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CN112697183B - Bolt looseness sensor and looseness monitoring system based on double-arc patch antenna - Google Patents

Bolt looseness sensor and looseness monitoring system based on double-arc patch antenna Download PDF

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Publication number
CN112697183B
CN112697183B CN202011379444.2A CN202011379444A CN112697183B CN 112697183 B CN112697183 B CN 112697183B CN 202011379444 A CN202011379444 A CN 202011379444A CN 112697183 B CN112697183 B CN 112697183B
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reader
antenna
component
arc
rfid tag
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CN112697183A (en
Inventor
谢丽宇
姜康
薛松涛
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Tongji University
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Tongji University
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/48—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using wave or particle radiation means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B15/00—Measuring arrangements characterised by the use of electromagnetic waves or particle radiation, e.g. by the use of microwaves, X-rays, gamma rays or electrons
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
    • G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
    • G06K19/067—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
    • G06K19/07—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips
    • G06K19/0716—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips at least one of the integrated circuit chips comprising a sensor or an interface to a sensor
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
    • G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
    • G06K19/067—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
    • G06K19/07—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips
    • G06K19/077—Constructional details, e.g. mounting of circuits in the carrier
    • G06K19/0772—Physical layout of the record carrier
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
    • G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
    • G06K19/067—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
    • G06K19/07—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips
    • G06K19/077—Constructional details, e.g. mounting of circuits in the carrier
    • G06K19/07749—Constructional details, e.g. mounting of circuits in the carrier the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
    • G06K19/07758—Constructional details, e.g. mounting of circuits in the carrier the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card arrangements for adhering the record carrier to further objects or living beings, functioning as an identification tag
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K19/00—Record carriers for use with machines and with at least a part designed to carry digital markings
    • G06K19/06—Record carriers for use with machines and with at least a part designed to carry digital markings characterised by the kind of the digital marking, e.g. shape, nature, code
    • G06K19/067—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components
    • G06K19/07—Record carriers with conductive marks, printed circuits or semiconductor circuit elements, e.g. credit or identity cards also with resonating or responding marks without active components with integrated circuit chips
    • G06K19/077—Constructional details, e.g. mounting of circuits in the carrier
    • G06K19/07749—Constructional details, e.g. mounting of circuits in the carrier the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
    • G06K19/07773—Antenna details
    • G06K19/07788—Antenna details the antenna being of the capacitive type

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Theoretical Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Electromagnetism (AREA)
  • Arrangements For Transmission Of Measured Signals (AREA)

Abstract

The bolt looseness sensor and the bolt looseness monitoring system based on the double-arc patch antenna are characterized by comprising an RFID tag, a reader and a setting module; the reader is responsible for wirelessly reading the information of the RFID label and processing the data. The RFID tag is arranged on the surface of the connected component; the RFID label is composed of two components, wherein the component I and the component II are positioned on the same surface. The RFID reader used for the control system transmits modulated electromagnetic wave signals to the RFID label at different frequencies, and when the power of the signals received by the RFID label reaches a threshold value, a chip in the RFID label can be activated; minimum transmission power P of reader required for activating labelmin(f) In relation to the frequency f of the signal transmitted by the reader, f is the frequency of the signal transmitted by the reader at the resonant frequency of the helical antenna in the RFID tagRMinimum transmit power P required to activate the tagmin(fR) And minimum. Compared with the existing sensing system, the sensing system has extremely low cost, and can be designed and built together with a structure as prefabricated equipment to build a real-time monitoring network.

Description

Bolt looseness sensor and looseness monitoring system based on double-arc patch antenna
Technical Field
The application relates to a bolt looseness monitoring technology.
Background
The bolt is widely applied to connection in the fields of civil engineering, traffic, aerospace and the like, and has the characteristics of high strength and detachability, so that the bolt has wider applicability. However, the bolt is easy to loosen under the action of long-term load, and serious potential safety hazards exist for the structure. Therefore, in the structure using the bolt connection, it is necessary to perform regular bolt monitoring to avoid structural damage due to loosening of the bolt.
Currently, the commonly used bolt monitoring techniques are: a bolt looseness monitoring method and a strain gauge electrical measurement method based on piezoelectric admittance are disclosed.
According to the bolt looseness monitoring method based on piezoelectric admittance, a piezoelectric sensor is pasted on a bolt, whether the bolt is loosened or not can be judged by measuring the peak frequency change in a piezoelectric admittance diagram, but the piezoelectric sensor needs to be excited through a lead, needs an expensive high-precision impedance analyzer, and is difficult to be applied to engineering practice in a large range.
The strain gage electrical measurement method accurately measures the bolt axial force by measuring the strain of a bolt screw, but the bolt axial force is not large, so that the measurement precision is not high, and the strain gage electrical measurement method is limited by installation conditions and is difficult to be widely applied.
Disclosure of Invention
In order to overcome the defects of the traditional bolt monitoring technology, the application provides a passive wireless bolt monitoring system based on a double-arc patch antenna; a system for monitoring loosening of a plurality of bolts in a large range is provided.
The invention needs to achieve the following aims:
(1) a passive wireless angle sensor based on a double-arc patch antenna can sense angle change, and the drift amount of the resonant frequency of the sensor has a clear relation with the angle size in a fixed range;
(2) the detection equipment can wirelessly detect the drift amount of the resonant frequency of the antenna, and accordingly calculates the rotation angle of the nut caused by the loosening of the bolt, so that the wireless detection of the loosening of the bolt is realized;
(3) the chip can store simple information such as ID, position of the patch antenna, and the like, and realizes large-range monitoring of the looseness of a plurality of bolts.
What the application needs to protect is the technical scheme of the embodiment 2:
a passive wireless bolt looseness monitoring system based on a double-arc patch antenna is characterized by comprising an RFID tag 1, a reader 4 and a setting module; the reader 4 is responsible for wirelessly reading the information of the RFID tag 1 and performing data processing;
the RFID tag 1 is arranged on the surface of the connected component 3; the RFID tag 1 consists of two components, wherein a first component 12 and a second component 13 are positioned on the same surface, and the specific structure is as follows:
the first component 12 is a circular plate, the center of the first component is provided with a hexagonal opening 12-1 and a metal inner arc 12-2, and the hexagonal opening 12-1 is used for being embedded and stably fixed on the outer edge of the screw cap 3-2;
the second component 13 is a rectangular plane and is used for being attached and fixed on the upper surface of the connecting component 3, and an intermediate plate is attached to the rectangular plane and is provided with a circular hole 13-1 and a metal outer arc 13-2; the second component is used as a main part of the electronic tag sensor and is also provided with a feed microstrip line 13-3 and a chip 13-4; the outer arc 13-2 is connected with the feed microstrip line 13-3, and the chip 13-4 is fixed on the intermediate plate and connected with the tail end of the feed microstrip line 13-3; embedding a circular plate of the first assembly into the circular hole 13-1 of the second assembly, rotating and contacting the surface of the connected member 3; the radians of the inner arc 12-2 and the outer arc 13-2 are the same, and the two arcs are matched with the initial position, so that the two arcs form the antenna capacitor of the electronic tag; when the first circular plate of the assembly rotates in the second circular plate of the assembly, the position of the inner arc 12-2 relative to the outer arc 13-2 is staggered, the internal capacitance of the antenna changes, and the working frequency of the antenna of the electronic tag in the equivalent circuit changes; when the measured nut 3-2 rotates relative to the connecting member 3 due to looseness, the circular plate of the first assembly 12 rotates together with the nut 3-2 synchronously, and the second assembly 13 is fixed on the connecting member 3, so that the inner arc 12-2 in the first assembly 12 and the outer arc 13-2 in the second assembly 13 rotate relatively, the internal capacitance of the antenna is disturbed, and the resonant frequency of the antenna is shifted.
The RFID tag 1 is arranged on the nut 3-2 to be tested and the connected component 3, and is responsible for converting the information of the nut rotation angle of the bolt 2 to be tested into an electromagnetic wave signal and transmitting the electromagnetic wave signal to the reader 4; the RFID tag comprises an antenna and a chip, and the inner circular arc plays a role of a sensing unit in angle measurement; along with the loosening of the bolt, the nut rotates, the inner arc in the first assembly and the outer arc in the second assembly rotate relatively, the facing area is changed, the internal capacitance of the antenna is changed, and the resonant frequency of the antenna is enabled to drift.
The reader 4 comprises a wireless transceiving module, a modulation and demodulation module, a control module and a digital processing module; through the wireless transceiving module and the modulation and demodulation module, the RFID reader detects the resonance frequency drift of the RFID tag, the resonance frequency drift is demodulated by the modulation and demodulation module and then is provided for the control module and the digital processing module, and the digital processing module calculates the relative rotation angle of the two components, namely the rotation angle of the nut according to the corresponding relation in the setting module, so as to judge the bolt state.
The control module is used for controlling an RFID reader of the system to transmit modulated electromagnetic wave signals to the RFID tag at different frequencies, and when the power of the signals received by the RFID tag reaches a threshold value, a core in the RFID tagThe patch can be activated. Minimum transmission power P of reader required for activating labelmin(f) In relation to the frequency f of the signal transmitted by the reader, f is the frequency of the resonant frequency of the antenna in the RFID tag when the reader transmits the signalRMinimum transmit power P required to activate the tagmin(fR) And minimum.
The digital processing module can determine the resonant frequency of the antenna in the RFID tag by searching for the transmitting frequency which enables the minimum transmitting power to reach the minimum value. When the facing area of the inner arc and the outer arc in the antenna changes, the capacitance of the antenna changes, and the resonant frequency drifts, the method can determine the drift amount of the resonant frequency, so as to obtain the generated turning angle value and the nut rotating angle, and judge the bolt state according to the nut rotating angle.
The system also comprises a storage module, wherein the codes and the position information of the tags carried by the chips in the electronic tag sensors are prestored, the system utilizes an RFID reader to transmit modulated electromagnetic wave signals to the tags, the codes of the tags can be identified, and when a plurality of RFID tags are arranged in the scanning range of the RFID reader, the reader can mark the bolt state of each measuring point according to the codes of the tags and quickly position the loosened bolts.
Has the advantages that:
(1) when the RFID tag in the sensing system is installed, the bolt does not need to be modified, and the RFID tag can be installed on the existing bolt, so that the RFID tag is more economical and practical;
(2) compared with the existing sensing system, the sensing system has extremely low cost, and can be designed and built together with a structure as prefabricated equipment to build a real-time monitoring network.
Drawings
Sensor application scenario illustration in the embodiment of FIG. 1
FIG. 2 is a perspective view of an RFID tag formed by a first component and a second component in embodiment 1
FIG. 3 schematic diagram of system configuration in embodiment 2
Detailed Description
The technical solutions provided in the present application will be further described with reference to the following specific embodiments and accompanying drawings. The advantages and features of the present application will become more apparent in conjunction with the following description.
It should be noted that the embodiments of the present application have a better implementation and are not intended to limit the present application in any way. The technical features or combinations of technical features described in the embodiments of the present application should not be considered as being isolated, and they may be combined with each other to achieve a better technical effect. The scope of the preferred embodiments of this application may also include additional implementations, and this should be understood by those skilled in the art to which the embodiments of this application pertain.
Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values.
The drawings in the present application are in simplified form and are not to scale, but rather are provided for convenience and clarity in describing the embodiments of the present application and are not intended to limit the scope of the application. Any modification of the structure, change of the ratio or adjustment of the size of the structure should fall within the scope of the technical disclosure of the present application without affecting the effect and the purpose of the present application. And the same reference numbers appearing in the various drawings of the present application designate the same features or components, which may be employed in different embodiments.
Example 1
Monitoring sensor (construction, structure principle)
As shown in figures 1 and 2 of the drawings,
the RFID tag 1 constitutes a sensing unit, and is placed on the surface of the member to be connected 3. The RFID tag 1 consists of two components, wherein a first component 12 and a second component 13 are positioned on the same surface, and the specific structure is as follows:
the first component 12 is a circular plate, the center of the first component is provided with a hexagonal opening 12-1 and a metal inner arc 12-2, and the hexagonal opening 12-1 is used for being embedded and stably fixed on the outer edge of the screw cap 3-2;
the second component 13 is a rectangular plane and is used for being attached and fixed on the upper surface of the connecting component 3, and an intermediate plate is attached to the rectangular plane and is provided with a circular hole 13-1 and a metal outer arc 13-2; the second component is used as a main part of the electronic tag sensor and is also provided with a feed microstrip line 13-3 and a chip 13-4; the outer arc 13-2 is connected with the feed microstrip line 13-3, and the chip 13-4 is fixed on the intermediate plate and connected with the tail end of the feed microstrip line 13-3;
embedding a circular plate of the first assembly into the circular hole 13-1 of the second assembly, rotating and contacting the surface of the connected member 3; the radians of the inner arc 12-2 and the outer arc 13-2 are the same, and the two arcs are matched with the initial position, so that the two arcs form the antenna capacitor of the electronic tag; when the first circular plate of the assembly rotates in the second circular plate of the assembly, the position of the inner arc 12-2 relative to the outer arc 13-2 is staggered, the internal capacitance of the antenna changes, and the working frequency of the antenna of the electronic tag in the equivalent circuit changes;
when the antenna works, when the tested nut 3-2 rotates relative to the connecting member 3 due to looseness, the circular plate of the first assembly 12 rotates together with the nut 3-2 synchronously, and the second assembly 13 is fixed on the connecting member 3, so that the inner arc 12-2 in the first assembly 12 and the outer arc 13-2 in the second assembly 13 rotate relatively, the internal capacitance of the antenna is disturbed, and the resonant frequency of the antenna is shifted.
Further, by way of example and not limitation, the material of the inner arc, the outer arc, the feed microstrip line and the ground plane is brass, and the material of the dielectric plate is RT 5880.
The application comprises the following steps:
the invention is suitable for monitoring the working state of a common bolt in engineering, and a sensor is required to be arranged on a fastened bolt and nut rod piece to be tested during measurement, and is particularly arranged and sleeved on a hexagon of a bolt to be tested 3-2. The initial installation needs to satisfy the assembly relationship between the first component 12 and the second component 13:
the first component 12 is connected with the nut 3-2, the second component 13 is fixed on the surface of the connected piece 3, and the rotation of the nut 3-2 causes the relative rotation between the first component and the second component.
Further, when the nut 3-2 rotates, the inner arc and the outer arc can rotate relatively, the relative overlapping area of the inner arc and the outer arc can change due to staggering, the capacitance of the antenna can change, and the resonant frequency of the antenna can change.
Further, when the tag 1 is installed, any initial relative area of the inner arc 6 and the outer arc 8 can be selected, and when the bolt 2 is loosened, the relative area of the inner arc 6 and the outer arc 8 is changed, so that the resonant frequency of the antenna is changed.
Furthermore, the shape of the opening of the circular plate of the first component 12 can be adjusted according to different shapes of the screw cap, so that the first component and the screw cap are more convenient to connect.
Further, to the bolt of different specifications, the size of the double-circular-arc-based patch antenna in this application can be adjusted and re-optimized to satisfy different demands.
Furthermore, according to the specification, mechanical parameters and thread pitch of the bolt, the angle of the nut rotation when the bolt changes from the preset pretightening force state to the completely pretightening force losing state can be determined. When the tag 1 is installed, any initial relative area of the inner arc and the outer arc can be selected, and when the bolt 2 is loosened on the connected component 3, the relative area of the inner arc and the outer arc is changed, and the resonant frequency of the antenna is changed. The characteristic can be used as an indicative index for judging that the bolt is changed from a state with pretightening force to a state without pretightening force completely.
Example 2 (application System, working principle)
Further, a monitoring system is provided based on example 1
As shown in figure 3 of the drawings,
the application discloses a passive wireless bolt looseness monitoring system based on a double-arc patch antenna, which can realize corner measurement without an external wired power supply.
A passive wireless bolt looseness monitoring system based on a double-arc patch antenna is characterized by comprising an RFID tag 1, a reader 4 and a setting module; the reader 4 is responsible for wirelessly reading information of the RFID tag 1 and performing data processing.
The RFID tag 1 is used as a sensor for monitoring the loosening and rotating angle of a nut of the bolt; referring to embodiment 1, the RFID tag 1 is mounted on the nut to be measured 3-2 and the connected member 3, and is responsible for converting information on the nut rotation angle of the bolt to be measured 2 into an electromagnetic wave signal and transmitting it to the reader 4. The RFID tag comprises an antenna and a chip, and the inner arc functions as a sensing unit in angle measurement. Along with the loosening of the bolt, the nut rotates, the inner arc in the first component and the outer arc in the second component rotate relatively, the facing area is changed, the internal capacitance of the antenna is changed, and the resonant frequency of the antenna is shifted;
according to the specification, mechanical parameters and thread pitch of the bolt, the angle of rotation of the nut when the bolt changes from a preset pretightening force state to a completely-lost pretightening force state is determined through tests, and a module is arranged for inputting to a system. When the tag 1 is installed, any initial relative area of the inner arc and the outer arc can be selected, when the bolt of the object to be tested is loosened, the relative area of the inner arc and the outer arc is changed, the resonant frequency of the antenna is changed, and the influence relation is determined through tests.
The reader 4 comprises a wireless transceiving module, a modulation and demodulation module, a control module and a digital processing module; the wireless transceiver module and the modem module are all known technologies in the field, and are not innovative points of the present application. Through wireless transceiver module, modem module, the RFID reader can detect the resonant frequency drift of RFID label, provides control module, digital processing module after modem module demodulation, and digital processing module calculates the relative corner of two subassemblies according to the corresponding relation in setting up the module, and then judges the bolt state promptly nut rotation angle.
The control module is used for controlling an RFID reader of the system to transmit modulated electromagnetic wave signals to the RFID tag at different frequencies, and when the power of signals received by the RFID tag reaches a threshold value, a chip in the RFID tag can be activated. Minimum transmission power P of reader required for activating labelmin(f) Dependent on the frequency f of the signal transmitted by the readerWhen the reader transmits a signal at the resonant frequency of the antenna in the RFID tag fRMinimum transmit power P required to activate the tagmin(fR) And minimum.
The digital processing module can determine the resonant frequency of the antenna in the RFID tag by searching for the transmitting frequency which enables the minimum transmitting power to reach the minimum value. When the facing area of the inner arc and the outer arc in the antenna changes, the capacitance of the antenna changes, and the resonant frequency drifts, the method can determine the drift amount of the resonant frequency, so as to obtain the generated turning angle value and the nut rotating angle, and judge the bolt state according to the nut rotating angle.
Example 3
On the basis of embodiment 2, realize carrying out passive wireless monitoring to the bolt looseness in a large scale.
The system also comprises a storage module, wherein the codes and the position information of the tags carried by the chips in the electronic tag sensors are prestored, the system utilizes an RFID reader to transmit modulated electromagnetic wave signals to the tags, the codes of the tags can be identified, and when a plurality of RFID tags are arranged in the scanning range of the RFID reader, the reader can mark the bolt state of each measuring point according to the codes of the tags and quickly position the loosened bolts.
The above description is only illustrative of the preferred embodiments of the present application and is not intended to limit the scope of the present application in any way. Any changes or modifications made by those skilled in the art based on the above disclosure should be considered as equivalent effective embodiments, and all the changes or modifications should fall within the protection scope of the technical solution of the present application.

Claims (5)

1. A passive wireless bolt looseness monitoring system based on a double-arc patch antenna is characterized by comprising an RFID tag 1, a reader 4 and a setting module; the reader 4 is responsible for wirelessly reading the information of the RFID tag 1 and performing data processing;
the RFID tag 1 is arranged on the surface of the connected component 3; the RFID tag 1 consists of two components, wherein a first component 12 and a second component 13 are positioned on the same surface, and the specific structure is as follows:
the first component 12 is a circular plate, the center of the first component is provided with a hexagonal opening 12-1 and a metal inner arc 12-2, and the hexagonal opening 12-1 is used for being embedded and stably fixed on the outer edge of the screw cap 3-2;
the second component 13 is a rectangular plane and is used for being attached and fixed on the upper surface of the connecting component 3, and an intermediate plate is attached to the rectangular plane and is provided with a circular hole 13-1 and a metal outer arc 13-2; the second component is used as a main part of the electronic tag sensor and is also provided with a feed microstrip line 13-3 and a chip 13-4; the outer arc 13-2 is connected with the feed microstrip line 13-3, and the chip 13-4 is fixed on the intermediate plate and connected with the tail end of the feed microstrip line 13-3; embedding a circular plate of the first assembly into the circular hole 13-1 of the second assembly, rotating and contacting the surface of the connected member 3; the radians of the inner arc 12-2 and the outer arc 13-2 are the same, and the two arcs are matched with the initial position, so that the two arcs form the antenna capacitor of the electronic tag; when the first circular plate of the assembly rotates in the second circular plate of the assembly, the position of the inner arc 12-2 relative to the outer arc 13-2 is staggered, the internal capacitance of the antenna changes, and the working frequency of the antenna of the electronic tag in the equivalent circuit changes; when the tested nut 3-2 rotates relative to the connecting component 3 due to looseness, the circular plate of the first component 12 rotates together with the nut 3-2 synchronously, and the second component 13 is fixed on the connecting component 3, so that the inner arc 12-2 in the first component 12 and the outer arc 13-2 in the second component 13 rotate relatively, the internal capacitance of the antenna is disturbed, and the resonant frequency of the antenna is shifted;
the RFID tag 1 is arranged on the nut 3-2 to be tested and the connected component 3, and is responsible for converting the information of the nut rotation angle of the bolt 2 to be tested into an electromagnetic wave signal and transmitting the electromagnetic wave signal to the reader 4; the RFID tag comprises an antenna and a chip, and the inner circular arc plays a role of a sensing unit in angle measurement; along with the loosening of the bolt, the nut rotates, the inner arc in the first assembly and the outer arc in the second assembly rotate relatively, the facing area is changed, the internal capacitance of the antenna is changed, and the resonant frequency of the antenna is enabled to drift.
2. The passive wireless bolt looseness monitoring system based on the double-arc patch antenna as claimed in claim 1, wherein the reader 4 comprises a wireless transceiver module, a modulation and demodulation module, a control module and a digital processing module; through the wireless transceiving module and the modulation and demodulation module, the RFID reader detects the resonance frequency drift of the RFID tag, the resonance frequency drift is demodulated by the modulation and demodulation module and then is provided for the control module and the digital processing module, and the digital processing module calculates the relative rotation angle of the two components, namely the rotation angle of the nut according to the corresponding relation in the setting module, so as to judge the bolt state.
3. The passive wireless bolt looseness monitoring system based on the double-arc patch antenna as claimed in claim 2, wherein the control module is used for controlling an RFID reader of the system to transmit modulated electromagnetic wave signals to the RFID tag at different frequencies, and when the power of the signals received by the RFID tag reaches a threshold value, a chip in the RFID tag can be activated; minimum transmission power P of reader required for activating labelmin(f) In relation to the frequency f of the signal transmitted by the reader, f is the frequency of the resonant frequency of the antenna in the RFID tag when the reader transmits the signalRMinimum transmit power P required to activate the tagmin(fR) And minimum.
4. The passive wireless bolt looseness monitoring system based on the double-arc patch antenna as claimed in claim 2 or 3, wherein the digital processing module can determine the resonant frequency of the antenna in the RFID tag by searching for the transmitting frequency which enables the minimum transmitting power to reach the minimum value; when the facing area of the inner arc and the outer arc in the antenna changes, the capacitance of the antenna changes, and the resonant frequency drifts, the method can determine the drift amount of the resonant frequency, so as to obtain the generated turning angle value and the nut rotating angle, and judge the bolt state according to the nut rotating angle.
5. The passive wireless bolt looseness monitoring system based on the double-arc patch antenna is characterized in that the system further comprises a storage module, the codes and the position information of the tags carried by the chips in the electronic tag sensors are prestored, the system transmits modulated electromagnetic wave signals to the tags by utilizing an RFID reader, the codes of the tags can be identified, when a plurality of RFID tags are arranged in the scanning range of the RFID reader, the reader can mark the bolt state of each measuring point according to the codes of the tags, and can quickly locate the loosened bolts.
CN202011379444.2A 2020-12-01 2020-12-01 Bolt looseness sensor and looseness monitoring system based on double-arc patch antenna Active CN112697183B (en)

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CN103630282A (en) * 2013-11-13 2014-03-12 同济大学 Bolt loosening monitoring method and implementation device thereof
US10411339B2 (en) * 2014-07-30 2019-09-10 E-Band Communications, Llc Position adjuster for millimeter wave antenna
CN108181659B (en) * 2018-02-11 2024-03-15 上海振华重工(集团)股份有限公司 Loosening detection device for fastener and detection method thereof
CN109034340A (en) * 2018-08-06 2018-12-18 天津云拓网络科技有限公司 A kind of electronic tag that monitoring bolt loosens
CN109272092B (en) * 2018-08-31 2022-02-01 重庆西南集成电路设计有限责任公司 UHF RFID tag capable of detecting screw looseness
CN209764001U (en) * 2019-04-15 2019-12-10 同济大学 passive wireless RFID displacement sensor adopting circular patch antenna
CN211718914U (en) * 2020-04-27 2020-10-20 温州华邦安全封条股份有限公司 Nut looseness investigation device
CN211855813U (en) * 2020-04-27 2020-11-03 温州华邦安全封条股份有限公司 Checking device

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