System for measuring the position of a counterweight

Abstract

Title: System for measuring the position of a counterweight The invention relates to a system for measuring the position of a counterweight (12) suspended alongside a support pole (11) of a catenary installation, the measuring system comprising: - a module (101) intended to be fixed on the support pole (11); - a mobile target (201) intended to be fixed on the counterweight (12) or on a cable (13) for suspending the counterweight (12), below the module (101); - a fixed target (301) intended to be fixed on the support pole (11) below the module (101), at a predetermined distance (P) from the module (101); the module (101) comprises a transmitter-receiver (102) of acoustic waves intended to be oriented towards the mobile target (201) and the fixed target (301), the mobile target (201) and the fixed target (301) intended to be oriented towards the module (101). Figure for abstract: Fig. 1

Description

Title of the invention: System for measuring the position of a counterweight

[0001] The field of the invention is that of the design and manufacture of railway metrology equipment.

[0002] More specifically, the invention relates to a system making it possible to help measure the tension and the maintenance of tension in a catenary.

[0003] To allow the proper functioning of the catenaries of railway networks, the latter must be kept taut with an adequate tension.

[0004] As an indication, a catenary can for example measure 1.5 or 2 kilometers long.

[0005] According to a first type of implementation, a catenary has a fixed point in its middle thus delimiting two sections each placed under tension from its end opposite the fixed point.

[0006] According to a second type of implementation, there is no fixed point and the catenary has a single continuous section tensioned from its two ends.

[0007] To achieve the tensioning and maintaining of a catenary, tensioning devices are known. These tensioning devices are for example known as pulley tensioning devices.

[0008] A tensioning device is fixed to a pole and serves as an interface between the catenary and the pole. The tensioning device comprises two elements which are connected by a weighted cable. Each element carries pulleys, and the weighted cable is wound around these pulleys.

[0009] More precisely, the weighted cable is wound around the pulleys and has a counterweight at one end hanging from a support. This counterweight thus tends to bring the two elements of the tensioning device closer together.

[0010] The counterweight of a tensioning device moves within a compensation range to tension the contact cable of the catenary at a constant mechanical tension within a defined temperature range. Indeed, the ambient temperature and weather conditions such as sunlight on a contact cable of a catenary can cause the contact cable to lengthen or retract.

[0011] Thus, a catenary is maintained at an adequate tension thanks to the tensioning device which transmits and multiplies the tension force exerted by the counterweight.

[0012] During a maintenance operation, maintenance agents must be able to check the tension of the catenary.

[0013] To carry out this control, measuring devices are known from the prior art which comprise a ruler permanently mounted on the tensioning device which makes it possible to easily read from the ground the spacing between the two elements of the tensioning device. It has More recently, measuring devices have been designed that allow an agent to obtain the measurement from the ground, using an electronic tablet that connects wirelessly to the measuring device.

[0014] From the document published under number US 2012 / 0319850 A1, a system is known for tracking the position, or measuring a displacement, of the counterweight. In addition to using the ambient temperature captured near the counterweight, the system described in this document implements a specific measuring device which is preferably a magnetostrictive linear position sensor, or a string potentiometer.

[0015] From the document published under number IT201800003748A1, a similar measuring device is also known comprising a transmitter of an electrical signal integral with the counterweight in such a way, as well as a receiver fixed on a support post on the side of the axis of movement of the counterweight and the transmitter.

[0016] These techniques, although allowing a precise measurement of the position of a counterweight to be obtained, can nevertheless require a complex and cumbersome installation to implement.

[0017] The invention aims in particular to overcome these drawbacks of the prior art.

[0018] More specifically, the invention aims to propose a technique for determining the position of a counterweight of a catenary system which is simple to implement.

[0019] The invention also aims to provide such a technique which can be at least as precise as those according to the prior art.

[0020] These objectives, as well as others which will appear subsequently, are achieved thanks to the invention which has as its subject a system for measuring the position of a counterweight suspended on the side of a support post of a catenary installation, the measuring system comprising: - a module intended to be fixed on the support post; - a mobile target intended to be fixed on the counterweight or on a counterweight suspension cable, below the module; characterized in that it comprises: - a fixed target intended to be fixed on the support post below the module, at a predetermined distance from the module; and in that the module comprises an acoustic wave transmitter-receiver intended to be oriented towards the moving target and the fixed target, the moving target and the fixed target intended to be oriented towards the module; and in that the system comprises electronic processing means comprising: - means for triggering the emission of an acoustic wave by the module; - means for determining a duration of interest between the emission of the acoustic wave and the reception of a first echo by the module resulting from a rebound of the acoustic wave on the moving target, and a reference duration between the emission of the acoustic wave and the reception of a second echo by the module resulting from a rebound of the acoustic wave on the fixed target; - means for calculating a distance of interest between the module and the moving target from the predetermined distance, the reference duration, and the duration of interest.

[0021] The system according to the invention makes it possible to determine the position of a counterweight of a catenary system in a manner that is particularly simple to implement. Furthermore, this solution is at least as precise as those according to the prior art.

[0022] By emitting an acoustic wave, the system calculates the distance of interest separating the module from the moving target, and makes it possible to determine the position of the counterweight of the catenary system.

[0023] The system according to the invention is particularly simple to implement thanks to the use of the emission and reception of an acoustic wave.

[0024] Indeed, it is sufficient to position the module high on the support post, in an up / down orientation that does not require perfect alignment with the vertical thanks to the fact that an acoustic wave does not only diffuse in a rectilinear manner. The acoustic background diffusion is also used by the system to be able to reach the fixed target and the moving target that are not located along the same axis with the module.

[0025] By knowing the predetermined distance separating the module from the fixed target, and thanks to the difference between the duration of interest and the reference duration, it is possible to determine the relative position of the moving target with respect to the module, and thus the position of the counterweight.

[0026] The measuring system according to the invention is at least as precise as the system according to the prior art. Indeed, the system according to the invention makes it possible to take into account environmental conditions which may influence the method of determining the position of the counterweight.

[0027] More precisely, thanks to the fixed target and its fixed position, at a predetermined distance from the module, the measuring system has a standard making it possible to take into account the influence of environmental conditions which can impact the propagation speed of an acoustic wave.

[0028] Preferably, the acoustic background is emitted in the ultrasonic frequency.

[0029] According to a preferred characteristic, the moving target and the fixed target comprise each a rebound surface made of an acoustic wave reflecting material intended to be oriented towards the module.

[0030] Thanks to this characteristic, the capacity of the moving target and the fixed target to effectively return an echo towards the module is optimized.

[0031] Advantageously, the moving target and the fixed target each comprise a rebound surface having a parabolic cross-section delimiting a hollow intended to be oriented towards the module.

[0032] In this case, the echoes returned by the fixed target and the moving target are more perceptible by the module, thus optimizing the module's ability to capture and differentiate the echoes.

[0033] According to a preferred design, the calculation means comprise: - a first subsystem for calculating a calculated speed of diffusion of an acoustic wave in the air from the predetermined distance and the reference duration; - a second subsystem for calculating the distance of interest between the module and the moving target from the calculated speed and the duration of interest.

[0034] The diffusion speed of acoustic background in the air calculated by the first calculation subsystem, then called “calculated speed”, corresponds to the speed at which acoustic background and its echoes diffuse between the module and the two targets.

[0035] Thanks to the duration of interest which corresponds to the time necessary for the acoustic wave to go from the module to the moving target, and to the time necessary for the first echo to go from the moving target to the module, and to the calculated speed, we obtain the sum of the distances traveled by the acoustic wave between the module and the moving target, and by the first echo between the moving target and the module.

[0036] Preferably, the module comprises an electronic processing unit integrating at least part of the electronic processing means.

[0037] The module can thus have at least partial, if not total, operating autonomy.

[0038] The electronic processing unit of the module can in particular be configured to integrate the means for triggering the emission of an acoustic wave, the means for determining the duration of interest and the reference duration, and the means for calculating the distance of interest.

[0039] Advantageously, the system also comprises a remote server, and telecommunications means between at least the remote server and the module.

[0040] In this case, the electronic processing unit of the module is configured to be able to exchange data with the remote server using telecommunications means.

[0041] The electronic processing unit of the module can for example transmit the calculated distance of interest to the remote server for archiving.

[0042] The invention also relates to a catenary installation comprising: - a support post; - a counterweight suspended on the side of the support post using a counterweight suspension cable; characterized in that it comprises the measuring system as described above, and in that: - the module is fixed on the support pole with its acoustic wave transmitter-receiver oriented downwards in a vertical up / down direction; - the mobile target is fixed, below the module, on the counterweight or on the counterweight suspension cable, being oriented towards the module; - the fixed target is fixed, below the module, on the support post, facing the module.

[0043] The installation has the same advantages as the measuring system previously described.

[0044] The invention also relates to a method for measuring the position of a counterweight suspended next to a support post of a catenary installation, the method implementing: - a module fixed to the support post, and comprising an acoustic wave transmitter-receiver oriented downwards in a vertical up / down direction; - a moving target fixed on the counterweight or on a counterweight suspension cable, below the module, and oriented towards the module; - a fixed target fixed on the support post, below the module, at a predetermined distance from the module, and oriented towards the module; the method comprising a measurement phase comprising: - a step of emitting an acoustic wave by the module in the direction of the moving target and the fixed target; - a step of receiving a first echo by the module resulting from a rebound of the acoustic wave on the moving target, and a second echo by the module resulting from a rebound of the acoustic wave on the fixed target; - a step of determining a duration of interest between the emission of the acoustic wave and the reception of the first echo by the module, and a reference duration between the emission of the acoustic wave and the reception of the second echo by the module; - a step of calculating a distance of interest between the module and the moving target from the predetermined distance, the reference duration, and the duration of interest.

[0045] The method has the same advantages as the previously described measuring system.

[0046] Advantageously, during the calculation step, the following procedure is carried out: - to the calculation of a calculated speed of diffusion of an acoustic wave in the air from the predetermined distance and the reference duration; - to the calculation of the distance of interest between the module and the moving target from the calculated speed and duration of interest.

[0047] According to a preferred design, the method comprises an installation phase prior to the measurement phase, the installation phase comprising: - a step of coupling the module and the fixed target on the support post, and the mobile target on the counterweight or on the counterweight suspension cable, the fixed target and the mobile target being positioned below the module; - a step of measuring and recording the predetermined distance separating the module from the fixed target.

[0048] Other characteristics and advantages of the invention will appear more clearly on reading the following description of different preferred embodiments of the invention, given as illustrative and non-limiting examples, and the appended drawings among which: [Fig.l] [Fig.l] is a schematic representation of a partial catenary installation, implementing a system according to the invention, for measuring the position of a counterweight of the catenary installation; [Fig.2] [Fig.2] is a schematic perspective representation of a module of the system according to the invention; [Fig.3] [Fig.3] is a schematic representation of the system according to one embodiment of the invention.

[0049] With reference to [Fig.l], a part of a catenary installation is shown.

[0050] This catenary installation includes: - a support post 11; - a ballasting system intended to maintain tension in a cable of the installation, the ballasting system comprising a counterweight 12 and a cable 13 for suspending the counterweight 12.

[0051] As can be seen, one of the ends of the cable 13 is secured to the counterweight 12.

[0052] Depending on the state of the catenary installation, and environmental conditions, the position of the counterweight 12 may vary in order to maintain the catenary in tension. The position of the counterweight may change within a compensation range. In the worst case, the counterweight 12 may touch the ground S of the installation following a break at the level of the catenary or the ballast system.

[0053] As detailed below, the system makes it possible to measure the position of the counterweight 12 which is suspended next to the post 11, and in particular to determine a dimension Y which corresponds to the distance separating the counterweight 12 from the underlying ground S.

[0054] With reference to Figures 1 to 3, the measuring system is described below.

[0055] The measuring system comprises: - a module 101 intended to be fixed on the support post 11; - a target, called a “moving target” 201 intended to be fixed on the counterweight 12 or on a cable 13 for suspending the counterweight 12, below the module 101; - a fixed target 301 intended to be fixed on the support post 11 below the module 101.

[0056] As detailed below, the position of the counterweight is intended to be measured using the sending of an acoustic wave U from the module 101 to the targets, and the return of the echoes E of the acoustic wave having bounced off the targets. The diffusion speed of an acoustic wave in the air is then used to determine the distance traveled by the acoustic wave and its echoes, and to calculate the position of the counterweight 12.

[0057] For this purpose, the module 101 comprises a transceiver 102 of acoustic waves.

[0058] The transceiver 102 is intended to be oriented towards the moving target 201 and the fixed target 301. In addition, the moving target 201 and the fixed target 301 are intended to be oriented towards the module 101.

[0059] By the expression "oriented", it is understood that the transceiver 102 is positioned so as to emit an acoustic wave U in the direction of the targets, and that the targets are positioned so as to be able to return an echo in the direction of the transceiver 102 of the module 101.

[0060] With reference to [Fig.2], the transmitter-receiver 102 is in particular of the type having a cone for transmitting and receiving acoustic waves whose generator G forms an angle A of + / -20° relative to the central axis C of the reception cone.

[0061] This transmitter-receiver 102 is more specifically of the type emitting and receiving acoustic waves in the ultrasonic range.

[0062] The transceiver 102 is more specifically configured to transmit and receive acoustic waves at a predetermined frequency.

[0063] The acoustic wave U is notably emitted at a frequency of 40kHz.

[0064] According to the present embodiment, and as schematically illustrated by [Fig.3], the module 101 also comprises: - an electronic processing unit 103; - an electric battery 104 supplying energy to the module 101.

[0065] According to one possible embodiment, the module 101 can be provided with solar sensors in order to recharge its electric battery 104.

[0066] With reference to [Fig.2], the module 101 further comprises coupling means 700 respectively to the support post 11. The coupling means 700 take the form of a magnetic element allowing the coupling of the module 101 to a metal post.

[0067] With reference to Figures 1 and 3, the fixed target 301 is fixed on the support post 11 at a predetermined distance P from the module 101.

[0068] This predetermined distance P is entered and recorded in the electronic processing unit 103.

[0069] Preferably, the fixed target 301 is fixed on the support post 11 at a distance which cannot be reached or exceeded by the moving target 201. As is apparent from the explanations which follow, this makes it easier to differentiate the echoes coming from the fixed target 301 and the moving target 201.

[0070] The moving target 201 and the fixed target 301 each comprise a rebound surface 2011, 3011 made of an acoustic wave reflecting material, intended to be oriented towards the module 101. This improves the quality of the echo E of the acoustic background U returned towards the module 101.

[0071] It is known that materials having a higher density have a better susceptibility to reflect an acoustic wave. For example, the rebound surfaces can be made of rigid plastic.

[0072] According to a conceivable embodiment, these rebound surfaces 2011, 3011 have a parabolic cross-section delimiting a hollow intended to be oriented towards the module 101. This also contributes to improving the quality of the echo E of acoustic background U returned in the direction of the module 101.

[0073] According to a first variant, the rebound surfaces 2011, 3011 of the moving target 201 and of the fixed target 301 are structurally identical to each other.

[0074] According to a second variant, the rebound surfaces 2011, 3011 of the moving target 201 and of the fixed target 301 are structurally different from each other.

[0075] These structural differences may be in terms of dimensions and / or in terms of geometry and / or in terms of surface relief.

[0076] These structural differences then aim to help differentiate the echo E resulting from the acoustic background rebound U on the rebound surface 2011 of the moving target 201 and the acoustic background rebound E U on the rebound surface 3011 of the fixed target 301.

[0077] For example, as schematically illustrated by [Fig.3], the rebound surface 2011 of the moving target 201 may correspond to twice the rebound surface 3011 of the fixed target 301.

[0078] According to another example not illustrated, the rebound surface 2011 of the moving target 201 may be continuous, so as to produce an echo with a single component, while the rebound surface 3011 of the fixed target 301 may have a detachment over part of its surface, so as to produce an echo having two components substantially offset in time.

[0079] As schematically illustrated by [Fig.3], the system also comprises electronic processing means 400.

[0080] These electronic processing means 400 comprise: - means 401 for triggering the emission of an acoustic wave U by the module 101; - means 402 for determining a duration of interest DI between the emission of the acoustic wave U and the reception of a first echo El by the module 101 resulting from a rebound of the acoustic wave U on the moving target 201, and a reference duration DR between the emission of the acoustic wave U and the reception of a second echo E2 by the module 101 resulting from a rebound of the acoustic wave U on the fixed target 301; - means 403 for calculating a distance of interest D between the module 101 and the moving target 201 from the predetermined distance P, the reference duration DR, and the duration of interest DI.

[0081] More specifically, the calculation means 403 comprise: - a first calculation subsystem 4031 of a calculated speed VC of diffusion of an acoustic wave U in the air from the predetermined distance P and the reference duration DR; - a second subsystem 4032 for calculating the distance of interest D between the module 101 and the moving target 201 from the calculated speed VC and the duration of interest DI.

[0082] According to the present embodiment, the electronic processing unit 103 of the module 101 forms part of the electronic processing means 400.

[0083] It is nevertheless conceivable that the electronic processing unit 103 forms all of the electronic processing means 400.

[0084] As illustrated by [Fig.3], the measurement system according to the present embodiment further comprises a remote server 500.

[0085] The measurement system also includes a separate electronic unit 600, such as an electronic tablet or a smartphone.

[0086] According to this embodiment, the remote server 500 as well as the separate electronic unit 600 also form parts of the electronic processing means 400.

[0087] The module 101, the remote server 500, as well as the separate electronic unit 600, are provided with wireless communication means in order to exchange data between them.

[0088] For the separate electronic unit 600, and for the module 101, at least part of these wireless communication means may take the form of near-field telecommunications means, for example in order to be able to configure the module 101 using the separate electronic unit 600.

[0089] For the module 101, as well as for the remote server 500, at least part of the wireless communication means can take the form of long-distance, low-power telecommunications means, for example of the type marketed under the registered trademark “LoraWAN”.

[0090] These long-distance, low-energy telecommunications means make it possible, for example, to communicate for archiving and monitoring the distance D separating the first module 101 from the second module 201.

[0091] In connection with the system previously described, the implementation of this system in the installation is described below, with reference to [Fig.l].

[0092] As shown, the installation has a support post 11 which extends parallel to a vertical direction V up / down. The up direction H and the down direction B of the vertical direction V up / down are shown in [Fig.l].

[0093] As can be seen: - module 101 is fixed to the support post 11; - the moving target 201 is fixed on the suspension cable 13 of the counterweight 12, and - the fixed target 301 is fixed on the support post 11.

[0094] The module 101 is positioned so as to be above the moving target 201, as well as the fixed target 301. In other words, the moving target 201 and the fixed target 301 are below the module 101.

[0095] By the expressions “counter-high” and “counter-low”, it is understood that the mobile target 201 and the fixed target 301 are not necessarily located directly above the module 101. Indeed, recourse is had to the capacity of the acoustic waves to diffuse according to a diffusion cone to facilitate the implementation of the system in the installation.

[0096] In order to allow the proper diffusion and reception of acoustic waves / echoes: - the transmitter-receiver 102 of the module 101 is oriented downwards B in the vertical direction V up / down; - the rebound surface of the moving target 201 is oriented upwards H in the vertical direction V up / down, in the direction of the module 101; - the rebound surface of the fixed target 301 is oriented upwards H in the vertical direction V up / down, in the direction of the module 101.

[0097] The method of measuring the position of a counterweight 12 is now described with reference to Figures 1 and 3.

[0098] This method is implemented by the system previously described. Accordingly, characteristics of the system previously described correspond to steps of the method.

[0099] The method comprises a measurement phase making it possible to determine a distance D separating the module 101 from the moving target 201.

[0100] This distance D, compared to other known distances, makes it possible to determine a variation in the position of the counterweight 12 over time.

[0101] Conventionally, the position of the counterweight 12 over time is evaluated using a dimension Y which corresponds to the distance separating the base of the counterweight 12 from the base of the post underlying the counterweight 12 (i.e. from the ground S underlying the counterweight, and which is flush with the base of the post). The calculation of the distance D thus makes it possible to determine the dimension Y, in particular in relation to previous known values ​​of this distance D and the dimension Y.

[0102] The measurement phase comprises a step of emitting an acoustic wave U by the module 101 in the direction of the moving target 201 and the fixed target 301.

[0103] Following the emission of this acoustic wave U, acoustic wave U diffuses downwards B towards the targets. The acoustic wave U then bounces off the moving target 201 and the fixed target 301. More specifically, acoustic wave U bounces off the rebound surfaces of these targets.

[0104] We can then distinguish a first echo El which results from the rebound of acoustic background U on the moving target 201, and a second echo E2 which results from the rebound of acoustic background U on the fixed target 301.

[0105] The measurement phase then includes: - a step of receiving the first echo El by the module 101, and the second echo E2 by the module 101; - a step of determining a duration of interest DI between the emission of the acoustic wave U and the reception of the first echo El by the module 101, and a reference duration DR between the emission of the acoustic wave U and the reception of the second echo E2 by the module 101; - a step of calculating a distance of interest D between the module 101 and the moving target 201 from the predetermined distance P, the reference duration DR, and the duration of interest DI.

[0106] As detailed previously, it is possible to distinguish the first echo E1 from the second echo E2 by positioning the fixed target 301 at a position that cannot be reached by the moving target 201, systematically causing the second echo E2 to arrive first or last with respect to the first echo E1, and / or a structural difference between the rebound surfaces of the fixed target 301 and the moving target 201, causing a perceptible difference between the signal resulting from the capture of the first echo E1 and the signal resulting from the capture of the second echo E2.

[0107] During the calculation step, the following is carried out: - to the calculation of a calculated speed VC of diffusion of an acoustic wave in the air from the predetermined distance P and the reference duration DR; - to the calculation of the distance of interest D between the module 101 and the moving target 201 from the calculated speed VC and the duration of interest DI.

[0108] During the reference duration DR, the acoustic wave U and the second echo E2 each travel the predetermined distance P. The following formula can thus be used: VC = D / (2.P)

[0109] In the same way, the acoustic wave U and the first echo El each travel the distance of interest D during the duration of interest DI. The following formula can thus be used: D = (VC.DI) / 2

[0110] Carrying out a plurality of measurement phases spaced apart in time makes it possible to follow the evolution of the position of the counterweight 12 over time.

[0111] Prior to the measurement phase, the method comprises an installation phase.

[0112] This installation phase includes: - a step of coupling the module 101 and the fixed target 301 on the support post 11, and the mobile target 201 on the counterweight 12 or on the cable 13 for suspending the counterweight 12, the fixed target 301 and the mobile target 201 being positioned below the module 101; - a step of measuring and recording the predetermined distance P separating the module 101 from the fixed target 301.

[0113] Preferably, the fixed target 301 and the mobile target 201 are installed at human height so as to facilitate this installation.

[0114] The module 101 can be installed using a telescopic pole. Perfect alignment of its top / bottom axis with the vertical direction V is not necessary thanks to the acoustic wave emission and reception cone of its transmitter-receiver.

[0115] The measuring and recording step can for example be carried out using a laser rangefinder, and the separate electronic unit 600 which makes it possible to record the predetermined distance P in the electronic processing unit 103 of the module 101.

[0116] The measurement phase can be carried out periodically, or upon request from the separate electronic unit 600 or the remote server 500 in order to obtain the value of the distance D.

[0117] This value of the distance D is then communicated to the remote server 500 in order to carry out monitoring.

[0118] According to a possible configuration, the dimension Y can also be recorded in the electronic processing unit 103 of the module 101, during the installation phase, so that the conversion between the distance D and the dimension Y is carried out directly by this electronic processing unit 103 and only the dimension Y is transmitted to the remote server 500.

Claims

Claims

1. System for measuring the position of a counterweight (12) suspended on the side of a post (11) supporting a catenary installation, the measuring system comprising: - a module (101) intended to be fixed on the post (11) support; - a mobile target (201) intended to be fixed on the counterweight (12) or on a cable (13) for suspending the counterweight (12), below the module (101); characterized in that it comprises: - a fixed target (301) intended to be fixed on the post (11) support below the module (101), at a predetermined distance (P) from the module (101); and in that the module (101) comprises a transmitter-receiver (102) of acoustic waves intended to be oriented towards the moving target (201) and the fixed target (301), the moving target (201) and the fixed target (301) intended to be oriented towards the module (101);and in that the system comprises electronic processing means (400) comprising: - means for triggering (401) the emission of an acoustic wave (U) by the module (101); - means for determining (402) a duration of interest (DI) between the emission of the acoustic wave (U) and the reception of a first echo (El) by the module (101) resulting from a rebound of the acoustic wave (U) on the moving target (201), and a reference duration (DR) between the emission of the acoustic wave (U) and the reception of a second echo (E2) by the module (101) resulting from a rebound of the acoustic wave (U) on the fixed target (301); - means (403) for calculating a distance of interest (D) between the module (101) and the moving target (201) from the predetermined distance (P), the reference duration (DR), and the duration of interest (DI).;

2. System according to the preceding claim, characterized in that the moving target (201) and the fixed target (301) each comprise a rebound surface (2011, 3011) made of an acoustic wave reflecting material intended to be oriented towards the module (101).

3. System according to any one of the preceding claims, characterized in that the moving target (201) and the fixed target (301) each comprise a rebound surface (2011, 3011) having a parabolic cross-section delimiting a hollow intended to be oriented towards the module (101).

4. System according to any one of the preceding claims, characterized in that the calculation means (403) comprise: - a first subsystem (4031) for calculating a calculated speed (VC) of diffusion of an acoustic wave in the air from the predetermined distance (P) and the reference duration (DR); - a second subsystem (4032) for calculating the distance of interest (D) between the module (101) and the moving target (201) from the calculated speed (VC) and the duration of interest (DI).

5. System according to any one of the preceding claims, characterized in that the module (101) comprises an electronic processing unit (103) integrating at least part of the electronic processing means (400).

6. Catenary installation comprising: - a support post (11); - a counterweight (12) suspended next to the support post (11) using a cable (13) for suspending the counterweight (12); characterized in that it comprises the measuring system according to any one of the preceding claims, and in that: - the module (101) is fixed on the support post (11) with its acoustic wave transmitter-receiver (102) oriented downwards (B) in a vertical direction (V) up / down; - the mobile target (201) is fixed, below the module (101), on the counterweight or on the suspension cable of the counterweight, being oriented towards the module (101); - the fixed target (301) is fixed, below the module (101), on the support post (11), being oriented towards the module (101).

7. Method for measuring the position of a counterweight (12) suspended next to a support pole (11) of a catenary installation, the method implementing: - a module (101) fixed on the support pole (11), and comprising a transmitter-receiver (102) of acoustic waves oriented downwards (B) in a vertical direction (V) up / down; - a mobile target (201) fixed on the counterweight (12) or on a cable (13) for suspending the counterweight (12), below the module (101), and being oriented towards the module (101); - a fixed target (301) fixed on the support post (11), below the module (101), at a predetermined distance (P) from the module (101), and being oriented towards the module (101); the method comprising a measurement phase comprising: - a step of emitting an acoustic wave (U) by the module (101) in the direction of the moving target (201) and the fixed target (301); - a step of receiving a first echo (El) by the module (101) resulting from a rebound of the acoustic wave (U) on the moving target (201), and a second echo (E2) by the module (101) resulting from a rebound of the acoustic wave (U) on the fixed target (301); - a step of determining a duration of interest (DI) between the emission of the acoustic wave (U) and the reception of the first echo (El) by the module (101), and a reference duration (DR) between the emission of the acoustic wave (U) and the reception of the second echo (E2) by the module (101); - a step of calculating a distance of interest (D) between the module (101) and the moving target (201) from the predetermined distance (P), the reference duration (DR), and the duration of interest (DI).

8. Method according to the preceding claim, characterized in that during the calculation step, the following is carried out: - to the calculation of a calculated speed (VC) of diffusion of an acoustic wave in the air from the predetermined distance (P) and the reference duration (DR); - calculating the distance of interest (D) between the module (101) and the moving target (201) from the calculated speed (VC) and the duration of interest (DI).

9. Method according to any one of claims 7 and 8, characterized in that it comprises an installation phase prior to the measurement phase, the installation phase comprising: - a step of coupling the module (101) and the fixed target (301) on the support post (11), and the mobile target (201) on the counterweight (12) or on the cable (13) for suspending the counterweight (12), the fixed target (301) and the mobile target (201) being positioned below the module (101); - a step of measuring and recording the predetermined distance (P) separating the module (101) from the fixed target (301).

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