Patent Publication Number: US-2019185035-A1

Title: Procedure for tracking radio equipped vehicles without odometer

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. non-provisional application claiming the benefit of French Application No. 17 62614, filed on Dec. 20, 2017, which is incorporated herein by reference in its entirety. 
     FIELD OF THE INVENTION 
     The present invention relates to a method for locating at least one railway vehicle in a railway network, the railway network comprising a plurality of first detection devices, each first detection device being configured to detect the passage of a railway vehicle in a first given perimeter associated with said first detection device, a plurality of second detection devices different from the first detection devices, each second detection device being configured to detect the passage of a railway vehicle in a second given perimeter associated with said second detection device and a centralized server, the method comprising, for each railway vehicle, the following steps: 
     detection by at least one of the first detection devices of the passage of said railway vehicle in the first perimeter; 
     transmission of a first detection signal by each first detection device having detected the presence of the railway vehicle in the first associated perimeter; 
     detection by at least one of the second detection devices of the passage of said railway vehicle in the second perimeter; 
     transmission of a second detection signal by each second detection device having detected the presence of the railway vehicle in the second associated perimeter; 
     reception of the at least one first detection signal and the at least one second detection signal by the centralized server; and 
     determination of the position of the railway vehicle on the railway network by the centralized server. 
     In the present document, a railway vehicle refers to any guided vehicle able to move over a track of a railway network, for example a train, tram, subway. 
     BACKGROUND 
     The precise location of the railway vehicles in the railway network is essential in order to see to the completely safe circulation of all of the railway vehicles traveling over the tracks of the railway network without risk of accident between two railway vehicles present on a same track. 
     Additionally, there is a need for maintenance operators to know the position of the various maintenance vehicles present on the railway network in order to resolve any problem affecting the railway network quickly. 
     To that end, it is known to have, in the railway network, a plurality of beacons and to equip the railway vehicles intended to transport travelers and/or goods with a beacon detector and an odometer making it possible to measure the distance traveled by the vehicle. Thus, the position of the railway vehicle is recalibrated upon each passage by a beacon of the railway network, the odometer making it possible to locate the railway vehicle precisely between two beacons. 
     However, such an odometer is expensive, and it is preferable to avoid equipping all maintenance vehicles with them, all of the latter not having the same requirements in terms of geolocation precision and communication security as the vehicles for transporting travelers and/or goods. 
     Document WO 2007/078704 describes a railway vehicle tracking method in a railway network using a detection device arranged in the railway network, such as a GPS device, for example, and a database comprising a map of the railway network. The railway vehicle is located in the railway network by comparison between the geographical data from the detection device and the database. 
     However, such a method is not fully satisfactory. Indeed, the method does not only use the geographical data from the detection device. As a result, in case of failure or poor precision of the detection device, for example for GPS in a tunnel, the railway vehicles are no longer located precisely in the railway network. 
     One aim of the invention is therefore to obtain a method for locating railway vehicles in a railway network that is inexpensive while allowing precise location at any moment of the railway vehicles. 
     SUMMARY 
     To that end, the invention relates to a method of the aforementioned type, wherein the determination of the position of each railway vehicle is made from the first detection signal and the second detection signal, by intersection of the first perimeter associated with said first detection signal and the second perimeter associated with said second detection signal. 
     The determination of the location of the railway vehicle is therefore made using at least two different location devices thus allowing greater precision and redundancy of the detection devices in case of failure of one of the detection devices. Thus, the determination of the location is precise and possible at any moment. 
     The method according to the invention may comprise one or more of the following features, considered alone or according to any technically possible combination: 
     the railway network further comprises a plurality of third detection devices, each third detection device being configured to detect the passage of a railway vehicle in a given third perimeter associated with said third detection device, the method also comprising the following steps:
         detection by at least one of the third detection devices of the passage of said railway vehicle in the third perimeter;   transmission of a third detection signal by each third detection device having detected the presence of the railway vehicle in the third associated perimeter;
 
the determination of the position of each railway vehicle further being made from the third detection signal, by intersection of the first perimeter associated with said first detection signal, the second perimeter associated with said second detection signal and the third perimeter associated with said third detection signal;
       

     the method further comprises a step for transmission by the centralized server of the position of each railway vehicle on the railway network to each railway vehicle; 
     the method further comprises a step for transmission by the centralized server of the position of the at least one railway vehicle on the railway network to an operator; 
     each detection device sends the detection signal to the detected railway vehicle, then said railway vehicle sends a request signal comprising the detection signals to the centralized server; 
     each railway vehicle further sends a unique identification code to the centralized server; 
     the railway vehicle has no on-board geolocation means; 
     the railway vehicle is a maintenance vehicle capable of performing maintenance on the railway network; 
     the geolocation devices are part of the list of the following devices:
         an axle counter;   a switch;   a beacon;   a GPS location system;   a radio antenna;   a laser detector;   a track circuit.       

     the centralized server records the history of the positions of each railway vehicle on the tracks of the railway network. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be better understood upon reading the following description, provided solely as an example and done in reference to the appended drawings, in which: 
         FIG. 1  is a schematic side view of two railway vehicles located in a railway network using a method according to the invention; and 
         FIG. 2  is a schematic side view of a railway vehicle located in a railway network using an alternative of the method according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
     The railway network  10 , shown in  FIG. 1 , comprises a plurality of railway vehicles  12 , a plurality of tracks  14 , at least one plurality of first detection devices  16 , at least one plurality of second detection devices  18 , advantageously, according to one embodiment, a plurality of third detection devices  20  and a centralized server  22 . 
     Each railway vehicle  12  is for example a train car transporting travelers and/or goods or a maintenance vehicle able to perform maintenance on the railway network  10  and/or to solve problems affecting the railway network  10 . For example, a maintenance vehicle is able to perform maintenance on the tracks  14  of the railway network  10 . 
     Each railway vehicle  12  is provided with wheels  23 . The wheels  23  are attached to the rest of the railway vehicle  12  by axles, not shown in the figures. 
     The wheels  14  are equipped with rails, the wheels  23  of the railway vehicles  12  being arranged on the rails. 
     Each railway vehicle  12  is able to circulate on the tracks  14  in order to move in the railway network  10 . 
     Each first detection device  16  is configured to detect the passage of the railway vehicle  12  in a given first perimeter P 1  associated with the first detection device  16 . 
     In the example shown in  FIG. 2 , the first detection devices  16  are axle counters located on the tracks  14 . Each axle counter is able to count the axles of a railway vehicle  12  passing over the track  14  associated with the axle counter. By comparing the number of axles counted by two axle counters located at two ends of a segment of a track  14 , the presence or absence of the railway vehicle  12  on the segment is deduced. The associated first perimeter P 1  is then the length of the segment. 
     The first detection devices  16  are for example distributed along the tracks  14  such that all of the tracks  14  of the railway network  10  are cut into segments. The first perimeter P 1  associated with a first detection device  16  is formed by the segment(s) on which the first detection device  16  is able to detect the presence of a railway vehicle  12 . 
     Each second detection device  18  is configured to detect the passage of the railway vehicle  12  in a given second perimeter P 2  associated with said second detection device  18 . 
     The second detection device  18  is different from the first detection device  16 . Different means that the first detection device  16  and the second detection device  18  do not work using a same technology and detect the railway vehicle  12  differently. 
     In the example shown in  FIG. 2 , the second detection devices  18  are switches capable of causing the railway vehicles  12  to change tracks  14 . 
     Each switch is configured to provide information making it possible to determine the branch on which a railway vehicle  12  passing on said switch is steering itself. The track  14  downstream from the switch on which the railway vehicle  12  is located is then known. The associated second perimeter P 2  is then the segment between two consecutive switches. 
     The second detection devices  18  are for example distributed along the tracks  14  such that all of the tracks  14  of the railway network  10  are cut into segments. The second perimeter P 2  associated with a second detection device  18  is formed by the segment(s) on which the second detection device  18  is configured to determine the presence of a railway vehicle  12 . 
     According to one embodiment, each third detection device  20  is configured to detect the passage of the railway vehicle  12  in a given third perimeter P 3  associated with said third detection device  20 . 
     The third detection device  20  is different from the first detection device  16  and the second detection device  18 . 
     In the example shown in  FIG. 2 , the third detection devices  20  are radio antennas arranged regularly along the tracks  14 . Each radio antenna is capable of detecting the passage of a railway vehicle  12  near said radio antenna. The third perimeter P 3  is then the detection zone surrounding the radio antenna. 
     The third detection devices  20  are for example distributed along the tracks  14  such that all of the tracks  14  of the railway network  10  are cut into segments. The third perimeter P 3  associated with a third detection device  20  is formed by the segment(s) on which the third detection device  20  is able to detect the presence of the railway vehicle  12 . 
     In the example described below, the railway network  10  comprises three different detection devices  16 ,  18 ,  20 . However, the invention applies once the railway network  10  comprises only two different detection devices. Advantageously, the railway network  10  of the method according to the invention comprises more than three different detection devices. Indeed, as shown by the explanation below, the more different detection devices the railway network  10  comprises, the more effective the localization of a railway vehicle  12  is. 
     The first detection devices  16 , the second detection devices  18  and the third detection devices  20  are advantageously chosen from among: an axle counter, a switch, a beacon, GPS location, a track circuit, a radio antenna or a laser detector installed on the tracks, the detection devices  16 ,  18 ,  20  being different from one another. 
     Advantageously, the railway network  10  according to the invention allows the detection of one or several railway vehicles  12  without on-board geolocation means, in particular an odometer, and thus allowing localization of railway vehicles  12 , in which on-board geolocation equipment has not been installed. This is for example the case for maintenance vehicles present in the railway network  10 . 
     A first method for locating a railway vehicle  12  in the railway network  10  according to the invention will now be described. 
     Initially, as shown in  FIG. 2 , the railway vehicle  12  is located on a track  14  of the railway network  10 . 
     At least a first detection device  16  is configured to detect the passage of the railway vehicle  12  in the perimeter P 1  associated with said first detection device  16 . 
     The first detection device  16  sends a first detection signal S 1 , the detection signal S 1  being sent to the centralized server  22  or the railway vehicle  12 . The first detection signal S 1  is representative of the location of a railway vehicle  12  in the first perimeter P 1  associated with first detection device  16 . Thus, in the case of an axle counter, the first signal S 1  is representative of the presence of the railway vehicle  12  on one of the segments associated with the axle counter. 
     At least a second detection device  18  is configured to detect the passage of the railway vehicle  12  in the perimeter P 2  associated with said second detection device  18 . 
     The second detection device  18  sends a second detection signal S 2 , the detection signal S 2  being sent to the centralized server  22  or the railway vehicle  12 . The second detection signal S 2  is representative of the location of a railway vehicle  12  in the second perimeter P 2  associated with second detection device  18 . Thus, in the case of a switch, the second signal S 2  is representative of the presence of the railway vehicle  12  on one of the tracks  14  associated with the switch. 
     Advantageously, at least a third detection device  20  detects the passage of the railway vehicle  12  in the perimeter P 3  associated with said third detection device  20 . The third detection device  20  sends a third detection signal S 3 , the detection signal S 3  being sent to the centralized server  22  or the railway vehicle  12 . The third detection signal S 3  is representative of the location of a railway vehicle  12  in the third perimeter P 3  associated with third detection device  20 . Thus, in the case of a radio antenna, the third signal S 3  is representative of the presence of the railway vehicle  12  in the detection zone associated with the radio antenna. 
     Thus, the at least one first detection signal S 1 , the at least one second detection signal S 2  and the at least one detection signal S 3  are received by the railway vehicle  12  or directly by the centralized server  22 . 
     The railway vehicle  12  advantageously receives the at least one first detection signal S 1 , the at least one second detection signal S 2  and the at least one detection signal S 3 . The railway vehicle  12  next sends a request signal S 4  comprising the at least one first detection signal S 1 , the at least one second detection signal S 2  and the at least one third detection signal S 3  to the centralized server  22 . 
     The passage of the three detection signals S 1 , S 2  and S 3  by the railway vehicle  12  thus makes it possible for the three detection signals S 1 , S 2  and S 3  to be sent using a unique request signal S 4  associated with the railway vehicle  12  allowing a simplified management at the centralized server  22 . 
     The request signal S 4  advantageously comprises an identification code associated uniquely with said railway vehicle  12  in order for the centralized server  22  to identify the railway vehicle  12  and distinguish it from the other railway vehicles  12  circulating on the tracks  14  of the railway network  10 . 
     The centralized server  22  receives the request signal S 4 . The centralized server  22  next determines the position of the railway vehicle  12  from the request signal S 4 . The determination of the position of the railway vehicle  12  is done systematically by intersection, or crossing, between a first perimeter P 1 , a second perimeter P 2  and advantageously a third perimeter P 3 . 
     The obtained position of the railway vehicle  12  is then much more precise than the position of the railway vehicle  12  estimated by each of the detection devices  16 ,  18 ,  20  considered separately. 
     In the example illustrated in  FIG. 2 , the switch detects that the railway vehicle  12  is on the track segment  14  comprising sections B 5  to B 12 . The axle counter detects that the railway vehicle  12  is located on the track segment  14  comprising sections B 7  to B 9 . A first radio antenna detects that the railway vehicle  12  is located in the zone comprising sections B 5  to B 7  and a second radio antenna detects that the railway vehicle  12  is located in the zone comprising section B 8 . By intersection, the centralized server  22  deduces from this that the railway vehicle  12  is located in sections B 7  and B 8 . 
     In case of failure or insufficient precision of one of the detection devices  16 ,  18 ,  20 , the perimeter P 1 , P 2 , P 3  associated with the defective detection device  16 ,  18 ,  20  is presumed to be the entire railway network  10  so as not to disrupt the determination of the position of the railway vehicle  12 . 
     The centralized server  22  advantageously records the history of the positions of the railway vehicle  12  in the railway network  10 . 
     The history of the positions of the railway vehicle  12  is taken into account in determining the position of the railway vehicle  12  in the railway network  10 . Following the intersection of the perimeters P 1 , P 2 , P 3  of the detection devices  16 ,  18 ,  20 , the centralized server  22  compares the position of the railway vehicle  12  determined by the intersection of the perimeters P 1 , P 2 , P 3  to the previous position of the railway vehicle  12  recorded by the centralized server  22 . The centralized server  22  verifies the consistency between the two positions. 
     If the two positions are considered to be consistent, the centralized server  22  records the position determined by the intersection of the perimeters P 1 , P 2  and P 3  and the centralized server  22  considers that the position determined by the intersection of the perimeters P 1 , P 2  and P 3  is the current position of the railway vehicle  12 . 
     Coherence between the two positions means that the two positions are separated by a distance smaller than the theoretical distance traveled by the railway vehicle  12  at a maximum speed estimated during the same time interval and that the railway vehicle  12  is still on the same track  14 . 
     If an incoherence is detected, for example an instantaneous change of tracks  14 , the centralized server  22  does not record the position determined by the intersection of the perimeters P 1 , P 2 , P 3  and considers that the preceding position of the railway vehicle  12  is still the current position of the railway vehicle  12 . 
     The centralized server  22  next advantageously sends a position signal S 5  comprising the position of the railway vehicle  12  in the railway network  10  estimated by the centralized server  22  to the railway vehicle  12 . The railway vehicle  12  thus knows its position in the railway network  10 . 
     The centralized server  22  also advantageously sends the position of the railway vehicle  12  to an operator. The operator is for example a maintenance operator and the railway vehicle  12  is for example a maintenance vehicle. The maintenance operator thus knows the position of the maintenance vehicle and can quickly access said maintenance vehicle to resolve a potential problem having occurred on the railway network  10 . 
     Alternatively, a second method for locating a plurality of railway vehicles  12  in the railway network  10  according to the invention will now be described. 
     Each railway vehicle  12  is located in the railway network  10  in a manner similar to the first localization method. 
     The second localization method differs from the first localization method in that the position signal S 5  sent by the central server  22  comprises the position of all of the railway vehicles  12  in the railway network  10 . 
     As illustrated in  FIG. 1 , each railway vehicle  12  advantageously receives the position signal S 5 . Thus, each railway vehicle  12  knows the position of the other railway vehicles  12  in the railway network  10 , thus allowing stronger circulation safety of the railway vehicles  12  in the railway network  10 . 
     The operator also advantageously receives the position signal S 5 . The operator therefore knows the position of all of the railway vehicles  12  in the railway network  10 . In case of any problems in the railway network  10 , the maintenance operator can thus choose the maintenance vehicle closest to the incident. 
     Owing to the features described above, the localization of the railway vehicles  12  in the railway network  10  is therefore done inexpensively, precisely and redundantly. Indeed, the localization of the railway vehicle  12  is done using detection devices  16 ,  18 ,  20  already located on the railway network  10  and therefore does not require additions of extra equipment in the railway network  10 . The railway vehicle  12  advantageously not having on-board geolocation means, the method according to the invention also does not require the installation of a specific device in the railway vehicle  12 . Furthermore, the location of each railway vehicle  12  being done systematically using at least two detection devices  16 ,  18 ,  20 , the positioning of the railway vehicle  12  is more precise than the positioning estimated by each detection device  16 ,  18 ,  20  taken separately. All of the railway devices  12  and the maintenance operators thus have a precise view of the position of each railway vehicle  12  in the railway network  10 . In case of failure of one of the detection devices  16 ,  18 ,  20 , the positioning of the railway vehicle  12  is still possible, thus allowing stronger railway security.