METHOD AND DEVICE FOR DETECTING A MOVEMENT OF A RAIL VEHICLE ALONG A RAILWAY

Description

Technisches Gebiet

[0001] The invention relates to a method for detecting the movement of a rail vehicle along a railway track and a device that can be attached to a rail vehicle for carrying out such a method. Stand der Technik

[0002] For safety reasons, modern rail vehicles are equipped with a train protection system. This system monitors the vehicle's speed to ensure it stays within the permitted maximum speed and complies with the prescribed speed reduction according to the braking curve by applying the brakes, for example, when entering a station. Reliable, accurate, and precise knowledge of the vehicle's speed relative to the ground is crucial.

[0003] To achieve the required accuracy of the vehicle speed, conventional measurement methods today use an I <ombination von mehreren verschiedenartigen Sensoren. Diese werden insbesondere aus folgenden ausgewählt: Cycle path sensors, radar sensors, optical path sensors, inertial navigation systems and global satellite navigation systems.

[0004] A combination is required because no single sensor technology can guarantee the required reliability and precision, especially because Wheel path sensors provide imprecise information due to the unavoidable slippage of the wheel relative to the rail in the case of driven and braked wheels, which does not correspond to the required true ground speed (TGS); radar sensors fail in snow, ice and dirt; optical path sensors are impaired in their function by dirt and dust; inertial navigation systems are sensitive to shocks and vibrations; global satellite navigation signals are not available or not reliably available in tunnels and narrow mountain valleys.

[0005] With these conventional methods, measurement errors accumulate involuntarily in a short time, which necessitates many expensive tracking beacons in the form of Eurobalises along the route to recalibrate the vehicle's odometry.

[0006] These limitations are overcome by magnetic odometry as described, for example, in the article by K. Ostaszewski et al.: "Magnetic odometry - Novel method for determining the speed of rail vehicles", ZEVrail, pp. 332-339, 09 / 2021 or in EP 3 663 769 A1 (MagSens Unternehmergesellschaft).

[0007] The operating principle is based on measuring the magnetic inhomogeneities of the track system and its subsoil. This results in magnetic signatures as location-dependent deviations in the magnetic field, which can be detected by magnetometers and exhibit characteristics that allow for identification. The system exploits the fact that, on sufficiently short timescales, the magnetic signature at a given location remains unchanged, so that two magnetometers separated along the direction of travel measure the same magnetic signature with a time offset. The magnetic signatures are detected by at least two magnetometers spatially separated along the direction of travel, which are usually mounted above the rail on the vehicle. Given a known, fixed distance Δ l two magnetometers in the direction of travel and the time offset measured by correlation Δt ( tThe vehicle speed can be determined from the signatures measured by two magnetometers. v ( t ) as a ratio of Δ l to Δt ( t ) .

[0008] However, this magnetic odometry method has two fundamental flaws: 1. As the vehicle speed v(t) decreases, the time delay increases. Δt ( t ) , This makes a precise determination of the vehicle speed impossible. 2. Consequently, this magnetic odometry method does not allow for standstill detection. However, this is essential for rail vehicles, as safety-relevant vehicle functions, such as the release of doors, depend on it.

[0009] EP 1 910 848 B1 (Pirelli & CS p. A.) discloses a method and a system for accurately measuring the speed of a moving object. This involves using several sensors arranged at a known distance from one another to generate measurement signals corresponding to physical quantities influenced by the object's motion. The speed is then calculated from the derivatives of these signals. Darstellung der Erfindung

[0010] The object of the invention is to create a method belonging to the aforementioned technical field for detecting the movement of a rail vehicle, which enables current and precise results even at low speeds.

[0011] The solution to the problem is defined by the features of claim 1. According to the invention, a method for detecting the movement of a rail vehicle along a railway track comprises the following steps: a) Within a first time interval, recording values ​​of a local magnetic flux density using at least three magnetic field sensors arranged at intervals on the rail vehicle in one direction of travel; b) Determining a first local magnetic signature from the values ​​recorded in the first time interval, corresponding to a first spatially dependent profile of the local magnetic flux density; c) Within a second time interval, recording values ​​of the local magnetic flux density using the at least three magnetic field sensors arranged on the rail vehicle; d) Determining a second local magnetic signature from the values ​​recorded in the second time interval, corresponding to a second spatially dependent profile of the local magnetic flux density;and e) Determining a distance traveled by the rail vehicle along the railway track from a comparison of the first local magnetic signature with the second local magnetic signature.

[0012] The method is therefore used to determine the true speed relative to the track or the ground (True Ground Speed).

[0013] The first and second time intervals are, as specified in more detail below, so short that the measured values ​​– taking into account the speed of the rail vehicle – allow the determination of the local magnetic signature and that ultimately – within the required accuracy – a determination of the motion parameters in real time is possible.

[0014] Within the scope of the inventive method, it is not necessary to determine absolute values ​​of the magnetic flux density. Because target quantities are ultimately derived from the comparison of the local magnetic signatures, relative quantities suffice, even those that depend only on the magnetic flux density, e.g., output currents or voltages of corresponding sensors, provided that the at least three sensors used behave identically. Suitable magnetic field sensors (magnetometers) include, for example, Hall sensors, magnetoresistive sensors, Förster probes, or flux-gate magnetometers.

[0015] The at least three magnetic field sensors are preferably arranged parallel to the direction of travel, so that the magnetic flux density is directly recorded along a line parallel to the track. However, it is also conceivable that the magnetic field sensors are spaced not only in the direction of travel but also horizontally perpendicular to it. Arrangements in which the sensors have different distances from the track are also possible. In particular, it can be advantageous if, in addition to the arrangement of magnetic field sensors in a line parallel to the direction of travel of the rail vehicle, further magnetic field sensors are arranged perpendicular to the direction of travel (horizontally and / or vertically), with the aim of detecting interference emissions from the rail vehicle with as few magnetic signatures as possible.The interference signals thus captured separately can then be taken into account in the measured magnetic signatures by destructive interference in such a way that the interference signal component in the measurements of the magnetic signatures is significantly reduced.

[0016] In general, processing the sensor signals, especially filtering out interference signals, can be helpful to improve the subsequent determination of the magnetic signature.

[0017] The inventive method primarily detects the magnetic field resulting from the structure of the track system and any adjacent surrounding elements. Separate elements for influencing the magnetic field, such as permanent magnets arranged along the track as used for train control, are not necessary. However, the presence of such elements does not impair the inventive method.

[0018] A local magnetic signature is a location-dependent distribution of the magnetic flux density, particularly along a line parallel to the roadway. Its usability as a signature in the present method requires that the absolute value of the flux density gradient in the considered space exceeds a certain minimum value, at least in certain areas. For the method, it is generally irrelevant which location is considered the beginning and which the end of such a signature. Studies have shown that the magnetic flux density exhibits considerable variations on scales of less than one meter. Therefore, it is sufficient to record and evaluate the flux density distribution within a suitably dimensioned area.

[0019] Comparing the first local magnetic signature with the second local magnetic signature essentially corresponds to determining a spatial offset resulting from the temporally staggered acquisition of the signatures – in contrast to determining the temporal offset in previously known magnetic odometry methods. In the inventive method, the signatures are recorded virtually in real time while the train is traveling along the track and used to determine the distance traveled; no comparison with data recorded during previous journeys is necessary.

[0020] The new magnetic odometry method overcomes the aforementioned shortcomings of previously known methods. It allows for the precise and accurate determination of the distance traveled within a given time interval, even during slow movements of the rail vehicle. This directly enables reliable speed determination as well as the detection of vehicle standstill or very slow vehicle movements.

[0021] The measurement rate is freely selectable and can – within the limits of the performance of the sensor and processing equipment used – easily be set very high if required.

[0022] Advantageously, the sampling rate of the at least three sensors is chosen such that the time interval between the second local magnetic signature and the first local magnetic signature is not significantly larger than the ratio between the mutual distance of adjacent magnetic field sensors of the at least three and an expected speed of the rail vehicle, i.e. Δ τ t i ≤ a Δ l v t i where Δ τ ( t i ) the current time interval (i.e., the reciprocal of the sampling rate), v ( t i ) the expected velocity and Δ l The distance between adjacent sensors is defined as a≤2, preferably a≤1.5, particularly preferably a≤1.2. This ensures that the local displacement of the rail vehicle relative to a specific signature is reliably detected.

[0023] In any case, it should be ensured that the time interval is not greater than the ratio between the distance between the first and last of the at least three magnetic field sensors and an expected speed of the rail vehicle.

[0024] In a first group of preferred embodiments, adjacent sensors of at least three are arranged at the same distance from each other, parallel to the direction of travel.

[0025] In a second group of preferred embodiments, the distances between adjacent sensors are different. In this case, the relationship between the smallest distance and the expected speed is advantageously considered. To process the signals from non-equidistantly arranged sensors, the sampled values ​​are advantageously interpolated in a first step to values ​​at equidistant intervals. Further processing then proceeds in the same way as with signals from equidistant sensors. A non-equidistant arrangement of the magnetic field sensors takes into account the conditions on the underside of the rail vehicle, which only permit the arrangement of magnetic field sensors in certain areas.

[0026] The expected speed can be variably defined based on predetermined speeds of the rail vehicle. For example, the last recorded speed is used, with a minimum sampling rate applied when the speed falls below a certain threshold, allowing the system to distinguish between stationary and moving rail vehicles within the required time. It is also possible to specify different sampling rates, for example, for stationary operation, a first, lower speed range, and a second, higher speed range. Naturally, more than three sampling rate presets are also possible.

[0027] Instead of a variable speed, a fixed speed value can also be chosen, e.g., the maximum permitted speed of the rail vehicle. This results in a certain sampling rate, which ensures that reliable data is recorded even at high speeds.

[0028] Preferably, the duration of the first time interval and the duration of the second time interval do not exceed the time difference between the second local magnetic signature and the first local magnetic signature. This ensures that the local signature is essentially captured at two specific points in time, making it possible to determine the spatial offset.

[0029] In first embodiments of the method according to the invention, the values ​​from the at least three magnetic field sensors are acquired essentially simultaneously in the first time interval, and the values ​​from the at least three magnetic field sensors are acquired essentially simultaneously in the second time interval. "Essentially simultaneously" means that slight time differences may occur due to latency. In practice, these differences can be kept so small that they do not result in any significant impairment of the signal quality.

[0030] In second embodiments of the inventive method, the values ​​of at least two of the at least three magnetic field sensors are acquired with a time offset in the first time interval, and the values ​​of at least two of the at least three magnetic field sensors are acquired with a time offset in the second time interval. The offset is preferably chosen such that the acquisitions occur in a temporal sequence in the direction of travel, i.e., in a given measurement cycle, the sensors located furthest forward in the direction of travel measure first, followed by those located further forward. Preferably, if adjacent sensors are spaced at identical distances, there is an identical time offset between adjacent sensors, i.e., a sequence of measurements "from back to front" results, with the same time interval between successive measurements.

[0031] The offset can be set as a constant or dynamically varied based on driving parameters, e.g. the current speed.

[0032] However, the magnetic field sensors can also be grouped together, with sensors of a specific group essentially measuring simultaneously.

[0033] Time-delayed data acquisition can simplify signal processing. In particular, it also allows for an increase in the effective distance between measurement points in the two time intervals when the speed of the rail vehicle increases, especially in a measurement sequence running in the direction of travel. This correspondingly longer baseline results in higher measurement accuracy.

[0034] Advantageously, the maximum mutual spacing of the at least three magnetic field sensors in the direction of travel exceeds the maximum length of magnetic signatures to be detected. Due to the magnetic inhomogeneities of the track system (and other influences independent of the track system), signatures of widely varying lengths can arise. Within the scope of the inventive method, it is neither necessary nor desirable to detect all possible signatures and use them to determine the movement of the rail vehicle. It is entirely sufficient if a sufficient number of local signatures are present within the considered length range so that the local displacement of the rail vehicle relative to at least one detected signature can always be determined along the entire track and at all relevant speeds.The maximum length of the magnetic signatures to be detected is therefore a quantity that can be specified based on the characteristics of the railway track.

[0035] The mutual spacing between adjacent magnetic field sensors (at least three) in the direction of travel is chosen such that the Nyquist sampling theorem is satisfied with respect to the portions of the magnetic signatures relevant for determining the distance traveled. This ensures that the local signature can actually be detected using the at least three magnetic field sensors. Again, only the signatures relevant for determining motion are considered. The Nyquist sampling theorem (also known as the Nyquist-Shannon sampling theorem or WI) <S-Abtasttheorem) besagt, dass ein auf eine maximale Frequenz f max A limited signal can be reconstructed from a sequence of equidistant samples if it is sampled at a frequency of at least 2 f max was sampled. In this case, this readily establishes a condition for the sensor distances in the local area. Because, as explained above, not all signatures need to be captured, but only those within a certain length range and, correspondingly, those within a certain frequency range, such a maximum frequency can be defined. Accordingly, the considered local signatures can be reconstructed from the measurements taken, provided the Nyquist-Shannon sampling theorem is satisfied.

[0036] Taking into account the aforementioned boundary conditions, information on the number of magnetic field sensors, their mutual distances and the sampling rate can be obtained from the characteristics of the existing signatures and the maximum speed of the rail vehicle.

[0037] In preferred embodiments of the invention, in particular 10 - 50 magnetic field sensors are used, wherein the mutual distances of adjacent sensors are equal and amount to 1 - 20 cm.

[0038] Within the framework of the inventive method, the instantaneous speed of the rail vehicle relative to the track (true ground speed) is determined in particular. This includes the additional step of determining the instantaneous speed as the ratio between the determined distance traveled Δ x ( t ) and the time interval Δ τ the second local magnetic signature from the first local magnetic signature. More than one of the determined path lengths can be used to determine the velocity, e.g., by using a suitable filter such as a moving average with appropriate weighting or a Kalman filter.

[0039] The inventive method is also particularly well suited for detecting when a rail vehicle is stationary. This is readily achieved based on the determined distance traveled; stationary status corresponds to the relationship Δ x ( t ) = 0. In contrast to previously known methods, where a considerable time interval between measurements is necessary at low speeds, the inventive method, through the essentially immediate acquisition of an entire local signature, enables the detection of movement even when measurements are taken in close succession. This is of great importance, as the reliable detection of a vehicle's standstill is linked to safety-relevant functions, such as the release of the doors for opening. Similarly, the rapid detection of a rail vehicle starting to roll is also advantageous from a safety perspective, enabling countermeasures or an alarm to be triggered without delay if necessary.

[0040] For functional testing of the inventive method, a test signal corresponding to a predetermined travel speed outside a possible speed range is advantageously generated and coupled at the magnetic field sensor stage. The analog or digital test signal corresponds to a possible waveform of a real signature. In particular, the predetermined travel speed is higher than the maximum speed achievable by the rail vehicle. The coupling can take place upstream of the magnetic field sensors by generating a magnetic field based on the test signal and having it detected by the magnetic field sensors, or it can be coupled directly downstream of the magnetic field sensors by superimposing the test signal onto the respective sensor signal. Subsequent processing is then based on the superimposed signal.

[0041] Because the test signal passes through the entire signal processing chain, malfunctions can be detected immediately based on deviations of the determined speed from the specified speed.

[0042] In particular, the coupling is permanent, so the system is constantly monitored. Alternatively, periodic checks using temporarily coupled test signals are also possible.

[0043] For carrying out the inventive method for detecting the movement of a rail vehicle along a railway track, a device that can be attached to a rail vehicle is particularly suitable, comprising a) at least three magnetic field sensors spaced apart on the rail vehicle in one direction of travel; b) a control system that receives measurement signals from the at least three magnetic field sensors and is operated in such a way that the movement of the rail vehicle is determined on the basis of the measurement signals according to the inventive method described above.

[0044] The magnetic field sensors can be arranged on a common carrier or in a common housing, or separately or in groups on the rail vehicle.

[0045] Further advantageous embodiments and combinations of features of the invention can be derived from the following detailed description and the entirety of the patent claims. Kurze Beschreibung der Zeichnungen

[0046] The drawings used to illustrate the exemplary embodiment show: Fig. 1A a schematic representation of a rail vehicle with a first embodiment of a system according to the invention for detecting movement of the rail vehicle; Fig. 1B the course of a component of the magnetic flux density along a track; Fig. 1C the positions of the magnetic field sensors of the system according to the invention along the track during successive measurements; Fig. 1D the comparison of the local magnetic signatures according to successive measurements; Fig. 2A a schematic representation of a rail vehicle with a second embodiment of a system according to the invention for detecting movement of the rail vehicle; Fig. 2B the course of a component of the magnetic flux density along a track; Fig. 2C the positions of the magnetic field sensors of the system according to the invention along the track during successive measurements; and Fig.2. Comparison of local magnetic signatures according to successive measurements.

[0047] Basically, identical parts in the figures are marked with the same reference symbols. Wege zur Ausführung der Erfindung

[0048] The following will be based on the Figuren 1A-D and 2A-D Two embodiments of a system and method according to the invention for determining the velocity v( t i ) of a rail vehicle 1 moving along a track 2 at a time t i As shown. In addition to speed, the system or method also provides information about the current location. x ( t i ) and enables reliable standstill detection, according to Δ x ( t i ) = 0 in the preceding time interval Δ τ ( t i ) = t i - t i-1 . The method is characterized by the fact that the aforementioned quantities can be determined with a selectable and, if required, high temporal accuracy and with a high selectable rate. R This has been done.

[0049] In the first described embodiment according to the Figuren 1A-1D The measured values ​​are obtained by means of n Magnetic field sensors detect the data simultaneously. In the second embodiment described later, according to the Figuren 2A-2D The measured values ​​are recorded one after the other in rapid succession.

[0050] The method according to both embodiments is based on measuring the magnetic inhomogeneities of the track system and the track bed. These form characteristic local signatures, which remain essentially unchanged at a location on sufficiently small timescales. These signatures are detected by n magnetic field sensors 11.1...11.n of the system 10 according to the invention at time intervals Δ τ measured, with the aim of determining the local displacement Δ x ( t ) the signatures relative to the rail vehicle 1 can be determined precisely, accurately in time, and with a high selectable measurement rate. This is in contrast to prior art magnetic odometry methods, where the time shift Δ t ( t ) the signature is determined via a temporal correlation when driving over it.

[0051] The n magnetic field sensors 11.1...11.n are arranged uniformly in the undercarriage of the rail vehicle 1 along a line that extends substantially above a rail in the direction of travel and parallel to the rail running surface. All magnetic field sensors 11.1...11.n are identically designed and calibrated. Various types of magnetic field sensors can be used within the scope of the inventive method, including in particular Hall sensors, magnetoresistive sensors, and Förster probes or fluxgate magnetometers.

[0052] The following parameters are observed regarding the number and placement of the magnetic field sensors: The length l = (n - 1) Δ l the n The maximum length of the magnetic field sensors arranged one behind the other is exceeded. L a magnetic signature, l > L; The distance Δ lThe sampling theorem of Nyquist (H. Nyquist: "Certain Topics in Telegraph Transmission Theory", Transactions of the American Institute of Electrical Engineers, Vol. 47, No. 2, pp. 617-644, 4 / 1928) of neighboring magnetic field sensors is satisfied with respect to the portion of the magnetic signatures in the spatial domain that is relevant for determining position and velocity.

[0053] Determining the sizes L, l and Δ l based on extensive measurements of magnetic signatures along a variety of routes with AC-based railway power supplies of all common frequencies such as 16.7 Hz and 50 Hz, routes with DC-based railway power supplies and non-electrified railway lines with bridges of various designs, tunnels and stations.

[0054] Values ​​in the following areas have proven suitable: 0.2 m < L < 2.0 m ; 0.01 m < Δ l < 0.2 m and consequently 0.3 m < l < 2.5 m

[0055] For example, 10 magnetic field sensors are spaced at a distance Δ l The magnetic field sensors are spaced 10 cm apart, thus covering a length of 0.9 m in the direction of travel. The magnetic field sensors 11.1...11.n are controlled by a control unit 12 and transmit their measured values ​​to it. The control unit 12 is connected to other rail vehicle components, in this case a display unit 21 for the driver, a recording unit 22, and an interface 23 for communication with internal vehicle systems, e.g., a higher-level control system, and / or external vehicle systems, e.g., a control center.

[0056] The operating principle is based on measuring the magnetic inhomogeneities of the track system and its surroundings. It utilizes the fact that, on sufficiently small timescales, the magnetic signature at a given location remains unchanged.

[0057] The magnetic signatures are acquired at time intervals Δ τ of the n Magnetic field sensors 11.1...11.n measure in one, two or all three orthogonal spatial directions simultaneously.

[0058] The time interval Δ τ the recurring ones n For magnetic field sensors 11.1...11.n, the simultaneously measured magnetic signatures must be chosen to be sufficiently small to allow for a usable determination of Δ x ( t i to ensure this. The inequality can serve as a guideline. Δ τ t i ≤ Δ l v t i , are used, whereby v ( t i ) the current speed of the vehicle at that time t i denoted. Slightly longer time intervals Δ τ are also possible, as mentioned above.

[0059] The time sampling interval Δ τ ( t i ) can adapt to the current speed v ( t i ) of the vehicle. It should be noted that the sampling interval Δ τ ( t i ) the reciprocal of the minimum required measurement rate R does not exceed. Δ τ t i ≤ 1 R .

[0060] Alternatively, the sampling interval Δ can be used. τ also the fixed value Δ τ ≤ Δ l v max to be determined, whereby v max denotes the maximum speed of the rail vehicle.

[0061] The Figuren 1B-1D illustrates the measurement method according to the first embodiment. Therein, it is designated B z ( x ) the zI <omponente der magnetischen Flussdichte als Funktion des Ortes x. Im Rahmen der Ausführungsbeispiele beinhalten die Messungen der Einfachheit halber lediglich diese eine Komponente, das Verfahren lässt sich aber ohne Weiteres auf die Verarbeitung von 2- oder 3-dimensionalen Messungen der Flussdichte verallgemeinern, d. h. die entsprechenden Magnetfeldsensoren können die magnetische Flussdichte in 2 oder 3 Polarisationsrichtungen erfassen.

[0062] The course 30 of the aforementioned component of the magnetic flux density along a section of the railway is shown in the Figur 1B shown.

[0063] In the Figur 1C are the positions of the magnetic field sensors 11.1...11.n of the system according to the invention along the railway track during successive measurements at the times t i -1 = t - Δ τ (below), t i = t (center) t i +1 = t + Δ τ (above) shown schematically. The areas of the track covered by the entire set of magnetic field sensors 11.1...11.n during successive measurements overlap considerably at the corresponding speed, so that the same magnetic field signature is recorded multiple times.

[0064] First, the relative displacement is determined. This is done by comparing successively measured magnetic signatures at time t. t i those in the time interval Δ τ = t i - t i -1 distance traveled Δ x ( t i ) determined. For this determination, measurements whose time interval is a multiple of Δ can also be used. τ The known distance Δ serves as the scale for determining the position. d = Δ l between adjacent magnetic field sensors. In the Figur 1D The graphs 30.1 and 30.2 are shown at the times... t i -1 = t - Δ τ or t i = t They can be compared with each other. The comparison between the curves 30.1 and 30.2 to determine the spatial displacement (relative to the rail vehicle) can be carried out using common methods. <orrelationsverfahren erfolgen.

[0065] Since the magnetic signatures are measured in the spatial domain according to Nyquist's sampling theorem, as mentioned, their progression at any equidistant locations between the n magnetic field sensors can be determined by interpolation. With regard to the progression 30.2, in the Figur 1D The grey dots also represent the measured values ​​of the individual magnetic field sensors 11.1...11.n, from which the signature was reconstructed.

[0066] The total distance traveled x ( t I ) currently t I results with x 0 ( t 0 ) = 0, the starting point of the rail vehicle at the beginning of the journey, to x t I = ∑ i = 0 I Δ x t i + x 0 t 0 .

[0067] This in turn determines the vehicle speed. v ( t i ) currently t i as follows: v t i = Δ x t i Δ τ t i , where Δ τ ( t i ) = t i - t i- 1 denotes the time interval under consideration.

[0068] The vehicle's standstill is determined by calculating the distance traveled Δ x ( t i ) in the time interval Δ τ ( t i ) = t i - t i -1 . If this value is zero, the vehicle is stationary.

[0069] The second embodiment, in which the measured values ​​of n Magnetic field sensors detect data in rapid succession, which is related to the Figuren 2B-D described. The measurement process is identical to the first embodiment except for the temporal sequence of data collection.

[0070] The magnetic signature is now replaced by the n Magnetic field sensors in rapid succession at time intervals of Δ δ ( t i ) seconds in succession. The relationship must be maintained. n Δ δ t i ≤ Δ τ t i must be adhered to. Δ τ ( t i ) denotes the sampling interval for measuring the magnetic signatures using the n magnetic field sensors.

[0071] Due to the staggered acquisition of the measurements, the distances between the locations where the n magnetic field sensors measure the magnetic signature of the track environment change. Advantageously, the sequence for recording the magnetic signature is performed in the direction of travel. This increases the effective distance Δ d ( t i ) between the measuring points with increasing vehicle speed v ( t i ) to Δ d t i = Δ l + v t i Δ δ t i .

[0072] It should be noted that for all v ( t i ) the aforementioned Nyquist sampling theorem with respect to Δ d ( t i ) is adhered to. The effective length d ( t i ) of the sensor consisting of the n Magnetic field sensors then d t i = n − 1 Δ d t i = n − 1 Δ l + n − 1 v t i Δ δ t i = l + n − 1 v t i Δ δ t i , where l = ( n - 1) Δ lthe length of n The magnetic field sensors arranged one behind the other on the vehicle in the direction of travel are designated. The positions of the magnetic field sensors 11.1...11.n of the system according to the invention along the track during successive measurement cycles with start times are shown. t i -1 = t - Δ τ (below), t i = t (center) t i +1 = t + Δ τ (above) are in the Figur 2C shown schematically.

[0073] Taking into account the effective distances between the locations for measuring the magnetic signature, the determination can be made of the vehicle's location, vehicle speed, and standstill detection The procedure is identical to that used in the first embodiment.

[0074] The time interval Δ τ ( t i ) distance traveled Δ x ( t i ) should determine the effective distance Δ d ( t i ) do not significantly exceed the values ​​between the measurement locations, i.e., essentially: Δ x t i ≤ Δ d t i .

[0075] The time interval Δ τ ( t i ) distance traveled Δ x ( t i ) is the product of the current vehicle speed v ( t i ) and the time sampling interval Δ τ ( t i ): Δ x t i = v t i Δ τ t i .

[0076] The time offset between the measurements of the individual magnetic field sensors can be uniform, or different time differences can be selected. Hybrid forms of the first and second embodiments are possible; that is, in further embodiments of the inventive method, some of the n magnetic field sensors can perform their measurements simultaneously, while other measurements take place at a time offset. The approach according to the second embodiment can readily be generalized to such operating modes.

[0077] The invention is not limited to the illustrated embodiments. In particular, the number and arrangement of the magnetic field sensors can be chosen differently. As mentioned above, the magnetic field can be detected in two or three dimensions; furthermore, data acquired at more than two measurement points can be used to determine the quantities to be measured.

[0078] In summary, the invention provides a method for detecting the movement of a rail vehicle, which enables current and precise results, especially at low speeds.

Claims

1. Method for detecting a movement of a rail vehicle (1) along a rail track (2), comprising the following steps: a) within a first time interval, detecting values of a local magnetic flux density by means of at least three magnetic field sensors (11.1...11.n) arranged on the rail vehicle at a distance in a direction of travel of the rail vehicle; and b) determining a first local magnetic signature from the values detected in the first time interval, corresponding to a first location-dependent profile of the local magnetic flux density; and characterized by the following steps: c) within a second time interval, detecting values of the local magnetic flux density by means of the at least three magnetic field sensors arranged on the rail vehicle; d) determining a second local magnetic signature from the values detected in the second time interval, corresponding to a second location-dependent profile of the local magnetic flux density; and e) determining a distance covered by the rail vehicle along the rail track from a comparison of the first local magnetic signature with the second local magnetic signature.

2. Method according to Claim 1, characterized in that a sampling rate of the at least three magnetic field sensors (11.1...n) is selected in such a way that Δ τ t i ≤ a Δ l v t i ′ where Δτ(ti) denotes a time distance of the second local magnetic signature from the first local magnetic signature, Δl denotes the mutual spacing of adjacent magnetic field sensors and v(ti) denotes the expected speed and a is less than 2, preferably less than 1.5, particularly preferably less than 1.2.

3. Method according to Claim 2, characterized in that the expected speed is fixed in a variable manner on the basis of predetermined speeds of the rail vehicle.

4. Method according to Claim 2 or 3, characterized in that a duration of the first time interval and a duration of the second time interval do not exceed the time distance of the second local magnetic signature from the first local magnetic signature.

5. Method according to Claim 4, characterized in that, in the first time interval, the values of the at least three magnetic field sensors are detected substantially simultaneously and in that, in the second time interval, the values of the at least three magnetic field sensors are detected substantially simultaneously.

6. Method according to Claim 4, characterized in that, in the first time interval, the values of at least two of the at least three magnetic field sensors are detected in a temporally offset manner and in that, in the second time interval, the values of at least two of the at least three magnetic field sensors are detected in a temporally offset manner, an offset being selected in particular in such a way that a temporal sequence of the detection takes place in the direction of travel .

7. Method according to one of Claims 1 to 6, characterized in that a maximum mutual spacing of the at least three magnetic field sensors in the direction of travel exceeds a maximum length of magnetic signatures to be detected.

8. Method according to one of Claims 1 to 7, characterized in that a mutual spacing of adjacent ones of the at least three magnetic field sensors in the direction of travel is selected in such a way that the Nyquist sampling theorem is satisfied with respect to the portions of the magnetic signatures in the local region that are relevant for the determination of the distance.

9. Method according to one of Claims 1 to 8, characterized by the additional step of determining an instantaneous speed of the rail vehicle as a ratio between the determined distance and the time distance of the second local magnetic signature from the first local magnetic signature.

10. Method according to one of Claims 1 to 9, characterized by the additional step of detecting a standstill of the rail vehicle on the basis of the determined distance.

11. Method according to one of Claims 1 to 10, characterized in that, for functional control, a test signal corresponding to a predefined travel speed is generated outside a possible speed range and is coupled in at the level of the magnetic field sensors.

12. Device which can be attached to a rail vehicle for detecting a movement of the rail vehicle (1) along a rail track (2), comprising a) at least three magnetic field sensors (11.1...n) arranged on the rail vehicle at a distance in a direction of travel of the rail vehicle; and b) a controller (12) which receives measurement signals from the at least three magnetic field sensors and is operated in such a way that the movement of the rail vehicle is determined on the basis of the measurement signals according to a method according to one of Claims 1 to 11.

13. Device according to Claim 12, characterized in that the magnetic field sensors are in each case arranged on the rail vehicle at the same distance from one another parallel to the direction of travel .

14. Device according to Claim 12, characterized in that the magnetic field sensors are arranged on the rail vehicle at different distances from one another.