An online electromagnetic tomography FPC diaphragm sensor device for monitoring railway turnout damage

Abstract

The present invention provides an online electromagnetic tomography FPC diaphragm sensor device for monitoring railway turnout damage. The device comprises an FPC diaphragm sensor, a front-end signal processor, and an electromagnetic tomography host. The FPC diaphragm sensor is attached to the surface of the railway turnout point rail or other rail member with an adhesive, the front-end signal processor is installed in a railway trackside cabinet as a trackside device, and the electromagnetic tomography host is installed in a railway maintenance department. The FPC diaphragm sensor is connected to the front-end signal processor via a signal cable, and the front-end signal processor is connected to the electromagnetic tomography host via a communication cable. One front-end signal processor manages a group of turnouts, and multiple front-end signal processors and the electromagnetic tomography host constitute an online turnout damage monitoring system. Based on electromagnetic tomography image reconstruction methods, the present invention achieves tomographic imaging of the distribution of superficial surface and internal defects of turnouts, enabling all-weather, uninterrupted crack monitoring of turnouts and early warning of turnout fractures.

Description

Technical Field

[0001] The present invention relates to the technical field of nondestructive testing and nondestructive flaw detection of railway rails, and in particular to an online electromagnetic tomography FPC sensor device for monitoring damage to railway switches. Background Art

[0002] As a key pillar of my country's transportation system, high-speed rail offers a safe, green, and efficient means of travel, and its importance is undeniable. However, as high-speed rail ages, its infrastructure is aging. Simultaneously, with increasing passenger volume, the need for track safety monitoring is urgent. Therefore, it is necessary to develop new track safety monitoring technologies that can provide real-time monitoring and early warning of critical railway infrastructure, ensuring reliable and efficient rail transportation.

[0003] Monitoring the condition of turnouts is a crucial component of track condition monitoring. Turnouts are the connecting devices that allow trains to switch from one track to another. High-speed rail turnouts have numerous rail components and complex assembly structures. They primarily consist of point rails, switch machines, stock rails, wing rails, and guard rails, making them a core piece of equipment for high-speed railway construction, operation, and maintenance. Furthermore, in addition to bearing the vertical pressure and lateral forces from the wheels, turnouts also handle the transition between wheels and rails, making them one of the weakest links in the track. Currently, my country has a large number of turnouts in service. Due to the lack of effective real-time monitoring methods for turnout damage, on-site maintenance primarily relies on manual inspections, which are inefficient, subject to significant human influence, and prone to missed inspections and misjudgments. The current lack of effective online monitoring methods stems from the unique structure of turnouts, limited sensor installation space, significant vibration interference, and the frequent movement of turnout points, making online monitoring difficult. Summary of the Invention

[0004] The embodiment of the present invention provides an electromagnetic tomography FPC sensor device for monitoring railway turnout damage, so as to achieve the purpose of real-time and effective monitoring of railway turnout damage.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions.

[0006] An online electromagnetic tomography FPC diaphragm sensing device for monitoring railway turnout damage, comprising: a flexible printed circuit (FPC) diaphragm sensor, a front-end signal processor, and an electromagnetic tomography host;

[0007] The FPC diaphragm sensor is attached to the rail waist surface of the railway switch point rail or other rail parts with an adhesive. The FPC diaphragm sensors are cascaded end to end to meet the coverage length requirement of the detected rail parts. The FPC diaphragm sensor is connected to the front-end signal processor via a signal cable.

[0008] The front-end signal processor is installed in a railway trackside cabinet as a trackside device. One front-end signal processor manages a group of turnouts. Multiple front-end signal processors are connected to the electromagnetic tomography host via communication cables to form a turnout damage online monitoring system.

[0009] Preferably, the electromagnetic tomography host generates an electromagnetic projection excitation magnetic field through a communication control front-end signal processor. The electromagnetic projection excitation magnetic field is modulated by the defect of the switch rail to generate a nonlinear electromagnetic modulation field. The boundary magnetic field measurement coil in the FPC diaphragm sensor detects the boundary magnetic field, which is collected by the front-end signal processor and transmitted to the electromagnetic tomography host. The electromagnetic tomography host uses the Tikhonov regularized image reconstruction algorithm to image the distribution of switch defects, thereby realizing switch flaw detection.

[0010] Preferably, the FPC diaphragm sensor contains an FPC coil array for electromagnetic tomography, which includes a reference projection synchronization coil, a cross electromagnetic projection excitation coil and a boundary magnetic field measurement coil. Under the action of the reference excitation signal, the reference projection synchronization coil generates a reference electromagnetic projection excitation magnetic field in the shallow layer of the switch, which is used as the excitation synchronization of the mixed electromagnetic excitation projection magnetic field; the cross electromagnetic projection excitation coil generates an electromagnetic projection excitation field with opposite directions and the same amplitude and phase according to the synchronization signal, and the cross electromagnetic projection excitation coils cross in an "8" shape to generate a circular magnetic circuit; the cross electromagnetic projection excitation coil generates a nonlinear electromagnetic modulation field modulated by the defects of the switch rail. When there are defects such as cracks in the switch, the boundary magnetic field measurement coil measures the boundary magnetic field changes of the nonlinear electromagnetic modulation field.

[0011] Preferably, the substrate material of the PFC diaphragm sensor is polyimide PI or polyester PET film.

[0012] Preferably, the FPC coil array in the FPC diaphragm sensor is composed of "8" cross-shaped, circular and rounded rectangular coils, and each coil has 40 turns.

[0013] Preferably, the cross-projection coil excitation coil and the boundary magnetic field measurement coil in the FPC coil array are located in the reference projection synchronization coil, and multiple boundary magnetic field measurement coils are located in the cross-electromagnetic projection excitation coil, ensuring global synchronization of the reference electromagnetic projection electromagnetic field and the mixed cross-electromagnetic projection electromagnetic field and the optimal coupling of the boundary magnetic field measurement coil and the electromagnetic projection excitation coil.

[0014] Preferably, the FPC diaphragm sensor has a thickness of 3 mm and is mounted on the rail waist curved surface of the railway turnout using cyanoacrylate adhesive. A layer of magnetic coupling tape is mounted on the surface of the FPC diaphragm sensor, and a layer of glass fiber aluminum foil tape is mounted on the outer layer of the magnetic coupling tape.

[0015] Preferably, the front-end signal processor includes a signal mixing and modulation unit, an excitation signal synthesis unit, an excitation signal channel control unit, a power amplification unit, a front weak signal amplification unit, an acquisition signal channel control unit, a comb filter unit and a signal acquisition and digital demodulation unit;

[0016] The excitation mixing modulation unit is used to generate a mixing excitation signal, and the mixing excitation signal is generated by calculation based on energy balance and magnetic field penetration depth;

[0017] The excitation signal synthesis unit is used to generate a reference projection synchronization signal, arrange the projection matrix signal according to the distribution of the cross-electromagnetic projection excitation coils, and generate a cross-electromagnetic projection excitation magnetic field using the projection matrix excitation combination signal amplified by the power amplification unit;

[0018] The excitation signal channel control unit is used to control the channel switching of the mixed excitation signal according to the distribution of the cross electromagnetic projection excitation coil on the FPC diaphragm sensor;

[0019] The front-end weak signal amplification unit is used to perform front-end low-noise amplification on the weak signal of the boundary magnetic field measurement coil to obtain an amplified boundary magnetic field detection signal;

[0020] The acquisition signal channel control unit is used to control the channel switching of the mixed excitation signal and the amplified boundary magnetic field detection signal according to the distribution of the cross electromagnetic projection excitation coil and the boundary magnetic field measurement coil on the FPC diaphragm sensor;

[0021] The comb filter unit is used to perform comb filtering on the multi-frequency signal modulated by the signal mixing modulation unit in the amplified boundary magnetic field detection signal, and obtain the multi-frequency boundary magnetic field measurement signal through the passband and stopband filter arrays;

[0022] The signal acquisition and digital demodulation unit is used to acquire the multi-frequency boundary magnetic field measurement signal output by the comb filter unit, and demodulate the nonlinear signal modulated by the defect in the multi-frequency boundary magnetic field measurement signal through a digital demodulation algorithm, and transmit the demodulated calculation result to the electromagnetic tomography host.

[0023] It can be seen from the technical solutions provided by the above-mentioned embodiments of the present invention that the embodiments of the present invention realize tomographic imaging of the distribution of shallow surface and internal defects of turnouts based on the electromagnetic tomography image reconstruction method, which can realize all-weather uninterrupted crack monitoring of turnouts and realize turnout fracture warning, which is of great significance and application value for ensuring rail transit safety.

[0024] Additional aspects and advantages of the present invention will be set forth in part in the following description, will become apparent from the following description, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 Schematic diagram of an application scenario of an electromagnetic tomography FPC sensor device for monitoring railway turnout damage provided by an embodiment of the present invention;

[0027] Figure 2 1 is a structural diagram of an electromagnetic tomography FPC sensor device for monitoring railway turnout damage provided by an embodiment of the present invention.

[0028] Figure 3 The figure is a schematic diagram of the coil design of an electromagnetic tomography FPC sensor device for monitoring railway turnout damage provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and are not to be construed as limiting the present invention.

[0030] It will be understood by those skilled in the art that, unless expressly stated otherwise, the singular forms "a", "an", "said" and "the" used herein may also include the plural forms. It should be further understood that the term "comprising" used in the description of the present invention refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when we refer to an element as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be intermediate elements. In addition, "connected" or "coupled" as used herein may include wireless connections or couplings. The term "and / or" used herein includes any unit and all combinations of one or more associated listed items.

[0031] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art in the art to which the present invention pertains. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art and, unless defined as such herein, will not be interpreted in an idealized or overly formal sense.

[0032] To facilitate understanding of the embodiments of the present invention, several specific embodiments will be further explained below with reference to the accompanying drawings, and each embodiment does not constitute a limitation on the embodiments of the present invention.

[0033] To address the difficulties in monitoring railway turnouts, the present invention proposes an FPC diaphragm sensor device using electromagnetic tomography (EMT) technology. Based on the electromagnetic tomography image reconstruction method, tomographic imaging of the distribution of shallow surface and internal defects of the turnout is achieved. This can realize all-weather and uninterrupted crack monitoring of the turnout and provide early warning of turnout fractures, which is of great significance and application value for ensuring rail transit safety.

[0034] The application scenario diagram of an electromagnetic tomography FPC sensor device for monitoring railway turnout damage provided by an embodiment of the present invention is as follows: Figure 1 As shown, this device utilizes the principles of electromagnetic tomography, arranging a reference projection synchronization coil, a cross-electromagnetic projection excitation coil, and a boundary magnetic field measurement coil array on an FPC substrate. This solves the problem of limited installation space due to the small gap between the switch point rail and the base rail. Furthermore, the nondestructive testing method of electromagnetic tomography can reconstruct shallow surface defects in conductive and magnetic metals, enabling detection of defects such as cracks in the area covered by the FPC diaphragm sensor. During online defect monitoring, the FPC diaphragm sensor is attached to the rail web surface of the switch point rail or other rail components, such as guardrails and frogs. A front-end signal processor is installed in a trackside cabinet and connected to a remote electromagnetic tomography host via a communication cable. The electromagnetic tomography host controls the front-end signal processor to implement mixed signal projection excitation and collect boundary magnetic field measurements in each projection direction. The electromagnetic tomography image reconstruction algorithm is then applied to reconstruct the switch defect.

[0035] The structure diagram of an electromagnetic tomography FPC sensor device for monitoring railway turnout damage provided by an embodiment of the present invention is as follows: Figure 2As shown, the device includes: an FPC diaphragm sensor, a front-end signal processor, and an electromagnetic tomography host. The FPC diaphragm sensor is attached to the rail waist surface of a railway switch point rail or other rail member with an adhesive. The FPC diaphragm sensors can be cascaded end to end to meet the required coverage length of the rail member being inspected. The FPC diaphragm sensor is connected to the front-end signal processor via a signal cable.

[0036] The front-end signal processor is installed in a railway trackside cabinet as a trackside device. One front-end signal processor manages a group of turnouts. Multiple front-end signal processors are connected to the electromagnetic tomography host via communication cables to form a turnout damage online monitoring system.

[0037] The electromagnetic tomography host generates an electromagnetic projection excitation magnetic field through communication control of the front-end signal processor. This electromagnetic projection excitation magnetic field is modulated by the defects of the turnout rail, generating a nonlinear electromagnetic modulation field. The boundary magnetic field measurement coil in the FPC diaphragm sensor detects the boundary magnetic field, which is collected by the front-end signal processor and transmitted to the electromagnetic tomography host. The electromagnetic tomography host uses the Tikhonov regularized image reconstruction algorithm to image the distribution of turnout defects, thereby realizing turnout flaw detection. Different from the regular flaw detection operation method of using a handheld instrument to scan or attach the probe to the turnout rail, the device constituted by this patent is an auxiliary system installed integrally with the turnout, which can realize all-weather uninterrupted online turnout defect monitoring.

[0038] The coil design diagram of an electromagnetic tomography FPC sensor device for monitoring railway turnout damage provided by an embodiment of the present invention is as follows: Figure 3 As shown, the coil is designed as an FPC coil array, comprising a reference projection synchronization coil, a cross-electromagnetic projection excitation coil, and a boundary magnetic field measurement coil. Under the action of a reference excitation signal, the reference projection synchronization coil generates a reference electromagnetic projection excitation magnetic field on the shallow surface of the turnout, which serves as the excitation synchronization for the mixed-frequency electromagnetic excitation projection magnetic field. The cross-electromagnetic projection excitation coil generates an electromagnetic projection excitation field with opposite directions but the same amplitude and phase according to the synchronization signal. The cross-electromagnetic projection excitation coils cross in an "8" shape, creating a circular magnetic circuit and increasing the magnetic field excitation intensity in the turnout sensing area. The cross-electromagnetic projection excitation coil generates a nonlinear electromagnetic modulation field modulated by defects in the turnout rail. When defects such as cracks exist in the turnout, the boundary magnetic field measurement coil measures the boundary magnetic field changes of the nonlinear electromagnetic modulation field.

[0039] The substrate material of the PFC diaphragm sensor is polyimide (PI) or polyester (PET) film.

[0040] The FPC coil array in the FPC diaphragm sensor is composed of "8" cross-shaped, circular and rounded rectangular coils, and each coil has 40 turns;

[0041] In the FPC coil array, the cross-projection coil excitation coil and the boundary magnetic field measurement coil are located within the reference projection synchronization coil, and multiple boundary magnetic field measurement coils are located within the cross-electromagnetic projection excitation coil. This ensures global synchronization of the reference electromagnetic projection electromagnetic field and the mixed cross-electromagnetic projection electromagnetic field, as well as optimal coupling between the boundary magnetic field measurement coil and the electromagnetic projection excitation coil. Preferably, the number of boundary magnetic field measurement coils is three.

[0042] The 3mm-thick FPC sensor is attached to the curved rail waist surface of a railway turnout using cyanoacrylate adhesive. To enhance the coupling strength of the FPC sensor's mixed-frequency electromagnetic projection excitation magnetic field to turnout defects and strengthen its immunity to noise magnetic fields in the field operating environment, a layer of magnetic coupling tape is applied to the sensor's surface. Furthermore, to protect the FPC sensor from harsh operating conditions such as rain, snow, and oil corrosion, a layer of glass fiber aluminum foil tape is applied over the magnetic coupling tape.

[0043] The front-end signal processor includes a signal mixing and modulation unit, an excitation signal synthesis unit, an excitation signal channel control unit, a power amplification unit, a front weak signal amplification unit, an acquisition signal channel control unit, a comb filter unit and a signal acquisition and digital demodulation unit;

[0044] The excitation mixing modulation unit is used to generate a mixing excitation signal, and the mixing signal is generated by calculation based on energy balance and magnetic field penetration depth;

[0045] The excitation signal synthesis unit is used to generate a reference projection synchronization signal and arrange the projection matrix signal according to the distribution of the cross electromagnetic projection excitation coils, so that the projection matrix excitation combination signal generates a projection excitation magnetic field;

[0046] The excitation signal channel control unit is used to control the channel switching of the excitation signal according to the distribution of the cross-electromagnetic projection excitation coil on the FPC diaphragm sensor;

[0047] The front-end weak signal amplification unit is used to perform front-end low-noise amplification on the weak signal of the boundary magnetic field measurement coil;

[0048] The acquisition signal channel control unit is used to control the channel switching of the excitation and boundary magnetic field measurement signals according to the distribution of the cross electromagnetic projection excitation coil and the boundary magnetic field measurement coil on the FPC diaphragm sensor;

[0049] The comb filtering unit is used to perform comb filtering on the multi-frequency signal modulated by the signal mixing modulation unit in the boundary magnetic field detection signal, and obtain a relatively pure multi-frequency boundary magnetic field measurement signal through the passband and stopband filter arrays;

[0050] The signal acquisition and digital demodulation unit is used to acquire the output signal of the comb filter unit, and demodulate the nonlinear signal modulated by the defect in the boundary magnetic field measurement signal through a digital demodulation algorithm, and then transmit the demodulated calculation result to the electromagnetic tomography host.

[0051] See attached Figure 1 and Figure 2 , Figure 1 and Figure 2 The main structure of the online electromagnetic tomography flexible diaphragm FPC sensor device for monitoring railway turnout damage is shown as an example. Figure 1 As shown, the rail waist surface of the railway switch point rail or other rail parts is mounted with cyanoacrylate adhesive, and the FPC diaphragm sensor can be connected in cascade connection through the connector. The FPC diaphragm sensor covers the most vulnerable area of ​​the switch area. Figure 1 As shown, the FPC diaphragm sensor mounted on the waist of the pointed rail is connected to the front-end signal processor through a signal cable, realizing the excitation signal driving of the reference projection synchronization coil and the cross electromagnetic projection coil in the FPC diaphragm sensor and the detection signal acquisition of the boundary magnetic field measurement coil. The signal cable is one of the implementation methods. Twisted pair cables, multi-strand thin coaxial cables or other cables with signal interference suppression can complete the signal transmission function; the front-end signal processor is connected to the electromagnetic tomography host through a communication cable.

[0052] The front-end signal processor generates an optimized multi-frequency signal through the signal mixing and modulation unit, and then the excitation signal synthesis unit generates an excitation signal according to the distribution of the cross-electromagnetic projection excitation coils. The excitation signal channel control unit controls the excitation signal to be output according to the excitation matrix. The output signal is amplified by the power amplifier unit to form an electromagnetic projection excitation magnetic field. The excitation magnetic field is nonlinearly modulated by the defects of the switch rail, changing the boundary magnetic field of the rail. The boundary magnetic field is amplified by the front weak signal amplification unit and switched by the acquisition signal channel control unit. It is sent to the comb filter unit to filter out noise outside the excitation optimization multi-frequency points. The filtered signal is collected by the signal acquisition and digital demodulation unit, and multi-frequency digital demodulation is performed after analog-to-digital conversion sampling. The demodulation result is then transmitted to the electromagnetic tomography host.

[0053] The electromagnetic tomography host uses the electromagnetic tomography Tikhonov regularized image reconstruction algorithm to image the defect distribution based on the reference projection synchronization information, cross-electromagnetic projection excitation information, acquisition signal demodulation information and prior sensitivity matrix information, thereby realizing the defect detection of turnout rail components and forming an online turnout damage monitoring system.

[0054] The implementation method of the Tikhonov regularized image reconstruction algorithm for turnout defect electromagnetic tomography is completed in two steps:

[0055] Step 1: Solve the forward problem of electromagnetic tomography of turnout damage.

[0056] In the FPC diaphragm sensor device for monitoring railway turnout damage, the turnout damage image reconstruction requires the combined output of boundary magnetic field measurements of the turnout damage sample under a specific projected excitation magnetic field. The solution to these combined output values ​​is defined as the electromagnetic tomography forward problem. Solving it can obtain sensitivity prior information based on spatial grid subdivision for defect image reconstruction. It is the prior information matrix required for the turnout damage electromagnetic tomography image reconstruction algorithm.

[0057] The positive problem of electromagnetic tomography for turnout damage detection is to obtain the boundary magnetic field induced alternating voltage value U of the boundary magnetic field measurement coil when the surface area V of the turnout to be tested is known to be distributed according to the spatial grid and has different morphological defects. This positive problem can be described as:

[0058] U=f(B excte (x,y,z),B object (x,y,z),μ(x,y,z),σ(x,y,z),ε(x,y,z)) (1)

[0059] Among them, B excite (x,y,z) and B object (x, y, z) are the electromagnetic projection excitation field distribution in the shallow surface area of ​​the tested turnout and the magnetic field distribution at a certain point where the turnout defect exists; μ(x, y, z) is the magnetic permeability distribution of the turnout rail, σ(x, y, z) is the electrical conductivity distribution of the turnout rail, and ε(x, y, z) is the dielectric constant distribution of the turnout rail.

[0060] In the present invention, preferably, the problem of electromagnetic tomography of turnout damage is solved by electromagnetic field finite element numerical simulation calculation. By dividing the measured spatial area into grids and setting the defect distribution in different subdivision units, the sensitivity matrix of each boundary magnetic field measurement coil under different electromagnetic projection excitation conditions is obtained through simulation calculation. The sensitivity matrix reflects the sensitivity of the output value of the boundary magnetic field measurement coil to the presence or absence of defect distribution in the subdivision unit when the defect distribution in the shallow surface spatial grid area of ​​the measured turnout rail changes. The sensitivity matrix elements are expressed as:

[0061] S p,d (k)=|V p,d,obj (k)-V p,d,emp (k)|,k=1,2,…,N (2)

[0062] Where p represents the electromagnetic projection excitation projection number, d is the boundary magnetic field measurement coil number, emp and obj represent the defect-free and defect-containing distributions, respectively, and k is the spatial mesh number. By setting defects for N mesh elements and then performing electromagnetic finite element simulations of electromagnetic projection excitation and boundary magnetic field calculations, we obtain a sensitivity matrix containing the detection sensitivities of all boundary magnetic field measurement coils under all excitation projections.

[0063] Step 2: Reconstruct the defect distribution image of the turnout damage electromagnetic tomography, that is, solve the inverse problem.

[0064] Once the sensitivity matrix is ​​obtained, defect distribution image reconstruction can be performed. Defect distribution reconstruction for turnout damage electromagnetic tomography involves using the sensitivity matrix obtained from the forward problem and the actual measurement values ​​obtained from the boundary magnetic field measurement coils to determine the defect distribution in the measured area, i.e., solving the inverse problem. After the sensitivity calculation is performed on the shallow surface spatial region of the turnout rail, the induced alternating voltage value of the boundary magnetic field measurement coil in the FPC diaphragm sensor can be expressed in matrix form:

[0065] U=S·g (3)

[0066] Among them, U is the induced voltage value vector of the N×1 order boundary magnetic field measurement coil, S is the N×M order sensitivity prior information matrix, and g is the gray value matrix of the grid corresponding to the M×1 order shallow surface spatial area of ​​the turnout. The gray value is a measure of the possibility of the existence of defects in the corresponding subdivision unit. The larger the gray value, the higher the possibility of the existence of defects.

[0067] Preferably, the electromagnetic tomography of turnout damage in the online electromagnetic tomography FPC diaphragm sensor device for monitoring railway turnout damage uses a Tikhonov regularized defect image reconstruction algorithm, which is an effective method for solving the ill-conditioned nature of the inverse reconstruction problem. When reconstructing the turnout damage image, a regularization factor is added to obtain the generalized inverse of the reconstructed turnout damage image calculation, solving the ill-conditioned matrix problem of the underdetermined electromagnetic excitation field equation of electromagnetic tomography. The matrix expression of the Tikhonov regularized reconstruction algorithm is as follows:

[0068] G=(S T S+μI) -1 S T U (4)

[0069] Where μ is the regularization factor, S is the sensitivity matrix that measures the sensitivity of all boundary magnetic field measurement coils under all electromagnetic projection excitations in the turnout FPC diaphragm sensor, and U is the amplitude and phase demodulation vector of the induced alternating voltages actually measured by the boundary magnetic field measurement coils in the turnout FPC diaphragm sensor. This formula can be used to calculate the probability distribution of damage for all subdivided elements in the shallow surface region of the turnout rail, thereby obtaining defect distribution information for the turnout rail.

[0070] In summary, the online electromagnetic tomography flexible diaphragm FPC sensing device for monitoring railway turnout damage provided by the present invention can accurately identify the defect distribution in the shallow surface space area of ​​the railway turnout, ensuring the safety and reliability of the steel rail turnout.

[0071] Compared with eddy current testing and ultrasonic testing, the FPC film-mounted sensor device for railway turnout damage monitoring provided by the present invention offers the advantage of being installable in confined spaces, particularly where the switch point rail meets the stock rail. The point rail becomes weaker and more susceptible to damage towards the end, and the sensor installation space becomes smaller, making it impossible to install traditional eddy current, ultrasonic, and optical probes. The device described in the present invention cleverly addresses this problem and represents a crucial safety technology and system for rail transportation.

[0072] The FPC design method used in the device described in the present invention facilitates standardized design, easily ensures sensor consistency, and offers low cost and high reliability. It is adaptable to the harsh operating environments of outdoor railway turnout sites, such as wind, rain, snow, and vibration. It enables long-term monitoring and early warning of turnout safety, ensuring railway transportation safety. This is particularly significant for high-speed railways, as high-speed trunk lines are busy and densely populated, resulting in a short window for turnout inspection. Manually carrying instruments on the track is extremely dangerous, and accidents are common. This device enables uninterrupted, all-weather monitoring of turnouts, reducing operational safety risks for turnout inspectors and improving the level of intelligent railway maintenance.

[0073] Those skilled in the art will appreciate that the accompanying drawings are merely schematic diagrams of an embodiment, and the modules or processes in the accompanying drawings are not necessarily required to implement the present invention.

[0074] Each embodiment in this specification is described in a progressive manner. The same or similar parts between the embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the device or system embodiments, since they are basically similar to the method embodiments, the description is relatively simple. For the relevant parts, refer to the partial description of the method embodiments. The device and system embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the scheme of this embodiment. A person of ordinary skill in the art can understand and implement it without making any creative efforts.

[0075] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. An online electromagnetic tomography FPC diaphragm sensor device for monitoring railway turnout damage, characterized in that: include: Flexible printed circuit (FPC) membrane sensor, front-end signal processor, and electromagnetic tomography host; The FPC diaphragm sensor is attached to the rail waist surface of the railway switch point rail or other rail parts with an adhesive. The FPC diaphragm sensors are cascaded end to end to meet the coverage length requirement of the detected rail parts. The FPC diaphragm sensor is connected to the front-end signal processor via a signal cable. The front-end signal processor is installed in a railway trackside cabinet as a trackside device. One front-end signal processor manages a group of turnouts. Multiple front-end signal processors are connected to the electromagnetic tomography host via communication cables to form a turnout damage online monitoring system. The FPC diaphragm sensor contains an FPC coil array for electromagnetic tomography, which includes a reference projection synchronization coil, a cross electromagnetic projection excitation coil and a boundary magnetic field measurement coil. Under the action of the reference excitation signal, the reference projection synchronization coil generates a reference electromagnetic projection excitation magnetic field in the shallow surface layer of the switch, which is used as the excitation synchronization of the mixed electromagnetic excitation projection magnetic field; the cross electromagnetic projection excitation coil generates an electromagnetic projection excitation field with opposite directions and the same amplitude and phase according to the synchronization signal, and the cross electromagnetic projection excitation coils cross in an "8" shape to generate a ring magnetic circuit; the cross electromagnetic projection excitation coil generates a nonlinear electromagnetic modulation field modulated by the defect of the switch rail member. When a crack defect exists in the switch, the boundary magnetic field measurement coil measures the boundary magnetic field change of the nonlinear electromagnetic modulation field; In the FPC diaphragm sensor coil array, the cross-projection coil excitation coil and the boundary magnetic field measurement coil are located in the reference projection synchronization coil, and multiple boundary magnetic field measurement coils are located in the cross-electromagnetic projection excitation coil, ensuring global synchronization of the reference electromagnetic projection electromagnetic field and the mixed cross-electromagnetic projection electromagnetic field and optimal coupling of the boundary magnetic field measurement coil and the electromagnetic projection excitation coil.

2. The device according to claim 1, characterized in that The electromagnetic tomography host generates an electromagnetic projection excitation magnetic field by controlling the front-end signal processor through communication. The electromagnetic projection excitation magnetic field is modulated by the defects of the switch rail to generate a nonlinear electromagnetic modulation field. The boundary magnetic field measurement coil in the FPC diaphragm sensor detects the boundary magnetic field, which is collected by the front-end signal processor and transmitted to the electromagnetic tomography host. The electromagnetic tomography host uses the Tikhonov regularized image reconstruction algorithm to image the distribution of switch defects, thereby realizing switch flaw detection.

3. The device according to claim 1, characterized in that The substrate material of the FPC diaphragm sensor is polyimide PI or polyester PET film.

4. The device according to claim 1, characterized in that The FPC coil array in the FPC diaphragm sensor is composed of "8" cross-shaped, circular and rounded rectangular coils, and each coil has 40 turns.

5. The device according to claim 1, characterized in that The FPC diaphragm sensor has a thickness of 3 mm and is mounted on the rail waist curved surface of the railway turnout using cyanoacrylate adhesive. A layer of magnetic coupling tape is mounted on the surface of the FPC diaphragm sensor, and a layer of glass fiber aluminum foil tape is mounted on the outer layer of the magnetic coupling tape.

6. The device according to claim 1, characterized in that The front-end signal processor includes a signal mixing and modulation unit, an excitation signal synthesis unit, an excitation signal channel control unit, a power amplification unit, a front weak signal amplification unit, an acquisition signal channel control unit, a comb filter unit and a signal acquisition and digital demodulation unit; The signal mixing modulation unit is used to generate a mixing excitation signal, and the mixing excitation signal is calculated and generated according to energy balance and magnetic field penetration depth; The excitation signal synthesis unit is used to generate a reference projection synchronization signal, arrange the projection matrix signal according to the distribution of the cross-electromagnetic projection excitation coils, and generate a cross-electromagnetic projection excitation magnetic field using the projection matrix excitation combination signal amplified by the power amplification unit; The excitation signal channel control unit is used to control the channel switching of the mixed excitation signal according to the distribution of the cross electromagnetic projection excitation coil on the FPC diaphragm sensor; The front-end weak signal amplification unit is used to perform front-end low-noise amplification on the weak signal of the boundary magnetic field measurement coil to obtain an amplified boundary magnetic field detection signal; The acquisition signal channel control unit is used to control the channel switching of the mixed excitation signal and the amplified boundary magnetic field detection signal according to the distribution of the cross electromagnetic projection excitation coil and the boundary magnetic field measurement coil on the FPC diaphragm sensor; The comb filter unit is used to perform comb filtering on the multi-frequency signal modulated by the signal mixing modulation unit in the amplified boundary magnetic field detection signal, and obtain the multi-frequency boundary magnetic field measurement signal through the passband and stopband filter arrays; The signal acquisition and digital demodulation unit is used to acquire the multi-frequency boundary magnetic field measurement signal output by the comb filter unit, and demodulate the nonlinear signal modulated by the defect in the multi-frequency boundary magnetic field measurement signal through a digital demodulation algorithm, and transmit the demodulated calculation result to the electromagnetic tomography host.

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