AU2013205670A1

AU2013205670A1 - Method and system for securing a movement of a rail vehicle, onboard controller in a rail vehicle and a rail vehicle

Info

Publication number: AU2013205670A1
Application number: AU2013205670A
Authority: AU
Inventors: Brice Andre; Michel Rousseau
Original assignee: Alstom Transport SA
Current assignee: Alstom Holdings SA
Priority date: 2012-05-03
Filing date: 2013-05-03
Publication date: 2013-11-21
Anticipated expiration: 2033-05-03
Also published as: AU2013205670B2; RU2638356C2; EP2660122A1; ES2746673T3; FR2990179A1; PL2660122T3; EP2660122B1; FR2990179B1; RU2013120512A

Abstract

Method and system for securing a movement of a rail vehicle, onboard controller in a rail vehicle and a rail vehicle The invention relates to a method for securing the movement of a rail vehicle traveling on a track, the rail vehicle having at least one wheel sensor adapted to provide information that is representative of the speed of rotation of the wheel, and having at least one acceleration sensor whereof the sensitive axis is parallel to the track, the method comprising the following steps: receiving (1060) at least one output value from one or more of the wheel sensors; receiving (1065) at least one output value from one of the acceleration sensors; determining at least one acceleration value from the output value(s) of one of the acceleration sensors; and using (1070, 1080, 1090) one or more received output values of the wheel sensor(s) for supervision of the rail vehicle depending on a comparison of one or more values of the acceleration with at least one reference acceleration value. Furthermore, the invention relates to a system for securing a movement of a rail vehicle, an onboard controller in a rail vehicle, and a rail vehicle. Figure 7 U-1 C'4JC - I T '-4 El

Description

1 Method and system for securing a movement of a rail vehicle, onboard controller in a rail vehicle and a rail vehicle This application claims priority from French Patent Application No. 12 54087 filed on 3 May 2012, the contents of which are to be taken as incorporated herein by this reference. 5 The present invention relates to a method for securing a movement of a rail vehicle traveling on a track, the rail vehicle having at least one wheel sensor adapted to provide information that is representative of the speed of rotation of the wheel. Furthermore, the present invention relates to a system for securing a movement of a rail vehicle, the rail 0 vehicle comprising at least one wheel sensor adapted to generate one or more output values that are representative of the rotation of the wheel, at least one acceleration sensor whereof the sensitive axis is parallel to the direction of the track, and a controller being connected to at least one of the wheel sensors and to at least one of the acceleration sensors, and onboard controller in a rail vehicle to secure it, the controller being adapted to be connected 5 to at least one wheel sensor adapted to generate one or more output values that are representative of the rotation of the wheel and to what at least one acceleration sensor where of the sensitive axis is parallel to the direction of the track, and a rail vehicle comprising: at least one wheel sensor adapted to generate one or more output values that are representative of the rotation of the wheel; at least one acceleration sensor whereof the 0 sensitive axis is parallel to the direction of the tracks; and such a controller. In Europe, many standards exist to secure the travel of a rail vehicle used in the form of automatic train protection systems. For instance, ETCS (European Train Control System) and PZB 90 (Punktfbrmige Zugbeeinflussung) are examples of such systems. In these systems, speed or braking curves as a function of the position of the train 25 define the maximum authorized speed for the train at all points on the track. If that speed is exceeded, after one or more warnings, the system brakes the train to stop it. In the ETCS system, the trains are provided with a movement authority in the form of a maximum distance the train is authorized to travel from a position of a balise that it has previously crossed and maximum authorized speeds on that track segment as a function of the position of the train. 30 To allow the implementation thereof, a speed curve as a function of the position of the train is calculated onboard a train. Said curve is specific to the train and the line profile on which the train is moving. It is determined as a function of the braking performance of the train, to guarantee stopping thereof before the end of its movement authority.

2 Such systems need a sophisticated odometric function onboard the train to determine the instantaneous position of the train as precisely as possible so as to control the maximum authorized speed thereof in that position. For example, systems to secure the movement of a train compute the maximum distance traveled to brake the train before a 5 dangerous point or before a maximum authorized speed reduction and a minimum distance traveled to clear a segment of the track already traveled or to be able to increase the speed of the train. The production of an odometric system is complex, and in order to guarantee an acceptable security level for such systems, it is necessary to add safety margins onto the 0 values of determined positions, which decreases the performance of the system. For example, current systems only using a wheel sensor making it possible to measure the speed need wide safety terminals, since the wheel sensors are sensitive to slipping or locking by the wheels of the train. Therefore, the current systems add a significant safety margin, for example approximately 3% of the measured speed, to compute the minimum 5 distance traveled and the maximum distance traveled. The error due to this margin increases with respect to the distance traveled. A precise odometric function is necessary both to guarantee safety and to offer an acceptable performance level. The aim of the present invention is to overcome the drawbacks of the state of the art, in particular to improve the use of data from a wheel sensor for a system or method for 0 securing a rail vehicle. The present invention aims to resolve the drawbacks of the prior art by providing a method for securing the movement of a rail vehicle traveling on a track, the rail vehicle having at least one wheel sensor adapted to provide information that is representative of the speed of rotation of the wheel, and having at least one acceleration sensor whereof the 25 sensitive axis is parallel to the track, the method comprising the following steps: - receiving at least one output value from one or more of the wheel sensors; - receiving at least one output value from one of the acceleration sensors; - determining at least one acceleration value from the output value(s) of one of the acceleration sensors; and 30 - using one or more received output values of the wheel sensor(s) for supervision of the rail vehicle depending a comparison of one or more acceleration values with at least one reference acceleration value. According to advantageous features: - the use comprises determining a distance, in particular a distance traveled, from one 35 or more received output value(s).

3 - the method further comprises the following step: determining at least one reliable instantaneous speed value from one or more received output value(s). - the use further comprises the following step: computing the maximum authorized speed values, in particular a maximum authorized speed curve, based on one or more 5 received output value(s), in particular using the distance, for example the distance traveled, and/or one or more reliable instantaneous speed value(s). - the maximum authorized speed curve is a function of time or distance. - the use of one or more received output value(s) for supervision of the rail vehicle comprises computing a minimum distance traveled and/or a maximum distance traveled by 0 the rail vehicle; and/or - the supervision of the rail vehicle comprises comparing the instantaneous speed of the rail vehicle with the maximum authorized speed and braking the rail vehicle as a function of the result of the comparison of the maximum authorized speed with the instantaneous speed. 5 Furthermore, the aim is achieved, according to the invention, by a system for securing a movement of a rail vehicle, the rail vehicle comprising at least one wheel sensor adapted to generate one or more output values that are representative of the rotation of the wheel, at least one acceleration sensor whereof the sensitive axis is parallel to the direction of the track, and a controller being connected to at least one of the wheel sensors and to at least 0 one of the acceleration sensors, characterized in that the controller is adapted to use one or more of the received output values from the wheel sensor(s) to supervise the rail vehicle depending on a comparison of one or more acceleration values determined from one or more output values of the acceleration sensor(s) with at least one reference acceleration value. According to advantageous features: 25 - the controller is adapted to carry out one or more steps of the method according to the invention. Furthermore, the aim is achieved, according to the invention, by an onboard controller in a rail vehicle to secure said vehicle, the controller being adapted to be connected to at least one wheel sensor adapted to generate one or more output values that are 30 representative of the rotation of the wheel and to at least one acceleration sensor whereof the sensitive axis is parallel to the direction of the track, characterized in that the controller is adapted to use one or more output values received from the wheel sensor(s) for supervision of the rail vehicle depending on a comparison of one or more acceleration values determined from one or more output values of the acceleration sensor(s) with at least one reference 35 acceleration value. According to advantageous features: 4 - the controller is adapted to implement one or more of the steps of the method according to the invention. Furthermore, the aim is achieved, according to the invention, by a rail vehicle comprising: at least one wheel sensor adapted to generate one or more output values that 5 are representative of the rotation of the wheel; at least one acceleration sensor whereof the sensitive axis is parallel to the direction of the track; and a controller according to the invention, the controller being connected to at least one of the wheel sensors and to at least one of the acceleration sensors. The invention and the advantages thereof will be better understood upon reading the 0 following description, provided solely as an example and done in reference to the appended drawings, in which: - Figure 1 is a schematic view of a rail vehicle on the track; - Figure 2 is a schematic view of the onboard equipment of a system for securing a rail vehicle according to the invention; 5 - Figure 3 is a schematic view of a rail vehicle on a slope; - Figure 4 is a flowchart of a method for securing a rail vehicle; - Figure 5 is a curve of the maximum authorized speed as a function of the instantaneous position; - Figure 6 is a curve of the maximum authorized speed as a function of time; 0 - Figure 7 is flowchart of part of a method according to one embodiment of the invention; and - Figure 8 is a curve of the maximum authorized speed as a function of time. Figure 1 schematically shows a train or rail vehicle 10 traveling on a track 11. The track 11 and the vehicle are secured using a system according to the invention. The rail 25 vehicle 10 comprises one or more cars, at least one of which comprises a pulling system, for example an engine. The aim of a system for securing a movement of a rail vehicle is to ensure that the rail vehicle 10 stops before a dangerous point and does not exceed a threshold point. Another aim of such a system is to ensure that the rail vehicle complies with the speed limits to avoid 30 an excess speed at dangerous points of the track 11, for example turns, locations where people are working on the track, level changes, etc. The system on the one hand comprises ground equipment, and on the other hand comprises equipment onboard the rail vehicle 10. The ground equipment is adapted to provide or send information to the onboard equipment. 35 The rail vehicle 10 comprises a controller 12 for securing the rail vehicle 10 that is connected to at least one wheel sensor 14 to determine an instantaneous speed of the rail 5 vehicle 10. It is further connected to a braking system 16, a track information receiver 18, an acceleration sensor 20, for example in the form of an accelerometer, and a display or control device 22 to provide the conductor with the necessary information. The braking system 16 is adapted to command the brakes of the rail vehicle 10 from 5 instructions received from the controller 12. The track information receiver 18 is arranged to receive the signals emitted by balises 32 positioned along the track. The acceleration sensor 20 has a sensitive axis in the direction of the track 11. In other words, it measures the acceleration parallel to the rails of the track 11. 0 The ground equipment comprises one or more balises 32 arranged along the track 11, which are adapted to send information to the rail vehicle 10. It further comprises a stop signal 34, such as a light, up to which the rail vehicle 10 is authorized to travel. The balises 32 are balises for the ETCS system, for example. A movement authority is defined upstream from the signal 34 due to the existence of 5 a dangerous point 36 on the track 11 downstream from the signal 34, for example a level change where the gate has not yet been closed. This movement authority is characterized by a maximum distance dA that the rail vehicle is authorized to travel from the determined point, here defined by the position of a balise 32. Thus, the movement authority defines the maximum segment of the track that the vehicle is authorized to travel without exceeding the 0 downstream end thereof. For example, the balises 32 can send the rail vehicle 10 information on the maximum distance dA that the rail vehicle is authorized to travel from the balise 32, the gradient of the track 11 and the maximum authorized speeds as a function of the position on the track, for example relative to a predefined distance from the balise 32 or another fixed reference point. 25 The gradient of the track designates the slope of the track. In one embodiment, the distance to be traveled and the maximum authorized speed values on the track 11 at a predefined distance are sent jointly, for example in the form of a maximum authorized speed curve as a function of distance. In other words, the balise 32 gives the rail vehicle 10 a movement authority in terms of distance and maximum authorized 30 speeds. In another embodiment, at least two types of balise 32 exist, a first type of which provides the movement authority to the vehicle, and the other, second type of which only provides a reference point to allow the rail vehicle to determine the distance already traveled from the last movement authority received by the rail vehicle.

6 In other embodiments, the information on the distance the rail vehicle 10 is authorized to travel and/or the maximum authorized speeds as a function of the distance on the track 11 are sent by another system, for example by a radio connection, such as GSM-R. In one alternative, the balises 32 are virtual balises that are defined by their position 5 on the track or their coordinates. The rail vehicle in that case comprises a receiver of a geolocation system connected to the controller 12. If the rail vehicle passes over a virtual balise, which is determined by comparing the instantaneous position of the rail vehicle and the position of the virtual balise, the information on the distance that the rail vehicle 10 is authorized to travel and/or the maximum authorized speeds as a function of the distance on 0 the track 11 are sent via radio connection. Figure 2 schematically shows the onboard equipment of the system for securing the travel of the rail vehicle. The method is implemented by software controlling the controller 12 onboard the rail vehicle 10. The controller 12 comprises a computation unit 120, for example an onboard 5 computer, adapted to compute the maximum authorized speed curve as a function of time as described below and comparing the instantaneous speed of the rail vehicle 10 with the maximum authorized speed at the considered moment. In another embodiment, the computation unit is adapted to compute a maximum authorized speed curve as a function of distance specific to that rail vehicle, a maximum distance traveled and/or a minimum 0 distance traveled. The wheel sensor 14 is connected to the computation unit 120 to provide information on the rotation of the wheel associated with the wheel sensor. For example, the wheel sensor 14 is adapted to continuously provide the computation unit 120 with pulses at a frequency proportional to the speed of rotation of the wheel and/or a measured 25 instantaneous speed. The sensor 14 is for example an angular position sensor of the wheel. In the method for securing the travel of the rail vehicle according to one embodiment, the wheel sensor 14 is used for odometry and tachymetry, for example to display the measured instantaneous speed for the conductor and/or to compare the measured instantaneous speed with the maximum authorized speed. 30 The acceleration sensor 20 is connected to the computation unit 120, which is adapted to determine, from information from the acceleration sensor 20, whether the information from the wheel sensor 14 is relevant and usable to compute the maximum authorized speed curve as a function of time, as will be described below. Owing to the acceleration sensor 20, according to the invention, the controller 12 or its computation unit 35 120 is adapted to determine whether the wheel of the rail vehicle is definitely not in a wheel slip or lock phase. Therefore, the controller 12 is adapted to determine whether the 7 information on the rotation of the wheel associated with the wheel sensor is usable for odometry. As illustrated in Figure 2, the track information receiver 18 is connected to the computation unit 120 and is adapted to provide it, each time it passes before a balise 32, 5 with a movement authority and/or the position. A memory 128 of the controller contains a model of the rail vehicle comprising a dynamic model thereof enabling the controller 12 to compute a braking and/or speed curve as a function of the position or time to comply with the received movement authority as explained in detail below. 0 Furthermore, the computation unit 120 controls a braking system 16. For example, if the computation unit of the controller 12 detects that the rail vehicle is traveling at a speed greater than the maximum speed defined by a speed curve as a function of time or distance, it commands the braking system 16 to perform emergency braking to ensure that the rail vehicle does not exceed a dangerous point, for example after an optional warning. 5 It will first be explained how a reliable speed value is deduced from a wheel sensor and an acceleration sensor. Then, a method is explained in which an application of a reliable speed value is used to compute a maximum authorized speed curve as a function of time that uses the minimum distance traveled and the maximum distance traveled by the rail vehicle. 0 Theoretically, using the acceleration values from the accelerometer for an accurate estimate of the speed of the rail vehicle is possible, but this is made complex by the influence of the gradient of the track 11, since the accelerometer measures the sum of the forces in the sensitive axis of the acceleration sensor 20. It is then necessary to know the precise gradient of the track 11. Furthermore, the gradient profile of the track 11 sent to the rail vehicle 10 in 25 the movement authority is not usable for such a computation. The method according to the invention proposes another solution to determine the precise instantaneous speed. Typically, when the rail vehicle 10 travels without exerting any acceleration or braking force, the values measured by the wheel sensor 14 are reliable, since there is no risk of slipping or locking. In general, these results are reliable when the wheel does not slip or lock. 30 Figure 3 shows the rail vehicle 10 on the track 11 having a slope with an angle a. In the case where the rail vehicle 10 is stopped on the track 11 with the brakes applied to prevent any movement. The forces acting on the rail vehicle 10 are the gravitational force 52, the braking force 50 (= M.g. sin a) and the reaction force 54 of the track (= M.g. cos a), with M the mass of the rail vehicle, g the acceleration of gravity, and a the angle between the 35 track and the horizontal. The normal force 54 corresponds to the force exerted by the track on the rail vehicle 10. The three cumulative forces 50, 52, 54 yield a force equal to zero, 8 since the rail vehicle is stopped. The acceleration sensor 20 only measures the braking force 50, which has a value equal to the gravitational force component in the direction of the track 11. In the case where the rail vehicle 10 travels effortlessly on the slope, the braking and 5 pulling forces for the track are zero, and only the part of the gravitational force, which is not measurable by an accelerometer, in the direction of the track (M.g. sin a) accelerates the rail vehicle 10. Therefore, the onboard acceleration sensor 20 does not measure the gravitational force 52 or its component in the direction of the track 11. Furthermore, the acceleration 0 sensor does not, due to its sensitive axis, measure the normal force 54 that is orthogonal to the sensitive axis of the acceleration sensor 34. The only force measured by the acceleration sensor 20 is that exerted by the pulling or braking on the track 11 and the frictional forces. In fact, the acceleration sensor measures the acceleration only in the direction of the track. Therefore, the acceleration sensor 20 can be used to determine and measure the force of 5 the rail vehicle 10 on the track 11. This then makes it possible to detect periods during which no slipping is possible: when the rail vehicle does not exert any pulling force. Likewise, this method makes it possible to detect periods during which no locking is possible: when the rail vehicle does not exert any braking force. In this way, it is then possible to determine the periods during which the wheel sensor 0 provides reliable information on the instantaneous speed of the rail vehicle. This reliable instantaneous speed can be used to calculate maximum authorized speed curves as a function of time, a maximum distance traveled and/or a minimum distance traveled. Below, a method for determining a speed curve as a function of time will be explained in which reliable information on the instantaneous speed is used to increase its performance. 25 Figure 4 shows a flowchart of the basic method for determining a speed curve as a function of time. It will be explained in conjunction with the maximum authorized speed curves in Figures 5 and 6. The use of reliable information on the instantaneous speed is then explained in conjunction with Figures 7 and 8. From a balise 32, a movement authority is provided in the form of a maximum 30 authorized speed curve 200 on the track 11 as a function of the position on the track, i.e., as a position of the distance with respect to a reference point, in particular consisting of the balise 32, and a maximum distance to be traveled dA from that balise. The rail vehicle 10 has a speed VO during passage over the balise 32. In one embodiment, the exact actual speed VO is not known by the controller 12. However, the 35 controller 12 knows a speed interval between VO,min and VO,max encompassing the actual speed of the rail vehicle VO.

9 The maximum authorized speed curve 200 as a function of distance illustrated in figure 5 provided by the balise 32 comprises three sections 202, 204, 206 with different maximum authorized speeds depending on the different track sections. The distance 0 corresponds to the position of the balise 32. 5 On the first section 202 of the track 11, the rail vehicle 10 is authorized to move at a first authorized maximum speed V1 over a first distance d 20 2 . On the second section 204 of the track 11, the rail vehicle is authorized to move at a second maximum authorized speed V2 over a second distance d 2 0 4 , and on the third section 206 of the track 11, the rail vehicle 10 is authorized to move at a third maximum authorized speed V3 over a third distance d 2 06 , 0 before reaching the end of the movement authority, where the rail vehicle must be stopped at the point 208. The three sections 202, 204, 206 together correspond to the maximum distance dA that the rail vehicle is authorized travel. From the sections 202, 204, 206 with their respective maximum authorized speeds V1, V2, V3, the computation unit 120 computes, during the step 1000 illustrated in figure 4, a 5 specific maximum authorized speed curve 210 as a function of the position of the vehicle on the track specifically for the rail vehicle in question 10, using the information on the dynamic model of the rail vehicle stored in the memory 128 and, if applicable, the track topology information. For example, information on the braking and/or acceleration capacities coming from the dynamic model of the rail vehicle stored in the memory 128 is used. 0 This specific maximum authorized speed curve as a function of distance 210 is different from the maximum authorized speed on the track 11 before or after a section change. It is therefore shown in dotted lines. As shown in Figure 4, in step 1001, the controller 12 computes a maximum authorized speed curve 300 as a function of time and no longer as a function of position, 25 from the specific maximum authorized speed curve as a function of the distance 210 by using the dynamic model of the rail vehicle stored in the memory 128. The maximum authorized speed curve 300 as a function of time is schematically illustrated in Figure 6. For illustration purposes, a specific maximum authorized speed curve 301 as a function of distance that corresponds to the maximum authorized speed curve as a function of time 300 30 is shown in Figure 5. The rail vehicle uses the curve 300 of the maximum authorized speed as a function of time to compare, at any moment during its journey, its instantaneous speed with the maximum authorized speed at that precise moment and to perform braking, in the event said maximum authorized speed is exceeded, for example after an optional warning. 35 The system and the method guarantee that at no time does the vehicle exceed the maximum authorized speed on the various sections of the track 11.

10 A maximum remaining travel time tA begins when the rail vehicle 10 passes by the origin of the maximum segment that the rail vehicle is authorized travel corresponding to the distance dA. The time tA for example begins when the rail vehicle passes over the balise 32 that sent the movement authority. 5 A simplified example of the construction of the maximum authorized speed curve 300 as a function of time that is done when the rail vehicle passes over the balise 32 is explained below. In a first time range 302, the maximum authorized speed increases by the instantaneous speed VO,max to up to the speed V1 that will be authorized during the time range 304 using the maximum acceleration capacity amax of the rail vehicle stored in the 0 memory 128. The rail vehicle reaches - theoretically for the computation of the curve 300 as a function of time - the maximum speed V1 after a time to after having traveled a distance do. In the case of a constant acceleration, the time is to=(V1-V0,max)/amax and the corresponding distance traveled is do=(V1 +V0,max) *to/2 . 5 The maximum speed V1 will be authorized during the time range 304. This maximum speed 304 corresponds to the time the rail vehicle needs to travel the distance between do and d 1 , if it travels at speed V1. To compute the maximum authorized speed curve 300 as a function of time over the section 204, the computation unit of the curve does not use the increase in the maximum authorized speed on the track from section 202 to section 204 to 0 go from V1 to V2, if it does not have reliable information on the fact that the rail vehicle 10 has already traveled the distance d 2 02 . This information for example comes from the balise placed between the sections 202 and 204, or from computing the minimum distance traveled using output signals from the wheel sensor 14 and the acceleration sensor 20, as will be explained later. 25 For example, if the rail vehicle had used the wheel sensor to estimate the distance d 2 0 2 , wheel slipping, for example during the acceleration from VO to V1, would have led to an overestimation of the distance traveled. Therefore, the rail vehicle could also be in the section 202 instead of the section 204. Consequently, if the method had authorized acceleration from V1 to V2, the rail vehicle would have traveled at an excess speed not 30 authorized on the section 202. Hereafter, it is assumed that position information is not obtained between the sections 202 and 204. The distance d 1 depends on the distance d 2 , which corresponds to the end of the section 204 and is known, and minimum guaranteed braking capacities af to reduce the 35 speed from V1 to V3 at the end of the section 204.

11 The rail vehicle traveling at speed V1 needs the time t 2 -t 1 =(V3-V1)/af corresponding to the time range 306 to reduce its speed to speed V3 and a distance between d 1 and d 2 that corresponds to (V3+V1)/2*(t 2 -t1). d 1 is deduced from the preceding equations. From that information, it is possible to compute the time t 1 until which the rail vehicle is authorized to 5 travel at the maximum speed V1, for example, t 1 = (d 1 -do)/V1 +to. The maximum authorized speed curve 300 as a function of time is now built until time t 2 . The time range 308 during which the maximum speed V3 is authorized, the time range 310 and the time t 3 from which the vehicle is required to reduce its speed, if it is 0 traveling at speed V3, are calculated similarly to the time ranges 304 and 306. Therefore, the maximum authorized speed curve 300 as a function of time is computed up to tA. The maximum authorized speed curve 300 as a function of time computed by the computation unit 120 depends on the maximum authorized speed on the track 200 which is, for example, stipulated by the rail authorities and the braking and acceleration capacities of 5 the rail vehicle 10. The speed curve 300 as a function of time then gives the maximum authorized speed for the rail vehicle for a given moment. The computation is done assuming that the rail vehicle is still traveling at the maximum authorized speed of the speed curve as a function of time, and that it is still using its maximum acceleration and/or minimal deceleration capacities guaranteed by the dynamic 0 model of the rail vehicle. In this way, the rail vehicle complying with these speed limits avoids exceeding the distance dA of its movement authority. The vehicle then still travels during the implementation of the method at the maximum speed given by the maximum authorized speed curve as a function of time 300. If vehicle were traveling at a speed below the maximum authorized speed curve as a function of time, 25 it would risk not reaching the end of the distance dA of its movement authority, as the time tA would be reached before then. In one embodiment, before generation of the maximum speed curve as a function of time, the instantaneous speed is considered zero initially, for example when the rail vehicle begins traveling after being stopped at the station. 30 The controller 12, in a speed supervising step 1020, using the instantaneous measured speed and the speed curve 300 as a function of time, ensures that the rail vehicle 10 complies with the maximum authorized speed. If the maximum authorized speed is exceeded, the controller 12, in particular during the supervising step 1020, orders emergency braking of the braking system 16. It should be noted that the information from the wheel 35 sensor 14 is used for such a tachymetry function.

12 Typically, the performance of the system and the method using speed curves as a function of time are improved if the vehicle uses more sensors and/or if more balises are installed on the track 33. This basic system using speed curves as a function of time dose not lose 5 performance with respect to a system based on the distance traveled if the distance traveled before the brakes are applied is greater than the distance to a next encountered balise which, in one embodiment, activates a new computation of the maximum authorized speed curve as a function of time. In one embodiment, the system allows the conductor the possibility of anticipating 0 braking and approaching a stopping point at a moderate speed without undergoing emergency braking. For example, when a conductor anticipates braking, he comes close to a moderate speed Vreiease well before risking emergency braking. The method and the system are enhanced to still further increase the performance when they continuously account for the minimum distance traveled and the maximum 5 distance traveled to compute an updated maximum authorized speed curve as a function of time. This is done through the knowledge of one or more reliable instantaneous speed values determined using the method according to the invention. This method then uses odometry based on the wheel sensor 14 and the acceleration sensor 20. One embodiment of the invention will then be described in conjunction with the 0 flowchart of Figure 7, which shows a flowchart of part of a method for securing a rail vehicle. For example, such a method is used in a time-based automatic train protection system. Nevertheless, the invention may also be used in other methods to secure the movement of a rail vehicle. The computation unit 120 deduces whether the information on the instantaneous 25 speed measured in the tachymetry step 1010 by the wheel sensor 14 is reliable and therefore usable for odometry to compute the maximum authorized speed curve 300 as a function of time. In step 1060, the controller 12 receives at least one output value from at least one of the wheel sensors 14. For example, the output value is a set of pulses, the frequency of 30 which is representative of the speed of rotation of the wheel. In another embodiment, the wheel sensor 14 itself delivers an instantaneous speed value, either the instantaneous speed of rotation of the wheel or an estimate of the instantaneous speed of the rail vehicle 10 computed as a simple product of the angular speed of the wheel by the radius thereof. In one embodiment, the estimate comprises a maximum instantaneous speed value and a minimum 35 instantaneous speed value when the computation unit 120 supplies a safety margin around the measured instantaneous speed value.

13 In the step 1065, the controller 12 receives an output value produced by the acceleration sensor 20. The output value is representative of the acceleration measured in the direction of the sensitive axis of the acceleration sensor 20. The acceleration value is positive if the rail vehicle 10 accelerates on a horizontal track 11 and negative if the rail 5 vehicle 10 brakes on a horizontal track 11. For example, the acceleration sensor itself delivers an acceleration value. The steps 1060 and 1065 may also be done in parallel or in the opposite order. In one embodiment, the measurement time of the acceleration sensor and/or the wheel sensor is recorded to synchronize the output values of the acceleration sensor 20 and the wheel sensors 14. 0 From the acceleration values, the computation unit 120 detects when the wheel sensor 14 yields reliable results that are usable to estimate a trip distance traveled or the instantaneous speed of the rail vehicle 10. In one embodiment, the computation unit 120 determines the periods during which the output values from the wheel sensor 14 to determine the instantaneous speed are usable to estimate the maximum distance traveled 5 (when the exerted braking force does not risk causing locking). Likewise, the computation unit 120 determines periods during which the output values from the wheel sensor 14 to determine the instantaneous speed are usable to estimate the minimum distance traveled (when the pulling force exerted does not risk causing slipping). These determinations are made in the step 1070, in which the acceleration values in 0 the direction of the track are compared with predetermined acceleration values. In the case of a computation of the maximum distance traveled, the instantaneous speed values or, if applicable, the instantaneous maximum speed values, are usable if the force measured by the accelerometer is greater than a first predetermined value (for example -0.4 m/s 2 ). In fact, in that case, it is certain that the rail vehicle does not brake enough for the 25 wheel to lock. As a result, the method guarantees that the instantaneous speed value determined by the wheel sensor will not lead to an underestimation of distance traveled. In the case of a computation of the minimum distance traveled, the instantaneous speed values, or if applicable, the instantaneous minimum speed values are usable if the force measured by the accelerometer is below a second predetermined value (for example, 30 0.4 m/s 2 ). In fact, in that case, it is certain that the rail vehicle does not pull enough for the wheel to slip. As a result, the method guarantees that the instantaneous speed value determined by the wheel sensor will not lead to an overestimation of the distance traveled. The step 1070 then ensures that the output values from the wheel sensor 14 are only used during reliable periods, therefore outside periods where there is a risk of slipping or 35 locking of the wheel to which the wheel sensor is assembled, and in other words, when the rail vehicle 10 travels without producing force on the rails.

14 In one embodiment, the predetermined acceleration values depend on the axle on which the wheel sensor is located. For example, a motorized or braked wheel has a different predetermined acceleration value from a non-motorized and/or non-braked wheel. In one embodiment, the frictional forces existing in the vehicle and measured by the 5 accelerometer are included in the margins taken around the measurement. If the instantaneous speed information, or if applicable, the instantaneous minimum speed values, measured by the wheel sensor(s) 14 are reliable and usable for odometry, in particular to estimate the minimum distance traveled, and/or to estimate the maximum distance traveled, they are then used in step 1080 to calculate a new maximum authorized 0 speed curve as a function of time, taking into account an estimate of the minimum distance traveled and/or the maximum distance traveled by the rail vehicle 10. Otherwise, no recalculation is done and step 1080 is skipped. The recalculation of the maximum authorized speed curve as a function of time using the maximum distance traveled is explained using Figure 8, which shows a speed curve as a 5 function of time 300 that corresponds to the speed curve as a function of time 300 of Figure 6. In step 1070, at moment t 5 , the controller 12 deduces a reliable instantaneous speed value 401 to compute the maximum distance traveled. This instantaneous speed 401 is below the maximum authorized speed shown by the speed curve 300 as a function of time. The computation unit takes the instantaneous speeds into account or, if applicable, the 0 instantaneous maximum speed values, from the wheel sensor 14. After the maximum traveled distance is computed, the controller 12 assumes, as a safety measure, so as to compute the maximum authorized speed curve 400 as a function of time, that the rail vehicle 10 then accelerates with its maximum acceleration capacity amax after the reliable instantaneous speed value 401 to achieve the maximum authorized speed V 1 at moment t 6 . 25 The computation is done as in the example described in light of Figure 6 using the maximum distance traveled as the starting point. Before the reliable value of the instantaneous speed 401, the controller assumes, so as to recalculate the maximum authorized speed curve 400 as a function of time, that the vehicle brakes between t 4 and t 5 with these maximum braking capacities from the maximum 30 authorized speed at moment t 4 to reach the speed 401 at moment t 5 . The crosshatched region shows a distance corresponding to the difference between dA and a point upstream from dA where the rail vehicle would stop if it did not recalculate the speed curve as a function of time. With the use of the instantaneous speed value 401, it is possible to see that the 35 maximum authorized movement time tA' of the rail vehicle 12 is increased with respect to the maximum authorized the time tA of the speed curve as a function of time 300.

15 In step 1090, which corresponds to step 1020 of Figure 4, the maximum authorized speed curves 300, 400 as a function of time are used to control the rail vehicle automatically, in particular to control the braking thereof if the rail vehicle exceeds the maximum authorized speed. The wheel sensor is used continuously for the tachymetry, 5 which is less sensitive to slipping or locking. In fact, no accumulation of the error made occurs in the case of a tachymetry application. The recalculation of the maximum authorized speed curve as a function of time using the minimum distance traveled is explained below. The controller computes a minimum position of the rail vehicle, i.e., a minimum 0 distance traveled. This minimum distance traveled is used to determine whether the rail vehicle has cleared a section or dangerous point so as, for example, to make it possible to regain speed after a limitation. It is possible to deduce the minimum distance traveled from the instantaneous speed values, or if applicable, the minimum instantaneous speed values of the rail vehicle, and maximum braking capacity. From there, in a case like that of the section 5 204 of figure 5, the entry into that section is guaranteed and allows the rail vehicle to accelerate up to the speed V2. If this computation is not done, the proposed system will impose the speed V1 on the entire journey until it passes a balise guaranteeing that it has left the section 202. If the system has deduced that the rail vehicle was in the section 204, it recalculates the maximum authorized speed curve as a function of time while allowing 0 acceleration up to the speed V2. In one embodiment, the rail vehicle is authorized to approach an end of movement authority (EOA) if it is traveling at or below a release speed (Vreiease). The release speed depends on the distance between a dangerous point 36 and the position of the end of movement authority EOA. For example, the distance between the EOA position and the 25 dangerous point is chosen so as to be able to reach the EOA position at the speed Vrelease while guaranteeing stopping at the dangerous point if the rail vehicle is EOA-tripped. The distance between the EOA position and the dangerous point is set by the infrastructure, and therefore the signaling system typically has no power over that distance. The invention proposes a system and a method for securing the movement of a rail 30 vehicle with a moderate cost and good performance. For example, it is possible to preserve compatibility with a ground infrastructure equipped for ETCS and to equip the rolling stock in an upgradable manner, and at the same time to have trains equipped with ETCS exist alongside those equipped with the system according to the invention. Other systems also exist for securing a rail vehicle, for example, systems where the 35 rail vehicle is controlled by directly using a maximum authorized speed curve with respect to the distance 210 by comparing the maximum authorized speed in a certain location with the 16 measured instantaneous speed. The speed curve as a function of distance 210 is computed by the rail vehicle. For these rail vehicle securing systems based on maximum authorized speed curves as a function of distance, the odometric function is crucial. The method and the system according to the invention may then be used to estimate the distance 5 that the vehicle has already traveled to recalculate the maximum authorized speed curve as a function of distance and its instantaneous position by using its dynamic performance of the rail vehicle.

Claims

1. A method for securing the movement of a rail vehicle (12) traveling on a track (11), the rail vehicle having at least one wheel sensor (14) adapted to provide information that is 5 representative of the speed of rotation of the wheel, and having at least one acceleration sensor (20) whereof the sensitive axis is parallel to the track (11), the method comprising the following steps: - receiving (1060) at least one output value from one or more of the wheel sensors (14); 0 - receiving (1065) at least one output value from one of the acceleration sensors (20); - determining at least one acceleration value from the output value(s) of one of the acceleration sensors; and - using (1070, 1080, 1090) one or more received output values of the wheel sensor(s) for supervision of the rail vehicle depending on a comparison of one or more acceleration 5 values with at least one reference acceleration value.

2. The method according to claim 1, characterized in that the use comprises determining a distance, in particular a distance traveled, from one or more received output value(s).

3. The method according to one of the preceding claims, further comprising the 0 following step: determining (1070) at least one reliable instantaneous speed value (401) from one or more received output value(s).

4. The method according to one of the preceding claims, characterized in that the use further comprises the following step: - computing (1080) the maximum authorized speed values (210, 300, 400), in 25 particular a maximum authorized speed curve, based on one or more received output value(s), in particular using the distance, for example the distance traveled, and/or one or more reliable instantaneous speed value(s) (401).

5. The method according to claim 4, characterized in that the maximum authorized speed curve is a function of time (300) or distance (200). 30

6. The method according to one of the preceding claims, characterized in that the use of one or more received output value(s) for supervision of the rail vehicle comprises computing a minimum distance traveled and/or a maximum distance traveled by the rail vehicle (10). 35

7. The method according to one of the preceding claims, characterized in that the supervision of the rail vehicle comprises comparing (1090) the instantaneous speed of the 18 rail vehicle with the maximum authorized speed and braking the rail vehicle (10) depending on the result of the comparison of the maximum authorized speed with the instantaneous speed.

8. A system for securing a movement of a rail vehicle (10), the rail vehicle comprising 5 at least one wheel sensor (14) adapted to generate one or more output values that are representative of the rotation of the wheel, at least one acceleration sensor (20) whereof the sensitive axis is parallel to the direction of the track (111), and a controller (12) being connected to at least one of the wheel sensors and to at least one of the acceleration sensors, characterized in that 0 the controller is adapted to use one or more of the received output values from the wheel sensor(s) (14) to supervise (1070, 1080, 1090) the rail vehicle depending on a comparison of one or more acceleration values determined from one or more output values of the acceleration sensor(s) (20) with at least one reference acceleration value.

9. The system according to claim 8, characterized in that the controller (12) is 5 adapted to carry out one or more steps of the method according to one of claims 1 to 7.

10. An onboard controller (12) in a rail vehicle to secure said vehicle, the controller being adapted to be connected to at least one wheel sensor adapted to generate one or more output values that are representative of the rotation of the wheel and to at least one acceleration sensor (20) whereof the sensitive axis is parallel to the direction of the track 0 (11), characterized in that the controller (12) is adapted to use one or more output values received from the wheel sensor(s) (14) for supervision (1070, 1080, 1090) of the rail vehicle depending on a comparison of one or more acceleration values determined from one or more output values of the acceleration sensor(s) (20) with at least one reference acceleration value. 25

11. The controller according to claim 10, characterized in that the controller is adapted to implement one or more of the steps of the method according to one of claims 1 to 7.

12. A rail vehicle (10) comprising: at least one wheel sensor (14) adapted to generate one or more output values that 30 are representative of the rotation of the wheel; at least one acceleration sensor (20) whereof the sensitive axis is parallel to the direction of the track (11); and a controller according to one of claims 10 to 11, the controller being connected to at least one of the wheel sensors and to at least one of the acceleration sensors. 35