RU2490153C1 - Method of remote detection of track conditions change ahead of running train - Google Patents

Abstract

FIELD: transport.

SUBSTANCE: invention relates to track safety control and serves for remote detection of changes in track conditions caused by rail structure faults and occurrence of dangerous objects in groundwork. Proposed method comprises recording of vibroacoustic pulses in rail resulted from interaction of wheel pairs with rail joints at equal opposite distances therefrom. Signals registered on train passing said rail joints are filtered out and accumulated. Note here that after passage of first train over known-good track said signals are converted to maximum affinity to conserve parameters of correcting circuit. In passage of the next train of track section - signal generator result of comparison is compared with preset threshold. In case it is exceeds decision is made about availability of affected track ahead of running train.

EFFECT: higher reliability of remote detection in real time conditions.

3 cl, 5 dwg

Description

The invention relates to systems for monitoring the state of extended objects and can be used for remote detection of dangerous changes in the state of the rail track, including defects in the rail or foreign objects installed in it.

There is an acoustic method for detecting a rail track malfunction during the movement of a train along the railway, according to which acoustic pulses are formed on the “board” of the rolling stock, they are transmitted through the wheelset to the rails, the presence of reflected pulses is recorded at the point of their formation, upon the occurrence of which they decide about a malfunction of the rail track in front of the running train (RF patent No. 2126339 C1, B61K 9/10, 02.20.1999). The disadvantages of the method are the low reliability of fault detection due to the presence of powerful vibroacoustic signals of wheel interaction with joints and defects in the rails in the rail, which imposes a limitation on the detection of only those defects in the track rails that are characterized by high reflectivity of vibroacoustic signals.

A known method for remote monitoring of the state of a railway track, based on the formation of a video image of a section of a track in front of an approaching train, transmission of a video image to a driver’s control panel and analysis of information received for dangerous changes on the track of a train in front (RF patent No. 2313465 C2, B61L 29/00, 04/27/2007). The disadvantages of this method are the undetectable defects in the rails, the dependence of the reliability of detection on weather conditions, the significant cost of the project in the case of control of long routes, the availability of easy "dazzle" cameras for the preparation of sabotage acts on selected sections of the route (by using noise generators in the frequency range of the video camera )

A known method of monitoring the critical condition of rolling stock on a rail track and registering its descent and a device for its implementation, according to which the vertical and transverse vibrational accelerations on running bogies and the acoustic emission energy from the zone of contact of the wheels with the rails are continuously recorded, compare the registered functions with the background and the comparison results identify the state of the rolling stock as “full-time”, “critical” or “descent” (RF patent No. 2399524 C1, B60T 7/12, 09/20/2010). However, the time for stopping a moving train during the transition from the critical mode to the descent mode, based on real conditions, is insufficient.

A device is known for remote detection of objects hidden on a railway track, which implements a method according to which, using a source of penetrating radiation and detectors mounted on a self-propelled cart, they “inspect” the rails and the rail track and, if there are inconsistencies in the parameters of the controlled objects of the technical documentation, decide on the availability hidden object on the railway track (RF patent No. 2425769 C1, B61K 9/00, 08/10/2011). The disadvantage of this method is the low speed of monitoring the condition of the rail track and the insufficient reliability of the paired pair: "the trolley moving in front of the train is the train."

Of the known technical solutions, the closest set of essential features to the claimed one is the “Rail and train monitoring system and method” (RF patent No. 2365517 C2, B61L 1/06, B61L 23/04, 08/27/2009). According to the method, vibroacoustic signals are continuously recorded in both rails of the rail track at the location of detection, these signals are compared and, in the absence of changes in the signal parameters in one channel (one of the rails), when the train approaches the detection site, a decision is made about the presence of a kink in the rail (a cracked rail). The disadvantage of this method is the fundamental impossibility of detecting foreign objects on the tracks due to avalanches, rockfalls, floats, etc., as well as the results of the preparation of sabotage acts, including the installation of ammunition. A more dangerous case is that a break in both rails is also not detected.

The aim of the proposed method is to increase the reliability of remote detection of dangerous changes in the state of the rail track in front of a moving train in real time.

This goal is achieved by registering only vibroacoustic signals from the interaction of wheel pairs with the rail joint at equally distant, if possible, rail track joints on both sides of it, the signals recorded when the train passes the joint are filtered and accumulated, the signals received from such operations the marked joints selected as signal generators are aligned when the first train passes a known-good path to obtain maximum similarity, and the parameters are correct The circuit is canned, when the next train passes the signal generator joint, the accumulated signals are compared and judged by the degree of difference between the presence or absence of changes in the rail track in front of the moving train. In addition, in the absence of a train in a controlled section of the track, the recording circuits are switched to low sensitivity mode, i.e. tripping only at the moment of interaction of the moving wheel with the joint at the place of its installation, and according to these triggering signals, the recording circuits closest along the rail from the joint are switched to the mode of increased sensitivity. The above operations to assess changes in sections of the rail track are carried out for each thread of the rail track.

The invention is illustrated by the following description and the accompanying drawings.

Figure 1 shows fragments of the image of vibro-acoustic vibrations in a rail recorded at a distance of 700 m from a moving train, for a) the normal state of the rail track and b, c) when metal objects are installed on the rail.

Figure 2 illustrates the effect of a local earth embankment on an extended metal object 100 m long on a change in the parameters of a vibroacoustic signal passing from the beginning to the end of the object: a) image of the experimental design, b) amplitude-frequency spectra of signals at points 1 and 2, c) - amplitude-frequency spectra of signals at points 2 and 4.

Figure 3 shows the spectral density of the sum of the recorded vibroacoustic signal and its accompanying noise 1 and separately noise 2.

Figure 4 shows the change in the signal-to-noise ratio at the receiving point at the monitoring object during the accumulation of signals.

Figure 5 shows the structural diagram of a device for remote detection of changes in the state of the rail track in front of a moving train, including track 1 with joints C _i spaced at distances L _ij (from the i-th junction - signal generator - to the j-th recording circuit 7) , detectors of 2 wheels above the joint, threshold circuits 3 with amplifiers, vibroacoustic transducers 4, electromagnets 5 in the form of “magnet suckers”, keys 6, recording circuits 7, two-input disjunction circuits 8, communication channel 9, comparison circuits 10. Indices

T _{i + m} , the outputs of the threshold circuits 3 with the detectors 2 of the appearance of the wheel above the joints are indicated, the indices P _in are the outputs of the recording circuits 7.

The problem of the propagation of elastic waves in rods is usually reduced to solving the wave equation, provided that the desired functions must satisfy the boundary conditions and the damping condition with increasing one coordinate to infinity. To get the necessary information, it is more productive to turn to the experiment.

When elastic waves propagate, its amplitude U decreases due to the divergence of rays and attenuation in the medium:

$$U=\frac{U_0}{r^b}{e}^{-\delta r}{e}^{j\left(\omega t-kr\right)}$$

where U ₀ = U (r = 0), r is the distance traveled by the wave; b is an indicator depending on the shape of the wave front (b = 1 for a spherical wave; b = 0 for a plane wave; b = 0.5 for a cylindrical wave); e - exhibitor; δ is the attenuation coefficient; ω is the angular frequency of the wave; k is the wave number.

Attenuation coefficient for mild steel δ = 0.2f, i.e. increases in proportion to the frequency f.

When two bodies come in contact, part of the vibrational energy passes from one body to another. This part is determined by the reflection and transparency coefficients of the interface of the bodies, or their wave impedances. With a normal longitudinal wave incident on the steel-air interface, only 0.002% of energy passes through the steel-organic glass interface - 25%. It can be concluded that when the rail comes into contact with a foreign object (earth embankment, metal or plastic object, etc.), part of the energy will go into this object and the signal propagating along the rail will weaken from the interaction of the wheelset with the rail junction. This indicates the fundamental possibility of detecting the embankment.

The experimental graphs in figure 1 confirm the statement. The effect of attenuation of signals from a running train is manifested at a distance of 700 m when installing metal objects 5 × 15 × 10 cm in size on a rail.

The effect of the emerging local earthen embankment with a length of 5 m on an extended metal object is illustrated in figure 2. If in the absence of the embankment the amplitude-frequency spectra of the path signals recorded at points 1 and 2, as well as at points 2 and 4, are indistinguishable (Fig. 2, b), then the same signal spectra at points 2 and 4 when the embankment appears (figure 2, c). The experiment confirms the practical possibility of detecting the presence of a local embankment on an extended metal object with modern measuring tools.

In addition to demonstrating the possibility of detecting the indicated changes in the state of the rail track in front of a moving train, it is necessary to decide on the implementation of the stated goal - improving the reliability of detection. The railway along the railway is a source of intense vibro-acoustic noise in the rail that does not carry information about changes in the state of the rail track. A train approaching along a nearby path to the place of detection is a source of false alarms in the decision-making scheme. It is proposed to introduce into the recording scheme three operations to suppress non-informative noise (to increase the signal-to-noise ratio).

The essence of the first filtering operation is to suppress non-informative frequency components of the signal arriving at the recording circuit, as illustrated in FIG. 3. Presented in figure 3. spectral noise densities and the “signal + noise” sums recorded in the experiment at a distance of 450 m from the pulse source allow us to conclude that it is advisable to introduce a band-pass filter with a passband of 120-1000 Hz into the signal processing channel.

, где n - число регистрируемых импульсов. Экспериментальные данные, иллюстрирующие реальный эффект от накопления сигналов и представленные на фиг.4, позволяют сделать заключение об их соответствии теоретическим.The essence of the second operation is to use the principle of accumulation in the signal processing channel. When a train passes a signal generator joint, several tens of pulses are generated, each of which at the input of the recording circuit reflects the same information about the state of the rail track in the section “train - recording circuit”. One of the options for using all the information received is accumulation, which allows, at best, to increase the signal-to-noise ratio in $$\sqrt{n}$$

where n is the number of detected pulses. Experimental data illustrating the real effect of the accumulation of signals and presented in figure 4, allow us to make a conclusion about their compliance with the theoretical.

The third comparison operation is used in the prototype. But in the proposed version, it is ineffective for solving the goal. To exclude “missed targets”, it is proposed to compare the signals that passed through the studied section of the rail track and the similarly long section along which the train has already passed are considered to be known to be working. To implement this operation, it is required in the recording circuits 7 to select only those pulses that are formed by a joint located in the middle between the detection points. Only in this case the proposed idea of comparison becomes productive. An embodiment of its implementation, as well as the method as a whole, is illustrated in FIG.

When a pair of trains passes a junction C _{i + 1,} detector 2 (strain gauge, photoelectric sensor, etc.) generates a signal that, through a threshold device 3 with an amplifier, is fed via communication channel 9 to disjunction schemes 8 serving joints with indices i and i + 2 . According to the output signals of the latter, the electromagnets 5 bring vibroacoustic transducers 4 into contact with the rail 1 and open the keys 6 through which, during the passage of the junction wheel C _{i + 1, the} signals excited in the rail enter the recording circuits 7. Translation of the vibroacoustic transducer 4 in the registration mode when the train is removed at a considerable distance, it is possible to protect them from powerful signals of interaction of the wheel with the joint C _{i + 1} at the installation site of the recording circuit 7. Each of the recording circuits 7 contains consequently included a band-pass filter and a drive of incoming signals (they are not shown in Figure 5). At the end of the set number of incoming signals, the accumulated signals are transmitted through the communication channel 9 to the comparison circuit 10, mounted, for example, at one of the stations adjacent to the stage. Since the analyzed sections of the track may differ in acoustic properties (although they are considered to satisfy the requirements of normative documentation), comparison schemes 10 when passing the obviously good working path 1 by the first train are adjusted so that the comparison results lead to zero. If, when passing through one of the following trains, the comparison result in any section exceeds the set level, a decision is made about the presence of a dangerous change in the parameters of the track section in front of the moving train. This decision is reflected in the mnemonic diagrams in the driver’s cab and at one of the stations adjacent to the stage.

Thus, the proposed method compares favorably with the prototype method, since

1) an increase in the reliability of remote detection of dangerous changes in the state of the rail track in front of a moving train is achieved by implementing filtering and accumulating operations during the interaction of the wheels of the cars with the joint;

2) the method covers an expanded nomenclature of railroad hazards;

3) the method “looks through” changes in the technical condition of the track at much greater distances from the approaching train;

4) according to the method, the adjustment (adjustment) of the recording circuits is carried out according to serviceable distillation, which allows not to take into account differences in the shapes of rail threads and other structural features of the track and thereby increases the reliability of the method.

Claims (3)

1. A method for remote detection of changes in the state of a rail track in front of a moving train, based on recording vibroacoustic signals at different points of the rail track, analyzing these signals and deciding on the results of the analysis, characterized in that only vibroacoustic signals from the interaction of the wheel with the junction of the rails are recorded equally the joints of the rail thread that are remote, if possible, from it, the signals recorded when the train passes through such a joint are subjected to filtering and accumulation operations Received after these operations, the signals from the junction are corrected when the first train passes a known-good path to the maximum similarity between them, and the parameters of the correcting circuit are preserved, when the next train passes the junction of the signal generator, the corrected signals are compared, and the result of the comparison is compared with the set threshold, when the excess of which they decide on the presence of changes in the track in front of a moving train. 2. The method according to claim 1, characterized in that the above operations are carried out for each thread of the rail track. 3. The method according to claim 1 or 2, characterized in that in the absence of a train in a controlled section of the track, the recording circuits are put into a low sensitivity mode - characterized by operation only when the moving wheel interacts with the joint at the installation location of the recording circuit, and these triggering signals are closest along the rail thread from the junction, the recording circuits are transferred to the mode of increased sensitivity.

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