Structure strain monitoring system and method based on radio frequency tag, and storage medium

Abstract

The invention discloses a structure strain monitoring system and method based on a radio frequency tag and a storage medium. The monitoring system comprises a radio frequency identification tag antenna sensor, a radio frequency reader and an upper computer. The radio frequency identification tag antenna sensor monitors the strain of the monitored structure in the length direction and the width direction in a double-frequency monitoring mode; the radio frequency reader reads and writes the radio frequency identification tag antenna sensor to complete the acquisition and transmission of identity characteristic information and physical sensing signals; and the upper computer carries out comparative analysis on the physical sensing signals through a Fries transmission equation to obtain service state physical quantity information of the tag antenna and complete health state evaluation of the monitored structure. According to the method, the base effect and the Poisson's ratio effect of the metal monitored structure are considered, and the stress-strain characteristics of the monitored structure are analyzed and evaluated according to the multi-order resonant frequency drift characteristics of the tag antenna before and after deformation, so that the monitoring is more accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of nondestructive testing and structural health monitoring, and in particular to a structural strain monitoring system, method and storage medium based on radio frequency tags. Background Art

[0002] During the service process, engineering structures are prone to deformation due to the multi-physical field loads of the environment, which affects the fatigue life of the structure and threatens the safety and reliability of equipment operation. Therefore, it is necessary to apply non-destructive testing or structural health monitoring technology to conduct safety evaluation of the service structure. Although traditional non-destructive testing technology can reliably evaluate the service status of the structure without destroying the inspected structure, the process is complicated and depends on the experience level of the operator. It is difficult to monitor the service status of the structure in real time and give timely evaluation opinions and control measures on its structural health status. Although the structural health monitoring technology developed in this way can overcome the above shortcomings, it still has certain limitations.

[0003] With the development of communication technology, the trend of integrating structural health monitoring technology with advanced industrial Internet of Things technology is becoming increasingly obvious, and sensors and structural health monitoring technologies based on the principle of radio frequency identification have emerged. This technology can not only rely on radio frequency identification tags to characterize the identity characteristics of the monitored structure, but also rely on radio frequency identification antennas to wirelessly transmit physical sensor signals based on the integration of other types of sensors, or can only rely on radio frequency identification antennas to detect and wirelessly transmit deformation state signals on the surface of the monitored structure, that is, the first-order resonant frequency of the tag antenna has a good linear mapping relationship with the antenna geometric size, thereby constructing a structural health monitoring system and the Internet of Things. However, the existing sensors and structural health monitoring methods based on the principle of radio frequency identification still have the problem of low accuracy in structural strain monitoring. Summary of the invention

[0004] In order to solve the problem of low structural strain monitoring accuracy of existing sensors and structural health monitoring methods based on the principle of radio frequency identification, the present invention proposes a structural strain monitoring system, method and storage medium based on radio frequency tags to solve the above problem.

[0005] The present application discloses a structural strain monitoring system based on radio frequency tags, including a radio frequency identification tag antenna sensor, a radio frequency reader and a host computer; The number of the RFID tag antenna sensor is at least one, and the strain in the length direction and the width direction of the monitored structure is monitored by dual-frequency monitoring; The radio frequency reader reads and writes the radio frequency identification tag antenna sensor in a two-way communication scanning mode, completing the collection and transmission of the identity feature information and physical sensor signal of the radio frequency identification tag antenna sensor; The host computer is connected to the radio frequency reader through a communication channel. The host computer compares and analyzes the physical sensor signal through the Friis transmission equation to obtain the physical quantity information of the service status of the tag antenna and complete the health status evaluation of the monitored structure.

[0006] Preferably, the RFID tag antenna sensor includes a tag antenna, a RFID chip, an anti-metal dielectric substrate and a sensitive element. The tag antenna is arranged on the surface of the monitored structure or embedded inside the monitored structure. The RFID chip is fixedly arranged on the tag antenna. The RFID chip can be read and written by a RFID reader. The tag antenna is connected to the sensitive element.

[0007] Preferably, the RFID tag antenna sensor satisfies impedance matching.

[0008] Preferably, the tag antennas are arranged singly along a predetermined direction of the monitored structure measurement point.

[0009] Preferably, the tag antennas are periodically arranged along the circumference of the monitored structure measurement points to form an antenna array.

[0010] Preferably, the radio frequency identification chip comprises a radio frequency module, a control module and a memory which are connected in sequence, and the radio frequency module is connected to the tag antenna.

[0011] Preferably, the tag antenna and the anti-metal dielectric substrate are bonded to the surface of the monitored structure by a curing adhesive to avoid electromagnetic interference of the metal substrate.

[0012] The present application also discloses a structural strain monitoring method based on radio frequency tags, using the structural strain monitoring system based on radio frequency tags to monitor the monitored structure, including the following steps: S1. Calibrate the drift characteristics of each order of resonant frequency of the RFID tag antenna sensor when the monitored structure undergoes substrate deformation of different forms and degrees, and thereby establish a mapping function relationship between the RFID tag antenna sensor and the deformation of the monitored structure measurement point in different directions; S2. Calibrate the stress and strain of the monitored structure to accurately measure the relationship between characteristic size, temperature, resonant frequency and strain of the RFID tag antenna sensor; S3. Construct a structural strain monitoring system based on radio frequency tags, monitor the strain in the length and width directions of the monitored structure through dual-frequency tag antenna sensors, read and write the identity feature information and physical sensor signals of the radio frequency identification tag antenna sensors set along different directions of the monitored structure measurement points through radio frequency readers, and compare and analyze the physical sensor signals through the Friis transmission equation to obtain the physical quantity information of the service status of the monitored structure; S4. In combination with the service condition and maintenance cycle of the monitored structure, the identity, spatial position, resonant frequency and spectrum of each RFID tag antenna sensor are regularly read and written by the RFID reader; S5. Through The tag antenna First-order resonant frequency Drift Characterizing Directional Strain , and evaluate the stress-strain state of the monitored structure in combination with the geometry and constitutive relations of the monitored structure; S6. The digitized information used for monitoring, transmission and analysis is monitored, transmitted and analyzed through the radio frequency identification chip, radio frequency reader and host computer storage system. The result information obtained from the analysis and the corresponding monitoring evaluation and control measures are stored in the host computer to form a historical service status ledger of the monitored structure, which is convenient for the evaluation, analysis and management of the monitored structure throughout its life cycle.

[0013] Preferably, the The tag antenna The calculation formula of the order resonant frequency drift is as follows:

[0014]

[0015] in, For the The tag antenna before deformation The resonant frequency, For the The tag antenna is deformed after The resonant frequency, For the The strain of each tag antenna as the monitored structure deforms, is the equivalent dielectric constant of the tag antenna, is the speed of light in vacuum, is the major axis length of the tag antenna, is the compensation length in the length direction, is the strain of the tag antenna dielectric substrate, is the Poisson’s ratio of the tag antenna dielectric substrate.

[0016] The present application also discloses a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and the computer program is used to execute the structural strain monitoring method based on radio frequency tags.

[0017] Beneficial effects of the present invention: The present invention not only takes into account the substrate effect of the monitored structure made of metal material, but also takes into account the Poisson's ratio effect of the geometric dimensions of the length and width directions of the monitored structure after the measuring point is deformed. It also analyzes and evaluates the stress-strain characteristics of the monitored structure measuring point in a predetermined direction based on the multi-order resonant frequency drift characteristics of the tag antenna before and after deformation, and comprehensively evaluates the main strain characteristics of the monitored structure, making the strain monitoring of the monitored structure more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structure of a structural strain monitoring system based on a radio frequency tag according to an embodiment of the present invention; Figure 2 Schematic diagram of an antenna array periodically arranged along the circumference of a monitored structure measurement point according to an embodiment of the present invention; Figure 3 A schematic diagram of a tag antenna-substrate circuit according to an embodiment of the present invention; Figure 4 Schematic diagram of the dual-frequency monitoring tag antenna structure of an embodiment of the present invention. DETAILED DESCRIPTION

[0019] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and examples.

[0020] The present application embodiment discloses a structural strain monitoring system based on radio frequency tags, such as Figure 1 As shown, it includes a radio frequency identification tag antenna sensor, a radio frequency reader and a host computer.

[0021] like Figure 2 and Figure 4 As shown, the number of RFID tag antenna sensors is at least one, and impedance matching is satisfied. The strain in the length and width directions of the monitored structure is monitored by dual-frequency monitoring, which is specifically used for horizontal and vertical strain monitoring. By etching slots on the patch to include multiple resonant frequency points, the current flows in the length and width directions near different resonant points. The length in the length direction and width direction is:

[0022]

[0023] in, is the resonant frequency when the current flows along the length direction, is the resonant frequency when the current flows along the width direction, is the speed of light in vacuum, is the compensation length in the length direction, is the compensation length in the width direction, is the relative dielectric constant of the tag antenna.

[0024] The RFID tag antenna sensor includes a tag antenna, an RFID chip, an anti-metal dielectric substrate and a sensitive element. The tag antenna is arranged singly along a predetermined direction of the monitored structure measurement point or periodically along the circumference of the monitored structure measurement point to form an antenna array. The tag antenna can use geometric configurations that have good anti-metal substrate effects, including but not limited to dipole antennas, circular pole antennas and microstrip antennas. Different from the existing linear antenna theoretical design method, the strain state monitoring of the monitored structure in the embodiment of the present application is mainly based on the multi-resonance frequency characteristics of the tag antenna, that is, based on the planar antenna theory. For the tag antennas arranged in a single direction along the predetermined direction of the monitored structure measurement point, and the antenna arrays arranged periodically along the circumference of the monitored structure measurement point, the deformation of the monitored structure will change the first antennas arranged in different directions. The characteristic size of the tag antenna changes the The first-order resonant frequency, the spectrum characteristics of the radiation signal and the spatial characteristics can be obtained from the The tag antenna The shift of the order resonant frequency characterizes the strain of the structure in this direction, and the stress-strain state of the structure is evaluated by combining the set and constitutive relationship of the monitored structure. Figure 2 As shown, for the tag antenna array, the The tag antenna The resonant frequency offset and corresponding strain of the tag antenna strain sensor in a given direction represented by the order resonant frequency drift can be combined with adjacent angles of the tag antenna sensor in different directions to comprehensively evaluate the principal strain and principal stress characteristics of the measuring point.

[0025] like Figure 3 As shown, the tag antenna in this embodiment includes a radiation patch and a feeder connected to the radiation patch. The radiation patch and the feeder are arranged on a dielectric substrate, and the reference ground is below the dielectric substrate. The tag antenna is arranged on the surface of the monitored structure or embedded inside the monitored structure. According to engineering needs, the tag antenna and the anti-metal dielectric substrate can be bonded to the surface of the monitored structure by a curing adhesive, and for a column / rod configuration structure, it can be fixed to the monitored structure by a clamp to avoid electromagnetic interference from the base of the metal structure. For a laminated structure, such as a composite laminate structure, the tag antenna can be embedded inside the monitored structure.

[0026] like Figure 1 and Figure 2As shown, the RFID chip is fixedly set on the tag antenna, including a RF module, a control module and a memory connected in sequence, and the RF module is connected to the tag antenna. The RF module transmits energy and clock synchronization to the control module, and the control module controls the data input and data output of the RF module. Authorized users can use the RF reader to perform read and write operations on the RFID chip, which is used to store the identity characteristics of the tag antenna in different directions of the measuring point, that is, the physical field information such as the characteristic resonant frequency. The tag antenna is also connected to matching thermal, pressure, electric, gas and light sensitive elements through an actuating mechanism to achieve changes in the spatial characteristic dimensions of the tag antenna.

[0027] The RF reader reads and writes the RFID tag antenna sensor in a two-way communication scanning mode, completing the collection and transmission of the identity feature information and physical sensing signal of the RFID tag antenna sensor. In particular, for a RF reader at a fixed position, the straight-line distance between the RF reader and the tag antenna can be roughly evaluated based on the impedance characteristics. In this embodiment, the RF reader can also be replaced by a portable mobile terminal with the same function.

[0028] The host computer is connected to the RF reader through a wireless or wired communication channel. The RF reader transmits the acquired tag antenna sensor identity feature information and physical sensor signals to the host computer. The host computer compares and analyzes the physical sensor signals through the Friis transmission equation to obtain the physical quantity information of the service status of the tag antenna, such as stress and strain, temperature field, resonant frequency, inductance, capacitance and magnetic field strength, etc., to complete the health status evaluation of the monitored structure and facilitate the formulation of management measures.

[0029] In a specific embodiment, the present application also discloses a structural strain monitoring method based on radio frequency tags, which uses the above-mentioned structural strain monitoring system based on radio frequency tags to monitor the monitored structure, including the following steps: S1. Calibrate the drift characteristics of each order of resonant frequency of the RFID tag antenna sensor when the monitored structure undergoes substrate deformation of different forms and degrees, and use this to establish the mapping function relationship between the RFID tag antenna sensor and the deformation of the monitored structure in different directions. That is, according to the influence of ambient temperature, anti-metallic medium and bonding interface, the relationship between characteristic size-temperature (or other environmental physical parameters)-resonant frequency-strain of the RFID terminal tag antenna strain sensor is obtained based on analytical derivation and numerical fitting correction.

[0030] S2. Use resistance strain and ultrasonic detection methods to calibrate the stress and strain of the monitored structure to facilitate accurate measurement of the relationship between characteristic dimensions, temperature, resonant frequency and strain of the RFID tag antenna sensor.

[0031] S3. Construct a structural strain monitoring system based on radio frequency tags, monitor the strains in the length and width directions of the monitored structure through dual-frequency tag antenna sensors, read and write the identity feature information and physical sensor signals of the radio frequency identification tag antenna sensors set along different directions of the monitored structure measurement points through radio frequency readers, and upload them to the host computer for analysis and processing. The host computer compares and analyzes the physical sensor signals through the Friis transmission equation, inversely characterizes the structural health status of the monitored structure, such as stress and strain, temperature field, resonant frequency, inductance, capacitance and magnetic field strength, and obtains the physical quantity information of the service status of the monitored structure.

[0032] S4. In combination with the service condition and maintenance cycle of the monitored structure, the identity, spatial position, resonant frequency, spectrum and other characteristic signals of each RFID tag antenna sensor are regularly read and written by the RFID reader.

[0033] S5. The deformation of the monitored structure will change the first The characteristic size of the tag antenna changes the The tag antenna First-order resonant frequency , Spectral characteristics of radiation signals and spatial characteristics , through the The tag antenna First-order resonant frequency Drift Characterizing Directional Strain , and evaluate the stress-strain state of the monitored structure in combination with the geometry and constitutive relations of the monitored structure.

[0034] No. The tag antenna The calculation formula of the order resonant frequency drift is as follows:

[0035]

[0036] in, For the The tag antenna before deformation The resonant frequency, For the The tag antenna is deformed after The resonant frequency, For the The strain of each tag antenna as the monitored structure deforms, is the equivalent dielectric constant of the tag antenna, is the speed of light in vacuum, is the major axis length of the tag antenna, is the compensation length in the length direction, is the strain of the tag antenna dielectric substrate, is the Poisson’s ratio of the tag antenna dielectric substrate.

[0037] S6. The digitized information used for monitoring, transmission and analysis is monitored, transmitted and analyzed through the radio frequency identification chip, radio frequency reader and host computer storage system. The result information obtained from the analysis and the corresponding monitoring evaluation and control measures are stored in the host computer to form a historical service status ledger of the monitored structure, which is convenient for the evaluation, analysis and management of the monitored structure throughout its life cycle.

[0038] In another specific embodiment, the present application further discloses a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program for executing a structural strain monitoring method based on a radio frequency tag.

[0039] Different from the existing RFID tag antenna strain sensing technology which is mostly based on the assumption of small antenna deformation, and does not consider the Poisson effect of the length and width geometric dimensions of the tag antenna after the monitored structure is deformed, and does not consider the high-order resonant frequency drift characteristics of the tag before and after the deformation of the tag antenna, the present application not only considers the substrate effect of the monitored structure made of metal material, but also considers the Poisson effect of the length and width geometric dimensions of the tag antenna after the deformation. It also analyzes and evaluates the stress-strain characteristics of the monitored structure measuring point in a given direction based on the multi-order resonant frequency drift characteristics of the tag antenna strain sensor before and after the deformation, and develops an antenna array periodically arranged along the circumferential direction of the monitored structure measuring point to comprehensively evaluate the principal stress and principal strain characteristics of the monitored structure measuring point.

[0040] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A structural strain monitoring system based on radio frequency tags, characterized in that: It includes a radio frequency identification tag antenna sensor, a radio frequency reader and a host computer; The number of the RFID tag antenna sensor is at least one, and the strain in the length direction and the width direction of the monitored structure is monitored by dual-frequency monitoring; The radio frequency reader reads and writes the radio frequency identification tag antenna sensor in a two-way communication scanning mode, completing the collection and transmission of the identity feature information and physical sensor signal of the radio frequency identification tag antenna sensor; The host computer is connected to the radio frequency reader through a communication channel. The host computer compares and analyzes the physical sensor signal through the Friis transmission equation to obtain the physical quantity information of the service status of the tag antenna and complete the health status evaluation of the monitored structure.

2. The structural strain monitoring system based on radio frequency tags according to claim 1 is characterized in that: The RFID tag antenna sensor includes a tag antenna, a RFID chip, an anti-metal dielectric substrate and a sensitive element. The tag antenna is arranged on the surface of the monitored structure or embedded inside the monitored structure. The RFID chip is fixedly arranged on the tag antenna. The RFID chip can be read and written by a RFID reader. The tag antenna is connected to the sensitive element.

3. The structural strain monitoring system based on radio frequency tags according to claim 2 is characterized in that: The radio frequency identification tag antenna sensor satisfies impedance matching.

4. The structural strain monitoring system based on radio frequency tags according to claim 3 is characterized in that: The tag antennas are arranged singly along a predetermined direction of a monitored structure measurement point.

5. The structural strain monitoring system based on radio frequency tags according to claim 4 is characterized in that: The tag antennas are periodically arranged along the circumference of the monitored structure measurement points to form an antenna array.

6. The structural strain monitoring system based on radio frequency tags according to claim 5 is characterized in that: The radio frequency identification chip comprises a radio frequency module, a control module and a memory which are connected in sequence, and the radio frequency module is connected to the tag antenna.

7. The structural strain monitoring system based on radio frequency tags according to claim 6 is characterized in that: The tag antenna and the anti-metal dielectric substrate are bonded to the surface of the monitored structure by a curing adhesive to avoid electromagnetic interference of the metal substrate.

8. A structural strain monitoring method based on radio frequency tags, characterized in that: The structure strain monitoring system based on radio frequency tags according to any one of claims 1 to 7 is used to monitor the monitored structure, comprising the following steps: S1. Calibrate the drift characteristics of each order of resonant frequency of the RFID tag antenna sensor when the monitored structure undergoes substrate deformation of different forms and degrees, and thereby establish a mapping function relationship between the RFID tag antenna sensor and the deformation of the monitored structure measurement point in different directions; S2. Calibrate the stress and strain of the monitored structure to facilitate accurate measurement of the relationship between characteristic size-temperature-resonance frequency-strain of the RFID tag antenna sensor; S3. Construct a structural strain monitoring system based on radio frequency tags, monitor the strain in the length and width directions of the monitored structure through dual-frequency tag antenna sensors, read and write the identity feature information and physical sensor signals of the radio frequency identification tag antenna sensors set along different directions of the monitored structure measurement points through radio frequency readers, and compare and analyze the physical sensor signals through the Friis transmission equation to obtain the physical quantity information of the service status of the monitored structure; S4. In combination with the service condition and maintenance cycle of the monitored structure, the identity, spatial position, resonant frequency and spectrum of each RFID tag antenna sensor are regularly read and written by the RFID reader; S5. Through The tag antenna Resonant frequency Drift Characterizing Directional Strain , and evaluate the stress-strain state of the monitored structure in combination with the geometry and constitutive relations of the monitored structure; S6. The digitized information used for monitoring, transmission and analysis is monitored, transmitted and analyzed through the radio frequency identification chip, radio frequency reader and host computer storage system. The result information obtained from the analysis and the corresponding monitoring evaluation and control measures are stored in the host computer to form a historical service status ledger of the monitored structure, which is convenient for the evaluation, analysis and management of the monitored structure throughout its life cycle.

9. The structural strain monitoring method based on radio frequency tags according to claim 8 is characterized in that: The said The tag antenna The calculation formula of the order resonant frequency drift is as follows: in, For the The tag antenna before deformation The resonant frequency, For the The tag antenna is deformed after The resonant frequency, For the The strain of each tag antenna as the monitored structure deforms, is the equivalent dielectric constant of the tag antenna, is the speed of light in vacuum, is the major axis length of the tag antenna, is the compensation length in the length direction, is the strain of the tag antenna dielectric substrate, is the Poisson’s ratio of the tag antenna dielectric substrate.

10. A computer-readable storage medium storing a computer program, characterized in that: The computer program is used to execute the structural strain monitoring method described in any one of claims 8-9.

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