A strain monitoring device and method based on radio frequency modulation

Abstract

The application discloses a strain monitoring device and method based on radio frequency modulation, and relates to the field of structural health monitoring.The device comprises a radio frequency transmission module for transmitting radio frequency electromagnetic waves outward, collecting mixed frequency electromagnetic waves, and determining strain information at a mechanical structure monitoring position according to the radio frequency electromagnetic waves and the mixed frequency electromagnetic waves; and a radio frequency stress sensor module for receiving the radio frequency electromagnetic waves, converting strain at the mechanical structure monitoring position into an oscillation frequency offset electrical signal based on the radio frequency electromagnetic waves, obtaining mixed frequency electromagnetic waves carrying strain information, and transmitting the mixed frequency electromagnetic waves outward.The application significantly improves the monitoring distance, guarantees high precision and long-term stability of micro-strain, and greatly reduces construction and maintenance costs.

Description

Technical Field

[0001] This application relates to the field of structural health monitoring, and in particular to a strain monitoring device and method based on radio frequency modulation. Background Technology

[0002] For large, long-span engineering structures (such as bridges, transmission towers, long pipelines, and large dams), the stress-strain state of key components during long-term service is an important indicator for assessing structural safety and service life. Therefore, long-term, stable strain monitoring of such structures is of significant engineering importance.

[0003] Most current strain gauge sensors use wired cabling, relying on cables for signal transmission and power supply. However, for ultra-long structures spanning hundreds of meters or even kilometers, wired deployment is not only difficult and costly to construct, but the cables themselves are also susceptible to damage from terrain, obstructions, and environmental corrosion, resulting in poor long-term reliability. To address the cabling challenges, some solutions have attempted to use short-range Bluetooth or short-range IoT transmission methods, but these wireless solutions typically have a transmission distance of only a few meters to tens of meters and require continuous power supply, still failing to meet the long-distance deployment requirements of large-scale, long-span projects.

[0004] In passive wireless strain measurement, existing technologies are mainly based on near-field electromagnetic coupling or traditional passive RFID principles. Near-field electromagnetic coupling relies on the mutual inductance between coils, limiting its effective measurement distance to the centimeter level and making it suitable only for extremely short-range sensing scenarios. Traditional UHF long-range passive RFID strain sensing uses a backscatter communication method with the transmitter and receiver operating at the same frequency. This results in the strong carrier signal from the transmitter easily drowning out the weak echo signal, leading to poor system anti-interference capabilities. Furthermore, the reflected signal attenuates to the fourth power with increasing distance, typically limiting the effective measurement distance to within 10 meters. These limitations make it difficult for existing technologies to simultaneously meet the dual requirements of "passive wireless" and "long-range high-precision monitoring," hindering their application in large-scale distributed long-term monitoring projects. Therefore, a technical solution capable of achieving passive wireless strain monitoring at distances of 100 meters or more is urgently needed. Summary of the Invention

[0005] The purpose of this application is to provide a strain monitoring device and method based on radio frequency modulation, which can improve the strain monitoring distance and ensure high accuracy and long-term stability of micro-strain levels, while reducing construction and maintenance costs.

[0006] To achieve the above objectives, this application provides the following solution: In a first aspect, this application provides a strain monitoring device based on radio frequency modulation, comprising: A radio frequency (RF) transmitting module is used to transmit RF electromagnetic waves outward, simultaneously acquire mixed electromagnetic waves, and determine strain information at the monitoring location of the mechanical structure based on the RF electromagnetic waves and the mixed electromagnetic waves. The radio frequency stress sensor module is used to receive the radio frequency electromagnetic wave, convert the strain at the monitoring position of the mechanical structure into an oscillation frequency offset electrical signal based on the radio frequency electromagnetic wave, obtain a mixed electromagnetic wave carrying strain information, and transmit the mixed electromagnetic wave outward.

[0007] In one embodiment, the radio frequency stress sensor module includes: a wireless power-gathering unit, an oscillation sensing unit, and a wireless mixing unit; the wireless power-gathering unit is used to receive the radio frequency electromagnetic waves and generate power to supply the oscillation sensing unit; when the wireless mixing unit is active, the wireless power-gathering unit is also used to supply power to the wireless mixing unit; the oscillation sensing unit is fixed at the monitoring position of the mechanical structure, and when deformation occurs at the monitoring position, the oscillation sensing unit converts the strain at the monitoring position into an oscillation frequency offset electrical signal; the wireless mixing unit mixes the oscillation frequency offset electrical signal with the radio frequency electromagnetic waves to obtain a mixed electromagnetic wave carrying strain information, and transmits the mixed electromagnetic wave outward.

[0008] In one embodiment, the wireless power supply unit includes a first receiving antenna, an impedance matching network, and a rectifier circuit connected in sequence. After receiving the radio frequency electromagnetic wave, the first receiving antenna transmits it to the rectifier circuit through the impedance matching network. The rectifier circuit rectifies the electromagnetic alternating current into direct current to power the oscillation sensing unit and, when the wireless mixing unit is active, powers the wireless mixing unit.

[0009] In one embodiment, the receiving frequency of the first receiving antenna is the same as the transmitting frequency of the radio frequency transmitting module.

[0010] In one embodiment, the wireless power supply unit further includes a filtering and smoothing circuit; the filtering and smoothing circuit is connected to the output terminal of the rectifier circuit and is used to filter and smooth the rectified DC power.

[0011] In one embodiment, the oscillation sensing unit loads the power generated by the wireless power supply unit onto the resonant device to generate narrow-frequency oscillation. When deformation occurs at the monitoring location, the resonant device experiences a frequency shift due to the force, thereby obtaining an electrical signal indicating the frequency shift.

[0012] In one embodiment, the wireless mixing unit includes a second receiving antenna, a mixing circuit, and a transmitting antenna connected in sequence; the second receiving antenna is used to receive radio frequency electromagnetic waves emitted by the radio frequency transmitting module; the mixing circuit is used to mix the oscillation frequency offset electrical signal with the radio frequency electromagnetic waves to obtain a mixed electromagnetic wave carrying strain information; the transmitting antenna is used to transmit the mixed electromagnetic wave outward.

[0013] In one embodiment, the receiving frequency of the second receiving antenna is the same as the transmitting frequency of the radio frequency transmitting module.

[0014] In one embodiment, the frequency of the radio frequency electromagnetic wave received by the wireless power-gathering unit is f0, the frequency of the oscillation frequency offset electrical signal generated by the oscillation sensing unit is f1, the frequency of the mixing electromagnetic wave is f0-f1 and / or f0+f1, and the frequency of the transmitting antenna is f0-f1 and / or f0+f1.

[0015] Secondly, this application provides a strain monitoring method based on radio frequency modulation, comprising: Radio frequency electromagnetic waves are emitted outward through a radio frequency transmission module; The radio frequency electromagnetic wave is received by the radio frequency stress sensor module. Based on the radio frequency electromagnetic wave, the strain at the monitoring position of the mechanical structure is converted into an oscillation frequency offset electrical signal to obtain a mixed electromagnetic wave carrying strain information, and the mixed electromagnetic wave is emitted outward. The mixed electromagnetic wave is acquired by a radio frequency transmission module, and the strain information at the monitoring location of the mechanical structure is determined based on the radio frequency electromagnetic wave and the mixed electromagnetic wave.

[0016] According to the specific embodiments provided in this application, this application has the following technical effects: By mapping structural strain to the frequency offset of a quartz crystal and using passive mixing to generate a mixing signal, this mixing signal is a low-frequency narrowband wave with strong diffraction and penetration capabilities. Furthermore, its frequency is far from the high-frequency carrier wave of the transmitter, effectively avoiding interference from strong co-frequency signals. This significantly increases the passive monitoring distance from several meters to tens of meters in traditional solutions to hundreds of meters or even kilometers, fully meeting the long-distance deployment requirements of large-scale, long-span projects. Moreover, in terms of measurement accuracy and long-term reliability, this application abandons the traditional amplitude-based measurement method, which is susceptible to interference, and instead adopts frequency-based measurement. The strain information is fully reflected in the frequency offset of the resonant device, unaffected by signal attenuation, environmental obstruction, and external electromagnetic interference. It can achieve accurate identification at the micro-strain level, ensuring high repeatability and stability during long-term service. Finally, in terms of system power consumption and engineering applicability, the sensing end does not require built-in batteries, active chips, or complex control circuits. It relies entirely on space radio frequency energy for power and passive mixing to achieve passive operation, truly achieving full-node wiring-free and maintenance-free operation. It can be pre-embedded inside the structure for a long time or deployed in high-altitude outdoor areas, significantly reducing the construction and operation and maintenance costs throughout the entire life cycle. It is especially suitable for engineering monitoring scenarios with large spans and dispersed deployments, such as bridges, dams, transmission towers, and long pipelines. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of a strain monitoring device based on radio frequency modulation, provided as an embodiment of this application.

[0019] Figure 2 This is a schematic flowchart of a strain monitoring method based on radio frequency modulation, provided as an embodiment of this application.

[0020] Figure 3 This is a schematic diagram of a Pierce oscillator circuit in one embodiment of this application. Detailed Implementation

[0021] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] The purpose of this application is to provide an integrated hardware architecture for non-contact stress detection that requires no wiring, has no built-in battery, and requires no contact.

[0023] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] In one exemplary embodiment, such as Figure 1 As shown, a strain monitoring device based on radio frequency modulation is provided, including a radio frequency transmission module 101 and a radio frequency stress sensor module 102.

[0025] The radio frequency transmission module 101 is used to transmit radio frequency electromagnetic waves to the outside, and simultaneously collect mixed electromagnetic waves, and determine the strain information at the monitoring position of the mechanical structure based on the radio frequency electromagnetic waves and the mixed electromagnetic waves.

[0026] The radio frequency stress sensor module 102 is used to receive the radio frequency electromagnetic wave, convert the strain at the monitoring position of the mechanical structure into an oscillation frequency offset electrical signal based on the radio frequency electromagnetic wave, obtain a mixed electromagnetic wave carrying strain information, and transmit the mixed electromagnetic wave outward.

[0027] Specifically, the radio frequency stress sensor module 102 includes: a wireless power supply unit 21, an oscillation sensing unit 22, and a wireless mixing unit 23.

[0028] The wireless power supply unit 21 is used to receive the radio frequency electromagnetic waves and generate power to supply the oscillation sensing unit 22. When the wireless mixing unit 23 is active, the wireless power supply unit 21 is also used to supply power to the wireless mixing unit 23.

[0029] In a specific application example, the wireless power supply unit 21 includes a first receiving antenna, an impedance matching network, and a rectifier circuit connected in sequence. After receiving the radio frequency electromagnetic wave, the first receiving antenna transmits it to the rectifier circuit via the impedance matching network. The rectifier circuit rectifies the electromagnetic alternating current into direct current to power the oscillation sensing unit 22, and also powers the wireless mixing unit 23 when it is active. The receiving frequency of the first receiving antenna is the same as or close to the transmission frequency of the radio frequency transmitting module 101.

[0030] In addition, the wireless power supply unit 21 also includes a filtering and smoothing circuit. The filtering and smoothing circuit is connected to the output terminal of the rectifier circuit and is used to filter and smooth the rectified DC power.

[0031] The oscillation sensing unit 22 is fixed at the monitoring position of the mechanical structure. When deformation occurs at the monitoring position, the oscillation sensing unit 22 converts the strain at the monitoring position into an electrical signal of oscillation frequency shift.

[0032] In a specific application example, the oscillation sensing unit 22 applies the power generated by the wireless power supply unit 21 to the resonant device, producing narrow-frequency oscillation. When deformation occurs at the monitoring location, the resonant device experiences a frequency shift due to the force, thus generating an electrical signal indicating the frequency shift. The resonant device is fixed at the monitoring location of the mechanical structure (typically two fixed beams in a module). The resonant device can be a quartz crystal or a silicon-based resonator.

[0033] The wireless mixing unit 23 is used to mix the oscillation frequency offset electrical signal with the radio frequency electromagnetic wave to obtain a mixed electromagnetic wave carrying strain information, and then transmits the mixed electromagnetic wave outward.

[0034] In a specific application example, the wireless mixing unit 23 includes a second receiving antenna, a mixing circuit, and a transmitting antenna connected in sequence. The second receiving antenna is used to receive radio frequency electromagnetic waves emitted by the radio frequency transmitting module 101. The mixing circuit is used to mix the oscillation frequency offset electrical signal with the radio frequency electromagnetic waves to obtain a mixed electromagnetic wave carrying strain information. The transmitting antenna is used to transmit the mixed electromagnetic wave outward. Specifically, the second receiving antenna can reuse the first receiving antenna or can be set independently. The mixing circuit can be a transistor mixing circuit, a field-effect transistor mixer, or a diode mixing circuit.

[0035] The receiving frequency of the second receiving antenna is the same as or close to the transmitting frequency of the radio frequency transmitting module 101. The transmitting frequency of the transmitting antenna, the transmitting frequency of the radio frequency transmitting module 101, and the frequency of the mixing electromagnetic wave are the same as or close to each other. The first receiving antenna, the second receiving antenna, and the transmitting antenna can all be narrowband antennas.

[0036] This application leverages the long-distance coupling and transmission capabilities of high-frequency radio frequency electromagnetic waves to achieve stable stress and strain monitoring of fixed nodes spaced hundreds of meters apart. It eliminates the need for cabling between monitoring nodes, overcoming wiring limitations imposed by terrain, span, and obstructive structures. This makes it suitable for engineering scenarios with large spans and dispersed deployments, such as long-distance bridges, transmission towers, long pipelines, and large dams. Furthermore, it can be permanently embedded within engineering structures, high-altitude frameworks, and uninhabited areas in the field, significantly reducing subsequent inspection, replacement, and maintenance costs, and meeting the requirements for long-term service monitoring in engineering projects.

[0037] Specifically, a closed-loop detection method using the same radio frequency module for both emission and acquisition is employed: the radio frequency transmitting module 101 emits radio frequency electromagnetic waves while simultaneously receiving mixed electromagnetic waves radiated by the radio frequency stress sensor module 102 at a distance; the minute strain of the monitored part is converted into an oscillation frequency offset electrical signal by the oscillation sensing unit 22, and then nonlinearly mixed with the radio frequency electromagnetic waves emitted by the radio frequency transmitting module 101 by the wireless mixing unit 23 to generate a difference frequency mixed signal. The real-time oscillation frequency of the quartz crystal 302 is inverted through the relationship of the mixing frequency difference, and the structural stress and strain are calculated from the frequency offset, achieving passive, non-contact, high-precision non-destructive monitoring at the hundreds of meters level, and supporting multi-node distributed synchronous strain measurement.

[0038] Based on the same inventive concept, this application also provides a strain monitoring method based on radio frequency modulation (RF modulation) using the aforementioned video-based RF modulation strain monitoring device. The solution provided by this method is similar to the solution described in the aforementioned device. Therefore, the specific limitations in one or more RF modulation-based strain monitoring method embodiments provided below can be found in the limitations of the RF modulation-based strain monitoring device described above, and will not be repeated here.

[0039] In one exemplary embodiment, such as Figure 2 As shown, a strain monitoring method based on radio frequency modulation is provided, including the following steps 201 to 203.

[0040] Step 201: Radio frequency electromagnetic waves are transmitted outward through the radio frequency transmission module 101.

[0041] Specifically, the radio frequency transmitting module 101 continuously radiates electromagnetic waves of a single frequency, the frequency of which is f{radio frequency}.

[0042] Step 202: The radio frequency electromagnetic wave is received by the radio frequency stress sensor module 102. Based on the radio frequency electromagnetic wave, the strain at the monitoring position of the mechanical structure is converted into an oscillation frequency offset electrical signal to obtain a mixed electromagnetic wave carrying strain information, and the mixed electromagnetic wave is emitted outward.

[0043] Specifically, the wireless power unit 21 in the radio frequency stress sensor module 102 extracts electrical energy: after the first receiving antenna receives radio frequency electromagnetic waves, it transmits them to the rectifier circuit through an impedance matching network; the rectifier circuit converts the electromagnetic AC into DC voltage (including voltage multiplier boost if necessary).

[0044] The DC voltage obtained by the wireless power unit 21 is applied to the oscillation circuit of the quartz device, driving the quartz device to generate oscillations at a fixed frequency, f{crystal}. The oscillation circuit employs, for example... Figure 3The Pierce oscillator circuit shown here primarily functions to convert the mechanical vibrations of a quartz device into stable electrical oscillation signals. The Pierce oscillator circuit mainly consists of the following parts: (1) Core active amplification device—CMOS inverter 301. In the Pierce oscillator circuit, it is biased in the amplification region (usually achieved through a megaohm-level feedback resistor embedded across the inverter) and used as an inverting amplifier. It provides the necessary gain and 180° phase shift for the oscillation to compensate for the resonant loss of the quartz crystal 302 and maintain the oscillation.

[0045] (2) Frequency Determination and Feedback Element – ​​Quartz Crystal 302. The quartz crystal 302 is connected between the output (drain) and input (gate) terminals of the CMOS inverter 301, forming a feedback path. It acts as a high-Q (quality factor) frequency-selective network, equivalent to an inductor. The circuit satisfies the oscillation phase condition only near the inherent series or parallel resonant frequency of the quartz crystal 302, thus outputting an extremely stable and singular narrow-frequency oscillation signal. When external strain is transmitted to the crystal, its equivalent reactance parameter changes, and the oscillation frequency shifts accordingly.

[0046] (3) Load capacitors – C1 and C2. The first capacitor C1 is connected between the input terminal of the inverter and ground (GND), and the second capacitor C2 is connected between the output terminal of the inverter and ground. These two capacitors, together with the quartz crystal 302, form a “three-point” capacitor resonant circuit. They not only determine the load capacitance value of the oscillation circuit and finely adjust the precise resonant frequency of the quartz crystal 302, but also play a role in stabilizing oscillation and filtering out high-order harmonics.

[0047] The working logic of the Pierce oscillator circuit is as follows: when the DC voltage output by the wireless power unit 21 is applied to the oscillator circuit, the CMOS inverter 301 is powered on and works in conjunction with C1, C2 and the quartz crystal 302 to oscillate, generating an electrical signal with a frequency of f{crystal}. This signal is then sent to the wireless mixer unit 23 as a source signal carrying strain information.

[0048] The wireless mixing unit 23 mixes the oscillation frequency offset electrical signal with the frequency transmitted by the radio frequency (RF) transmitting module 101, and then transmits it through the transmitting antenna. Taking a MOSFET for mixing as an example, the gate is connected to the electrical signal generated by the oscillation circuit of the quartz device; the source is connected to the electrical signal received by the second receiving antenna; the source signal drives the transmitting antenna to radiate electromagnetic waves; the source signal is the mixed electromagnetic wave, f{mixing} = |f{RF} ± f{crystal}|. Here, the transmitting antenna can also act as a narrowband filter for frequency selection, distinguishing whether the radiated frequency is f{RF} + f{crystal} or f{RF} - f{crystal}. Here, f{mixing} is the frequency of the mixed electromagnetic wave.

[0049] When a quartz device is fixed to a strain-sensitive mechanical structure, stress is generated in the quartz device when the structure is strained. This stress causes a change in the quartz's vibration frequency f{crystal}. This change also corresponds to a change in f{mixing frequency}.

[0050] Step 203: Acquire the mixed electromagnetic wave through the radio frequency transmission module 101, and determine the strain information at the monitoring position of the mechanical structure based on the radio frequency electromagnetic wave and the mixed electromagnetic wave.

[0051] Specifically, after the radio frequency transmitting module 101 receives the mixed electromagnetic wave radiated by the transmitting antenna, it converts it to the frequency domain and compares it with the frequency of the radio frequency electromagnetic wave to obtain f{crystal}. Further calibration can be used to determine the strain at the sensor end.

[0052] This application also provides two application scenarios, both of which utilize the aforementioned strain monitoring device based on radio frequency modulation.

[0053] Application Scenario 1: Health monitoring of long-span bridge structures.

[0054] The bridge towers, main cable anchorage zones, and critical welds of steel box girders of long-span cable-stayed or suspension bridges are subjected to alternating loads and wind-induced vibrations over long periods, making them core components for structural safety. Existing wired strain gauges face extreme difficulties in wiring high above the bridge towers and along the kilometer-long main cable lines, resulting in high construction risks and enormous maintenance costs. On the other hand, short-range wireless solutions cannot cover all critical sections due to the open space on the bridge deck and the large spacing between nodes.

[0055] This application allows for the deployment of multiple radio frequency (RF) stress sensing modules at intervals of hundreds of meters along the main cable or the bottom of the steel box girder of a bridge. Radio frequency transmitting / receiving base stations are centrally deployed at bridge towers or piers, achieving wire-free coverage of critical nodes throughout the bridge. Each RF stress sensing module operates passively, powered entirely by radio frequency, requiring no battery replacement. It can be permanently embedded in the concrete of the anchorage zone or welded inside the steel box girder, and periodically polled by the base station to obtain strain data from each node, effectively supporting the bridge's full life-cycle safety assessment.

[0056] Application Scenario 2: Stress monitoring of long-distance buried / overhead pipelines.

[0057] Long-distance oil and gas pipelines and urban heating networks often traverse uninhabited areas, rivers, ditches, or elevated utility tunnels. The terrain along these pipelines is complex, and the spans are enormous. Critical bends, welds, and crossing sections require long-term monitoring of additional stress caused by geological subsidence or thermal expansion and contraction. Traditional wired monitoring requires laying power and signal cables along the pipeline, which involves a large amount of excavation and is expensive. Furthermore, in the field, these cables are easily chewed by animals or broken during construction. Battery-powered solutions face the challenge of regular replacement, and with long pipelines often stretching hundreds of kilometers, maintenance is almost impossible.

[0058] This application allows for the installation of a radio frequency (RF) stress sensing module every few hundred meters along the pipeline, firmly attached to the strain-sensitive area of ​​the pipeline's outer wall. Wireless power supply and data acquisition are achieved using RF transmitting base stations deployed along the pipeline. The RF stress sensing module employs a passive, chip-free architecture, adapting to harsh environments such as high and low temperatures and humidity in the field. It can operate maintenance-free for extended periods, providing timely alarms for abnormal strains such as pipeline thermal displacement and settlement, thus offering reliable assurance for the safe operation of the pipeline.

[0059] In summary, this application has at least the following advantages over the prior art: (1) The measurement distance is greatly improved, realizing passive wireless strain measurement at the level of hundreds of meters or even kilometers. This application maps the structural strain to the frequency offset of the quartz crystal, and then generates a difference frequency mixing signal through passive mixing; the mixing is a low-frequency narrowband signal, which has a much stronger diffraction, penetration and long-distance transmission capability than the traditional RFID co-frequency signal; at the same time, it avoids the high-frequency strong carrier interference of the transmitter, and the increase of the transmitter power does not affect the detection of the weak mixing signal, realizing stable passive monitoring at hundreds of meters.

[0060] (2) The measurement accuracy and long-term stability are significantly improved. This application adopts frequency-type measurement instead of traditional amplitude-type measurement, which is not affected by signal attenuation, obstruction and electromagnetic interference; it ensures that the frequency shift under micro-strain can be accurately identified, and the measurement accuracy and repeatability are far superior to traditional solutions.

[0061] (3) Ultra-low power consumption, all nodes are passive and maintenance-free. Through the architecture of radio frequency wireless power supply, passive mixing without active chips, sensor nodes without batteries, active MCUs, and no wiring required, it works passively by relying entirely on space radio frequency energy, with power consumption close to zero. It can be pre-buried in the structure or in the high-altitude field for a long time without the need for later replacement and maintenance.

[0062] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.

[0063] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0064] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A strain monitoring device based on radio frequency modulation, characterized in that, include: A radio frequency (RF) transmitting module is used to transmit RF electromagnetic waves outward, simultaneously acquire mixed electromagnetic waves, and determine strain information at the monitoring location of the mechanical structure based on the RF electromagnetic waves and the mixed electromagnetic waves. The radio frequency stress sensor module is used to receive the radio frequency electromagnetic wave, convert the strain at the monitoring position of the mechanical structure into an oscillation frequency offset electrical signal based on the radio frequency electromagnetic wave, obtain a mixed electromagnetic wave carrying strain information, and transmit the mixed electromagnetic wave outward.

2. The strain monitoring device based on radio frequency modulation according to claim 1, characterized in that, The radio frequency stress sensor module includes: a wireless power supply unit, an oscillation sensing unit, and a wireless mixer unit; The wireless power unit is used to receive the radio frequency electromagnetic waves and generate power to power the oscillation sensing unit; when the wireless mixer unit is active, the wireless power unit is also used to power the wireless mixer unit. The oscillation sensing unit is fixed at the monitoring position of the mechanical structure. When deformation occurs at the monitoring position, the oscillation sensing unit converts the strain at the monitoring position into an electrical signal of oscillation frequency shift. The wireless mixing unit is used to mix the oscillation frequency offset electrical signal with the radio frequency electromagnetic wave to obtain a mixed electromagnetic wave carrying strain information, and then transmits the mixed electromagnetic wave outward.

3. The strain monitoring device based on radio frequency modulation according to claim 2, characterized in that, The wireless power supply unit includes a first receiving antenna, an impedance matching network, and a rectifier circuit connected in sequence. After the first receiving antenna receives the radio frequency electromagnetic wave, it transmits it to the rectifier circuit through the impedance matching network. The rectifier circuit rectifies the electromagnetic AC power into DC power to power the oscillation sensing unit and to power the wireless mixing unit when the wireless mixing unit is active.

4. The strain monitoring device based on radio frequency modulation according to claim 3, characterized in that, The receiving frequency of the first receiving antenna is the same as the transmitting frequency of the radio frequency transmitting module.

5. The strain monitoring device based on radio frequency modulation according to claim 3, characterized in that, The wireless power supply unit also includes a filtering and smoothing circuit; the filtering and smoothing circuit is connected to the output terminal of the rectifier circuit and is used to filter and smooth the rectified DC power.

6. The strain monitoring device based on radio frequency modulation according to claim 2, characterized in that, The oscillation sensing unit loads the power generated by the wireless power supply unit onto the resonant device to generate narrow-frequency oscillation. When deformation occurs at the monitoring location, the resonant device experiences a frequency shift due to the force, thereby obtaining an electrical signal indicating the frequency shift.

7. The strain monitoring device based on radio frequency modulation according to claim 2, characterized in that, The wireless mixing unit includes a second receiving antenna, a mixing circuit, and a transmitting antenna connected in sequence. The second receiving antenna is used to receive radio frequency electromagnetic waves emitted by the radio frequency transmitting module; The mixing circuit is used to mix the oscillation frequency offset electrical signal with the radio frequency electromagnetic wave to obtain a mixed electromagnetic wave carrying strain information. The transmitting antenna is used to transmit the mixed electromagnetic wave outward.

8. The strain monitoring device based on radio frequency modulation according to claim 7, characterized in that, The receiving frequency of the second receiving antenna is the same as the transmitting frequency of the radio frequency transmitting module.

9. The strain monitoring device based on radio frequency modulation according to claim 7, characterized in that, The frequency of the radio frequency electromagnetic wave received by the wireless power-gathering unit is f0, the frequency of the oscillation frequency offset electrical signal generated by the oscillation sensing unit is f1, the frequency of the mixing electromagnetic wave is f0-f1 and / or f0+f1, and the frequency of the transmitting antenna is f0-f1 and / or f0+f1.

10. A strain monitoring method based on radio frequency modulation, using the strain monitoring device based on radio frequency modulation as described in any one of claims 1-9, characterized in that, The method includes: Radio frequency electromagnetic waves are emitted outward through a radio frequency transmission module; The radio frequency electromagnetic wave is received by the radio frequency stress sensor module. Based on the radio frequency electromagnetic wave, the strain at the monitoring position of the mechanical structure is converted into an oscillation frequency offset electrical signal to obtain a mixed electromagnetic wave carrying strain information, and the mixed electromagnetic wave is emitted outward. The mixed electromagnetic wave is acquired by a radio frequency transmission module, and the strain information at the monitoring location of the mechanical structure is determined based on the radio frequency electromagnetic wave and the mixed electromagnetic wave.

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