One-way strain smart aggregate based on patch antenna, monitoring sensor system and method

Abstract

The application relates to a one-way strain intelligent aggregate based on a patch antenna, a monitoring sensor system and a method, the intelligent aggregate is packaged with a cement-based protective layer as a whole, and further comprises a substrate, a radiation patch, a movable radiation patch, a movable substrate and a transmission rod which are sequentially arranged, and a radio frequency identification chip fixed on the substrate and used for sensing a resonance frequency; the radio frequency identification chip is connected with the radiation patch; the radiation patch is electroplated and attached to the surface of the substrate, the movable radiation patch is electroplated and attached to the surface of the movable substrate; the other surface of the movable radiation patch is closely attached to the radiation patch, forming a combined radiation patch which is overlapped in the upper and lower parts and can be short-circuited by being mutually dislocated; one end of the transmission rod is fixed to the movable substrate, and the other end of the transmission rod is extended and fixed on the cement-based protective layer and used for transmitting one-way strain to form mutual dislocation in the combined radiation patch when the intelligent aggregate is deformed along the transmission rod under stress. Compared with the prior art, the application has the advantage of realizing passive wireless monitoring.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of structural health monitoring, in particular to a one-way strain intelligent aggregate based on a patch antenna, a monitoring sensing system and a method. BACKGROUND

[0002] Concrete, as an important building material, has been widely used in civil engineering. Concrete itself is a kind of building material with good durability, but in the long-term use process, due to the effect of external environment and load and other factors, the concrete material will deteriorate, which will cause hidden troubles for the safe and reliable operation of the structure. Therefore, it is necessary to perceive the deformation state and environmental factors affecting the durability of the concrete structure throughout the life cycle of the concrete structure, so as to timely discover the safety hidden trouble of the structure and take necessary measures to ensure the safe and reliable use of the structure.

[0003] In recent years, concrete intelligent aggregate with the advantages of locality and distribution has been gradually applied to the internal damage monitoring of concrete. Intelligent aggregate refers to encapsulating a sensing unit for concrete monitoring to make it an intelligent component that can be implanted in concrete, which not only has the function of ordinary aggregate, but also can realize the perception of internal information of concrete.

[0004] However, the current intelligent aggregate based on piezoelectric material still needs continuous power supply and cable for signal transmission, which does not match the long-term service life of the concrete structure, so its application in actual engineering is still limited to a certain extent.

[0005] Therefore, it is necessary to study a concrete intelligent aggregate suitable for passive wireless monitoring to overcome its dependence on cable and power supply. SUMMARY

[0006] The purpose of the present application is to provide a one-way strain intelligent aggregate based on a patch antenna for passive wireless monitoring and temperature correction compensation, a monitoring sensing system and a method.

[0007] The purpose of the present application can be achieved by the following technical solutions:

[0008] According to the first aspect of the present application, a one-way strain intelligent aggregate based on a patch antenna is provided, the overall structure is encapsulated by a cement-based protective layer, the intelligent aggregate further comprises a substrate, a radiation patch, a movable radiation patch, a movable substrate and a transmission rod arranged in sequence, and a radio frequency identification chip fixed on the substrate for sensing the resonant frequency; the radio frequency identification chip is connected with the radiation patch;

[0009] The radiation patch is plated and attached to the surface of the substrate, and the moving radiation patch is plated and attached to the same surface of the moving substrate; the other surface of the moving radiation patch is closely attached to the radiation patch to form a combined radiation patch that is partially overlapped and can be short-circuited by mutual displacement.

[0010] One end of the transmission rod is fixed to the substrate, and the other end is fixed to the cement-based protective layer to transmit one-way strain when the smart aggregate deforms along the transmission rod under stress to form a combined radiation patch that is mutually displaced.

[0011] Preferably, the radio frequency identification chip is connected to the radiation patch through the provided microstrip feed line.

[0012] Preferably, the microstrip feed line is provided at a distance away from the center line of the radiation patch to excite the radiation patch to resonate in two directions in the plane.

[0013] Preferably, the space where the substrate, radiation patch, moving radiation patch, and moving substrate are located is sequentially provided with a protective layer for support and protection and a waterproof coating for preventing water and corrosive media from entering the interior of the concrete.

[0014] Preferably, the space where the transmission rod extends out of the protective layer and is located inside the cement-based protective layer is filled with filler particles for bearing part of the vertical stress of the transmission rod and allowing the transmission rod to move in the parallel direction.

[0015] Preferably, the radiation patch, moving radiation patch, and microstrip feed line are all made of copper.

[0016] Preferably, the substrate and moving substrate are both RT5880 dielectric plates.

[0017] According to the second aspect of the present application, a patch antenna-based one-way strain smart aggregate, a monitoring sensor system, and a method for monitoring the one-way strain smart aggregate are provided. The system includes a smart aggregate embedded in a concrete structure, an outgoing coaxial cable, a wideband antenna, and a reader for reading the information of the radio frequency identification chip in the one-way strain smart aggregate and processing the data. The smart aggregate is any of the patch antenna-based one-way strain smart aggregates.

[0018] One end of the outgoing coaxial cable is connected to the radio frequency identification chip, and the other end is connected to the wideband antenna outside the concrete.

[0019] Preferably, the reader includes the following sub-modules:

[0020] A wireless transceiver module for receiving the resonance frequency shift signal emitted by the one-way strain smart aggregate;

[0021] A modulation and demodulation module is configured to demodulate signals received by the wireless transceiver module;

[0022] A digital processing module is configured to calculate the uniaxial strain and temperature change data of the embedded intelligent aggregate in the concrete structure according to the corresponding relationship.

[0023] A control module is configured to emit modulated electromagnetic wave signals of different frequencies to the intelligent aggregate embedded in the concrete structure to activate the RFID chip in the intelligent aggregate.

[0024] According to a third aspect of the present application, a method for the uniaxial strain intelligent aggregate monitoring sensor system is provided, which comprises the following steps:

[0025] 1) The control module emits modulated electromagnetic wave signals of different frequencies to the intelligent aggregate embedded in the concrete structure; when the signal power received by the intelligent aggregate reaches a set threshold, the RFID chip 11 is activated;

[0026] 2) After the RFID chip is activated, the antenna of the radiation patch generates current and emits electromagnetic wave signals with tag number and measurement point position information; the signals are received by the wireless transceiver module and processed by the modulation and demodulation module to obtain the tag number and position information of the corresponding intelligent aggregate;

[0027] 3) The digital processing module determines the transverse and longitudinal resonance frequencies of the radiation patch in the intelligent aggregate by finding the minimum value of the threshold transmission power of the signal when the RFID chip is activated;

[0028] 4) After decoupling the determined transverse and longitudinal resonance frequencies, the uniaxial strain of the concrete structure at the embedded position of the intelligent aggregate is obtained, and the temperature at the monitoring point is measured simultaneously; the temperature compensation correction is performed on the strain monitoring value to obtain the temperature self-compensated uniaxial strain data.

[0029] Compared with the prior art, the present application has the following advantages:

[0030] 1) Passive wireless: the passive wireless RFID sensing technology is combined with the embedded form of intelligent aggregate, information transmission is performed through electromagnetic waves, energy input is not required through pre-installed batteries or wires, problems such as energy supply and wired signal transmission required by traditional concrete embedded sensors are avoided, labor for installation of intelligent aggregate and cost of the sensing system are greatly reduced, and the arrangement is more flexible and less likely to fail under natural disasters.

[0031] 2) One-way strain and temperature parameter synchronous monitoring: based on the corresponding relationship between the one-way strain and temperature change of the concrete and the two-direction resonant frequency of the internal patch antenna of the intelligent aggregate, the shift amount of the horizontal and vertical resonant frequency of the internal patch antenna of the intelligent aggregate simultaneously represents the one-way strain and environmental temperature change of the structure, realizing the synchronous monitoring of multiple monitoring variables by a single sensor, and having high practicability;

[0032] 3) Temperature offset correction: the resonant characteristics of the dual-frequency patch antenna are utilized, and the microstrip line eccentric feeding is adopted to excite the two-direction resonant frequency of the patch antenna, wherein the horizontal direction of the radiating patch corresponds to one resonant mode, and the vertical direction corresponds to another resonant mode, and the overall radiating patch size change and environmental temperature change will affect the resonant frequency of the antenna, when the one-way strain or temperature change of the concrete structure occurs at the embedding position of the intelligent aggregate, the two-direction resonant frequency of the internal patch antenna of the intelligent aggregate changes, the change of the resonant frequency can be obtained passively and wirelessly by the reader, and then the monitoring of the one-way strain of the concrete structure and the compensation and correction of the temperature offset are realized, and the accuracy of the monitoring is improved;

[0033] 4) Good stability: the sensing unit is protected by the cement-based material, the waterproof coating and the carbon fiber protective layer, so that the sensing unit is not affected by the erosive environment in the concrete, and the internal strain of the concrete is transmitted through the transmission rod;

[0034] 5) High signal effectiveness: the electromagnetic shielding effect of the reinforcement cage can be effectively overcome through the coaxial cable and the external broadband antenna device of the concrete, so that the signal of the passive and wireless intelligent aggregate can be better read by the reader. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 It is a one-way strain intelligent aggregate structure of the application;

[0036] Figure 2 It is a radiating patch feeding mode schematic diagram;

[0037] Figure 3 It is a one-way strain intelligent aggregate monitoring sensing system structure schematic diagram of the application;

[0038] The figure legend: 1 - substrate, 2 - radiating patch, 3 - moving radiating patch, 4 - moving substrate, 5 - protective layer, 6 - waterproof coating, 7 - cement-based protective layer, 8 - transmission rod, 9 - filling particle, 10 - microstrip feed line, 11 - radio frequency identification chip, 12 - coaxial cable, 13 - broadband antenna, 14 - reader, 1401 - wireless transceiver module, 1402 - modulation and demodulation module, 1403 - digital processing module, 1404 - control module. DETAILED DESCRIPTION

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0040] Example

[0041] like Figure 1 As shown, this embodiment provides a unidirectional strain smart aggregate based on a patch antenna. The overall structure is encapsulated with a cement-based protective layer 7. The smart aggregate also includes a substrate 1, a radiating patch 2, a movable radiating patch 3, a movable substrate 4, and a transmission rod 8 arranged in sequence, as well as a radio frequency identification chip 11 fixed on the substrate 1 for sensing the resonant frequency; the radio frequency identification chip 11 is connected to the radiating patch 2.

[0042] The lower surface of the substrate 1 is plated with copper and completely covers the substrate 1. The radiating patch 2 is electroplated and bonded to the upper surface of the substrate 1, and the movable radiating patch 3 is electroplated and bonded to the upper surface of the movable substrate 4. The other side of the movable radiating patch 3 is tightly bonded to the radiating patch 2, forming a combined radiating patch that overlaps vertically and can be staggered and short-circuited. The radiating patch 2 corresponds to one resonant mode in the lateral direction and another resonant mode in the longitudinal direction. The resonant frequencies of the two resonant modes are related to the size of the combined radiating patch and the dielectric constant of the substrate. When the smart aggregate deforms, a relative displacement occurs between the movable radiating patch 3 and the radiating patch 2, which in turn causes a change in the longitudinal length of the combined radiating patch, thus changing its longitudinal resonant frequency.

[0043] One end of the transmission rod 8 is fixed to the movable substrate 4, and the other end extends out and is fixed to the cement-based protective layer 7. It is used to transmit unidirectional strain when the smart aggregate is deformed by force along the transmission rod 8 so as to form mutual displacement within the combined radiation patch.

[0044] like Figure 2 As shown, the radio frequency identification chip 11 and the radiating patch 2 are connected by a microstrip feed line 10.

[0045] The microstrip feed line 10 is positioned at a predetermined distance from the center line of the radiating patch 2 to excite the radiating patch 2 in resonant modes in two directions of the plane.

[0046] The space where the substrate 1, the radiation patch 2, the moving radiation patch 3 and the moving substrate 4 are located is sequentially provided from inside to outside with a protective layer 5 for supporting protection and a waterproof coating 6 for avoiding the entry of water and erosive media inside the concrete. The protective layer 5 in the embodiment is a high-strength carbon fiber material, which serves to support stress and protect the internal antenna. The waterproof coating 6 adopts epoxy resin to avoid the influence of water and erosive media inside the concrete.

[0047] The space where the transmission rod 8 extends out of the protective layer 5 and is inside the cement-based protective layer 7 is filled with filling particles 9 for bearing part of the vertical stress of the transmission rod 8 and enabling the transmission rod 8 to move in parallel.

[0048] The materials of the radiation patch 2, the moving radiation patch 3 and the microstrip feed line 10 are all copper.

[0049] The substrate 1 and the moving substrate 4 are both RT5880 dielectric plates.

[0050] The cement-based protective layer 7 in the embodiment adopts UHPC ultra-high performance concrete material, which serves to assist in supporting stress and protection, and is suitable for being integrated with concrete pouring.

[0051] It is emphasized that the unidirectional strain in the application (i.e. the plane where the vertical radiation patch 2 is located) is not in the traditional sense of horizontal direction. In actual monitoring application scenarios, the unidirectional strain intelligent aggregate device is buried according to the direction of the stress that needs to be monitored and sensed.

[0052] Next, the embodiment gives a unidirectional strain intelligent aggregate monitoring and sensing system based on a patch antenna, which comprises a unidirectional strain intelligent aggregate buried in a concrete structure, a lead-out coaxial cable 12, a wideband antenna 13, and a reader 14 for reading the information of a radio frequency identification chip 11 in the unidirectional strain intelligent aggregate and performing data processing; the unidirectional strain intelligent aggregate is any one of the unidirectional strain intelligent aggregates described above.

[0053] One end of the lead-out coaxial cable 12 is connected with the radio frequency identification chip 11, and the other end is connected with the wideband antenna 13 outside the concrete.

[0054] The reader 14 comprises the following sub-modules:

[0055] A wireless transceiver module 1401 is configured to receive the resonance frequency shift signal emitted by the unidirectional strain intelligent aggregate;

[0056] A modulation and demodulation module 1402 is configured to demodulate the signal received by the wireless transceiver module 1401.

[0057] The digital processing module 1403 is used for calculating the unidirectional strain and temperature change data of the unidirectional strain intelligent aggregate embedded position in the concrete structure according to the decoupling of the corresponding relationship;

[0058] The control module 1404 is used for emitting modulated electromagnetic wave signals of different frequencies to the unidirectional strain intelligent aggregate embedded in the concrete structure, so as to activate the radio frequency identification chip 11 in the unidirectional strain intelligent aggregate.

[0059] Next, the method embodiment of the present application is given, and a method for the patch antenna-based unidirectional strain intelligent aggregate monitoring sensing system is provided, which comprises the following steps:

[0060] 1) The control module 1404 emits modulated electromagnetic wave signals of different frequencies to the unidirectional strain intelligent aggregate embedded in the concrete structure; when the signal power received by the unidirectional strain intelligent aggregate reaches a set threshold value, the radio frequency identification chip 11 is activated;

[0061] 2) After the radio frequency identification chip 11 is activated, the antenna of the radiation patch 2 generates a current and emits an electromagnetic wave signal with tag number and measuring point position information, and the signal is received by the wireless transceiver module 1401 and processed by the modulation and demodulation module 1402 to obtain the tag number and position information of the corresponding unidirectional strain intelligent aggregate;

[0062] 3) The digital processing module 1403 determines the transverse and longitudinal resonance frequencies of the radiation patch 2 in the unidirectional strain intelligent aggregate by finding the transmission frequency at which the threshold value of the signal for activating the radio frequency identification chip 11 reaches a minimum value;

[0063] 4) After decoupling the determined transverse and longitudinal resonance frequencies, the unidirectional strain of the concrete structure at the embedded position of the unidirectional strain intelligent aggregate is obtained, and the temperature at the monitoring point is measured synchronously, the temperature compensation correction is performed on the strain monitoring value, and the unidirectional strain data after temperature self-compensation is obtained.

[0064] Wherein, the temperature self-compensation principle is as follows:

[0065] The radiation patch 2 and the moving radiation patch 3 form a combined radiation patch, the transverse direction of the combined radiation patch corresponds to a resonant mode, and the longitudinal direction corresponds to another resonant mode, and the resonant frequencies of the two resonant modes are related to the size of the combined radiation patch and the dielectric constant of the substrate. When the one-way strain smart aggregate is deformed, the relative displacement between the moving radiation patch 3 and the radiation patch 2 will cause the length of the combined radiation patch to change, so that the longitudinal resonant frequency changes. When the temperature inside the concrete changes, the dielectric constant of the substrate 1 and the moving substrate 4 will change, and the length and width of the radiation patch 2 and the moving radiation patch 3 will also change, so that the transverse and longitudinal resonant frequencies of the combined radiation patch change. The corresponding longitudinal and transverse resonant frequency formulas are as follows:

[0066]

[0067]

[0068] Where c is the propagation speed of electromagnetic waves in vacuum, L and W are the longitudinal and transverse dimensions of the combined radiation patch, ΔT represents the temperature change inside the concrete, ΔL 应变 represents the relative displacement between the radiation patch 3 and the radiation patch 2 caused by the strain of the concrete, ΔL 温度 and ΔW 温度 represent the changes in the longitudinal and transverse dimensions of the combined radiation patch caused by temperature changes, Δε e represents the change in the dielectric constant of the antenna substrate caused by temperature changes. and are the coefficients of the longitudinal resonant frequency change with temperature and the coefficients of the transverse resonant frequency change with temperature, is the coefficient of the longitudinal resonant frequency change with the strain of the concrete, and the above coefficients can be calculated by theory. According to the formula, the temperature change ΔT of the concrete can be calculated from the change value of the transverse resonant frequency of the combined radiation patch, and the influence of temperature change on the longitudinal resonant frequency is calculated, and then the strain value ΔL 应变 inside the concrete is obtained according to the change value of the longitudinal resonant frequency, which is the strain value after temperature compensation correction.

[0069] In summary, by measuring the longitudinal and transverse resonant frequencies of the passive wireless smart aggregate based on the patch antenna, the one-way strain inside the concrete and the temperature parameters inside the concrete can be monitored synchronously, so that the smart aggregate sensor has a temperature self-compensation function, and no additional temperature sensor is needed to correct the temperature deviation of the longitudinal resonant frequency.

[0070] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any skilled person in the art can easily think of various equivalent modifications or replacements within the technical range disclosed by the present application, and these modifications or replacements shall be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A one-way strained smart aggregate based on a patch antenna, characterized in that, The whole structure is encapsulated by a cement-based protective layer (7), the intelligent aggregate further comprises a substrate (1), a radiation patch (2), a movable radiation patch (3), a movable substrate (4) and a transmission rod (8) arranged in sequence, and a radio frequency identification chip (11) fixed on the substrate (1) for sensing the resonant frequency; the radio frequency identification chip (11) is connected with the radiation patch (2); The radiation patch (2) is electroplated and attached to the surface of the substrate (1), and the movable radiation patch (3) is electroplated and attached to the same side of the movable substrate (4); the other side of the movable radiation patch (3) is closely attached to the radiation patch (2) to form a combined radiation patch with overlapping upper and lower parts and being capable of being short-circuited by mutual displacement; One end of the transmission rod (8) is fixed to the movable substrate (4), and the other end extends out of the cement-based protective layer (7) to form a combined radiation patch by transmitting unidirectional strain when the intelligent aggregate is deformed along the transmission rod (8) under stress; The space where the substrate (1), the radiation patch (2), the movable radiation patch (3) and the movable substrate (4) are located is further provided with a protective layer (5) for supporting and protecting from inside to outside, and a waterproof coating (6) for preventing water and corrosive medium in the concrete from entering; The space where the transmission rod (8) extends out of the protective layer (5) and is inside the cement-based protective layer (7) is filled with filling particles (9) for bearing part of the vertical stress of the transmission rod (8) and moving the transmission rod (8) in parallel.

2. A one-way strained smart aggregate based on a patch antenna according to claim 1, characterized in that, The radio frequency identification chip (11) and the radiation patch (2) are connected through the microstrip feed line (10) provided.

3. A one-way strained smart aggregate based on a patch antenna according to claim 2, characterized in that, The microstrip feed line (10) is provided at a distance away from the center line of the radiation patch (2) to excite the resonant mode of the radiation patch (2) in two directions in the plane.

4. The unidirectional strained smart aggregate based on patch antenna of claim 1, wherein, The materials of the radiation patch (2), the movable radiation patch (3) and the microstrip feed line (10) are all copper.

5. The unidirectional strained smart aggregate based on patch antenna according to claim 1, wherein, The substrate (1) and the movable substrate (4) are both RT5880 dielectric plates.

6. A one-way strained smart aggregate monitoring sensor system based on patch antenna, characterized in that, The system comprises intelligent aggregates embedded in the concrete structure, a coaxial cable (12), a broadband antenna (13), and a reader (14) for reading the information of the radio frequency identification chip (11) in the intelligent aggregate and processing data; the intelligent aggregate is the unidirectional strain intelligent aggregate based on the patch antenna according to any one of claims 1-5; One end of the coaxial cable (12) is connected with the radio frequency identification chip (11), and the other end is connected with the broadband antenna (13) outside the concrete.

7. The one-way strain smart aggregate monitoring sensor system based on patch antenna of claim 6, wherein, The reader (14) comprises the following sub-modules: A wireless transceiver module (1401) for receiving the resonant frequency offset signal emitted by the intelligent aggregate; A modulation and demodulation module (1402) for demodulating the signal received by the wireless transceiver module (1401); A digital processing module (1403) for calculating the unidirectional strain and temperature change data of the embedded position of the intelligent aggregate in the concrete structure according to the corresponding relationship; The control module (1404) is configured to emit modulated electromagnetic wave signals of different frequencies to the smart aggregate embedded in the concrete structure to activate the radio frequency identification chip (11) in the smart aggregate.

8. A method for the patch antenna based one-way strained smart aggregate monitoring sensor system of claim 7, characterized in that, The method comprises the following steps: 1) The control module (1404) emits modulated electromagnetic wave signals of different frequencies to the smart aggregate embedded in the concrete structure; when the signal power received by the smart aggregate reaches a set threshold, the radio frequency identification chip (11) is activated; 2) After the radio frequency identification chip (11) is activated, the antenna of the radiation patch (2) generates current and emits electromagnetic wave signals with tag number and monitoring point position information; the signals are received by the wireless transceiver module (1401) and processed by the modulation and demodulation module (1402) to obtain the tag number and position information of the corresponding smart aggregate; 3) The digital processing module (1403) determines the transverse and longitudinal resonant frequencies of the radiation patch (2) in the smart aggregate by finding the minimum value of the threshold emission power of the signal when the radio frequency identification chip (11) is activated; 4) After decoupling the determined transverse and longitudinal resonant frequencies, the one-way strain of the concrete structure at the embedding position of the smart aggregate is obtained, and the temperature of the monitoring point is synchronously measured; the temperature compensation correction is performed on the strain monitoring value to obtain the one-way strain data after temperature self-compensation.

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