CN215971533U - Rail transit axle counting system - Google Patents

Abstract

The utility model provides a rail transit axle counting system, which comprises: a sensor component and a fastener, the sensor component being connected to the fastener; n fiber bragg grating sensors are fixed in the sensor component; the N fiber grating sensors at least comprise a second fiber grating sensor and a fourth fiber grating sensor; the second fiber grating sensor and the fourth fiber grating sensor are arranged at two ends inside the sensor component. The axle counting system is highly integrated, so that the installation steps are simplified, the difficulty and cost of engineering construction are reduced, the maintenance and the replacement are easy, and the safety of a train axle counting product is effectively improved.

Description

Rail transit axle counting system

Technical Field

The utility model belongs to the technical field of rail transportation safety monitoring, and particularly relates to a rail transit axle counting system.

Background

After years of development, railway transportation technology has great influence on application fields and coverage areas. More stringent requirements are placed on the safety of rail transport. At present, two main ways of track axle counting are provided, namely an electric axle counting scheme, a magnetic axle counting scheme and a fiber grating axle counting scheme.

The track circuit mainly forms an electric loop by an axle and a track, is a device consisting of a conductor, a steel rail insulator, a power transmission device, a power receiving device and a current limiting resistor, and is used for judging whether a train occupies an interval to be detected. When the electromagnetic axle counter is used for counting axles, a transmitting coil and an induction coil are required to be arranged on two sides of a track respectively, so that an axle counting point is in a magnetic field. When the train passes through the axle counting point, the induced electromotive force on the induction coil is changed relative to the induced electromotive force without wheels, so that the train passes through the axle counting point, the axle counting is realized, and the function of monitoring the occupation of the track is realized.

In summary, the track circuit and the electromagnetic axle counter must be implemented with equipment disposed outdoors and highly dependent on their excellent electrical transmission characteristics.

In the article of 'analysis of influence of lightning stroke on track circuit' (Chinese drawing classification number: U284.2), it is proposed that axle counting equipment is easily damaged by lightning especially in thunderstorm seasons, so that the equipment is damaged, traffic transportation is greatly influenced, trains cannot run safely, and serious accidents can be caused in severe cases. In the article of research on common interference sources and anti-interference methods of electromagnetic induction type axle counting equipment (classification number of middle drawing: U284.47), it is proposed that most of the interference faults of the axle counting equipment of state railways are caused by electromagnetic interference such as lightning damage, surge, overvoltage and the like. Although the domestic introduction of axle counting technology has been for more than 10 years and is applied to a large area in a plurality of railway offices, the problem of electromagnetic interference is still not effectively solved.

Since its birth, the fiber grating sensing technology has the characteristics of electrical insulation, electromagnetic interference resistance, corrosion resistance, strong chemical stability, long distance and the like, and is widely applied to environments with strong electromagnetic interference and variable humidity. And the axle counting product developed based on the fiber bragg grating does not need to place electromagnetic sensitive equipment in an outdoor environment, so that the problems of the electrical equipment can be avoided, and the product is not fatigued to cope with the influences of electromagnetic interference and the like of an application scene.

Utility model patent CN200920088856.3 discloses a train meter axle and judgement scheme based on two independent fiber grating sensors. When the train is rolled on the two fiber grating sensors in sequence, the wavelength drift values of the two sensors respectively generate a pulse at adjacent moments, and the train running direction is judged according to the coming sequence of the pulses. The disadvantage of this solution is that the driving direction can only be determined by sorting the first pulse measured by the two fiber gratings. If the first pulse comes in wrong order, the system may obtain wrong driving direction, and the rail transportation safety is seriously affected. Patent CN201610956103.4 pastes two fiber grating on the both sides of foil gage, fixes the foil gage in the rail bottom wholly again, and when a train came, the wavelength change of two fiber grating was the big reversal such as, can play the effect of sensitization. And because the two fiber gratings are in the same temperature environment, the temperature influence can be mutually compensated and eliminated. The method adopts a mechanical structure as a whole, takes a spring as one of main devices for strain transmission, and is easy to displace along with the vibration of the track to generate noise. And the track is easy to generate high-frequency vibration, and the mechanical structure used in the scene for a long time is easy to age, thus threatening the transportation safety of the track.

The sensor mounting mode of the axle counting point of the prior patent is complex, and each axle counting point needs to be provided with a plurality of sensors.

Therefore, a railway traffic axle counting scheme which is convenient for high integration level and simple and convenient in construction is urgently needed.

SUMMERY OF THE UTILITY MODEL

In order to solve the above problems, the present invention provides an axle counting system for rail transit, comprising:

a sensor component and a fastener, the sensor component being connected to the fastener;

n fiber bragg grating sensors are fixed in the sensor component;

the N fiber grating sensors at least comprise a second fiber grating sensor and a fourth fiber grating sensor;

the second fiber grating sensor and the fourth fiber grating sensor are arranged at two ends inside the sensor component.

Furthermore, the second fiber grating sensor and the fourth fiber grating sensor are arranged at a certain distance along the horizontal axial direction of the sensor component, and the fixing direction of each fiber grating sensor is consistent with the horizontal axial direction of the sensor component.

Further, the fastener includes a first fastener and a second fastener.

Furthermore, the N fiber grating sensors further include a first fiber grating sensor and a fifth fiber grating sensor, which are respectively fixed to the first fastener and the second fastener;

and the first fiber bragg grating sensor and the fifth fiber bragg grating sensor are respectively used for monitoring the loosening condition of the first fastening piece and the second fastening piece.

Further, the first fastener and the second fastener are both bolts.

Further, the system further comprises: and the third fiber grating sensor is fixed in the sensor part and is vertical to the horizontal axis of the sensor part.

Furthermore, the sensor component at least has one side surface which is a strip-shaped hard substrate, and the second fiber grating sensor and the fourth fiber grating sensor are fixed on a horizontal axial line of the sensor component substrate at a certain distance.

Further, the sensor part comprises a shell, the bottom wall of the shell is a hard substrate, and the second fiber grating sensor and the fourth fiber grating sensor are arranged in the shell and attached to the bottom wall.

Further, the system further comprises: and the demodulator is connected with the N fiber bragg grating sensors.

Further, the demodulator includes:

the system comprises a broadband light source module, a first demodulation system, a second demodulation system, a primary coupler, N optical isolators, N optical circulators, N secondary couplers and 2N tertiary couplers, wherein the first demodulation system and the second demodulation system are redundant with each other;

the second-stage coupler and the third-stage coupler are both one-to-two couplers;

the first-stage coupler is divided into N paths;

wherein the primary coupler is connected with the broadband light source module;

the primary coupler is respectively connected with the N optical isolators;

each optical isolator is respectively connected with a corresponding optical circulator;

each optical isolator is respectively connected with a corresponding secondary coupler;

each secondary coupler is respectively connected with two corresponding tertiary couplers;

and the two tertiary couplers connected with the same secondary coupler are respectively connected with the first demodulation system and the second demodulation system.

The rail transit axle counting system has the following advantages:

the axle counting system is highly integrated, so that the mounting steps are simplified, the difficulty and cost of engineering construction are reduced, the maintenance and the replacement are easy, and the safety of a train axle counting product is effectively improved;

redundant demodulation systems contained in the system can independently process and output data and compare the data, so that the reliability is improved;

the first fiber grating sensor and the fifth fiber grating sensor can also realize self-checking of the axle counting system, safety is improved, and the third fiber grating sensor performs temperature compensation and accuracy is improved.

Additional features and advantages of the utility model will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the utility model. The objectives and other advantages of the utility model will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.

FIG. 1 is a schematic structural diagram of a rail transit axle counting system according to an embodiment of the utility model;

FIG. 2 is a schematic diagram of an optical path module of a demodulator according to an embodiment of the utility model

FIG. 3 shows a schematic diagram of a demodulator according to an embodiment of the utility model;

FIG. 4 illustrates an edge filter modulation principle according to an embodiment of the present invention;

FIG. 5(a) is a schematic diagram showing the effect of different grating reflectivities on the ratio of electrical signals according to an embodiment of the present invention;

FIG. 5(b) is a schematic diagram showing the effect of different grating 3dB bandwidths on the ratio of electrical signals according to an embodiment of the utility model;

fig. 6 is a diagram illustrating the result of wavelength variation of two sets of demodulation systems according to an embodiment of the present invention.

Description of reference numerals:

1 sensor component

11 first fiber grating sensor

12 second fiber grating sensor

13 third fiber grating sensor

14 fourth optical fiber grating sensor

15 the fifth fiber grating sensor

2 demodulator

21 broadband light source module

22 one-to-five coupler

23 optical isolator

24 optical circulator

25 one-to-two coupler A

26 one-to-two coupler B

27 one-to-two coupler C

28 Linear Filter A

29 linear filter B

3 fastener

31 first fastener

32 second fastener

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The embodiment of the utility model provides a rail transit axle counting system, which comprises the following components as shown in figure 1: the sensor component 1 is connected with the fastener 3; n fiber grating sensors are fixed in the sensor part 3 and form a fiber grating sensor group; the N fiber grating sensors at least comprise a second fiber grating sensor 12 and a fourth fiber grating sensor 14; the second fiber grating sensor 12 and the fourth fiber grating sensor 14 are arranged at two ends inside the sensor component. Further, the second fiber grating sensor 12 and the fourth fiber grating sensor 14 are disposed at a certain distance along the horizontal axial direction of the sensor component 1, and the fixing direction of the second fiber grating sensor 12 and the fixing direction of the fourth fiber grating sensor 14 are also parallel to the axial direction of the sensor component 1, that is, the fixing direction of each fiber grating sensor is consistent with the horizontal axial direction. Here, the horizontal axial direction of the sensor element 1 is the horizontal axial direction shown in fig. 1, that is, the long side direction of the rectangle, and is also the direction parallel to the rail when the sensor element 1 is arranged on the rail.

Specifically, the second fiber grating sensor 12 and the fourth fiber grating sensor 14 are packaged in the sensors, and are arranged at a certain distance along the horizontal axial direction of the sensor component 1, that is, when the sensor component is arranged at the bottom of a track, the distribution directions of the second fiber grating sensor 12 and the fourth fiber grating sensor 14 are parallel to the track direction, and the arrangement directions of the fiber grating sensors are parallel to the track direction, so as to collect strain signals of a train passing through the track. Without loss of generality, the sensor component at least has one side surface which is a strip-shaped hard substrate, such as a rectangular steel plate, and the second fiber grating sensor 12 and the fourth fiber grating sensor 14 are distributed on a horizontal axial line of the sensor component substrate, such as a horizontal central axis line, and two fiber grating sensors are fixed at a certain distance, so that strain signals collected by the two sensors when a train passes through can be analyzed and then used for judging the train running direction. The two sensors respectively modulate the light intensity corresponding to the grating in the wavelength of the continuous light in the C waveband, when a train passes through and strain is transmitted to the fiber grating sensor group through a steel rail, the central wavelength of the reflected light of the grating shifts, the reflected light intensity of the continuous light in the C waveband regularly changes, and the axle counting direction of the train is realized according to the change rule.

The fastening pieces 3 comprise a first fastening piece 31 and a second fastening piece 32, and the N fiber grating sensors further comprise a first fiber grating sensor 11 and a fifth fiber grating sensor 15 which are respectively fixed on the first fastening piece 31 and the second fastening piece 32 and are respectively used for monitoring the loosening condition of the first fastening piece 31 and the second fastening piece 32. In the embodiment of the present invention, the first fastening member 31 and the second fastening member 32 are both bolts. In other embodiments, the fasteners may also be in the form of staples or rivets. The embodiment of the present invention preferably uses adjustable and easily replaceable bolts, that is, the first fastening member 31 is a fixing bolt a, and the second fastening member is a fixing bolt B.

The first fiber grating sensor 11 and the fifth fiber grating sensor 15 are respectively packaged in a fixing bolt a and a fixing bolt B of the fixing sensor, specifically, holes are respectively arranged at one end of the fixing bolt a and one end of the fixing bolt B, and the fiber grating sensors are fixedly arranged in the holes. The hole may be formed by punching a hole in the end face of the fixing bolt on the side remote from the thread, the hole having the same central axis as the fixing bolt without loss of generality. After the installation is finished, the system records the corresponding wavelength of the respective gratings of the first fiber grating sensor 11 and the fifth fiber grating sensor 15, and when the bolt is loosened, the wavelength of the grating changes, and the system gives an alarm. Specifically, when the wavelength change of the grating exceeds a certain threshold value or the change state of the wavelength is maintained to exceed a certain time threshold value, the system gives an alarm, and maintenance personnel can fasten or replace and maintain the bolt according to the alarm information.

The N fiber grating sensors further include a third fiber grating sensor 13, the third fiber grating sensor 13 is fixed in the sensor component 1, and the third fiber grating sensor 13 is perpendicular to the second fiber grating sensor 12, that is, perpendicular to the horizontal axis of the sensor component 1. The third fiber grating sensor 13 is packaged in a sensor component, and when the sensor component is installed, the direction of the third fiber grating sensor 13 is perpendicular to the track direction, is not influenced by strain generated when a train passes by, and is used for temperature compensation.

In the embodiment of the utility model, five fiber bragg grating sensors are packaged in one sensor component, and when the fiber bragg grating sensor is used, the sensors are arranged at the bottom of a rail, because five fiber bragg grating sensors are packaged in one sensor component, the sensor component can be installed in one sleeper, and one axle counting point can realize all the functions of axle counting only by one sensor, thereby saving the cost, simplifying the steps of engineering installation, being more beneficial to ensuring the accuracy and the stability of the installation direction of the sensor by adopting the integrated sensor component, and the stability of the installation of the sensor components is monitored in real time (realized by the first fiber grating sensor 11 and the fifth fiber grating sensor 15), the reliability of strain signal acquisition is improved, the third fiber grating sensor 13 which is not affected by stress is used for temperature compensation, so that the demodulation accuracy is further improved.

In the embodiment of the present invention, the sensor component 1 includes a substrate for transmitting the stress signal, and the third fiber grating sensor 13, the second fiber grating sensor 12, and the fourth fiber grating sensor 14 are fixed (e.g., bonded, welded) on the substrate, and are covered with a cover plate to encapsulate the fiber grating sensors, so as to perform protection and fixing functions. The sensor component may also include a housing, the bottom wall of the housing is a rigid substrate, such as a steel plate, for transmitting a stress signal, and the third fiber grating sensor 13, the second fiber grating sensor 12, and the fourth fiber grating sensor 14 are enclosed in the housing and attached to the bottom wall. Without loss of generality, the housing is rectangular. The fastening members (fixing bolts a and B) can fix the substrate to the bottom of the rail through the fixing holes of the sensor unit 1. For the sensor unit 1 of the housing structure, a fastener is passed through the housing to fix the sensor unit 1 to the bottom of the rail.

The system also comprises a demodulator 2, wherein the demodulator 2 is connected with the N fiber grating sensors and is used for collecting wavelength signals of the N fiber grating sensors. In the embodiment of the present invention, the demodulator adopts a two-out-of-two redundancy architecture, as shown in fig. 2, which is a light path module of the demodulator, and the demodulator includes a power panel, a first demodulation system (demodulation system a), a second demodulation system (demodulation system B), and a broadband light source module, specifically, an ASE light source (amplified spontaneous emission light source), a first-stage coupler, N optical isolators, N optical circulators, N second-stage couplers, and 2N third-stage couplers, where the second-stage coupler and the third-stage coupler are all one-to-two couplers, that is, 3N one-to-two couplers are provided.

The first demodulation system and the second demodulation system are redundant with each other, and the secondary coupler and the tertiary coupler are one-to-two couplers; the first-stage coupler is an N-path coupler; wherein the primary coupler is connected with the broadband light source module; the primary coupler is respectively connected with the N optical isolators; each optical isolator is respectively connected with a corresponding optical circulator; each optical isolator is respectively connected with a corresponding secondary coupler; each secondary coupler is respectively connected with two corresponding tertiary couplers; and the two tertiary couplers connected with the same secondary coupler are respectively connected with the first demodulation system and the second demodulation system.

The primary coupler is used for dividing the light source into N paths, so that each path of light source respectively reaches one of the N fiber bragg grating sensors; the light sources divided into N paths are respectively transmitted to the corresponding fiber bragg grating sensors through the corresponding optical isolators and the corresponding optical circulators; the reflected light of the N fiber bragg grating sensors is output through the corresponding optical circulators; the N secondary couplers divide the corresponding reflected light into two paths of optical signals (namely strain signals of the fiber bragg grating sensor are fed back in the form of optical signals) respectively and input the optical signals into the first demodulation system and the second demodulation system respectively; in a first demodulation system, N three-level couplers divide N received optical signals into two paths, wherein one path of optical signal is subjected to edge filtering modulation; similarly, in the second demodulation system, N three-stage couplers divide the received N optical signals into two paths, and one of the optical signals is subjected to edge filtering modulation. The two demodulation systems demodulate signals independently and then carry out information interaction, and a two-out-of-two redundancy structure is realized.

In the embodiment of the present invention, N is 5, that is, the five fiber bragg grating sensors are disposed in the sensor component as an example for explanation, as shown in fig. 2, the demodulator 2 includes a first-stage coupler, that is, a one-to-five coupler 22, five optical isolators 23, five optical circulators 24, fifteen one-to-two couplers, ten (2N) linear filters, and twenty (4N) photoelectric converters; wherein, fifteen one-to-two couplers include: the 5 secondary couplers, namely a one-to-two coupler A25, are used for dividing the reflected light into two paths and are respectively used for inputting the two demodulation systems; the 5 three-stage couplers, namely a one-to-two coupler B26, are used for transmitting the reflected light to the demodulation system A after being divided into two paths; and 5 three-stage couplers, namely a one-to-two coupler C27, are used for dividing the reflected light into two paths and transmitting the two paths to the demodulation system B.

In another embodiment, N may be 2, that is, the data processing of the axis counting direction may be performed using only the data of the second fiber grating sensor and the fourth fiber grating sensor, N may be 4, the data processing of the axis counting direction may be performed using the data of the second fiber grating sensor, the fourth fiber grating sensor, and the data of the first fiber grating sensor and the fifth fiber grating sensor, N may be 3, that is, the data processing of the axis counting direction may be performed using the data of the second fiber grating sensor, the fourth fiber grating sensor, and the data of the third fiber grating sensor, or further, more fiber grating sensors may be used for data acquisition and processing.

The power panel is used for supplying power to the broadband light source module 21 to enable the broadband light source module to output continuous light in a C wave band, the continuous light in the C wave band is divided into five paths through the five-in-one coupler 22, and the five paths of continuous light are transmitted to the first fiber grating sensor 11, the second fiber grating sensor 12, the third fiber grating sensor 13, the fourth fiber grating sensor 14 and the fifth fiber grating sensor 15 through the optical isolator 23 and the optical circulator 24 in sequence.

The five paths of structures are consistent, the grating in the fiber grating sensor in each path modulates the light intensity corresponding to the grating in the wavelength of the continuous light in the C waveband, and when the wavelength of the grating changes, the central wavelength of the reflected light of the grating shifts. The reflected light is output through the path reflected and output by the corresponding optical circulator 24, and is divided into two identical optical signals through the one-to-two coupler a, that is, the signal reflected by the fiber grating sensor is divided into two paths of identical signals, which are output to the demodulation system a and the demodulation system B, the two demodulation systems demodulate the signals independently, and then perform information interaction, thereby realizing a two-out-of-two redundant structure.

The system adopts the edge filtering mode to demodulate, and for a demodulation system A25, a one-to-two coupler B26 is used for respectively dividing five paths of reflected light into two paths respectively to form 10 paths of reflected light modulation signals: a _1_ a, A _1_ b, A _2_ a, A _2_ b, A _3_ a, A _3_ b, A _4_ a, A _4_ b, A _5_ a, A _5_ b. Illustratively, one path is edge-filtered and modulated by a linear filter a 28 to obtain a reflected light modulation signal a _1_ a, the light intensity of the reflected light modulation signal is proportional to the grating wavelength, and the photoelectric converter converts the reflected light modulation signal into a corresponding reflected light modulation electrical signal; the other path A _1_ b directly enters the photoelectric converter without passing through the linear filter, the reflected light emitted by the fiber grating sensor is converted into a reflected light reference electrical signal, the ratio of the reflected light modulation electrical signal to the reflected light reference electrical signal is used as the basis for wavelength demodulation, and meanwhile, the error caused by common mode factors is eliminated.

For the demodulation system B, the five reflected lights received by the demodulation system B are divided into two paths by a one-to-two coupler C27 to form 10 reflected light modulation signals: b _1_ a, B _1_ B, B _2_ a, B _2_ B, B _3_ a, B _3_ B, B _4_ a, B _4_ B, B _5_ a, B _5_ B. Illustratively, one path is edge-filtered and modulated by a linear filter B29 to obtain a reflected light modulation signal B _1_ a, the light intensity of the reflected light modulation signal is proportional to the grating wavelength, and the photoelectric converter converts the reflected light modulation signal into a corresponding reflected light modulation electrical signal; the other path B _1_ B directly enters the photoelectric converter without passing through the linear filter, the reflected light emitted by the fiber grating sensor is converted into a reflected light reference electrical signal, the ratio of the reflected light modulation electrical signal to the reflected light reference electrical signal is used as the basis for wavelength demodulation, and meanwhile, the error caused by common mode factors is eliminated.

As shown in fig. 3, an optical path module of the system converts the strain signal reflected by the first fiber grating sensor into four paths a _1_ a, a _1_ B, B _1_ a, and B _1_ B, wherein the two paths a _1_ a and a _1_ B are equivalent to B _1_ a and B _1_ B, a _1_ a and a _1_ B are output to a demodulation system a for demodulation, B _1_ a and B _1_ B are output to a demodulation system B for demodulation, a _1_ a and B _1_ a are reflected light modulated optical signals modulated by a linear filter, and a _1_ B and B _1_ B are reflected light reference optical signals not modulated by the linear filter. The other four ways are the same. Demodulation system a and demodulation system B are communicatively coupled. The power supply module supplies power to the demodulation system A, the demodulation system B and the optical path module.

The gratings in the first fiber grating sensor 11, the second fiber grating sensor 12, the third fiber grating sensor 13, the fourth fiber grating sensor 14 and the fifth fiber grating sensor 15 respectively modulate the light intensity corresponding to the grating in the wavelength of the continuous light in the C waveband, when the central wavelength of the reflected light of the grating shifts, the reflected light intensity of the continuous light in the C waveband changes regularly, the larger the shift of the wavelength of the grating is, the larger the reflectivity of the corresponding filter is, the stronger the light intensity after filtering by the filter is, the monotonous rise of the transmissivity of the linear filter in the selected waveband is, and according to the characteristic, the edge filtering (belonging to linear filtering) modulation is performed on the reflected light. As shown in fig. 4, the broken line is a filter transmission spectrum type, and the two peak-shaped curves are grating reflection spectra, wherein the solid line curve (left) is the grating initial reflection spectrum, and the broken line curve (right) is the reflection spectrum of the grating after being subjected to external changes (such as strain or temperature).

The demodulation system A converts five reflective optical modulation optical signals A _1_ a, A _2_ a, A _3_ a, A _4_ a and A _5_ a (each fiber grating sensor corresponds to one reflective optical modulation optical signal and one reflective optical reference optical signal) and five corresponding reflective optical reference optical signals A _1_ b, A _2_ b, A _3_ b, A _4_ b and A _5_ b into five reflective optical modulation electrical signals and five corresponding reflective optical reference electrical signals by using an optical-electrical converter, and then respectively makes ratios to obtain five electrical signal ratios (the electrical signal ratios can eliminate the influence of light source jitter and additional loss of other optical devices on the signals and improve the signal-to-noise ratio), and demodulating the wavelength values corresponding to the five fiber grating sensors at the moment through the ratio of the five electric signals, and further analyzing the states of the five fiber grating sensors at the moment. Judging whether the mounting bolt of the sensor is loosened according to the wavelength variation of the first fiber grating sensor 11 and the fifth fiber grating sensor 15; according to the temporary strain signals of the second fiber bragg grating sensor 12 and the fourth fiber bragg grating sensor 14 of the train and the sequence of the strain signals, carrying out train axle counting; and calculating the temperature change of the external environment according to the wavelength variation of the third fiber grating sensor 13 and performing temperature compensation.

In the above technical solution, the demodulation system B converts five reflective optical modulation optical signals B _1_ a, B _2_ a, B _3_ a, B _4_ a, and B _5_ a (each fiber grating sensor corresponds to one reflective optical modulation optical signal and one reflective optical reference optical signal) and five corresponding reflective optical reference optical signals B _1_ B, B _2_ B, B _3_ B, B _4_ B, and B _5_ B into five reflective optical modulation electrical signals and five corresponding reflective optical reference electrical signals by using an optical-electrical converter, and then respectively makes ratios to obtain five electrical signal ratios (the electrical signal ratios can eliminate the influence of light source jitter and additional loss of other optical devices on the signals, and improve the signal-to-noise ratio), and demodulating the wavelength values corresponding to the five fiber grating sensors at the moment through the ratio of the five electric signals, and further analyzing the states of the five fiber grating sensors at the moment. Judging whether a sensor mounting bolt is loosened or not according to the wavelength variation of the first fiber bragg grating sensor and the fifth fiber bragg grating sensor; according to the temporary strain signals of the second fiber bragg grating sensor and the fourth fiber bragg grating sensor of the train and the sequence of the strain signals, carrying out train axle counting; and calculating the temperature change of the external environment according to the wavelength variation of the third fiber bragg grating sensor and performing temperature compensation.

In the technical scheme, the central wavelengths of the first fiber grating sensor, the second fiber grating sensor, the third fiber grating sensor, the fourth fiber grating sensor and the fifth fiber grating sensor are 1550nm and 3dB, the bandwidths are 0.3nm, and the reflectivity is 80%; the transmissivity of the linear filter monotonously rises in the wavelength range of 1550-1556 nm, the linear filter has good consistency, the linear filter adopts a high-precision filter, and the linearity is not more than 0.0165%.

Based on the rail transit axle counting system, the embodiment of the utility model also provides a rail transit axle counting method, which is used for counting axles according to the strain signals by collecting the strain signals of the N fiber bragg grating sensors. In the embodiment of the utility model, two redundant demodulation systems are adopted to judge the passing condition of the train; when the two demodulation systems determine that the axle passes through under the specified condition, the axle counting and direction information is output. The axle counting and direction information comprises axle counting information and direction information, the axle counting information indicates that a train passes through, and the direction information indicates the direction of the train passing through. The embodiment of the present invention does not limit the expression form of the axle counting and direction information, and for example, the axle counting and direction information may be represented by a numerical value, where the numerical value is increased by 1 when the train passes in a specific direction (e.g., forward direction), and the numerical value is decreased by 1 when the train passes in a direction opposite to the specific direction (reverse direction). Wherein, adopt two sets of redundant demodulation systems to judge the train condition of passing through includes: and (3) adopting a dynamic strain parameter threshold and/or a dynamic time threshold as two demodulation systems to judge the specified conditions of passing of the axis.

Further, the step of judging the designated conditions of passing through the shaft by using the dynamic strain parameter threshold as two demodulation systems comprises the following steps: when the first demodulation system in the two demodulation systems calculates that the shaft passes through, the second demodulation system in the two demodulation systems is informed; the second demodulation system dynamically sets and judges an upper limit value and/or a lower limit value of a strain parameter when the second demodulation system judges that a shaft passes through; and the second demodulation system judges whether an axis passes through according to the upper limit value and/or the lower limit value of the dynamically set strain parameter.

The method for judging the appointed conditions of passing through the shaft by adopting the dynamic time threshold as two demodulation systems comprises the following steps: when the first demodulation system in the two demodulation systems calculates that the shaft passes through, the second demodulation system in the two demodulation systems is informed; the second demodulation system dynamically sets a time threshold according to the change speed of the wavelength change quantity of the strain signal; and when the second demodulation system calculates that an axle passes through the second demodulation system within the dynamically set time threshold, outputting axle counting and direction information, and otherwise, reporting an error. The dynamically set time threshold is a specified period of time from the receipt of a notification that the first demodulation system has an axis elapsed.

In the embodiment of the utility model, the strain signal is demodulated by adopting an edge filtering mode. Specifically, a strain signal is divided into two paths, wherein one path of strain signal is subjected to edge filtering modulation to obtain a reflected light modulation signal; converting the reflected light modulation signal into a corresponding reflected light modulation electrical signal; the other of the two paths of strain signals is directly converted into a reflected light reference electrical signal; and taking the ratio of the reflected light modulation electric signal to the reflected light reference electric signal as the basis of wavelength demodulation.

The rail transit axle counting method provided by the embodiment of the utility model comprises the following steps:

calibrating the ratio of the central wavelength of the grating to an electric signal, wherein the electric signal ratio is the ratio of a reflected light modulation electric signal to a reflected light reference electric signal;

performing edge filtering demodulation on the strain signal, and amplifying the reflected light modulation electric signal and the reflected light reference electric signal based on the optical transmission loss of the rail transit axle counting system;

and judging whether an axis passes by adopting a redundant demodulation system, and outputting axis counting and direction information when the axis passes by.

The first demodulation system and the second demodulation system respectively and independently process and output signals. The output axle counting and direction information is used by the train control system at the previous stage to judge the occupation and idle state of a certain section according to the axle counting and direction information collected by the whole section.

The ordinal numbers of first, second, etc. in the present invention are used only to distinguish different systems or components.

The respective steps are exemplified in detail below.

Step 1: the wavelength demodulation is carried out by adopting an edge filtering mode, and a linear relation which is in one-to-one correspondence is formed between the central wavelength of the grating and the ratio of the electrical signals (the ratio of the reflected light modulation electrical signal to the reflected light reference electrical signal) by utilizing the edge filtering modulation function of the linear filter on the grating reflected light. The demodulation result of the wavelength variation is mainly influenced by the linear filter, but in the embodiment of the utility model, because the division operation of the ratio of the electric signals is adopted, the influence of the 3dB bandwidth and the reflectivity of the fiber grating sensor and the flatness of the ASE light source on the fiber grating sensor can be eliminated in the process of the division operation, thereby improving the universality of the demodulation system. As shown in fig. 5(a), the influence of different grating reflectances on the electrical signal ratio is small, and in the process of changing the reflectivity from 20% to 80% (6000 sampling points in total, as shown by the horizontal axis, the sampling points with the change rate of 20% -80%) with the 3dB bandwidth of 600pm and the center wavelength of 1552nm as an example, the electrical signal ratio on the vertical axis is changed from 0.401 to 0.4014, and the change is small, so that the influence of the reflectivity of the linear filter can be reduced by using the electrical signal ratio as the reference of the wavelength change amount. Correspondingly, fig. 5(b) shows a schematic diagram of the influence of different grating 3dB bandwidths on the ratio of the electrical signals according to the embodiment of the present invention, where the 3dB bandwidth changes from 100pm to 2nm (split into 300 sampling points as shown by the abscissa of the figure) with the example of 1552nm and 80% reflectivity, and the fluctuation range of the ratio of the electrical signals is 0.4014-0.4017, and the change is small.

According to the characteristic, the demodulation system calibrates the central wavelength of the grating and the ratio before use, and the demodulation system A and the demodulation system B calibrate the same signal simultaneously so as to reduce the demodulation error between the two systems. The system adopts a linear filter with good consistency, the calibration process can be multiplexed in a plurality of demodulators only once, and the sensor component 1 and the demodulator 2 are mutually independent, so that the middle and later period maintenance of engineering application is facilitated;

step 2: the demodulator demodulates in an edge filtering mode, so that the system is sensitive to light intensity, and loss analysis is performed aiming at unequal laying distances between the sensor and the demodulator and various complex installation environments in engineering application. In order to meet the system requirements, the demodulation system A and the demodulation system B can perform self-adaptive amplification on each path of reflected light reference electric signals through a program control amplification circuit, based on the light transmission loss of a rail transit axle counting system, the reflected light modulation electric signals and the reflected light reference electric signals are amplified to be close to the maximum voltage value acquired by the system ADC, and meanwhile, each group of reflected light reference electric signals and the reflected light modulation electric signals corresponding to the reflected light reference electric signals are controlled to have the same amplification factor so as to ensure the precision and the resolution of wavelength demodulation. Therefore, the universality and the stability of the demodulation system in the engineering field can be improved, and the demodulation errors caused by different light intensity losses due to different optical fiber transmission distances in field installation are avoided.

And step 3: five beams of reflected light output by the first fiber grating sensor, the second fiber grating sensor, the third fiber grating sensor, the fourth fiber grating sensor and the fifth fiber grating sensor comprise wavelength signals for acquiring the axle counting and direction information, the five beams of reflected light are divided into five groups of same signals through five one-to-two couplers and are respectively output to the demodulation system A and the demodulation system B for demodulation at the same time, and for the alarm error specified by the system, only one demodulation system is required to detect the alarm error, and then the whole system performs alarm output; for the axle counting and direction information, when one demodulation system calculates that an axle passes through, the other demodulation system is informed, and in a period of time t, feedback information calculated that the axle passes through by the other demodulation system is received to output the axle counting and direction information to the upper-level system, otherwise, an error is reported; similarly, when one demodulation system receives that another demodulation system has calculated that there is an axis passing, it must calculate that there is an axis passing and inform another demodulation system within a period of time t (time threshold), and then output the axis counting and direction information to the upper-level system, otherwise report an error. The upper system is a common upper system of the demodulation system a and the demodulation system B, such as a master control system.

Because the two demodulation systems have an error of the absolute value of the wavelength when processing the same signal, when the vehicle speed is slow or the vehicle is just stopped, the response time difference of the two demodulation systems is possibly larger than the set time threshold t, and the system misjudgment is caused, so the system adopts a dynamic strain parameter threshold mode or a dynamic time threshold mode to carry out axle counting logic judgment, and can also adopt the dynamic strain parameter threshold mode and the dynamic time threshold mode to carry out axle counting logic judgment.

Dynamic strain parameter threshold: since the demodulator 2 uses the relative value to determine the axle counting logic, the device error and the calibration error will cause the demodulation results of the two demodulation systems to be different for the unified strain signal, as shown in fig. 6, the dashed curve is the demodulation result of the demodulation system a, and the implementation curve is the demodulation result of the demodulation system B. In the demodulation result of the demodulation system A, when the wavelength variation reaches the point A of the broken line curve at the threshold moment for judging that the axis passes through, corresponding to the time t1, the wavelength variation of the curve is realized at the point B and does not reach the threshold yet; in the demodulation result of the demodulation system B, the time at which the wavelength variation reaches the threshold value for determining that the axis has passed is the point C of the broken line curve, and corresponds to the time t 2. A deviation between t1 and t2, that is, a deviation value of the wavelength variation demodulated by the two demodulation systems, may cause the time elapsed since the two demodulation systems calculated the axis to exceed the default time threshold of the system. Aiming at the point, a dynamic strain parameter threshold value mode is adopted, when one demodulation system calculates that an axis passes through by using a set strain parameter threshold value, the other demodulation system is informed, the other demodulation system adjusts the upper and lower limit threshold values of the strain parameter of the demodulation system, and the judgment condition is properly relaxed, if the upper limit threshold value is reduced by Npm and the lower limit threshold value is increased by Npm, the other demodulation system can make a judgment within the specified time of the system and feed back to the demodulation system of the axis which is calculated first. For example, the demodulation system a calculates a result that an axis passes through according to a default strain parameter threshold Spm set by the system, and notifies the demodulation system B, and if the demodulation system B does not calculate the result that the axis passes through yet when receiving the notification, the demodulation system a adjusts the strain parameter threshold of itself to be a difference between the default strain parameter threshold and a specified tolerance, such as Spm ± Lpm. The addition or subtraction of the specified tolerance from the default strain parameter threshold may be determined according to whether the wavelength variation stage is in an ascending stage or a descending stage, or the strain parameter threshold may be directly set as an interval range after the default parameter threshold is added or subtracted by the specified tolerance without considering the variation stage. When the strain parameter enters the range, the axis is considered to pass through. And then, the strain parameter threshold value of the demodulation system B is recovered to be the default strain parameter threshold value. Similarly, if the demodulation system B calculates the passing of the axis by using the default system threshold, the demodulation system a may set the strain parameter threshold of itself as the default strain parameter threshold plus or minus the designated tolerance after receiving the notification.

The strain parameter refers to a parameter of a system for acquiring a train-passing reaction track strain signal, such as reflected light wavelength, wavelength variation and the like of a light grating sensor. In the embodiment of the utility model, the strain parameter is a wavelength variation.

Dynamic time threshold: in the case of a slow vehicle speed, the wavelength variation of the wavelength variation within the allowable system time threshold may not reach the strain parameter threshold through which the axle passes, resulting in an error in the normal axle counting. In contrast, the setting of the time threshold t by the demodulation system a and the demodulation system B dynamically demodulates the wavelength variation according to the speed of the wavelength variation, and the demodulation system records the derivative of the wavelength variation with respect to the variation time as the setting condition of the time threshold t when performing the axis counting determination. When the vehicle speed is slow, the change speed of the wavelength change amount is also slow, and accordingly the time threshold is set to be longer, so that error reporting is avoided. When the vehicle is static, t can be set to be infinite, namely, only the dynamic strain parameter threshold value is adopted for carrying out axle counting judgment, and the dynamic time threshold value is not adopted.

And 4, step 4: the demodulation system A and the demodulation system B respectively and independently process and output signals, and the train control system at the upper stage judges the occupation and idle state of a certain section according to the axle counting and direction information collected by the whole section.

And if the output results of the demodulation system A and the demodulation system B are the same, the main control system considers that the axle counting result is reliable and judges the idle occupation of the next section, and if the output results are different, the main control panel gives an alarm.

In step 3 of the above technical scheme, the demodulation system converts strain signals (specifically strain values) sensed by the second fiber grating sensor and the fourth fiber grating sensor into grating center wavelength variation of the second fiber grating sensor and the fourth fiber grating sensor. The grating center wavelength and the electrical signal ratio have a corresponding relation, the wavelength can be obtained through the electrical signal ratio, and the grating center wavelength variation, referred to as wavelength variation for short, can be obtained according to the difference between the wavelength demodulated in real time and the wavelength in the initial static state.

And the demodulation system acquires the sequence of the grating center wavelength variation of the second fiber grating sensor and the grating center wavelength variation of the fourth fiber grating sensor reaching a set threshold value, so that the running direction of the train is determined.

Details not described in this specification are within the skill of the art that are well known to those skilled in the art.

Although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims (10)

1. A rail transit axle counting system, comprising:

a sensor component and a fastener, the sensor component being connected to the fastener;

n fiber bragg grating sensors are fixed in the sensor component;

the N fiber grating sensors at least comprise a second fiber grating sensor and a fourth fiber grating sensor;

the second fiber grating sensor and the fourth fiber grating sensor are arranged at two ends inside the sensor component.

2. The rail transit axle counting system of claim 1,

the second fiber grating sensor and the fourth fiber grating sensor are arranged at a certain distance along the horizontal axial direction of the sensor part, and the fixing direction of each fiber grating sensor is consistent with the horizontal axial direction of the sensor part.

3. The rail transit axle counting system of claim 1,

the fasteners include a first fastener and a second fastener.

4. The rail transit axle counting system of claim 2, wherein the N fiber grating sensors further comprise a first fiber grating sensor and a fifth fiber grating sensor fixed to the first fastener and the second fastener, respectively;

and the first fiber bragg grating sensor and the fifth fiber bragg grating sensor are respectively used for monitoring the loosening condition of the first fastening piece and the second fastening piece.

5. The rail transit axle counting system of claim 3, wherein the first and second fasteners are each bolts.

6. The rail transit axle counting system of claim 1, further comprising: and the third fiber grating sensor is used for temperature compensation, is fixed in the sensor part and is vertical to the horizontal axis of the sensor part.

7. The rail transit axle counting system of claim 1, wherein the sensor member has at least one rigid substrate having a strip shape on one side, and the second fiber grating sensor and the fourth fiber grating sensor are fixed at a distance on a horizontal axis of the sensor member substrate.

8. The rail transit axle counting system of claim 1, wherein the sensor component comprises a housing, the bottom wall of the housing is a rigid substrate, and the second fiber grating sensor and the fourth fiber grating sensor are mounted in the housing and attached to the bottom wall.

9. The rail transit axle counting system according to any one of claims 1 to 8, further comprising: and the demodulator is connected with the N fiber bragg grating sensors.

10. The rail transit axle counting system of claim 9, wherein the detuner comprises:

the system comprises a broadband light source module, a first demodulation system, a second demodulation system, a primary coupler, N optical isolators, N optical circulators, N secondary couplers and 2N tertiary couplers, wherein the first demodulation system and the second demodulation system are redundant with each other;

the second-stage coupler and the third-stage coupler are both one-to-two couplers;

the first-stage coupler is divided into N paths;

wherein the primary coupler is connected with the broadband light source module;

the primary coupler is respectively connected with the N optical isolators;

each optical isolator is respectively connected with a corresponding optical circulator;

each optical isolator is respectively connected with a corresponding secondary coupler;

each secondary coupler is respectively connected with two corresponding tertiary couplers;

and the two tertiary couplers connected with the same secondary coupler are respectively connected with the first demodulation system and the second demodulation system.

Images