to "init"
mode because the segments sent by the first-level tracking (segments representing past information) are no longer of interest.
In the example of figure 17, the movement is from left to right (known direction of travel), the mode is "nominal" and the first-level tracking gives the segment S18. The candidate segments are shown in short broken lines. The segments S60 and S61 cannot be candidates because this would require a change of direction (rule 3). The segments S80 and S81 cannot be candidates because it is necessary to pass via a junction (rule 2). Applying the abovementioned method readily makes it possible to determine all of the candidate segments while complying with the rules R1, R2 and R3.
In figure 18, the direction of travel becomes impossible to determine, the mode is "nominal", and the online tracking gives segment S18 at input.
Otherwise, this would mean that the train has changed direction (see example below): this is rule R3. It is for this reason that these segments are not sought in the method described above.
If the direction of travel changes or if the direction of travel is unknown (rule R3 no longer applies), for each successor segment obtained in the previous part, it is sought, for each successor segment obtained by the processing operation described above, whether its previous segment is declared to be a junction in the high-integrity database 2. If this is the case, all of the segments preceding this junction should be added to the list of candidates of the first-level tracking (transition [B]).
For each predecessor segment obtained through the processing operation described above, it is sought in the same way whether its following segment is a junction. If this is the case, all of the segments following this segment should be added to the list of candidates of the first-level tracking (transition [B]).
If there are too many junctions to resolve, there is a return to "init"
mode because the segments sent by the first-level tracking (segments representing past information) are no longer of interest.
In the example of figure 17, the movement is from left to right (known direction of travel), the mode is "nominal" and the first-level tracking gives the segment S18. The candidate segments are shown in short broken lines. The segments S60 and S61 cannot be candidates because this would require a change of direction (rule 3). The segments S80 and S81 cannot be candidates because it is necessary to pass via a junction (rule 2). Applying the abovementioned method readily makes it possible to determine all of the candidate segments while complying with the rules R1, R2 and R3.
In figure 18, the direction of travel becomes impossible to determine, the mode is "nominal", and the online tracking gives segment S18 at input.
26 In this case, the segments S60 and 561 become candidates and the segment 561 is added to the list of candidates of the first-level tracking list. Specifically, let us imagine that the real position is represented by the yellow star and that the train sets off again in the other direction, passing via S61. If S61 is not a candidate, the points are not resolved and the train is not indicated on the correct segment.
To sort the candidate segments, the segments compatible with the heading produced by the high-integrity geographical location device are identified. This should be between the minimum heading and the maximum heading of the candidate segment portion. These minimum and maximum bounds should take into account the uncertainty of the heading of the high-integrity geographical location device as well as the uncertainty of the high-integrity map database.
If there has not been any change of direction and if the direction is known, then a segment may be a candidate only if its previous segment has already been a candidate. This algorithm makes it possible to manage the rule R4 regarding the heading variation. This algorithm may be supplemented by monitoring the temporal variation of the heading of the high-integrity geographical location device.
In the example of figures 19 and 20, the points junction S19 has not yet been resolved. The first-level tracking has identified the candidate segments S20 and S50. The second-level tracking candidates, following application of the above selection methods, are S18, S20, S50 and S21. S51 is not a candidate because its heading is not compatible with the heading of the high-integrity geographical location device. When the train is moving (it is imagined that it takes the lower branch), since the segments S51 and S52 are not candidates (because of the criterion regarding the heading), then S53 cannot be a candidate, even though its heading is compatible. The points S19 are thus resolved correctly by selecting the branch S20 and S21.
The search for candidate segments thus helps to resolve the points. It makes it possible to return to "nominal" mode by eliminating segments that are no longer candidates. It then updates the list of online segments (transition [C]).
To sort the candidate segments, the segments compatible with the heading produced by the high-integrity geographical location device are identified. This should be between the minimum heading and the maximum heading of the candidate segment portion. These minimum and maximum bounds should take into account the uncertainty of the heading of the high-integrity geographical location device as well as the uncertainty of the high-integrity map database.
If there has not been any change of direction and if the direction is known, then a segment may be a candidate only if its previous segment has already been a candidate. This algorithm makes it possible to manage the rule R4 regarding the heading variation. This algorithm may be supplemented by monitoring the temporal variation of the heading of the high-integrity geographical location device.
In the example of figures 19 and 20, the points junction S19 has not yet been resolved. The first-level tracking has identified the candidate segments S20 and S50. The second-level tracking candidates, following application of the above selection methods, are S18, S20, S50 and S21. S51 is not a candidate because its heading is not compatible with the heading of the high-integrity geographical location device. When the train is moving (it is imagined that it takes the lower branch), since the segments S51 and S52 are not candidates (because of the criterion regarding the heading), then S53 cannot be a candidate, even though its heading is compatible. The points S19 are thus resolved correctly by selecting the branch S20 and S21.
The search for candidate segments thus helps to resolve the points. It makes it possible to return to "nominal" mode by eliminating segments that are no longer candidates. It then updates the list of online segments (transition [C]).
27 To construct the measurements, the tracking makes it possible to reduce the positional uncertainty by eliminating incompatible candidate segments from the geographical location data via the abovementioned rules (in particular by using the heading of the database).
If the positional uncertainty at the end of the tracking is less than the uncertainty of the geographical location position and the mode is nominal, the filter of the geographical location device may be recalibrated using a position measurement provided by the tracking. This position measurement makes it possible to reduce the positional uncertainty.
With regard to providing the user with the segment or segments and the associated uncertainty, this comprises the following elements:
- three coordinates of the estimated position resulting from the high-integrity geographical location;
- three coordinates of the estimated speed resulting from the high-integrity geographical location;
- an estimated segment and an associated curvilinear abscissa, in "nominal" mode;
- an estimated speed and an associated uncertainty, in "nominal"
mode;
- a direction of movement, if the modulus of the speed is greater than its uncertainty, in "nominal" mode;
- a positional uncertainty expressed by a set of segments with their minimum and maximum abscissas in all of the modes; and - an indicator of the tracking mode ("nominal", "degrade", "init").
The system may be used on its own, for applications with a criticality of the order of 10-5/h to 10-7/h. To provide a "catastrophic"
criticality service (10-9/h to 10-19/h), it is possible to use two high-integrity geographical location devices 1, Ibis each using a high-integrity device dissimilar from the other, as illustrated in figure 21.
If the positional uncertainty at the end of the tracking is less than the uncertainty of the geographical location position and the mode is nominal, the filter of the geographical location device may be recalibrated using a position measurement provided by the tracking. This position measurement makes it possible to reduce the positional uncertainty.
With regard to providing the user with the segment or segments and the associated uncertainty, this comprises the following elements:
- three coordinates of the estimated position resulting from the high-integrity geographical location;
- three coordinates of the estimated speed resulting from the high-integrity geographical location;
- an estimated segment and an associated curvilinear abscissa, in "nominal" mode;
- an estimated speed and an associated uncertainty, in "nominal"
mode;
- a direction of movement, if the modulus of the speed is greater than its uncertainty, in "nominal" mode;
- a positional uncertainty expressed by a set of segments with their minimum and maximum abscissas in all of the modes; and - an indicator of the tracking mode ("nominal", "degrade", "init").
The system may be used on its own, for applications with a criticality of the order of 10-5/h to 10-7/h. To provide a "catastrophic"
criticality service (10-9/h to 10-19/h), it is possible to use two high-integrity geographical location devices 1, Ibis each using a high-integrity device dissimilar from the other, as illustrated in figure 21.
28 A "com/mon" consolidation module 4 then consolidates the outputs of the two tracking devices, as is performed in critical aeronautical systems. For example, the consolidated position is a weighted barycenter between the position of the main device and that of the additional device and the protection interval of which consists of the combination of the protection intervals of the main device and of the secondary device.
If the risk of lack of integrity of the device 1, 2, 3 is 10-6/h and the risk of lack of integrity of the bis device ibis, 2bi5, 3bi5 is 10-3/h, then the probability of having both sources faulty at the same time is 10-9/h. This improvement is true if the two devices do not have a common mode up to 10-9/h.
One example of figure 21 consists of a device 1, 2, 3 ("control"
chain) whose source is a GPS/IMU hybridization and a bis device ("monitoring" chain) whose source is a Galileo/IMU hybridization, considering that the GPS and Galileo systems are independent, subject to certain precautions to deal with the common mode, i.e. the disturbance of the GPS
and Galileo signals in the vicinity of the ground.
In this example, the database may constitute a common mode. To reduce this common mode, it is possible to limit the use of the database in one of the two chains. Thus, in figure 21, the source of the device 1, 2, 3 uses the track deviation measurements produced by the tracking device, whereas the source of the bis device Ibis, 2bi5, 3bi5 does not use the track deviation measurements. The result is that the accuracy of the bis device is lower, but this is partly offset by the fact that the protection radii of the bis device are calculated for a lower criticality (10-3/h instead of 10-6/h).
If the risk of lack of integrity of the device 1, 2, 3 is 10-6/h and the risk of lack of integrity of the bis device ibis, 2bi5, 3bi5 is 10-3/h, then the probability of having both sources faulty at the same time is 10-9/h. This improvement is true if the two devices do not have a common mode up to 10-9/h.
One example of figure 21 consists of a device 1, 2, 3 ("control"
chain) whose source is a GPS/IMU hybridization and a bis device ("monitoring" chain) whose source is a Galileo/IMU hybridization, considering that the GPS and Galileo systems are independent, subject to certain precautions to deal with the common mode, i.e. the disturbance of the GPS
and Galileo signals in the vicinity of the ground.
In this example, the database may constitute a common mode. To reduce this common mode, it is possible to limit the use of the database in one of the two chains. Thus, in figure 21, the source of the device 1, 2, 3 uses the track deviation measurements produced by the tracking device, whereas the source of the bis device Ibis, 2bi5, 3bi5 does not use the track deviation measurements. The result is that the accuracy of the bis device is lower, but this is partly offset by the fact that the protection radii of the bis device are calculated for a lower criticality (10-3/h instead of 10-6/h).
Claims (7)
1. A high-integrity autonomous location system for locating a train in a rail network reference frame, comprising:
- a high-integrity geographical location device (1) for high-integrity geographical location in a global geographical reference frame, comprising an inertial unit, a GNSS receiver, and a hybridization module for hybridizing the measurements provided by the inertial unit and the GNSS receiver, configured so as to provide the three position coordinates, the three speed components, and the heading angle of the train in the global geographical reference frame as well as their respective integrity protection intervals with respect to critical events that may affect the high-integrity geographical location device, so that the probability of the position or the speed or the heading angle being outside the integrity protection intervals is less than once every million hours;
- a high-integrity map database (2) of the rail network, configured so as to provide data geographically representing the rail network in the form of segments and information representative of areas of the surroundings of the railway track exhibiting a risk of reflected GNSS
paths in order to maintain the integrity of the geographical location device, and - a tracking device (3) for tracking the train, configured so as to autonomously determine an identifier of the rail network segment on which the train is located, a high-integrity position of the train on this segment in the rail network reference frame, and the protection interval associated with the position of the train on the segment based on data provided by the high-integrity map database and the positions, speeds, headings and integrity protections provided by the high-integrity geographical location device, by resolving ambiguities of candidate segments, such that the probability of the train not being at the indicated location of the rail network is less than once every million hours, the tracking device being configured so as to retroactively provide said information representative of areas of the surroundings of the railway track exhibiting a risk of reflected GNSS paths to the high-integrity geographical location device during the movement of the train;
the high-integrity geographical location device being configured so as either to use only GNSS satellites for which the direction of the line of sight does not exhibit a risk of reflected paths at the location of the train, or to modify the weighting given to the various GNSS satellites used at the location of the train.
- a high-integrity geographical location device (1) for high-integrity geographical location in a global geographical reference frame, comprising an inertial unit, a GNSS receiver, and a hybridization module for hybridizing the measurements provided by the inertial unit and the GNSS receiver, configured so as to provide the three position coordinates, the three speed components, and the heading angle of the train in the global geographical reference frame as well as their respective integrity protection intervals with respect to critical events that may affect the high-integrity geographical location device, so that the probability of the position or the speed or the heading angle being outside the integrity protection intervals is less than once every million hours;
- a high-integrity map database (2) of the rail network, configured so as to provide data geographically representing the rail network in the form of segments and information representative of areas of the surroundings of the railway track exhibiting a risk of reflected GNSS
paths in order to maintain the integrity of the geographical location device, and - a tracking device (3) for tracking the train, configured so as to autonomously determine an identifier of the rail network segment on which the train is located, a high-integrity position of the train on this segment in the rail network reference frame, and the protection interval associated with the position of the train on the segment based on data provided by the high-integrity map database and the positions, speeds, headings and integrity protections provided by the high-integrity geographical location device, by resolving ambiguities of candidate segments, such that the probability of the train not being at the indicated location of the rail network is less than once every million hours, the tracking device being configured so as to retroactively provide said information representative of areas of the surroundings of the railway track exhibiting a risk of reflected GNSS paths to the high-integrity geographical location device during the movement of the train;
the high-integrity geographical location device being configured so as either to use only GNSS satellites for which the direction of the line of sight does not exhibit a risk of reflected paths at the location of the train, or to modify the weighting given to the various GNSS satellites used at the location of the train.
2. The system as claimed in claim 1, wherein the tracking device (3) is configured so as to retroactively provide high-integrity measurements of lateral deviation and heading deviation of the train with respect to the railway track of the rail network to the high-integrity geographical location device (1), the hybridization module being configured so as to take said measurements into account.
3. The system as claimed in either of the preceding claims, wherein the tracking device is configured so as to:
- eliminate the candidate segments not contained at least partly within the protection intervals provided by the high-integrity geographical location device, - compare the heading angle provided by the high-integrity geographical location device and the heading angle of the segments from the database that are compatible with the chaining of the rail network, and - select the segments compatible with the protection interval of the heading angle provided by the high-integrity geographical location device, and for which the following segment or the previous segment, depending on the direction of travel, has already been a candidate segment.
- eliminate the candidate segments not contained at least partly within the protection intervals provided by the high-integrity geographical location device, - compare the heading angle provided by the high-integrity geographical location device and the heading angle of the segments from the database that are compatible with the chaining of the rail network, and - select the segments compatible with the protection interval of the heading angle provided by the high-integrity geographical location device, and for which the following segment or the previous segment, depending on the direction of travel, has already been a candidate segment.
4. The system as claimed in one of the preceding claims, wherein the tracking device is configured so as to perform a correlation along the curvilinear abscissa between the successive heading angles provided by the high-integrity geographical location device and the successive headings taken by each of the candidate segments, so as to select a single segment.
5. The system as claimed in one of the preceding claims, wherein the tracking device (3) is configured so as to determine a high-integrity speed and direction of movement of the train, by projecting, onto the direction of the current segment, the speed and its protection interval as provided by the high-integrity location device.
6. The system as claimed in one of the preceding claims, wherein said data representing the rail network in the form of segments comprise, for each segment, the position coordinates and the heading angle in the global geographical reference frame, the length of the segment, the value of a parameter representative of the curvature and its variation, the value of parameters for chaining the segment with other segments, and the values of the limits in terms of the position error and the heading error of this segment.
7. The system as claimed in one of the preceding claims, comprising:
- an additional high-integrity geographical location device (1 bis) for high-integrity geographical location in a global geographical reference frame, different from the high-integrity geographical location device, configured so as to provide the position, the speed and the heading of the train as well as their respective integrity protections;
- an additional high-integrity map database (2bi5) of the rail network, identical or similar to the high-integrity map database of the rail network, configured so as to provide data representing the rail network in the form of segments;
- an additional tracking device (3bi5) for tracking the train, identical or similar to the tracking device for tracking the train, configured so as to determine a high-integrity autonomous position of the train in the rail network reference frame and a corresponding rail network segment identifier, based on data provided by said additional high-integrity map database and the respective positions, speeds, headings and integrity protections provided by the additional high-integrity geographical location device, by resolving ambiguities of candidate segments; and - a consolidation module (4) for consolidating the integrity protections provided by the tracking device for tracking the train and the additional tracking device for tracking the train, providing a consolidated segment identifier and a consolidated position on the segment, as well as the consolidated protection interval, such that the risk of lack of integrity of the consolidated outputs is much smaller than the risk of lack of integrity of the outputs of the two devices taken separately, the consolidated position being calculated by weighted barycenter of the position of the main device and of the additional device, and the protection interval being calculated by combining the protection intervals of the main device and of the secondary device.
- an additional high-integrity geographical location device (1 bis) for high-integrity geographical location in a global geographical reference frame, different from the high-integrity geographical location device, configured so as to provide the position, the speed and the heading of the train as well as their respective integrity protections;
- an additional high-integrity map database (2bi5) of the rail network, identical or similar to the high-integrity map database of the rail network, configured so as to provide data representing the rail network in the form of segments;
- an additional tracking device (3bi5) for tracking the train, identical or similar to the tracking device for tracking the train, configured so as to determine a high-integrity autonomous position of the train in the rail network reference frame and a corresponding rail network segment identifier, based on data provided by said additional high-integrity map database and the respective positions, speeds, headings and integrity protections provided by the additional high-integrity geographical location device, by resolving ambiguities of candidate segments; and - a consolidation module (4) for consolidating the integrity protections provided by the tracking device for tracking the train and the additional tracking device for tracking the train, providing a consolidated segment identifier and a consolidated position on the segment, as well as the consolidated protection interval, such that the risk of lack of integrity of the consolidated outputs is much smaller than the risk of lack of integrity of the outputs of the two devices taken separately, the consolidated position being calculated by weighted barycenter of the position of the main device and of the additional device, and the protection interval being calculated by combining the protection intervals of the main device and of the secondary device.
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| PCT/EP2019/061110 WO2019211302A1 (en) | 2018-05-03 | 2019-04-30 | High-integrity autonomous system for locating a train in a railway network reference system |
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| FR3147635A1 (en) * | 2023-04-07 | 2024-10-11 | Gts France Sas | Integrity control method, computer program and associated device |
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- 2018-05-03 FR FR1800423A patent/FR3080823B1/en active Active
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2019
- 2019-04-30 CN CN201980029935.3A patent/CN112135764B/en active Active
- 2019-04-30 WO PCT/EP2019/061110 patent/WO2019211302A1/en active Application Filing
- 2019-04-30 EP EP19720619.6A patent/EP3787951A1/en active Pending
- 2019-04-30 CA CA3100131A patent/CA3100131A1/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP4283342A1 (en) * | 2022-05-27 | 2023-11-29 | AZD Praha S.R.O. | Method for determination of interval estimation of velocity magnitude of railway vehicle using gnss and subsystem to implement this method |
Also Published As
| Publication number | Publication date |
|---|---|
| FR3080823A1 (en) | 2019-11-08 |
| FR3080823B1 (en) | 2022-04-29 |
| CN112135764B (en) | 2022-12-20 |
| CN112135764A (en) | 2020-12-25 |
| EP3787951A1 (en) | 2021-03-10 |
| WO2019211302A1 (en) | 2019-11-07 |
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