WO2019211302A1

WO2019211302A1 - High-integrity autonomous system for locating a train in a railway network reference system

Info

Publication number: WO2019211302A1
Application number: PCT/EP2019/061110
Authority: WO
Inventors: Nicolas VERCIER; Christian Mehlen; Denis Bouvet; Philippe LAVIRON
Original assignee: Thales
Priority date: 2018-05-03
Filing date: 2019-04-30
Publication date: 2019-11-07
Also published as: CA3100131A1; EP3787951A1; CN112135764B; FR3080823B1; CN112135764A; FR3080823A1

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.

Description

Integrated and autonomous tracking system of a train in a

railway network reference system

The present invention relates to an integrated and autonomous positioning system of a train in a railway network reference system.

It is known systems locating a train on a rail network by dedicated ground infrastructure, which guarantee the integrity of the location, ie the risk that the train is not on the specified section is smaller than an acceptable limit. This limit is related to the risk of a serious event, such as a collision or derailment, and the ability of the rail traffic control system. These devices have a very high cost.

Non-autonomous solutions require ground infrastructures that have a high maintenance cost. The cost of the ETCS L2 type signaling is approximately 200 K € per km of track, so its deployment is limited to high traffic lines. The present solution has a much lower cost depending on the level of integrity envisaged, which makes it possible to rehabilitate lines of the secondary network at lower cost.

There are also geographical localization devices, honest and autonomous. By geographical location is meant the location of a mobile in a frame linked to the Earth, such as longitude, latitude, and altitude; integrates the association with the location of an integrity protection interval or error ellipsoid and an alarm signal (the risk that the indicated position is outside the ellipsoid, without an alarm not raised, is smaller than an acceptable limit); and by autonomous the non-use of dedicated infrastructures.

A device based on GNSS receiver and UMI inertial measurement unit is an example of this type of geographic location device, integrated and autonomous. For example, European Patent EP 3018447B1. For this type of device, the service provided does not locate the train with a guarantee of integrity: as soon as the error ellipsoid is greater than the half-distance between the tracks, it is no longer possible to locate the train on the track. rail network in a safe way.

An object of the invention is to overcome the problems mentioned above.

It is proposed, according to one aspect of the invention, an integrated and autonomous localization system of a train in a railway network reference system comprising:

a geographic location device (1) integrates into a global geographic reference system comprising an inertial unit, a GNSS receiver, and a hybridization module of the measurements provided by the inertial unit and the GNSS receiver configured to provide the three position coordinates, the three velocity components, and the heading angle of the train in the global geographic repository and their respective integrity protection intervals with respect to dreaded events that may affect the geographical location device, so that the the probability that the position or heading speed or angle is outside the integrity protection intervals is less than once every million hours;

a cartographic database (2) integrates a railway network configured to provide data representing the railway network geographically in the form of segments; and information representative of areas of the railway environment presenting a risk of reflected GNSS paths for maintaining the integrity of the geographical location device; and

a train tracking device (3) configured to autonomously determine a railway network segment identifier on which the train is located, an integrated position of the train on this segment in the rail network reference system, and the protection associated with the position of the train on the segment from data provided by the integrated cartographic database and positions, speeds, caps and integrity protections provided by the geographical location device integrates, by resolution of candidate segment ambiguities, so that the probability of the train not being at the indicated location of the rail network is less than one once every million hours, the tracking device being configured to provide retroactively, during the movement of the train, the geographic location device integrates said information representative of areas of the environment of the railway with a risk of GNSS paths think;

the integrated geographical location device being configured to use only GNSS satellites whose direction of the visual axis does not present a risk of reflected paths to location of the train, or to change the weighting given to the various GNSS satellites used in the location of the train.

Such a system provides the integrated location service in the repository of interest, and not in the initial geographic repository. It makes it possible to upgrade low-cost devices based on UMI and GNSS, which provide an integrity service in a geographical reference system, and to have excellent system availability regardless of climatic conditions.

Thus, if the geographic location device uses one or more sensors whose measurements are likely to be corrupted by the environment of the railway, the feedback can reduce this risk. For example for a GNSS type sensor, the measurements, from satellites for which the geometrical configuration of the objects near the track presents a risk of alteration, can be ignored a priori, so as not to compromise the integrity of the geographical location device.

In one embodiment, the tracking device is configured to retroactively provide, to the integrated geographical location device, intact lateral deviation and course deviation measurements of the train relative to the railroad track, the module hybridization being configured to take into account said measurements. Thus, the geographical location device can benefit from additional measures, which are likely to improve its performance, without compromising its integrity.

In one embodiment, the tracking device is configured to:

eliminating the candidate segments not contained at least partly in the protection intervals provided by the integrated geographical location device,

comparing the heading angle provided by the integrated geographical location device and the heading angle of the segments of the database compatible with the chaining of the rail network, and

selecting segments that are compatible with the heading angle protection interval provided by the integrated geographical location device, and whose next segment or preceding segment according to the direction of travel has already been a candidate segment.

Thus, the device is able to safely reduce the number of candidate segments, to discriminate the only true segment on which the train is located.

A candidate segment is a segment that has already been selected by the tracking device by one of the methods mentioned above. The set of candidate segments is stored from one calculation cycle to another to determine the candidate segments of the next calculation cycle which depend on the candidate segments of the previous calculation cycle and the new data provided by the integrated geographical location device. as detailed later.

According to one embodiment, the tracking device is configured to perform a correlation along the curvilinear abscissa between the successive course angles provided by the geographical location device. integrates and the successive caps taken by each of the candidate segments, so as to select a single segment.

Thus, the tracking device is able to discriminate the true segment of the other candidate segments when they follow different trajectories in cap.

In one embodiment, the tracking device is configured to determine an integral speed and direction of travel of the train, by projecting on the direction of the current segment of the speed and its protection interval, provided by the integrated locating device.

Thus, the tracking device provides additional information in addition to the positioning information. Reliable speed and direction information is essential for train control and traffic management.

According to one embodiment, said data representing the railway 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 geographic reference, the length of the segment, the value of a parameter representative of the curvature and its variation, and the value of chaining parameters of the segment with other segments, and the values of the limits of the position error and the heading error of this segment.

Thus, a small number of parameters makes it possible to represent a significant length of the rail network. The chosen representation makes it possible to calculate precisely the coordinates of geographical position and the heading angle of any point belonging to the segment, from its curvilinear abscissa. According to one embodiment, the tracking device comprises, for resolving ambiguities of the candidate segments:

a module configured to perform an instantaneous resolution function based on the distance; and or

a module configured to perform an instantaneous resolution function based on the heading; and or

a module configured to perform a routing resolution function.

Thus, we take advantage of all the geometric characteristics of the railroad to identify.

In one embodiment, the system further comprises: an additional geographical location device integrates into a global geographic reference system, different from the integrated geographical location device, configured to provide the position, the speed, and the heading of the train as well as their respective integrity protections;

an additional database of cartographic data integrates railway network, identical or similar to the map database integrates rail network, configured to provide data representing the railway network in the form of segments;

an additional train tracking device, identical or similar to the train tracking device, configured to determine an integrated and autonomous position of the train in the railway network reference system and a corresponding railway network segment identifier, from data provided by said additional cartographic database integrates and respective positions, speeds, caps and integrity protections provided by the additional geographical localization device integrates, by resolution of ambiguities of candidate segments; and

a module for consolidating the integrity protections provided by the train tracking device and the additional train tracking device providing a consolidated segment identifier and a consolidated position on the segment, as well as the protection interval consolidated, so that the risk of non-integrity of the consolidated outputs is much smaller than the risk of non-integrity of the outputs of the two devices taken separately, the consolidated position being calculated by weighted barycentre of the position of the main device and the additional device, and the protection interval being calculated by meeting the protection intervals of the primary device and the secondary device.

By identical or similar, we mean an element supposed to be identical but realized by two different entities, like the database which is assumed to be identical but can be realized by two different entities and contain some unfortunate differences.

The invention will be better understood by studying a few embodiments described by way of non-limiting examples and illustrated by the appended drawings in which:

- Figure 1 schematically illustrates an embodiment of an integrated and autonomous location system of a train in a railway network reference, according to one aspect of the invention;

FIGS. 2 to 4 schematically illustrate how the geographical uncertainty ellipse results in the existence of several 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 an 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 an embodiment of an integrated and autonomous location system of a train in a railway network reference, according to one aspect of the invention.

In all the figures, the elements having identical references are similar. In the present description, the embodiments described are in no way limiting, and the characteristics and functions well known to those skilled in the art are not described in detail. FIG. 1 represents an integrated and autonomous localization system of a train in a railway network reference system comprising:

a geographic location device 1 integrates into a global geographic repository configured to provide the position, the speed, and the heading of the train and their respective integrity protections against dreaded events that may affect the location device geographical integrity;

a cartographic database 2 integrates a rail network configured to provide data representing the railway network geographically in the form of segments; and

a train tracking device 3 configured to autonomously determine a railway network segment identifier on which the train is located, an integrated position of the train on this segment in the railway network reference system, and the associated protection interval at the position of the train on the segment from data provided by the integrated map 2 database and positions, speeds, caps and integrity protections provided by the geographic location device 1 integrates, by resolution of segment ambiguities of the railway network. From an integrated geographic location 1 (geographical position, geographical speed, geographic heading), the system performs a tracking 3 which uses a database 2 (describing the rail network) and which aims to provide the user with the identifier of the current segment with guaranteed integrity.

The tracking device 3 may further provide lateral deviation and course deviation measurements of the train relative to the track to the geographic location device 1, to improve its performance. These measures of deviation are integral, which is essential, because otherwise these measures could corrupt the device of geographical location 1. The tracking device 3 can also provide information enabling the geographical location device 1 to maintain the integrity of its measurements, taking into account the environment of the railway. In this mode of operation, the cartographic database 2 includes descriptive elements of the environment of the railway when it is likely to corrupt the measures of the integrated tracking system.

The system also provides the abscissa on the segment, the speed of the train on the segment, and the direction of movement, in an integral and independent manner of the tachometer system based on the observation of the movement of the wheels.

Thus, we start from an integrated location, as illustrated in FIG. 2, and thanks to the database 2, we move on to a protection uncertainty represented by the short broken lines of FIG.

With the tracking device 3, a position uncertainty represented by the short broken lines of FIG.

The present invention applies to the railway field, and generally to all positions and speeds of rail vehicles, such as trains, streetcars, and other road construction vehicles.

The integrated geographical location device 1 can comprise a GNSS receiver coupled to an UMI inertial measurement unit by an integrated hybridization, for example described in the Thai patent EP 3018447.

Railway Network Database 2 describes the network as segments, and defines the characteristics of each segment by geometric characteristics (such as the start of segment coordinates, the length of the segment, and the value of the clothoid or spline parameters). ) and chaining characteristics in the network (by example: identifying successor and predecessor segments). In a mode of use, the database 2 may also contain descriptive elements of the environment in the vicinity of the position considered. The tracking device 3 receives as input the location information provided by the integrated geographical location device (geographic position, geographical speed, geographic heading, protection radii at 10 ^x / h and associated alarms) and uses the database to identify the current segment so that the probability that the train is not on the indicated segment, without an alarm being raised, is less than 10 ^x / h.

The integrated geographic location device 1 produces the following information:

- the geographical position (longitude, latitude, altitude);

- the position protection ellipsoid parameters at 10 ^x / h (North, East, Vertical, North / East, North / Vertical, East / Vertical components);

- the geographical heading angle;

- Interval protecting heading at 10-x / h;

- 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 integrity is no longer assured). The geographical location device 1 is integral in the sense that the probability (taking into account the normal, rare and abnormal events that may affect this data source) that the measurements produced by the location are outside the range of protection announced by the device 1 geographical location, without an alarm being raised, is lower than the specified risk (eg 10 ⁶ / h).

The Thai patent EP3018447 describes an example of IMU / GNSS hybridization providing all this information. Generally, IMU / GNSS hybridization usually produces position, speed and heading angle, but also roll and pitch angles. In the present invention the heading plays an important role for the routing resolution, but not the roll and pitch angles.

Note that, since the train is moving on a locally flat terrain, the volume or protection interval is locally reduced to the intersection of the ellipsoid with this plane (which is an ellipse). The map database 2 satisfies the following conditions of integrity:

for each segment of the railway network described in the database, the chaining information is not erroneous (identifier of the segment and contiguous segments); and

for each segment described in the database, the positioning information enables 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 indicated error limits. in the description of the segment.

More rigorously, these conditions are held with a given risk: for example if the risk of non-integrity of the database is 10 ⁶ / h, and the average number of segments visited by the train is 100 segment / 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 different possible choices in the course of the network, here three branches (of different plots) are represented, implementing two junctions (cross box).

A junction is a segment of zero length that has one input and two possible outputs. The junction exists only in one direction: if the train rolls in the other direction, the junction does not create an alternative. In one embodiment, the database 2 further contains descriptive elements of the environment, when it is likely to corrupt the integrity of the device 1 geographical location integrity. For example, if one of the sensors used by the integrated geographical device 1 is a GNSS receiver, it can be corrupted by the contribution of the environment close to the position occupied by the train, particularly in a zone presenting a risk of journeys. GNSS reflected on surrounding buildings or an area presenting a risk of radio frequency interference (radiofrequency pollution near a telecommunication repeater, or a specific industrial site). The descriptive elements of an area at risk of reflected paths can, for example, provide the distance and the height of the buildings with respect to the considered point of the railway, which allows the device 1 of integrated geographical location to select only the satellites GNSS whose orientation of the visual axes does not present a risk, or to modify the weighting given to the various axes in the calculation of the integral position, so as to guarantee that the protective ellipsoid is not underestimated when the train is in the vicinity of the risk zone. The descriptive elements of a zone at risk of interference may be limited to the only "do not use" indication, so that the integrated geographical location source does not use the GNSS measurements in the vicinity of this zone.

The tracking device 3 implements rules that reflect the stress of the rails, and ambiguity resolution methods that reduce the number of possible segments among all segments of the rail network.

The main rules taken into account by the tracking device are as follows:

- R1: the train can not leave the zone of uncertainty provided by the integrated location in input. In Figure 6, only the short broken lines are possible for the true position with the risk of error given. - R2: the train can not jump from a current segment to a non-adjacent segment without going through a junction. This makes it possible to benefit from the past situation: for example, as illustrated in FIG. 7, the train was previously on segment 2, so it can not now be on segment 1 even if the uncertainty of the geographical position in entry allows to be there.

- R3: The train can not return to a previous segment if its direction of movement has not changed. For example, in FIG. 8, if the position uncertainty grows due to a loss of GNSS signal, as shown in FIG. 9, the fact that the train has passed the top track now becomes plausible unless one knows that the direction of travel has not changed. The change of direction is monitored from the speed provided by the location source with a given risk.

- R4: The train can not change branch (set of successive segments) without undergoing a variation of course. If the new branch is parallel to the previous one, the heading variation is momentary (it corresponds to the passage on the switch). If the new branch is not parallel, the change of course continues. These events are monitored by the heading angle provided by the location source with a given risk.

The main methods of ambiguity resolution implemented in the tracking device 3 are as follows:

instantaneous resolution based on the distance: the segments (described in the database 2) whose positions are outside the integrity ellipse provided by the integrated geographic location device 1 are discarded. The uncertainty of the integrated cartographic database 2 is also taken into account in this decision. - cap-based instantaneous resolution: Candidate segments whose heading range does not intersect with the heading range provided by the integrated geographical location device 1 are discarded. The uncertainty of the integrated cartographic database 2 is also taken into account in this decision.

- Switching resolution: when the current position and its uncertainty indicate the proximity of a switch, the switch resolution function is activated. It analyzes the successive course measurements provided by the integrated geographical location device 1 and evaluates the correlation of these measurements with the geometric heading values, along the two candidate trajectories, extracted from the cartographic database integrates 2. The length of the displacement, on which this analysis is carried out, and the decision thresholds are calculated taking into account the position and heading uncertainties produced by the device 1 of integrated geographical location as well as uncertainties of the cartographic database integrates 2, so that the probability of a bad decision is limited. When the switch is diverging (i.e. non-parallel channels at the switch output), the resolution function also analyzes the positional deviation with respect to the two candidate trajectories.

The tracking device 3 has several functions: first level tracking: the inputs of this function are the position, the heading and the associated protections (ellipsoid protecting the position, protection range of the heading, alarm), provided by the device 1 geographic location integrates, as well as the description of segments of the database integrates 2. The first-level tracking identifies the temporal sequence of segments, and implements the referral resolution (see above) whenever necessary. The first level tracking is activated at a sufficiently high frequency (typically 10 Hz) to be able to follow the sequence of 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 has only one segment, depending on the level of uncertainty of the entries, the first level tracking is not always able to identify the current segment: in this case the list contains several candidates

second-level tracking: The entries for 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 geographic location device integrates 1, as well as the description segments of the database integrates 2. This function is activated at a lower rate (typically 1 Hz) because the calculation volume can be important. This function analyzes the list of candidates identified by the first-level tracking and confronts it with the one built from the outputs (position and associated protection) produced by the integrated geographic location device 1, in order to detect complex cases (see figure illustrating the outgoing switch followed by an incoming switch). The elimination of false candidates implements the instantaneous distance-based and heading-based resolutions, as well as the speed measurement that can detect changes of direction. The implemented processes use the protection information (on the position, on the heading, on the speed, on the contents of the database) so that the probability of bad decision is limited. In case of cold start, all segments of the database integrates 2 are candidates. outputs and associated indicators: this function calculates the operational outputs (segment identifier, segment abscissa, x-axis protection interval, direction of motion, segment velocity, speed protection interval, alarm, mode Operating). generation of deviation measurements: when the operating mode indicates "nominal", only one segment is candidate, the position on the segment is known with the associated protection interval, and the geographical direction is known with the protection interval associated. can then calculate the lateral difference between the position produced by the integrated geographical device 1 and the track, as well as the difference between the heading produced by the geographic device integrates 1 and that of the track, as well as the associated uncertainty intervals .

- production of descriptive elements of the environment of the railway: if the database integrates 2 also contains a description of the elements of environment likely to corrupt the integrity of the integrated geographic device 1, the tracking device 3 can provide this information to the geographic device integrates 1 when the tracking device 3 is in "nominal" operating mode, because in this case, the knowledge of the segment and the position on the segment, as well as its associated protection interval, allows to identify in the integrated 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" (several segments are possible ), these descriptive elements are also provided, but considering the worst contribution offered by the candidate segments in the database. e data.

FIG. 10 illustrates an example of a complex situation in which the possible reversal of the direction of movement of the train must be taken into account in the tracking device.

FIG. 11 represents the tracking device 3.

The tracking 3 is divided into two parts: a first level tracking portion 3a and a second level tracking portion 3b. The choice to make this tracking in two parts is mainly because the second level tracking 3b requires a lot of calculations and it must be done at a lower frequency. The purpose of first level 3a tracking is: determine the curvilinear abscissa associated with all the candidate segments according to the current position resulting from the integrated geographical location and the previous curvilinear abscissae, to update all the candidate segments each time a junction is encountered thanks to the database and update the tracking mode (see below),

to resolve referrals under certain conditions (see below), to develop the position-heading deviations produced by the geographic location module, and the position and course calculated from the database, and to provide them geographic location integrates when only one segment is a candidate, and

to provide a set of candidate segments and curvilinear abscissas associated with the second level tracking 3b. The purpose of second level tracking 3b is:

- determine the set of possible segments using:

o the uncertainty associated with the geographic location position integrates, and

o all possible segments provided by online tracking,

- use the different geographical location parameters and their associated uncertainties to reduce the set of potential candidates in order to solve the potential junctions,

- Providing geographic location integrates a geographical position measurement calculated from the database, if the position produced by the tracking device is found to have a better uncertainty than that produced by the integrated location module. This is an additional feature, which offers a possibility of occasional resetting of the geographical location device, which improves its performance, and therefore improve the future availability of the tracking device,

- provide the end user:

o the set of possible segments and the associated minimum and maximum curvilinear abscissae, o the estimated position,

the curvilinear abscissa (s) estimated according to the tracking mode. There are three modes in the tracking:

a nominal mode in which all the junctions have been solved and the tracking is able to provide:

o only one estimated segment and an associated curvilinear abscissa, o an uncertainty expressed by the minimum and maximum curvilinear abscissae on this segment, or by a set of several segments with their minimum and maximum curvilinear abscissae if the uncertainty extends over several segments contiguous.

a "degraded" mode and an "init" mode in which the tracking is capable of providing:

o several estimated segments and several associated curvilinear abscissae,

o uncertainty expressed by a set of segments with their minimum and maximum curvilinear abscissa.

The "init" mode is activated when there is no information on the possible candidate segments before searching for the second level tracking candidate segments 3b. The "init" mode is also activated if the internal geographical location device activates its integrity alarm signal.

The first level tracking 3a starts from the "init" mode and is initialized either:

from an external help providing a segment, an associated curvilinear abscissa and the uncertainty associated with this abscissa (init),

- from the supply of a segment, an abscissa and an associated uncertainty resulting from the search function of the candidate segments. There is different types of segment resolutions as explained below: the resolution used here is the resolution in "init" mode.

At the "init" mode output, a segment, a curvilinear abscissa and an associated uncertainty are available. We then enter the nominal mode.

The inputs are then the current position P provided by the geographical location solution (position, heading, speed, uncertainties) and the preceding segment (or the preceding segments), which is provided either by the "init" mode or by the list of candidate segments from the first-level tracking of the previous cycle (these segments being provided with their curvilinear abscissa), to which the segments identified by the second-level tracking 3b have been added or removed. From these entries we recalculate all the possible segments and the curvilinear abscissas associated with the current time as follows.

Let P be the current position and be a candidate segment from the previous iteration called id. Let s be the curvilinear abscissa associated with the estimated point P1 of the candidate segment. In P1 we calculate the directional vector of the tangent to the segment. The vector P1 P is projected on the direction vector calculated above. The value of the scalar product gives an approximation of the curvilinear abscissa (As) difference between the point P1 and the projected point P on the track. We update the value of s with s = s + As to recalculate a new point P1. Iterates until the dot product has become weak to obtain a new estimated position on the P2 path. FIG. 12 shows the rail in short broken lines, P1 the estimated position on the segment at the previous instant, P the current position sent by the integrated geographic location and P2 the position after iteration.

If the position P2 has a curvilinear abscissa greater than the declared length of the segment id, we search in the database integrates 2 which is the next segment. If the next segment is not a junction, move to the new segment with a new curvilinear abscissa. If the next segment is a junction, we create a new possible candidate and at the exit we have two possible segments with two curvilinear abscissa.

The routing resolution in line tracking 3a is realized only if:

- we are in degraded mode (in nominal mode, there is nothing to solve and in "init" mode it is the second level tracking 3b that performs the work),

- and if the position and its uncertainty are entirely contained in the candidate segments. In fact, in the opposite case, one could arrive at erroneous conclusions: as in the following example illustrated by FIGS. 13 and 14.

In the example of FIGS. 13 and 14, the segments S20 and S50 are the candidate segments. In the first configuration of Figure 13, the routing resolution is enabled. In the second configuration of Figure 14 the switching resolution is disabled because the uncertainty overflows on the segment S51. In the second configuration, it is possible to choose the segment 20 because the true position heading is consistent with the segment 20 and the two candidate segments are segments 20 and 50.

The routing resolution can be done in three ways: by instantaneous comparison of the heading between the heading of the geographical location solution and the heading of the candidate segments to the estimated curvilinear abscissa,

looking at whether only one segment is contained in the confidence ellipse, and

by correlation between the successive caps from the integrated geographical location module and the successive caps taken by each of the candidate segments over a given length, this makes it possible to eliminate the heading error related to the position uncertainty. At the end of the referral resolution, there is available a set of candidate segments and their associated curvilinear abscissa that can be transmitted to the second level tracking. In nominal mode when the estimated position and uncertainty are contained in the candidate segment, the tracking measurements can be calculated. This is the lateral deviation from the track and the estimated course at the curvilinear abscissa. This information is sent to the integrated geographic location device with their associated uncertainties. The uncertainty depends on the accuracy of the database and the uncertainty on the curvilinear abscissa.

The lateral deviation from the channel is calculated as the scalar product between the director vector perpendicular to the channel at the estimated curvilinear abscissa and the P2P vector where P2 is the estimated position on the track and P is the estimated position sent by the geographical location device.

Below is the detail of the resolution of the candidate segments.

The resolution in "init" mode does not make assumptions on the segments that can be candidates.

We start from an estimate of position and its confidence ellipse resulting from the integrated location: cross and ellipse in full lines in figure 15 in the diagram below. For all segments of the database integrates 2 (all segments are potential candidates), we search for those included in the ellipse.

To see if a segment belongs to an ellipse, we start by sampling the segment. The sampling distance must be a fraction of the minimum length between the position uncertainty and the segment length. Then for each point, we see if it is contained in the ellipse: the points contained in an ellipse of great axis a and small axis b satisfy the equation: u ² / a ² + v ² / b ² <= 1, where u and v are the coordinates of the point of the segment in the coordinate system 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 segment branch (and not one segment) is a candidate, one segment has been found to provide either the list of first-level tracking segments or the initialization of first-level tracking: transition [A ] A change to nominal mode is also ordered. The candidate segment to be supplied is the 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 the sake of simplicity, the uncertainty is that of the estimated position initially provided, even if one sees that one could do better by geometric considerations.

At the end of this search, we are able to output a set of candidate segments as well as the minimum and maximum abscissa per segment of the points contained in the ellipse that we call smin, smax. (We are looking for a single branch of segments and not a 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 the same branch. So we can switch to nominal mode. The segment provided for online tracking is segment 2.

This search is used to manage rule R1.

The second type of resolution, in nominal and degraded mode, is a resolution on a restricted number of segments from the list of segments from the first level tracking. This is the most complex part of the algorithm.

The search starts from the different segments provided by the first level tracking. For each segment resulting from the first level tracking (only one in nominal mode and several in degraded mode), all of its previous and possible segments are searched. The set of possible next and previous segments belongs to the confidence ellipse provided by the integrated location device 1. The confidence ellipse has a larger axis whose value for the required integrity (10-n / h) This value is deduced from the information sent by the integrated geographic location by diagonalising the position covariance matrix. For each id, abscissa s and length L segment, provided by the first level tracking, all preceding and following segments of the id segment, which are within one R length (in terms of curvilinear integral) of the abscissa s of the id segment, are considered included in the confidence ellipse. This is an approximation that will be completed using another method described later.

The search for the following segments is done as well. For each id segment 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 all the segments that directly follow id are searched in the database. The value of R is then updated for the next segments R = R- (L-s),

For each immediate successor of id noted id1 of length denoted L1, the same procedure is applied. If R-L1> 0, then the immediate successors of id1 are searched in the database and the value of R is further reduced R = R - L1,

- The previous operation starts again until R is zero.

At the end of the procedure, a list of successor segments is available and for each successor segment, a minimum abscissa and a maximum abscissa is associated. The same operation is performed in the other direction for the predecessor segments.

In fact a segment longer than R can be contained in the confidence ellipse since the segments are not straight lines. The segments and abscissae found in the previous method are supplemented by searching segments whose at least one point is contained in the ellipse using the method presented in the "init" mode. Only the next and previous segments of each segment provided by the first level tracking have retained. The following and previous segments are obtained by browsing the database from each segment provided by online tracking.

The implementation of the two methods described above is more rigorous with respect to the integrity data provided by the integrated geographic location device 1 than the use simply based on the search for the segments in the ellipsoid, since the uncertainty is taken into account according to the direction of the way.

This search for successor and predecessor segments makes it possible to manage the fact that one can not jump from one segment to another without going through a junction: rule R2. Indeed a segment included in the ellipse, which is neither the successor nor the predecessor of a candidate segment resulting from the research detailed above, is not a candidate.

The direction of advancement is then determined. The speed is obtained by projection of the geographical velocity vector, produced by the geographical location device, on the direction of the tangent to the segment. The velocity protection interval is the interval delimited by the intersection of the speed protection ellipse, produced by the geographic location device, with the segment. The direction of travel is clearly identified when the speed modulus is greater than the half speed protection interval.

If the direction of advancement does not change, segments that are predecessor segments of a successor segment, or segments that are successor segments of a predecessor segment, can not be candidates. Otherwise it would mean that the train has changed meaning (see example below): this is the rule R3. For this reason, these segments are not searched for in the method described above.

If the direction of progress changes or if the direction of advancement is unknown (the rule R3 no longer applies), for each successor segment obtained in the previous part, we look, for each successor segment obtained by the previously described treatment if its previous segment is declared as a junction in the built-in database 2. If so, all segments preceding this junction must be added to the list of first-level tracking candidates (transition [B]) .

For each predecessor segment obtained by the treatment described above, we look in the same way if its next segment is a junction. If this is the case, all segments following this segment must be added to the list of first level tracking candidates (transition [B]).

If there are too many junctions to solve we go back 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 one moves from the left to the right (known direction of advance), the mode is "nominal" and the first level tracking gives the segment S 18. In short broken lines the segments are represented S60 and S61 can not be candidates because a change of direction is required (rule 3) Segments S80 and S81 can not be candidates because it is necessary to go through a junction (rule 2). the method mentioned above makes it possible to determine all the candidate segments in accordance with the rules R1, R2 and R3.

In FIG. 18, the direction of progress becomes impossible to determine, the mode is "nominal", and line tracking gives the input S18 segment.

In this case the segments S60 and S61 become candidates and the segment S61 is added to the list of candidates of the tracking list of first level. Indeed imagine that the real position is represented by the yellow star and the train goes in the other direction through S61. If S61 is not a candidate, the referral is 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 integrated geographic location device are identified. This must be between the minimum cap and the maximum cap of the candidate segment portion. These minimum and maximum bounds must take into account the uncertainty of the heading of the integrated geographical location device as well as the uncertainty of the integrated cartographic database.

If there has been no change in direction and the direction is known, then a segment can only be a candidate if its previous segment has already been a candidate. This algorithm makes it possible to manage the rule R4 on the variation of heading. This algorithm can be supplemented by a monitoring of the temporal variation of the heading of the integrated geographical location device.

In the example of FIGS. 19 and 20, the switching junction S19 has not yet been solved. First-level tracking identified candidate segments S20 and S50. Second level tracking candidates, after applying the previous selection methods, are S18, S20, S50 and S21. S51 is not a candidate because its course is not compatible with the course of the integrated geographic localization device. When the train moves (we imagine that it takes the lower branch), since the segments S51 and S52 are not candidates (because of the criterion on the heading), then S53 can not be candidate, although its course be compatible. Thus the switch S19 is solved correctly by selecting the branch S20 and S21.

The search for candidate segments thus contributes to resolving referrals. It allows to return to "nominal" mode by removing the segments that are no longer candidates, and it updates the list of segments online (transition [C]).

For measurement construction, tracking reduces position uncertainty by eliminating non-candidate segments. compatible geographic location data via the rules mentioned above (including using the heading of the database).

If the position 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 can be adjusted using a measurement of position provided by the tracking. This position measurement makes it possible to reduce the position uncertainty.

For the provision to the user of the segment (s) and associated uncertainty, it includes the following:

three coordinates of the estimated position resulting from the integrated geographical location;

three coordinates of the estimated speed resulting from the geographical location integrates;

an estimated segment and an associated curvilinear abscissa, in "nominal" mode;

an estimated speed and associated uncertainty, in "nominal" mode;

a direction of movement, if the modulus of the speed is greater than its uncertainty, in "nominal" mode;

a position uncertainty translated by a set of segments with their minimum and maximum abscissae in all modes; and

an indicator of the tracking mode ("nominal", "degraded", "init").

The system can be used alone, for criticality applications of the order of 10 ⁵ / h to 10 ⁷ / h. To provide a "catastrophic" criticality service (10 ⁹ / h at 10 ¹ / h), it is possible to use two homogeneous geographical location devices 1, 1 bis each using an integrated device that is dissimilar to the other, as shown in FIG. figure 21. A consolidation module 4 of the "com / mon" type then consolidates the outputs of the two tracking devices, similar to what is done in critical aeronautical systems, for example the consolidated position is a weighted center of gravity between the position of the main device and that of the additional device and whose protection interval consists of the meeting of the protection intervals of the main device and the secondary device.

If the risk of non-integrity of the device 1, 2, 3 is 10 ⁶ / h and the risk of non-integrity of the device bis 1 bis, 2bis, 3bis is 10 ³ / h, then the probability of having both sources failing simultaneously is 10 ⁹ / h. This improvement is true if the two devices have no common mode up to 10 ⁹ / h. An example of FIG. 21 consists of a device 1, 2, 3

(chain "command") whose source is a hybridization GPS / UMI and a device bis (chain "monitoring") whose source is a hybridization Galileo / UMI, considering that the GPS and Galileo systems are independent, with some precautions for to deal with the common mode of disruption of GPS and Galileo signals in the vicinity of the ground.

In this example, the database can be a common mode. To reduce this common mode, one can limit the use of the database in one of the two chains. Thus, in FIG. 21, the source of the device 1, 2, 3 uses the measurements of deviation from the path produced by the tracking device, whereas the source of the device bis 1 bis, 2bis, 3bis does not use the measurements. from gap to track. The consequence is that the accuracy of the device bis is less, but it is partly compensated by the fact that the protective radii of the bis device are calculated for a lower criticality (10 ³ / h instead of 10 ⁶ / h).

Claims

1. Integrated and autonomous positioning system of a train in a railway network reference system comprising:

a geographical location device (1) integrates into a global geographic reference system comprising an inertial unit, a GNSS receiver, and a hybridization module of the measurements provided by the inertial unit and the GNSS receiver configured to supply the three position coordinates, the three velocity components, and the heading angle of the train in the global geographic repository and their respective integrity protection intervals with respect to dreaded events that may affect the geographical location device, so that the the probability that the position or heading speed or angle is outside the integrity protection intervals is less than once every million hours;

a cartographic database (2) integrates a railway network configured to provide data representing geographically the railway network in the form of segments and information representative of zones of the railway environment presenting a risk of GNSS paths reflected to maintain the integrity of the geographic location device, and

a train tracking device (3) configured to autonomously determine a railway network segment identifier on which the train is located, an integrated position of the train on this segment in the rail network reference system, and the protection associated with the position of the train on the segment from data provided by the integrated map database and positions, speeds, caps and integrity protections provided by the geographical location device integrates, by resolution of segment ambiguities candidates, so that the probability of the train not being at the designated location of the rail network is less than once every million hours, the tracking device being configured to provide, retroactively, during the movement of the train, the geographical location device integrates said information representative of areas of the railway environment presenting a risk of reflective GNSS paths;

the integrated geographical location device being configured to use either only GNSS satellites whose direction of the visual axis does not present a risk of paths reflected at the location of the train, or to change the weighting given to the various GNSS satellites used at the location of the train.

2. System according to claim 1, wherein the tracking device (3) is configured to retroactively provide, to the integrated geographical location device (1), integrated measurements of lateral deviation and course deviation of the train relative to to the railway track of the rail network, the hybridization module being configured to take into account said measures.

3. System according to one of the preceding claims, wherein the tracking device is configured to:

4. System according to one of the preceding claims, wherein the tracking device is configured to perform a correlation along the curvilinear abscissa between the successive course angles provided by the integrated geographic location device and the successive caps taken by each of the candidate segments, so as to select a single segment.

5. System according to one of the preceding claims, wherein the tracking device (3) is configured to determine a speed and direction of movement of the train, by projecting on the direction of the current segment of the speed and its interval. protection provided by the integrated tracking device.

6. System according to one of the preceding claims, wherein said data representing the railway network in the form of segments comprise for each segment the position coordinates and the heading angle in the global geographic reference, the length of the segment, the value a parameter representative of the curvature and its variation, the value of chaining parameters of the segment with other segments, and the values of the limits of the position error and the heading error of this segment.

7. System according to one of the preceding claims, comprising:

an additional geographical location device (1 bis) integrates into a global geographic reference system, different from the integrated geographical location device, configured to provide the position, the speed, and the heading of the train as well as their respective integrity protections;

- an additional base (2a) of map data integrates the railway network, identical or similar to the map database integrates the rail network, configured to provide data representing the railway network in the form of segments;

an additional device (3a) for tracking the train, identical or similar to the train tracking device, configured to determine an integrated and autonomous position of the train in the railway network reference system and a corresponding railway network segment identifier, starting from data provided by said additional cartographic map integrates and respective positions, speeds, caps and integrity protections provided by the additional geographic localization device integrates, by resolving ambiguities of candidate segments; and a consolidation module (4) for the integrity protections provided by the train tracking device and the additional train tracking device providing a consolidated segment identifier and a consolidated position on the segment, as well as the protection interval. consolidated, so that the risk of non-integrity of the consolidated outputs is much smaller than the risk of non-integrity of the outputs of the two devices taken separately, the consolidated position being calculated by weighted barycentre of the position of the main device and the additional device, and the protection interval being calculated by meeting the protection intervals of the primary device and the secondary device.