CN112344846A - Strain sensor based on radio frequency identification technology for tunnel strain monitoring - Google Patents
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Abstract
The invention discloses a strain sensor based on radio frequency identification technology for monitoring tunnel strain, which comprises: the Wheatstone bridge is used for being attached to the surface of the deformation part to be detected of the structure, and the voltage difference value at the two ends of the Wheatstone bridge changes along with the deformation of the structure; the RFID tag is connected with the Wheatstone bridge through a wire, and is used for acquiring a voltage difference signal of the Wheatstone bridge, converting the voltage difference signal into a radio frequency digital signal and sending the radio frequency digital signal; the RFID reader is used for receiving the radio frequency digital signal sent by the RFID label, reducing the radio frequency digital signal into a voltage difference signal and transmitting the voltage difference signal; and the upper computer is used for receiving the voltage signal difference transmitted by the RFID reader and obtaining the strain of the deformation part to be detected of the structure according to the voltage signal difference. The strain sensor is used for non-contact identification, so that a large number of data lines are prevented from being arranged; and the anti-interference is strong, the recognition speed is fast, and the service life is long.
Description
Technical Field
The invention belongs to the technical field of tunnel monitoring devices, and particularly relates to a strain sensor based on a radio frequency identification technology and used for tunnel strain monitoring.
Background
The commonly used strain sensors at present comprise a resistance type strain gauge, a vibrating wire type strain gauge and a Bragg fiber grating sensor. The resistance type strain gauge is generally made by winding constantan wire or nickel-chromium wire into a grid shape and clamping the grid shape in two layers of insulating sheets, and the principle of measuring strain is as follows: the resistance of the wire is related to the length and cross-sectional area of the wire, in addition to the properties of the material. The wire is adhered to the member, and when the member is deformed under a force, the length and the cross-sectional area of the wire are changed along with the member, so that the resistance is changed. The vibrating wire strain gauge measures strain by using the change relation between the vibration frequency of a wire and the tension of the wire. When the stress in the structure to be measured changes, the strain gauges synchronously sense deformation, and the deformation is transmitted to the vibrating wire through the front end seat and the rear end seat to be converted into the change of the stress of the vibrating wire, so that the vibration frequency of the vibrating wire is changed. The electromagnetic coil excites the vibrating wire and measures the vibration frequency thereof, and the frequency signal is transmitted to the reading device through the cable, so that the strain inside the measured structure can be measured. The principle of bragg grating sensors is based on the drift theory of the bragg wavelength of the fiber grating. The bragg grating is affected by stress or temperature change, the grating pitch changes, the wavelength of the reflected wave changes accordingly, and different wavelengths are reflected. And measuring the change of the reflection wavelength by using a grating demodulator so as to measure strain information.
The strain sensors described above have their own advantages, while having unavoidable disadvantages: the sensors need to be arranged in a wired mode, and when the number of measuring points is large, wiring is complex; in some cases where a large amount of wiring is impossible, the applicability thereof is greatly limited; the monitoring process needs real-time power supply, and when the structure is affected by fire and the power supply fails, the sensor cannot obtain data of the structure in case of disaster; the signal acquisition equipment is expensive, and the operation and maintenance cost is high.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a strain sensor based on radio frequency identification technology for tunnel strain monitoring aiming at the defects of the prior art, which is non-contact identification and avoids the arrangement of a large number of data lines; and the anti-interference is strong, the recognition speed is fast, and the service life is long.
In order to solve the technical problems, the invention adopts the technical scheme that a strain sensor based on radio frequency identification technology for monitoring tunnel strain comprises:
the Wheatstone bridge is used for being attached to the surface of the deformation part to be detected of the structure, and the voltage difference value at the two ends of the Wheatstone bridge changes along with the deformation of the structure;
the RFID tag is connected with the Wheatstone bridge through a wire, and is used for acquiring a voltage difference signal of the Wheatstone bridge, converting the voltage difference signal into a radio frequency digital signal and sending the radio frequency digital signal;
the RFID reader is used for receiving the radio frequency digital signal sent by the RFID label, reducing the radio frequency digital signal into a voltage difference signal and transmitting the voltage difference signal;
the upper computer is used for receiving the voltage signal difference transmitted by the RFID reader and obtaining the strain of the deformation part to be detected of the structure according to the voltage signal difference;
the Wheatstone bridge is formed by connecting a first resistance-type strain gauge, a second fixed resistor and a first fixed resistor in turn by leads, and a connection point is respectively led out between every two resistance-type strain gauges;
the first resistance type strain gauge is used for being attached to the surface of a to-be-detected deformation part of the structure and deforming along with the deformation of the structure;
and the second resistance type strain gauge is used for being fixed on the periphery of the deformation part to be detected of the structure and eliminating the influence of temperature change on the resistance values of the two strain gauges.
Furthermore, the RFID tag comprises a voltage signal input port, a grounding end, a tag radio frequency chip, a tag antenna and a button cell; the voltage signal input port, the grounding end, the tag antenna and the button battery are all connected with the tag radio frequency chip;
the voltage signal input port and the grounding terminal are respectively connected with the first connecting point and the second connecting point through wires; the voltage difference signal acquisition module is used for acquiring a voltage difference signal between two connection points;
the two poles of the button battery are respectively connected with the third connecting point and the fourth connecting point through wires;
the tag radio frequency chip is used for receiving the voltage difference signal, converting the voltage difference signal into a radio frequency digital signal and sending the radio frequency digital signal to the tag antenna;
the connection point between the first fixed resistor and the first resistance-type strain gauge is a first connection point; the connection point between the first resistance-type strain gauge and the second resistance-type strain gauge is a third connection point; the connection point between the second resistance type strain gauge and the second fixed resistor is a second connection point; the connection point between the second fixed resistor and the first fixed resistor is a fourth connection point.
Furthermore, the RFID reader comprises a reader radio frequency chip, a reader antenna, a data processing module and a USB interface, wherein the reader antenna and the data processing module are both connected with the reader radio frequency chip, and the USB interface is connected with the data processing module;
the reader radio frequency chip receives and transmits the radio frequency digital signal sent by the tag antenna through the reader antenna; the reader radio frequency chip also sends information to the tag antenna through the reader antenna;
the data processing module is used for receiving a radio frequency digital signal sent by a radio frequency chip of the reader and converting the radio frequency digital signal into a voltage difference signal;
and the USB interface is used for receiving the voltage difference signal sent by the data processing module and transmitting the voltage difference signal to the upper computer.
Further, the first resistance strain gauge and the second resistance strain gauge are the same strain gauge.
Further, the first fixed resistor and the second fixed resistor are the same resistor.
The invention also discloses a strain sensor group based on the radio frequency identification technology for monitoring the strain of the tunnel, which is characterized by comprising a plurality of Wheatstone bridges and RFID labels, wherein the number of the Wheatstone bridges is consistent with that of the RFID labels; and the plurality of RFID labels are in signal connection with one RFID reader.
The invention has the following advantages: 1. for non-contact identification, data transmission between the RFID tag and the RFID reader does not need to be connected with a data line, so that a large number of data lines are prevented from being arranged; and the anti-interference is strong, and the recognition speed is high. 2. The resistance strain gauges are utilized to form a Wheatstone bridge, differential voltage signals are output under the excitation of an external power supply, and the resistance change of the strain gauges is measured according to the relation between the resistance change and the output voltage change so as to solve the strain, so that the sensitivity is high, the error is small, the size is small, and the weight is light.
Drawings
FIG. 1 is a schematic structural diagram of a strain sensor based on RFID;
FIG. 2 is a schematic diagram of the Wheatstone bridge;
FIG. 3 is a schematic view of the RFID tag;
FIG. 4 is a schematic diagram of the RFID reader;
FIG. 5 is a schematic diagram of a Wheatstone bridge;
FIG. 6 is a schematic diagram of an analog-to-digital conversion sample;
FIG. 7 is a diagram illustrating quantization and encoding of the ADC;
wherein: 1. a Wheatstone bridge; an RFID tag; 3, RFID reader; 4, an upper computer; 5. a first resistive strain gage; 6. a second resistive strain gage; 7. a first fixed resistor; 8. a second fixed resistor; 9. a first connection point; 10. a second connection point; 11. a third connection point; 12. a fourth connection point; 13. a voltage signal input port; 14. a ground terminal; 15. a radio frequency chip; 16. a tag antenna; 17. a button cell; 18. a positive electrode; 19. a negative electrode; 20. a reader radio frequency chip; 22. a data processing module; and 23, USB connection.
Detailed Description
The invention relates to a strain sensor based on radio frequency identification technology for monitoring tunnel strain, which comprises the following components: the Wheatstone bridge 1 is used for being attached to the surface of a to-be-detected deformation part of the structure, and the voltage difference value at two ends of the Wheatstone bridge changes along with the deformation of the structure. And the interface of the RFID tag 2 is connected with the wire of the Wheatstone bridge 1 and is used for acquiring a voltage difference signal of the Wheatstone bridge 1, converting the voltage difference signal into a radio frequency digital signal and sending the radio frequency digital signal. And the RFID reader 3 is used for receiving the radio frequency digital signal sent by the RFID label 2, restoring the radio frequency digital signal into a voltage difference signal and transmitting the voltage difference signal. And the upper computer 4 is used for receiving the voltage signal difference transmitted by the RFID reader 3 and obtaining the strain of the deformation part to be detected of the structure according to the voltage signal difference.
The wheatstone bridge 1 is formed by sequentially connecting a first resistance-type strain gage 5, a second resistance-type strain gage 6, a second fixed resistor 8 and a first fixed resistor 7 through leads, and a connection point is respectively led out between every two strain gages.
The first resistance strain gauge 5 is used for being tightly attached to the surface of a to-be-detected deformation part of the structure and deforming along with the deformation of the structure. And the second resistance type strain gauge 6 is used for being fixed on the periphery of a deformation part to be detected of the structure and eliminating the influence of temperature change on the resistance values of the two strain gauges. The second resistance strain gauge (6) is used as a temperature compensation gauge and is arranged under the same temperature field as the first resistance strain gauge (5), and the first resistance strain gauge and the second resistance strain gauge undergo the same temperature change, so the resistance changes of the first resistance strain gauge 5 and the second resistance strain gauge 6 caused by the temperature change are the same, the Wheatstone bridge 1 is still in an equilibrium state, and the influence of the temperature change on strain measurement is eliminated. The second resistive strain gage 6 is fixed in position close to the first resistive strain gage 5, but it cannot be fixed to the structure to which the first resistive strain gage 5 is attached. One of the fixing methods is to fix the structure on the wall surface of the tunnel around the structure, and the fixing method is realized by packaging the structure, the second fixed resistor 8, the first fixed resistor 7 and the connecting lead in a protective film, and fixing the protective film by adopting an adhesive or other methods.
The RFID tag 2 comprises a voltage signal input port 13, a grounding terminal 14, a tag radio frequency chip 15, a tag antenna 16 and a button battery 17; the voltage signal input port 13, the grounding terminal 14, the tag antenna 16 and the button cell 17 are all connected with the tag radio frequency chip 15.
The voltage signal input port 13 and the ground terminal 14 are also wire-connected to the first connection point 9 and the second connection point 10, respectively; the voltage difference signal is used for collecting the voltage difference signal between the two connecting points. Two poles of the button cell 17 are respectively connected with the third connection point 11 and the fourth connection point 12 through wires. The tag radio frequency chip 15 is configured to receive the voltage difference signal, convert the voltage difference signal into a radio frequency digital signal, and send the radio frequency digital signal to the tag antenna 16.
The connection point between the first fixed resistor 7 and the first resistance strain gauge 5 is a first connection point 9; the connection point between the first resistance-type strain gauge 5 and the second resistance-type strain gauge 6 is a third connection point 11; the connection point between the second resistance type strain gauge 6 and the second fixed resistor 8 is a second connection point 10; the connection point between the second fixed resistor 8 and the first fixed resistor 7 is a fourth connection point 12.
The RFID reader 3 comprises a reader radio frequency chip (20), a reader antenna 21, a data processing module 22 and a USB interface 23, wherein the reader antenna 21 and the data processing module 22 are both connected with the reader radio frequency chip 20, and the USB interface 23 is connected with the data processing module 22; the reader radio frequency chip 20 receives and transmits the radio frequency digital signal sent by the tag antenna 16 through the reader antenna 21; the reader rf chip 20 also sends information to the tag antenna 16 via the reader antenna 21.
And the data processing module 22 is configured to receive the radio frequency digital signal sent by the reader radio frequency chip 20, and convert the radio frequency digital signal into a voltage difference signal. And the USB interface 23 is used for receiving the voltage difference signal sent by the data processing module 22 and transmitting the voltage difference signal to the upper computer 4.
The invention also discloses a strain sensor group based on the radio frequency identification technology for monitoring the strain of the tunnel, which comprises a plurality of Wheatstone bridges 1 and RFID labels 2, wherein the number of the Wheatstone bridges 1 is consistent with that of the RFID labels 2; the plurality of RFID tags 2 are each in signal connection with one RFID reader 3.
As shown in fig. 1, the first resistive strain gauge 5 and the second resistive strain gauge 6 have the same type, and one of the first resistive strain gauge 5 and the second resistive strain gauge is directly adhered to the surface of the structure. The first resistive strain gage 5 and the second resistive strain gage 6 are placed in the same temperature field. The second resistance-type strain gauge 6 is used as a temperature compensation gauge, the influence of temperature change on the resistance value of the strain gauge is eliminated, the first resistance-type strain gauge 5, the second resistance-type strain gauge 6, the second fixed resistor 8 and the first fixed resistor 7 are sequentially connected through wires, and a connection point is led out between every two strain gauges.
The first resistance strain gauge 5 and the second resistance strain gauge 6 are completely the same resistance strain gauges, and have the same parameters of sensitivity, resistance value, etc., and the resistances are respectively R1、R3Then R is1＝R3＝R0。
The first fixed electrodeThe resistor 7 and the second fixed resistor 8 are resistors with the same resistance value, and the resistors are respectively R2、R4. Due to R1:R2＝R3:R4As can be seen from the principle of voltage division, the wheatstone bridge 1 is a balanced bridge, and the voltage difference between the first connection point 9 and the second connection point 10 is 0.
When the strain sensor based on the radio frequency identification technology is used, the first resistance-type strain gauge 5 is used for being attached to the surface of a deformation part to be detected of a structure, the second resistance-type strain gauge 6 is adhered to the nearby area of the deformation part to be detected, and the first resistance-type strain gauge 5 and the second resistance-type strain gauge 6 are placed in the same temperature field, so that when the temperature changes, the resistance value changes of the first resistance-type strain gauge 5 and the second resistance-type strain gauge 6 caused by the temperature changes are delta RT. By
It can be seen that the wheatstone bridge 1 is still a balanced bridge and the voltage difference between the first connection point 9 and the second connection point 10 is still 0.
When the deformation part of the structure to be measured deforms, the first resistance type strain gauge 5 is strained, and small resistance change delta R, namely R occurs1＝R0+ Δ R, the bridge is out of balance and a voltage difference Δ U is stored between the first connection point 9 and the second connection point 10. Because the delta U and the delta R are in a linear relation, the delta U is used for solving the delta R according to a derivation formula, and then the relation among the resistance value change delta R, the sensitivity K and the strain epsilon of the resistance strain gauge is utilized:
the strain epsilon at the first resistance type strain gauge 5 is obtained by the above formula, namely the strain at the deformation position to be measured of the structure.
As shown in fig. 2, the RFID tag 2 includes a voltage signal input port 13, a ground terminal 14, a radio frequency chip 15, a tag antenna 16, and a button battery 17; the voltage signal input port 13, the grounding terminal 14, the tag antenna 16 and the button cell 17 are all connected with the radio frequency chip 15;
the voltage signal input port 13 and the grounding terminal 14 are also respectively connected with the first connection point 9 and the second connection point 10 through wires; the voltage difference signal acquisition module is used for acquiring a voltage difference signal between two connection points;
the two poles of the button battery 17 are respectively connected with the third connection point 11 and the fourth connection point 12 through leads;
the tag radio frequency chip 15 is configured to receive the voltage difference signal, convert the voltage difference signal into a radio frequency digital signal, and send the radio frequency digital signal to the tag antenna 16.
The voltage between the first connection point 9 and the second connection point 10 in the wheatstone bridge 1 is picked up via a voltage signal input 13 and a ground 14. The radio frequency chip 15 contains an a/D conversion circuit, and performs analog-to-digital conversion on the acquired voltage difference between the first connection point 9 and the second connection point 10, and converts the voltage difference into a 12-bit digital signal, as shown in fig. 4 and 5. As shown in fig. 6, the voltage across the tag antenna 16 connected to the tag rf chip 15 is then modulated in accordance with the beat of the data stream by means of load modulation, so that the voltage varies regularly according to a certain waveform. The tag antenna 16 transmits the voltage change across it to the reader antenna 21 using spatial coupling. The button battery 17 is used as a power supply to supply power to the RFID tag 2; meanwhile, the anode 18 and the cathode 19 of the button cell 17 are connected with the third connection point 11 and the fourth connection point 12 of the wheatstone bridge 1 by wires to supply power to the wheatstone bridge 1. When the RFID tag is not used, the RFID tag 2 is in a dormant state, and the power consumption is low. When the RFID tag 2 receives the radio frequency signal transmitted by the RFID reader 4, it enters a working state.
The RFID reader 3 comprises a reader radio frequency chip (20), a reader antenna 21, a data processing module 22 and a USB interface 23, wherein the reader antenna 21 and the data processing module 22 are both connected with the reader radio frequency chip 20, and the USB interface 23 is connected with the data processing module 22.
The reader rf chip 20 receives and transmits the rf digital signal sent by the tag antenna 16 through the reader antenna 21; the reader rf chip 20 also sends information to the tag antenna 16 via the reader antenna 21.
The data processing module 22 is configured to receive the radio frequency digital signal sent by the reader radio frequency chip 20, and convert the radio frequency digital signal into a voltage difference signal. And the USB interface 23 is used for receiving the voltage difference signal sent by the data processing module 22 and transmitting data to the upper computer 4 by using a data line. And the upper computer 4 calculates the received voltage information to obtain the strain information of the measuring point. The upper computer 4 is a computer.
The strain sensor based on the radio frequency identification technology is used in the following process that the first resistance type strain gauge 5 of the Wheatstone bridge 1 is firmly adhered to the surface of a deformation position to be detected of the structure; the first connection point 9 and the second connection point 10 of the wheatstone bridge 1 are connected to a voltage signal input port 13 and a ground terminal 14 of the RFID tag 2 by wires, respectively. The third connection point 11 and the fourth connection point 12 of the wheatstone bridge 1 are respectively connected with the anode 18 and the cathode 19 of the button cell 17 through wires. The RFID reader 3 is close to the RFID tag 2, when the RFID reader 3 enters a radio frequency identification range, the RFID reader 3 transmits a signal to activate the RFID tag 2, and the RFID tag 2 transmits information to the RFID reader 3 through a radio frequency signal; after receiving the information, the RFID reader 3 processes and restores the information into voltage information, and transmits the voltage information to the upper computer 4 through the USB interface 23; and the upper computer 4 receives the voltage information and calculates the strain at the measuring point by using the derived formula.
The principle of the wheatstone bridge 1 for measuring strain is described above with reference to fig. 5.
a. A common circuit for measuring strain is a wheatstone bridge. A wheatstone bridge is a bridge circuit consisting of four resistors, which are respectively called the legs of the bridge. In the bridge there are two fixed resistors, R respectively2、R4(ii) a In addition R1、R3Two identical resistance strain gauges. R1、R2And R3、R4A voltmeter is connected between the two. The two ends of the whole bridge are connected with a voltage source. When the bridge balances R1:R2＝R3:R4When the voltage is measured, the voltage at two ends of the voltmeter is 0 according to the voltage division principle. When R is1When the voltage changes, the voltage between the two points A, B in the graph changes, the change of the resistance of the strain gauge can be known by collecting the change of the voltage, and the strain at the position can be deduced to realize the purpose of measurement.
b. Factors that affect the resistance of a strain gage are temperature in addition to strain. R1R of adjacent arm3As a temperature compensation plate with R1Placed in the same temperature field without participating in the strain measurement. In this way, the effect of temperature on the bridge measurement is eliminated.
c. When the bridge is balanced, R1:R2＝R3:R4In the circuit, the potential difference between the two points AB is 0. If at this time, the strain gauge R1Increase the resistance Δ R, i.e. R, by a small amount1＝R0+ Δ R, the bridge is out of balance, and a certain potential difference U exists between points AB and AB in the circuitAB. If the voltage of the bridge power supply is U0According to the voltage division principle of the series resistors and taking the point C in the circuit as a zero potential reference point, the output voltage of the bridge is as follows:
make the bridge ratio
According to the condition of the balance of the bridge,
and when Δ R is much less than R0In the meantime, the tiny items in the denominator are omitted,
comprises the following steps:
d. from equation 2, between the two arms of the Wheatstone bridgeVoltage difference UABAnd the resistance value change delta R of the resistance strain gauge is in a linear relation. Accordingly, U can be obtained from the measurementABAnd calculating the Delta R. And then according to the known relation between the sensitivity K of the resistance strain gauge and the strain epsilon:
and calculating epsilon.
The principle of analog-to-digital a/D conversion described above, as shown in fig. 6 and 7:
a. the tag radio frequency chip 15 performs analog-to-digital a/D conversion on the voltage difference between the first connection point 9 and the second connection point 10 acquired through the voltage signal input port 13 and the ground 14, wherein the a/D conversion is used for converting analog signals with continuous time and continuous amplitude into digital signals with discrete time and discrete amplitude. Since the digital signal itself has no practical significance and only represents a relative size, a reference analog quantity is required for a/D conversion as a standard for conversion. In the present invention, the maximum input voltage between the voltage signal input port 13 and the ground terminal 14 is 1.15V, which is used as a reference voltage. The digital quantity of the output represents the magnitude of the input voltage relative to the reference voltage. The a/D conversion goes through the steps of sampling, quantization and encoding. Sampling means that the voltage between the first connection point 9 and the second connection point 10, which is taken via the voltage signal input 13 and the ground 14, is replaced by a sequence of voltage samples at regular intervals. The sampled voltage sample sequence is approximated by discrete quantized voltages having a certain interval, and the continuous amplitude of the voltage sample sequence is changed into a finite number of discrete values having a certain interval. The coding is to represent the quantized value by binary digits according to a certain rule, and then to convert the quantized value into a binary digital signal stream.
b. In FIG. 7, VINIs the voltage difference between the first connection point 9 and the second connection point 10 collected through the voltage signal input port 13 and the ground terminal 14; eFSRThe maximum input voltage between the voltage signal input port 13 and the ground terminal 14 is 1.15V in the present invention, and is also used as the reference voltage in the present invention.
The input voltage of A/D conversion circuit is related to the output code by simple relation
VIN＝outputcode*LSBsize
c. The output port code is a radio frequency digital signal output by the tag radio frequency chip 15 after performing a/D conversion on the acquired voltage difference between the first connection point 9 and the second connection point 10, and the LSBsize is a Least significant bit, namely a significant bit, LSB, in the radio frequency digital signal.
d. Wherein N is the number of bits of the rf digital signal, and the tag rf chip 15 of the present invention outputs a 12-bit 0-1 digital signal, so that N is 12.
The strain sensor based on the radio frequency identification technology measures the strain quantity
Table 1 shows the mean square error of the strain measurement using the strain sensor and strain gauge based on rfid as described in the present invention, and the comparison result of the strain measurement using the conventional dynamic and static strain gauges under the same experimental conditions.
The resistance values of the two fixed resistors are both 120 ohms, and the initial resistance values of the resistance type strain gauges are both 120 ohms.
In the 1 st test, the strain of the reduced-scale model beam is measured by respectively using the strain sensor based on the RFID and the Wheatstone bridge and a Jiangsu Tester dynamic and static strain tester (TST3827E), and 60 data points are measured in one test.
In the 2 nd experiment, the strain of the reduced-scale model beam is measured by respectively using the strain sensor based on the RFID and the Wheatstone bridge and a Jiangsu Tester dynamic and static strain tester (TST3827E), and 60 data points are measured in one experiment.
In the 3 rd test, the strain of the reduced scale model beam is measured by respectively using the strain sensor based on the RFID and the Wheatstone bridge and a Jiangsu Tester dynamic and static strain tester (TST3827E), and 120 data points are measured in one test.
In the 4 th test, the strain of the reduced-scale model beam is measured by respectively using the strain sensor based on the RFID and the Wheatstone bridge and a Jiangsu Tester dynamic and static strain tester (TST3827E), and 120 data points are measured in one test.
In the 5 th test, the strain of the reduced-scale model beam is measured by respectively using the strain sensor based on the RFID and the Wheatstone bridge and a Jiangsu Tester dynamic and static strain tester (TST3827E), and 120 data points are measured in one test.
TABLE 1 Strain measurement mean square error
From the above data, the mean square error between the two was 87.07 μ ∈, microstrain, 1 μ ∈ 10-6Epsilon, which meets the strain measurement precision requirement of civil engineering.
Claims (6)
1. A strain sensor based on radio frequency identification technology for tunnel strain monitoring, comprising:
the Wheatstone bridge (1) is used for being attached to the surface of a to-be-detected deformation part of the structure, and the voltage difference value at the two ends of the Wheatstone bridge changes along with the deformation of the structure;
the interface of the RFID tag (2) is connected with the Wheatstone bridge (1) through a wire, and the RFID tag is used for acquiring a voltage difference signal of the Wheatstone bridge (1), converting the voltage difference signal into a radio frequency digital signal and sending the radio frequency digital signal;
the RFID reader (3) is used for receiving the radio frequency digital signal sent by the RFID label (2), restoring the radio frequency digital signal into a voltage difference signal and transmitting the voltage difference signal;
the upper computer (4) is used for receiving the voltage signal difference transmitted by the RFID reader (3) and obtaining the strain of the deformation part to be detected of the structure according to the voltage signal difference;
the Wheatstone bridge (1) is formed by sequentially connecting a first resistance-type strain gage (5), a second resistance-type strain gage (6), a second fixed resistor (8) and a first fixed resistor (7) through leads, and a connection point is respectively led out between every two of the first resistance-type strain gages;
the first resistance type strain gauge (5) is used for being attached to the surface of a to-be-detected deformation part of the structure and deforming along with the deformation of the structure;
and the second resistance type strain gauge (6) is used for being fixed on the periphery of a deformation part to be detected of the structure and eliminating the influence of temperature change on the resistance values of the two strain gauges.
2. The strain sensor based on radio frequency identification technology for tunnel strain monitoring as claimed in claim 1, characterized in that the RFID tag (2) comprises a voltage signal input port (13), a ground terminal (14), a tag radio frequency chip (15), a tag antenna (16) and a button cell (17); the voltage signal input port (13), the grounding terminal (14), the tag antenna (16) and the button battery (17) are connected with the tag radio frequency chip (15);
the voltage signal input port (13) and the grounding terminal (14) are also respectively connected with the first connection point (9) and the second connection point (10) through wires; the voltage difference signal acquisition module is used for acquiring a voltage difference signal between two connection points;
the two poles of the button battery (17) are respectively connected with the third connection point (11) and the fourth connection point (12) through leads;
the tag radio frequency chip (15) is used for receiving the voltage difference signal, converting the voltage difference signal into a radio frequency digital signal and sending the radio frequency digital signal to the tag antenna (16);
the connection point between the first fixed resistor (7) and the first resistance-type strain gauge (5) is a first connection point (9); the connection point between the first resistance-type strain gauge (5) and the second resistance-type strain gauge (6) is a third connection point (11); the connection point between the second resistance type strain gauge (6) and the second fixed resistor (8) is a second connection point (10); and a connection point between the second fixed resistor (8) and the first fixed resistor (7) is a fourth connection point (12).
3. The strain sensor based on the radio frequency identification technology for tunnel strain monitoring is characterized in that the RFID reader (3) comprises a reader radio frequency chip (20), a reader antenna (21), a data processing module (22) and a USB interface (23), wherein the reader antenna (21) and the data processing module (22) are both connected with the reader radio frequency chip (20), and the USB interface (23) is connected with the data processing module (22);
the reader radio frequency chip (20) receives and transmits the radio frequency digital signal sent by the tag antenna (16) through the reader antenna (21); the reader radio frequency chip (20) also sends information to the tag antenna (16) through the reader antenna (21);
the data processing module (22) is used for receiving a radio frequency digital signal sent by the reader radio frequency chip (20) and converting the radio frequency digital signal into a voltage difference signal;
and the USB interface (23) is used for receiving the voltage difference signal sent by the data processing module (22) and transmitting the voltage difference signal to the upper computer (4).
4. A radio frequency identification technology based strain sensor for tunnel strain monitoring according to claim 2 or 3, characterized in that the first and second resistive strain gauges (5, 6) are the same strain gauge.
5. Strain sensor based on radio frequency identification technology for tunneling strain monitoring according to claim 4, wherein the first fixed resistance (7) and the second fixed resistance (8) are the same resistance.
6. The strain sensor group for tunnel strain monitoring based on the radio frequency identification technology is characterized by comprising a plurality of Wheatstone bridges (1) and RFID tags (2), wherein the number of the Wheatstone bridges (1) is consistent with that of the RFID tags (2); the plurality of RFID tags (2) are in signal connection with an RFID reader (3).
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113324853A (en) * | 2021-05-28 | 2021-08-31 | 中国建筑第八工程局有限公司 | Shear deformation detection device and detection method thereof |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20120109560A1 (en) * | 2009-02-15 | 2012-05-03 | Board Of Regents, The University Of Texas System | Remote Interrogation of a Passive Wireless Antenna Sensor |
| CN203535667U (en) * | 2013-11-15 | 2014-04-09 | 威海北洋电气集团股份有限公司 | Tunnel-based read-write device based on RFID technology |
| CN203719620U (en) * | 2014-03-03 | 2014-07-16 | 陈维林 | Portable low-power static state resistance strain gauge |
| CN206514804U (en) * | 2016-12-22 | 2017-09-22 | 陕西电器研究所 | A kind of label type wireless senser |
| CN206944922U (en) * | 2017-07-21 | 2018-01-30 | 山东大学 | A kind of road strain parameter automatic acquisition device based on Radio Transmission Technology |
| CN107941151A (en) * | 2017-12-21 | 2018-04-20 | 上海岩土工程勘察设计研究院有限公司 | A kind of three-dimensional laser scanner fixed mechanism, subway tunnel acquisition system and method |
-
2020
- 2020-11-06 CN CN202011233092.XA patent/CN112344846A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20120109560A1 (en) * | 2009-02-15 | 2012-05-03 | Board Of Regents, The University Of Texas System | Remote Interrogation of a Passive Wireless Antenna Sensor |
| CN203535667U (en) * | 2013-11-15 | 2014-04-09 | 威海北洋电气集团股份有限公司 | Tunnel-based read-write device based on RFID technology |
| CN203719620U (en) * | 2014-03-03 | 2014-07-16 | 陈维林 | Portable low-power static state resistance strain gauge |
| CN206514804U (en) * | 2016-12-22 | 2017-09-22 | 陕西电器研究所 | A kind of label type wireless senser |
| CN206944922U (en) * | 2017-07-21 | 2018-01-30 | 山东大学 | A kind of road strain parameter automatic acquisition device based on Radio Transmission Technology |
| CN107941151A (en) * | 2017-12-21 | 2018-04-20 | 上海岩土工程勘察设计研究院有限公司 | A kind of three-dimensional laser scanner fixed mechanism, subway tunnel acquisition system and method |
Non-Patent Citations (1)
| Title |
|---|
| 陆川: "《智慧城市"电子信息+"视角下的总体规划》", 31 December 2018 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113324853A (en) * | 2021-05-28 | 2021-08-31 | 中国建筑第八工程局有限公司 | Shear deformation detection device and detection method thereof |
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