A crack detection device and system based on RFID sensor

Abstract

The present invention discloses a crack detection device and system based on RFID sensor, the device comprises: a first patch module, a second patch module and a dielectric substrate; the first patch module comprises a radio frequency chip, a first microstrip line and a first ground plane, the radio frequency chip and the first microstrip line are arranged on the upper surface of the dielectric substrate, the radio frequency chip is connected to the first microstrip line, the first microstrip line is connected to the first ground plane, and the first ground plane is arranged on the lower surface of the dielectric substrate; the second patch module comprises a second microstrip line, a capacitor and a second ground plane, the second microstrip line is arranged on the upper surface of the dielectric substrate, the second microstrip line is connected to the capacitor, the capacitor is connected to the second ground plane, and the second ground plane is arranged on the lower surface of the dielectric substrate. The technical solution proposed by the present invention makes the sensing resonant frequency of the same depth crack at multiple positions of the second patch module consistent by setting the capacitor, thereby alleviating the technical problem that the detection of metal cracks is affected by the position of the crack relative to the device.

Description

Technical Field

[0001] The present invention relates to the field of industrial flaw detection and testing, and in particular to a crack detection device and system based on RFID sensors. Background Art

[0002] Surface cracks appear on metal components during their service. When the cracks expand to a certain extent, the healthy service status of the engineering components will change, posing a risk to the safety of the structure itself and possibly causing major property losses and safety accidents. Therefore, it is necessary to detect surface cracks on metal components.

[0003] In the prior art, the solution of embedded system combined with wired sensors is widely used in crack detection. In this system, each sensor needs to deploy signal transmission lines and power lines, and the system wiring is complex and intertwined, which is not conducive to application in large-scale industrial scenarios. Compared with wired sensors, wireless passive sensors are more suitable for application in large-scale engineering scenarios. RFID (Radio Frequency Identification) sensing is an emerging structural health monitoring technology with a passive and wireless information transmission method, which alleviates the problem of traditional crack sensor lines. Radio frequency sensors have the advantages of simple structure, low manufacturing cost, light weight, small size and high detection sensitivity.

[0004] In engineering practice, when the RF sensor detects the same crack depth at different positions on the metal surface, the resonant structure generates an extremely strong near-surface electromagnetic field in a certain area. After the electromagnetic signal resonates, the electromagnetic field intensity is unevenly distributed, resulting in uneven current. Affected by the position of the crack relative to the RF sensor, the detection accuracy is low, which is prone to false detection and missed detection, limiting its actual engineering application. Summary of the invention

[0005] (I) Purpose of the invention

[0006] The purpose of the present invention is to propose a crack detection device and system based on RFID sensor on the basis of radio frequency sensor, so as to alleviate the technical problem of false detection caused by the depth of cracks on the metal surface being affected by the detection position.

[0007] (II) Technical solution

[0008] To solve the above problems, the first aspect of the present invention provides a crack detection device based on an RFID sensor, comprising: a first patch module, a second patch module and a dielectric substrate; the first patch module comprises a radio frequency chip, a first microstrip line and a first ground plane, the radio frequency chip and the first microstrip line are arranged on the upper surface of the dielectric substrate, the radio frequency chip is connected to the first microstrip line, the first microstrip line is connected to the first ground plane, and the first ground plane is arranged on the lower surface of the dielectric substrate; the second patch module comprises a second microstrip line, a capacitor and a second ground plane, the second microstrip line is arranged on the upper surface of the dielectric substrate, the second microstrip line is connected to the capacitor, the capacitor is connected to the second ground plane, and the second ground plane is arranged on the lower surface of the dielectric substrate; the first patch module and the second patch module form a resonant coupling system, and the resonant frequency is 860MHz-960MHz.

[0009] In one embodiment, the radio frequency chip is connected to the first end and the second end of the first microstrip line, and the structure formed by the first end and the second end matches the size of the radio frequency chip.

[0010] In one embodiment, the second microstrip line forms a closed loop area, and the first microstrip line and the radio frequency chip are arranged in the closed loop area.

[0011] In one embodiment, the size of the first microstrip line is adjustable, and the position of the first ground plane is adjustable within the closed loop region.

[0012] In one embodiment, the dielectric substrate is a polymer material with a relative dielectric constant ranging from 2.2 to 3, a loss tangent ranging from 0.001 to 0.003, and a thickness of 0.5 to 1 mm.

[0013] In one embodiment, the second microstrip line includes four microstrip lines, each of which has equal length and width, and the enclosed closed loop area is a rectangular ring. The four diagonal outer sides of the rectangular ring are cut off, and the cut size does not exceed half of the width of the microstrip line.

[0014] In one embodiment, the outer sides of the four diagonal corners of the rectangular ring are respectively connected to capacitors, and the capacitance values ​​of the capacitors are equal, and the capacitance value ranges from 8pf to 11pf.

[0015] In the second aspect of the present invention, a crack detection system based on an RFID sensor is provided, comprising: a crack detection device provided by the first aspect of the present invention; the crack detection device is arranged above the metal plate and is used to perform depth detection on cracks formed on the surface of the metal plate.

[0016] (III) Beneficial effects

[0017] The above technical solution of the present invention has the following beneficial technical effects: the second patch module is provided with a capacitor, which has an adjusting effect on the antenna resonance point and phase in the second patch module. In forming a resonant coupling system, the induced current is adjusted by adjusting the antenna resonance point and phase, so that the second microstrip line forms a uniform current distribution, and the sensing resonance frequency of the same depth crack at multiple positions of the second patch module is kept consistent, which alleviates the technical problem that the detection of metal cracks is affected by the position of the crack relative to the device.

[0018] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific implementation mode of the present invention or the technical solution in the prior art, the drawings required for use in the specific implementation mode or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are one implementation mode of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 This is a schematic structural diagram of a crack detection device based on an RFID sensor according to an embodiment of the present invention;

[0021] Figure 2 This is a partial structural schematic diagram of a first patch module of a crack detection device based on an RFID sensor according to an embodiment of the present invention;

[0022] Figure 3 for Figure 1 Schematic diagram of surface current distribution of the device shown in when there is no crack at a typical frequency;

[0023] Figure 4 for Figure 1 A schematic diagram showing the relationship between crack depth and return loss obtained when the device shown in the figure is subjected to simulation testing;

[0024] Figure 5 for Figure 1 The device shown in the figure is a schematic diagram of a curve showing the change of the relative position between the geometric center of the device and the crack when the depth of a metal crack of 0.5 mm is simulated and detected;

[0025] Figure 6 for Figure 1 The device shown in the figure is a schematic diagram of a curve showing the change of the relative position between the geometric center of the device and the crack when the depth of a metal crack of 1 mm is simulated and detected;

[0026] Figure 7 for Figure 1The device shown in the figure is a schematic diagram of a curve showing the change of the relative position between the geometric center of the device and the crack when the depth of a metal crack of 1.5 mm is simulated and detected;

[0027] Figure 8 for Figure 1 The device shown in the figure is a schematic diagram of a curve showing the change of the relative position between the geometric center of the device and the crack when the depth of a metal crack of 2 mm is simulated and detected;

[0028] Fig. 9 for Figure 1 A schematic diagram of the resonance frequency fluctuation of the device for detecting the depth of a metal crack and the relative position of the crack;

[0029] Fig.10 The figure is a schematic diagram of the structure of a crack detection system based on an RFID sensor according to an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in conjunction with specific implementations and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present application. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concepts of the present application.

[0031] The present application will be described in more detail below with reference to the accompanying drawings. In each of the accompanying drawings, the same elements are represented by similar reference numerals. For the sake of clarity, the various parts in the accompanying drawings are not drawn to scale. In the description of the present invention, it should be noted that the terms "first", "second", and "third" are used only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0032] Figure 1 The figure is a schematic structural diagram of a crack detection device based on an RFID sensor according to an embodiment of the present invention.

[0033] refer to Figure 1The embodiment of the present invention provides a crack detection device based on an RFID sensor, comprising: a first patch module, a second patch module and a dielectric substrate 30; the first patch module comprises a radio frequency chip 11, a first microstrip line 12 and a first ground plane, the radio frequency chip 11 and the first microstrip line 12 are arranged on the upper surface of the dielectric substrate 30, the radio frequency chip 11 is connected to the first microstrip line 12, the first microstrip line 12 is connected to the first ground plane, and the first ground plane is arranged on the lower surface of the dielectric substrate 30; the first ground plane is not shown in the figure; the second patch module comprises a second microstrip line 21, a capacitor 22 and a second ground plane 23, the second microstrip line 21 is arranged on the upper surface of the dielectric substrate, the second microstrip line 21 is connected to the capacitor 22, the capacitor 22 is connected to the second ground plane 23, and the second ground plane 23 is arranged on the lower surface of the dielectric substrate 30; the first patch module and the second patch module form a resonant coupling system, and the resonant frequency is 860MHz-960MHz.

[0034] It should be noted that when the RF chip 11 receives electromagnetic field energy and is activated, it is coupled to the second microstrip line 21 through the first microstrip line 12. Under the drive of the electric field, the free electrons in the second microstrip line 21 move and generate an induced current. When the crack detection device provided in the embodiment of the present invention is located above the metal crack, different crack depths will disturb the current in different ways, thereby causing unique resonance characteristics. In the prior art, when detecting the same crack depth at different positions on the metal surface, due to the uneven current of the second microstrip line 21, affected by the position of the crack relative to the crack detection device, the sensing resonance frequency of the same depth crack at multiple positions of the second microstrip line 21 is inconsistent. In the embodiment of the present invention, a capacitor 22 is connected between the second microstrip line 21 and the second ground plane connection 23. The capacitor 22 has an adjusting effect on the antenna resonance point and phase in the second patch module, so that the second microstrip line 21 forms a uniform current distribution, thereby making the sensing resonance frequency of the same depth crack at multiple positions of the second microstrip line 21 consistent.

[0035] In addition, it is also necessary to explain that after the capacitor 22 is connected, the current of the second microstrip line 21 is phase compensated, which can ensure that the radiation field of the radiation unit is consistent, thereby achieving near-field uniformity. The embodiment of the present invention has no restriction on the form of the capacitor 22, for example, it can be a ceramic capacitor. In order to realize the sensing of the radio frequency signal, the first ground plane and the second ground plane 23 cannot be set directly below the second microstrip line 21. The first ground plane and the second ground plane 23 can be set to be independent of each other, or they can be set to be mutually conductive.

[0036] Figure 2 This is a schematic diagram of the partial structure of a first patch module of a crack detection device based on an RFID sensor according to an embodiment of the present invention.

[0037] refer to Figure 2In one embodiment, the RF chip 11 is connected to the first end 121 and the second end 122 of the first microstrip line 12, and the structure formed by the first end 121 and the second end 122 matches the size of the RF chip. Exemplarily, the first end 121 and the second end 122 form an opening structure for mounting the RF chip 11, and the RF chip 11 is arranged on the opening structure. The size of the opening structure should match the size of the RF chip 11, and the resonant frequency of the overall structure works in the 860MHz-960MHz RFID segment through the selection of the structural shape and size.

[0038] In one embodiment, the second microstrip line forms a closed loop region, and the first microstrip line and the radio frequency chip are arranged in the closed loop region. Figure 1 , the first microstrip line 12 and the RF chip 11 are located in a closed loop area surrounded by the second microstrip line 21. Exemplarily, the first microstrip line 12, the RF chip 11 and the second microstrip line 21 are located on the same plane, such as Figure 1 The upper surface of the dielectric substrate 30 is shown.

[0039] In one embodiment, the size of the first microstrip line is adjustable, and the position of the first ground plane is adjustable within the closed loop region. Figure 1 The position of the first ground plane can be adjusted inside the closed loop area formed by the second microstrip line 21 .

[0040] In one embodiment, the dielectric substrate is a polymer material with a relative dielectric constant ranging from 2.2 to 3, a loss tangent ranging from 0.001 to 0.003, and a thickness of 0.5 to 1 mm.

[0041] It should be noted that the embodiments of the present invention may use a flexible board made of polymer material, which is relatively thin and is conducive to the miniaturization of the device.

[0042] refer to Figure 1 In one embodiment, the second microstrip line 21 includes four microstrip lines, each of which has the same length and width, and the enclosed closed loop area is a rectangular ring, and the four diagonal outer sides of the rectangular ring are cut off, and the cut size does not exceed half of the width of the microstrip line. It should be noted that the cut size exceeding half of the width of the microstrip line will introduce parasitic reactance, thereby causing phase and amplitude errors of the resonant signal and affecting the transmission characteristics of the signal.

[0043] In one embodiment, the outer sides of the four diagonal corners of the rectangular ring are respectively connected to capacitors, and the capacitance values ​​of the capacitors are equal, and the capacitance value ranges from 8pf to 11pf.

[0044] Figure 3 for Figure 1 Schematic diagram of the surface current distribution of the device shown in when there is no crack at typical frequencies.

[0045] refer to Figure 3 At a frequency of 914 MHz, the first patch module fails to excite the second patch module, and the surface current of the second patch module is weak. In one embodiment, the frequency is set at 916 MHz, the first patch module excites the second patch module, and the surface current of the second patch module reaches a maximum value. At this time, the surface current directions of the second microstrip line 21 are superimposed in the same direction to form a uniform current distribution, so that crack detection can be performed.

[0046] Figure 4 for Figure 1 Schematic diagram of the relationship between crack depth and return loss obtained when the device shown in the figure is performing simulation testing.

[0047] refer to Figure 4 , exemplarily, the crack width is set to 1mm, where the no-crack curve represents the echo loss of the crack detection device when the crack depth is 0. When the crack depth is 0.5mm, 1mm, 1.5mm, 2mm, the corresponding sensing resonant frequencies are 914MHz, 912MHz, 911MHz, 910MHz, respectively. It can be seen that different crack depths make the coupling strength between the first patch module and the second patch module different, and the resonant frequency shifts.

[0048] Figure 5 for Figure 1 The device shown in the figure is a schematic diagram of a curve showing the change in the relative position of the device's geometric center and the crack when the depth of a metal crack of 0.5 mm is simulated and detected.

[0049] refer to Figure 5 For example, the 0mm position indicates that the geometric center of the crack detection device intersects the crack, and the positive 10mm position indicates that the crack is directed toward the coordinate axis relative to the geometric center of the dielectric substrate. Figure 1 The horizontal movement of 10mm in the positive direction indicates that the crack is moving towards the geometric center of the dielectric substrate. Figure 1 The negative direction of the middle coordinate axis is horizontally moved by 10 mm. The crack depth of 0.5 mm is detected at the positions of 0 mm, positive 10 mm and negative 10 mm, and the corresponding sensor resonance frequency is 914 MHz.

[0050] Figure 6 for Figure 1 The device shown in the figure is a schematic diagram of a curve showing the change in the relative position of the device's geometric center and the crack when the depth of a metal crack of 1 mm is simulated and detected.

[0051] refer to Figure 6 For example, the distance between the geometric center of the device and the crack is 0mm, positive 10mm and negative 10mm respectively, and the crack depth is 1mm, and the corresponding sensing resonance frequency is 912MHz.

[0052] Figure 7 for Figure 1The device shown in the figure is a schematic diagram of the curve showing the change of the relative position of the device's geometric center and the crack when the depth of a metal crack of 1.5 mm is simulated and detected.

[0053] refer to Figure 7 , exemplarily, the distance between the geometric center of the device and the crack is respectively at 0mm, positive 10mm and negative 10mm positions, and the crack depth is 1.5mm, and the corresponding sensing resonance frequency is 911MHz.

[0054] Figure 8 for Figure 1 The device shown in the figure is a schematic diagram of a curve showing the change in the relative position of the device's geometric center and the crack when the depth of a metal crack of 2 mm is simulated and detected.

[0055] refer to Figure 8 , exemplarily, the distance between the geometric center of the device and the crack is respectively at 0mm, positive 10mm and negative 10mm positions, and the crack depth is 2mm, and the corresponding sensing resonance frequency is 910MHz.

[0056] Fig. 9 for Figure 1 The device shown in the figure is a bar chart showing the resonance frequency fluctuation of the metal crack depth detection device and the relative position of the crack.

[0057] refer to Fig. 9 The resonant frequencies of cracks of the same depth at multiple positions remain consistent, indicating that crack detection is insensitive to relative position. The detection of metal cracks in the embodiments of the present invention is less affected by the position of the crack relative to the device, thereby improving the detection accuracy. Once the resonant frequency of the crack detection sensor is determined, the resonant frequency range can be queried to obtain the crack depth of the metal to be tested.

[0058] Fig.10 The figure is a schematic diagram of the structure of a crack detection system based on an RFID sensor according to an embodiment of the present invention.

[0059] refer to Fig.10 The embodiment of the present invention provides a crack detection system based on an RFID sensor, comprising: a crack detection device 1 provided in the above embodiment; the crack detection device 1 is arranged above a metal plate 2, and is used to detect the depth of a crack 3 formed on the surface of the metal plate. Exemplarily, the crack 3 is arranged on the surface of the metal plate 2, and a relationship between the crack depth and the sensing resonance frequency can be established, and the magnitude of the sensing resonance frequency shift represents the depth of the crack. The detected crack position change is the moving distance of the crack 1 relative to the geometric center of the dielectric substrate 30.

[0060] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

[0061] The modules in the system device of the embodiment of the present invention can be merged, divided and deleted according to actual needs.

Claims

1. A crack detection device based on RFID sensor, characterized in that: include: A first patch module, a second patch module and a dielectric substrate; The first patch module includes a radio frequency chip, a first microstrip line and a first ground plane, wherein the radio frequency chip and the first microstrip line are arranged on the upper surface of the dielectric substrate, the radio frequency chip is connected to the first microstrip line, the first microstrip line is connected to the first ground plane, and the first ground plane is arranged on the lower surface of the dielectric substrate; The second patch module includes a second microstrip line, a capacitor and a second ground plane, the second microstrip line is arranged on the upper surface of the dielectric substrate, the second microstrip line is connected to the capacitor, the capacitor is connected to the second ground plane, and the second ground plane is arranged on the lower surface of the dielectric substrate; The first patch module and the second patch module form a resonant coupling system with a resonant frequency of 860 MHz to 960 MHz.

2. The device according to claim 1, characterized in that The radio frequency chip is connected to the first end and the second end of the first microstrip line, and the structure formed by the first end and the second end matches the size of the radio frequency chip.

3. The device according to claim 2, characterized in that The second microstrip line forms a closed loop area, and the first microstrip line and the radio frequency chip are arranged in the closed loop area.

4. The device according to claim 3, characterized in that The size of the first microstrip line is adjustable, and the position of the first ground plane is adjustable within the closed loop area.

5. The device according to claim 1, characterized in that The dielectric substrate is a polymer material with a relative dielectric constant ranging from 2.2 to 3, a loss tangent ranging from 0.001 to 0.003, and a thickness of 0.5 to 1 mm.

6. The device according to claim 3, characterized in that The second microstrip line includes four microstrip lines, each of which has the same length and width, and the enclosed closed loop area is a rectangular ring. The four diagonal outer sides of the rectangular ring are cut off, and the cut size does not exceed half of the width of the microstrip line.

7. The device according to claim 6, characterized in that The outer sides of the four diagonal corners of the rectangular ring are respectively connected to capacitors, and the capacitance values ​​of the capacitors are equal, and the capacitance value range is 8pf-11pf.

8. A crack detection system based on RFID sensor, characterized in that: A crack detection device according to any one of claims 1 to 7; The crack detection device is arranged above the metal plate and is used for performing depth detection on cracks formed on the surface of the metal plate.

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