WO2018101626A1 - Sensor for monitoring tendon tensile strength and tendon tensile strength diagnosis system using same - Google Patents

Abstract

An eddy current sensor device includes a coil part and a casing. The coil part includes: an excitation coil for generating a first magnetic field; and a sensing coil for detecting an electrical signal corresponding to a second magnetic field generated by an eddy current induced into a target structure by a first magnetic field, and to a synthetized magnetic field of the first magnetic field. The casing encompasses the coil part and blocks the same from the outside while accommodating the same therein. A magnetic part, which is accommodated and fixed inside the casing in order to fix the casing and the coil part to the target structure by magnetic force, can be further included. An eddy current sensor for the tensile strength of a tendon for providing stress changing on the basis of the tensile strength is provided on the surface of at least one wedge, which is press-fitted between the tendon and an anchor head such that a magnetic permeability thereof changes according to the stress of the tendon. A tensile strength monitoring part provides an excitation signal to the eddy current sensor, and calculates information on the tensile strength of the tendon by using the electrical signal detected by the eddy current sensor. If the calculated tensile strength drops below an allowable threshold value, a danger alert is automatically issued. In a test vehicle, driving power is provided to the tensile strength monitoring part in a magnetic induction manner, and tendon tensile strength information measured by the eddy current sensor can be collected from the tensile strength monitoring part.

Description

Tendon tension monitoring sensor and Tendon's tension diagnosis system

The present invention relates to a structural safety diagnosis, and more particularly, to a technology for diagnosing safety of a structure by monitoring a tension force of the tendon in a structure in which a tendon is installed.

Post-tensioning (PT) is a widely used method for the design of concrete bridges and high-rise buildings. It uses pre-stress to the structure by using tendons made of tendons. Increase the strength of the structure. Tendon, a major member of the process, gradually relaxes his tension over time. Due to the relaxation of tension on the structure, the safety of the structure can be threatened. In order to prevent this problem, it is necessary to accurately monitor the PT tendon tension and to develop a technique for preventing damage to the structure due to the weakening of the tension.

Various studies have been conducted to accurately measure the tension of PT tendons mounted on structures. As a representative technique for monitoring tension relaxation, techniques using an electromagnetic sensor, a fiber optic sensor, or an elongation sensor have been proposed. The technique using the electromagnetic sensor is installed in the form of passing the tendon in the center of the cylindrical electromagnetic sensor. Magnetize the tendon by generating a strong magnetic field to ensure sufficient measurement resolution. At this time, since the power of several hundred watts is required instantaneously to magnetize the tendon, the size is large, and there is a limit in terms of practicality for use in actual civil construction sites. The fiber optic sensor technique is applied to the construction of a new type of tendon in which an optical fiber is inserted. Fiber optic sensors are quite expensive and require very long fiber optics to build bridges ranging from several to tens of kilometers, resulting in high initial installation costs. The technique using the elongation sensor is a method in which the elongation sensor is attached to the anchor head as a whole to indirectly measure the tension force of the tendon using the elongation state of the anchor head. The disadvantage is that it can monitor extreme load changes such as tendon cutting rather than tendon tension monitoring. In addition, although the price per unit of elongation sensor is small, the number of sensors required for multi-tendon measurement requires attention to processing management and monitoring data.

One object of the present invention for solving the above problems can be easily installed in the wedge of the PT tendon fixing unit, to monitor the degree of tension relaxation of the PT tendon by measuring the change in the magnitude of the eddy current by causing an eddy current in the wedge It is possible to provide an eddy current sensor device that can increase the measurement accuracy by blocking the influence of an external magnetic field.

Another object of the present invention is to provide a system for diagnosing the tension force of the tendon of the structure which can automatically alarm when the magnitude of the tendon falls below the allowable threshold while monitoring the tension force using the eddy current sensor device.

Another object of the present invention is to measure the tension force of the tendon using the eddy current sensor device, and to provide and collect information about the power required for driving the eddy current sensor device and the tendon tension force measured by the eddy current sensor device in a magnetic induction manner. Tendon's tension diagnosis system can be provided.

In order to achieve the above object of the present invention, the eddy current sensor device according to the embodiments of the present invention includes a coil portion and a casing. The coil unit is configured to sense an excitation coil for generating a first magnetic field, an electrical signal corresponding to a second magnetic field generated by an eddy current induced by a first magnetic field in a target structure and a composite magnetic field of the first magnetic field. It includes a coil. The casing surrounds the coil part while receiving the inside, and is made of a material having a magnetic shielding ability to block a magnetic field from flowing into the coil part from the outside.

In an exemplary embodiment, the eddy current sensor device may further include a magnetic force for receiving and fixing the inside of the casing to improve the sensitivity of the eddy current sensor while magnetically fixing the casing and the coil to the target structure. .

In an exemplary embodiment, the coil unit may be interpolated into the excitation coil to form a double cylinder of the sensing coil and the excitation coil.

In example embodiments, the eddy current sensor device may further include a coil case surrounding connectors of the excitation coil and the sensing coil and provided with connectors connected to the excitation coil and the sensing coil, respectively.

In an exemplary embodiment, the coil unit may have a shape in which the sensing coil and the excitation coil are arranged in a two-layer structure via a flexible printed circuit board (FPCB) having a predetermined shape.

In an exemplary embodiment, the coil portion includes a plurality of FPCB-type coil portion, and a flexible connection member disposed between the plurality of FPCB-type coil portion to connect the plurality of FPCB-type coil portion to form a closed loop, The FPCB type coil unit may have a structure in which the sensing coil and the excitation coil are arranged in a two-layer structure via a flexible printed circuit board (FPCB) having a predetermined shape.

In an exemplary embodiment, the eddy current sensor device may further include a magnetic force for receiving and fixing the inside of the casing to improve the sensitivity of the eddy current sensor while magnetically fixing the casing and the coil to the target structure. .

In an exemplary embodiment, a plurality of coil parts may be provided, and a plurality of magnetic force parts may be provided, such as the coil part, and one coil may be provided for each coil part. The eddy current sensor device may further include a plurality of elastic members that support the coils by being fixed to the target structure by providing elastic force to each permanent magnet while fixing the plurality of magnetic forces inside the casing. Can be.

In order to achieve the above object of the present invention, the tendon tension force diagnosis system according to the embodiments of the present invention indents the tendon force of the tendon (tendon) between the tendon and the anchor head to provide a variable stress based on the tension force And to monitor through at least one wedge whose magnetic permeability changes with the stress of the tendon. The tendon tension diagnosis system includes an eddy current sensor and a tension monitoring unit. The eddy current sensor is installed on the surface of the at least one wedge, the excitation coil for generating a first magnetic field based on the excitation signal, and the eddy current generated by the eddy current induced in the at least one wedge by the first magnetic field A coil unit including a second magnetic field and a sensing coil configured to detect an electrical signal corresponding to the synthesized magnetic field of the first magnetic field; And a casing surrounding the coil part while being accommodated therein and made of a material having a magnetic shielding ability to block a magnetic field from flowing into the coil part from the outside. The tension force monitoring unit provides the excitation signal to the eddy current sensor, and calculates information on the tension force of the tendon using the electrical signal detected by the eddy current sensor.

In an exemplary embodiment, the tension monitoring unit (i) performs a measurement of the electrical signal n times through the eddy current sensor under an initial tension condition to calculate a first dispersion value (σ ₀ ), and (ii) Even when the tension force of the tendon is changed as the elapsed time, the second dispersion value σ ₁ is calculated by performing the same measurement of the electrical signal n times through the eddy current sensor, and (iii) the calculated first dispersion value ( Implement an algorithm that calculates the damage index through probability statistical analysis of σ ₀ ) and the second variance value (σ ₁ ), and (iv) automatically generates a risk alert when the calculated damage index exceeds the acceptable threshold. It can have a function to execute a programmed program.

In an exemplary embodiment, the tendon tension diagnosis system is received and fixed inside the casing to magnetically enhance the sensitivity of the eddy current sensor while magnetically fixing the casing and the coil to a surface of the at least one wedge. It may further include wealth.

In an exemplary embodiment, the tension monitoring unit includes: a waveform generator for providing the excitation signal having a predetermined frequency based on a transmission control signal; A digitizer for digitizing the electrical signal corresponding to the second magnetic field to provide a digital electrical signal; And a controller configured to provide the transmission control signal to the waveform generator and to receive the digital electrical signal from the digitizer to calculate the tension force of the tendon.

In an exemplary embodiment, the control unit may include a function of alerting a danger when the magnitude of the calculated tension falls below an acceptable threshold.

In an exemplary embodiment, the control unit may use the transmission control signal and the reception control signal for synchronization between the waveform generator and the digitizer by providing a reception control signal to the digitizer to receive the digital electrical signal. have.

In an exemplary embodiment, the number of the predetermined frequencies may be plural.

In an exemplary embodiment, the tension monitoring unit compares the first digital electrical signal acquired during the first time interval of the digital electrical signal with the second digital electrical signal acquired during the second time interval of the digital electrical signal. It may be to determine the tendon damage index.

In an exemplary embodiment, the tendon tension diagnosis system is coupled to the primary force coil installed in the movable body, the structure in which the eddy current sensor is installed, the primary coil coupled to the primary coil and inductively coupled to the tension monitoring unit A power and data radio transmitter including a secondary coil; And installed in the movable body and connected to the primary side coil to provide power necessary for driving the eddy current sensor and the tension monitoring unit through the power and data wireless transmission unit in a magnetic induction manner and from the tension monitoring unit. The wireless transmission and data receiving unit for collecting information about the tension of the magnetic induction method may further include.

In an exemplary embodiment, the movable body is a vehicle, and the structure may be at least one of roads and bridges that the vehicle can carry.

The tendon tension monitoring system according to the embodiments of the present invention uses a magnetic force to attach the eddy current sensor to the wedge surface, so the installation method is very simple. In addition, the magnetic force providing magnetic force can efficiently generate the eddy current at the wedge surface can improve the sensitivity of the sensor.

By using the casing with excellent magnetic shielding function to wrap the coil part of the eddy current sensor, not only can the sensor accuracy be improved by blocking external magnetic factors, but also there is an advantage that the coil part can be safely protected from the outside.

In addition, the present invention has the advantage that it is possible to facilitate the safety management of the structure by automatically generating a danger alarm when the tension force of the tendon falls below the acceptable threshold.

The present invention can provide the driving power to the eddy current sensor and the data collection from the eddy current sensor wirelessly by the magnetic induction method using the inspection vehicle, it is possible to simplify the tendon tension monitoring system to reduce the initial cost In addition, it can reduce the maintenance costs of the system and provide the advantage of easy data collection.

1 is an exploded perspective view showing the configuration of a cylindrical eddy current sensor according to an embodiment of the present invention.

FIG. 2A is a plan sectional view of a coil portion of a cylindrical eddy current sensor according to an embodiment of the present invention, and FIG. 2B is a sectional view taken along a cutting line A-A '.

Figure 3 shows a state in which the cylindrical eddy current sensor according to an embodiment of the present invention is installed on the wedge surface of the anchor head.

4 is a cross-sectional view taken along the line BB ′ of FIG. 3.

Figure 5 is a block diagram showing the configuration of a system for monitoring the tension force of the PT tendon using a cylindrical eddy current sensor according to an embodiment of the present invention.

Figure 6 is a flow chart illustrating a tension force measurement procedure of the PT tendon tension force monitoring system according to embodiments of the present invention.

7 (a) and 7 (b) are diagrams for explaining the damage index of tendons calculated by the tendon tension monitoring system shown in FIG.

FIG. 8 is a flowchart illustrating an algorithm for calculating a damage index and processing an automatic warning of a risk due to tension relaxation by processing PT tension force tension monitoring data measured in a PT tension force monitoring system according to embodiments of the present invention.

9 shows an example of an eddy current graph measured under an initial tension force condition.

10 shows an example of an eddy current graph measured under changed tension conditions.

11 shows an example of a graph for performing hypothesis testing using the difference between the initial tension force and the changed tension force.

12 shows an example of a graph for automatically determining whether PT tendon tension is lowered through damage index-based online monitoring.

13 illustrates a coil arrangement of an FPCB type eddy current sensor according to another embodiment of the present invention.

14 is a cross-sectional view of the FPCB type eddy current sensor according to an embodiment of the present invention installed on the wedge surface of the anchor head.

FIG. 15 is a plan view illustrating a coil unit for an FPCB type eddy current sensor, in which three FPCB type eddy current sensors shown in FIG. 13 are connected in a circular closed loop shape through a flexible connecting member.

16 is a schematic conceptual diagram of a wireless sensor node system for tendon tension monitoring employing an eddy current sensor according to an embodiment of the present invention.

17 is a flowchart illustrating a wireless power supply to a sensor node and wireless acquisition of data detected by the sensor node using the tendon tension monitoring wireless sensor node system shown in FIG. 16.

With respect to the embodiments of the present invention disclosed in the text, specific structural to functional descriptions are merely illustrated for the purpose of describing embodiments of the present invention, embodiments of the present invention may be implemented in various forms and It should not be construed as limited to the embodiments described in.

As the inventive concept allows for various changes and numerous modifications, particular embodiments will be illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to a specific disclosed form, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms may be used for the purpose of distinguishing one component from another component. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component.

When a component is referred to as being "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but it may be understood that other components may be present in between. Should be. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that there is no other component in between. Other expressions describing the relationship between components, such as "between" and "immediately between," or "neighboring to," and "directly neighboring to" should be interpreted as well.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "having" are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof that is described, and that one or more other features or numbers are present. It should be understood that it does not exclude in advance the possibility of the presence or addition of steps, actions, components, parts or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in the commonly used dictionaries should be construed as meanings consistent with the meanings in the context of the related art and shall not be construed in ideal or excessively formal meanings unless expressly defined in this application. .

Hereinafter, with reference to the accompanying drawings, it will be described in detail a preferred embodiment of the present invention. The same reference numerals are used for the same elements in the drawings, and duplicate descriptions of the same elements are omitted.

1 is an exploded perspective view showing the configuration of a cylindrical eddy current sensor 200 according to an embodiment of the present invention. 2 (a) and 2 (b) are a planar cross-sectional view and a side cross-sectional view of the coil unit 210 of the cylindrical eddy current sensor 200 shown in FIG. 1. 3 illustrates a state in which the cylindrical eddy current sensor 200 illustrated in FIG. 1 is installed on the surface of the wedge 330 of the anchor head 370, and a part of the casing 260 is cut away so that the inside of the eddy current sensor 200 is visible. Shows the state. 4 is a cross-sectional view taken along the line BB ′ of FIG. 3.

1 and 2, the cylindrical eddy current sensor 200 includes a coil unit 210. According to the embodiment, the coil unit 210 includes an excitation coil 220 in which the conductive wire is wound in a cylindrical shape, and a sensing coil 240 in which the conductive wire is wound in a cylindrical shape. The outer diameter of the sensing coil 240 is smaller than the inner diameter of the exciting coil 220, and the inner diameter is larger than the diameter of the tendon 310 to be monitored. The sensing coil 240 is interpolated in the excitation coil 220 such that the two coils 220 and 240 may be combined in a double cylindrical shape. The sensing coil 240 and the exciting coil 220 may be bonded with an adhesive, for example. The double cylindrical combination of the excitation coil 220 and the sensing coil 240 may be wrapped in the coil case 215 to form a cylindrical coil unit 210. Connectors 217 may be provided in the coil case 215. The connector 217 may be used to provide an excitation signal ES to the eddy current sensor 200 and to receive the voltage signal VS from the eddy current sensor 200 (to be described later). In this way, the sensing coil 240 of the sensor 200 may be disposed inside to efficiently monitor the magnetic field change. The exciting coil 220 may form a magnetic field on the outside.

According to the exemplary embodiment, the cylindrical eddy current sensor 200 may include a casing 260 that encloses the coil part 210 while receiving the inside thereof and blocks the outside. In order to block the magnetic field from flowing into the coil unit 210 from the outside, the casing 260 is preferably made of a material having a good magnetic permeability having a high magnetic permeability. For example, the casing 260 may be made of an alloy such as ferromagnetic or ferrimagnetic, permalloy, sendast, ferrite, or the like. The casing 260 may be cylindrical to accommodate the coil unit 210 therein. The axial upper surface of the cylindrical casing 260 is open, and the lower surface may be a closed surface with openings through which the tendon 310 can pass.

An adhesive may be used to fix the eddy current sensor 200 to a structure (hereinafter, referred to as a “target structure”) 300 that is a tension monitoring target. However, when the adhesive is used, the monitoring result may change depending on the adhesive. Depending on the type of adhesive, the thickness of the adhesive, the position of the adhesive affects the sensitivity of the eddy current sensor 200 may reduce the reliability of the monitoring results. To alleviate this drawback of the adhesive, magnetic force can be used to secure the eddy current sensor 200 to the target structure 300.

According to an embodiment, the cylindrical eddy current sensor 200 may further include a magnetic force unit. The magnetic part may be embodied as, for example, the permanent magnet 250. The permanent magnet 250 may have a donut shape having an inner diameter smaller than the outer diameter of the coil part 210 and larger than the tendon 310, and the outer diameter smaller than the inner diameter of the casing 260. The permanent magnet 250 may be accommodated in the casing 260 and fixed to the casing 260. The permanent magnet 250 may be fixed to the casing 260 with an adhesive, for example, or may be press-fitted to the casing 260. The casing 260 is divided into a part to which the permanent magnet 250 is press-fitted and the remaining part, and the two parts may be combined by, for example, screwing. The eddy current sensor 200 may be fixed to the target structure 300 by the magnetic force of the target structure 300 of the permanent magnet 250.

The target structure 300 may include tendons 310 and wedges 330. Tenton 310 may penetrate anchor head 370 and press one or more wedges 330 between anchor head 370 and tendon 310. The tendon 310 may be caught by the wedge 330 and fixed to the anchor head 370. Specifically, a wedge insertion hole 372 may be formed in the anchor head 370. The wedge insertion hole 372 is a tapered circular opening. That is, the wedge insertion hole 372 is a circular opening gradually decreasing in diameter while going in the positive first direction D1. The tendon 310 is inserted into the tapered wedge insertion hole 372 of the anchor head 370 while being firmly coupled to one or more wedges 330. That is, one or more wedges 330 may be embedded between the tendon 310 and the wedge insertion hole 372 of the anchor head 370. The tendon 310 is held very firmly by the wedges 330 so that slip in the first direction D1 does not occur. The tendon 310 may be firmly fixed to the anchor head 370 through the wedge 330. In the case of introducing the permanent magnet 250, the wedges 330 may be made of a material having a large bonding force with the permanent magnet 250. The wedges 330 can be made of ferromagnetic material, for example.

When the cylindrical eddy current sensor 200 is actually installed, as shown in FIGS. 3 and 4, the permanent magnet 250 is fixed to the inner bottom of the casing 260, and the coil part 210 is disposed on the permanent magnet 250. Can be arranged. The cylindrical eddy current sensor 200 may be installed on the surface of the wedges 330 while the coil unit 210, the permanent magnet 250, and the casing 260 are extrapolated to the tendon 310. The permanent magnet 250 fixedly mounted to the casing 260 is positioned on the wedges 330 and the eddy current sensor 200 may be fixed to the wedge 330 surfaces by the attraction force with the wedges 330. . The figure shows that three wedges 330 are installed, which is exemplary and the number of wedges 330 may be two or four or more. In this installation state, the coil unit 210 may be parallel to the surface of the wedge 330 so that the direction of the central axis of the coil unit 210 may be the same as the normal direction with respect to the surface of the wedge 330. The casing 260 may be sized to cover all of the wedges 330.

As such, the cylindrical eddy current sensor 200 is installed on the surface of the wedges 330 of the anchor head 370 which is extrapolated to the tendon 310 and at the same time the stress increases in proportion to the magnitude of the tension force of the tendon 310. By generating eddy currents on the surfaces of the wedges 330 according to the first magnetic field B1 generated by the excitation coil 220, the sensing coil 240 detects the second magnetic field B2 generated based on the eddy currents. The magnitude of the tension of tendon 310 can be detected.

5 is a block diagram illustrating the configuration of a system 100 for monitoring the tension of PT tendon 310 using a cylindrical eddy current sensor 200.

Referring to FIG. 5, the tendon tension monitoring system 100 includes a waveform generator 150, an eddy current sensor 200, a structure (hereinafter referred to as a “target structure”) 300, a digitizer 400, and a target to be monitored for tension. The control unit 500 is included. The eddy current sensor 200 generates the first magnetic field B1 toward the target structure 300 based on the applied excitation signal ES to induce the eddy current EC on the surfaces of the wedges 300 of the target structure 300. Then, the electrical signal VS corresponding to the second magnetic field B2 generated by the eddy current EC is detected. The waveform issuer 150 provides the eddy current sensor 200 with an excitation signal ES having a predetermined frequency based on the transmission control signal TCS. The digitizer 400 digitizes the electric signal VS corresponding to the second magnetic field B2 detected by the eddy current sensor 200 to provide a digital electric signal DVS. The control unit 500 provides the transmission control signal TCS to the waveform generator 150 to generate the first magnetic field B1, and provides the reception control signal RCS to the digitizer 400 to provide the digitizer 400. The digital electrical signal DVS.

6 is a flowchart illustrating a tension force measurement procedure of the tension force monitoring system 100 of the PT tendon 310 according to embodiments of the present invention.

1 to 6, the controller 500 provides the waveform generator 150 with a transmission control signal TCS (S100). The waveform generator 150 provides the excitation signal ES having a predetermined frequency to the eddy current sensor 200 based on the transmission control signal TCS (S110). The magnitude of the excitation signal ES and the frequency of the excitation signal ES may vary according to the transmission control signal TCS. In an exemplary embodiment, the number of predetermined frequencies may be plural. For example, the frequency of the excitation signal ES may be determined according to the transmission control signal TCS. The frequency range of the excitation signal ES may be from 10 Hz to 1 MHz. When using a plurality of frequencies, the tension monitoring system 100 may acquire more various digital voltage signals DVS. When the tension monitoring system 100 acquires more various digital voltage signals DVS, the safety of the target structure 300 can be diagnosed more accurately. The excitation signal ES may be an alternating current signal.

The eddy current sensor 200 provides the first magnetic field B1 based on the excitation signal ES (S120). The excitation signal ES may be transmitted to the excitation coil 220 included in the sensor 200. As a result, an alternating current flows through the exciting coil 220 to generate a first magnetic field B1 around the sensor 200. The first magnetic field B1 may be formed along the first direction D1 toward the surface of the wedges 330 as shown in FIG. 5.

As the first magnetic field B1 is applied to the wedge 330 of the target structure 300, an eddy current EC is induced on the surface of the wedge 330. The second magnetic field B2 is generated by the eddy current EC and is provided to the sensor 200 (S130). The second magnetic field B2 induces a voltage component while linking with the coils 220 and 240 of the sensor 200. The first magnetic field B1 and the second magnetic field B2 generated due to the eddy current EC induced on the surface of the wedge 330 bridge with the sensing coil 240. The two coils are combined with the sensing coil 240 to derive a voltage signal VS corresponding to the changed magnetic field.

In detail, the magnetic field may change in the wedge 330 of the target structure 300 by the first magnetic field B1 generated from the cylindrical eddy current sensor 200. When the magnetic field is changed in the target structure 300 by the first magnetic field B1, a swirl eddy current EC may occur on the surface of the wedge 330 of the target structure 300. The eddy current EC may be generated along the second direction D2. The second magnetic field B2 directed to the sensor 200 may be generated by the swirl eddy current EC generated on the surface of the wedge 330. The second magnetic field B2 may be applied to the sensing coil 240 of the sensor 200. The magnetic flux direction -D1 of the second magnetic field B2 may be opposite to the magnetic flux direction D1 of the first magnetic field B1. As a result, a first magnetic field B1 and a second magnetic field B2 are applied to the sensing coil 240, and a voltage signal VS corresponding to a change in the combined magnetic field of the two magnetic fields may be induced. The magnitude of the voltage signal VS may be determined based on the strength of the eddy current EC. For example, the magnitude of the voltage signal VS may increase as the intensity of the eddy current EC increases, and the magnitude of the voltage signal VS may decrease as the intensity of the eddy current EC decreases.

The digitizer 400 digitizes the voltage signal VS corresponding to the second magnetic field B2 and provides a digital voltage signal DVS (S140). For example, the voltage signal VS corresponding to the second magnetic field B2 may be an analog signal. The digitizer 400 converts the voltage signal VS corresponding to the analog signal into the digital voltage signal DVS.

The controller 500 provides the reception control signal RCS to the digitizer 400 to receive the digital voltage signal DVS. The digitizer 400 transmits a digital voltage signal DVS obtained by digitizing the voltage signal VS corresponding to the second magnetic field B2 to the controller 500 based on the reception control signal RCS provided from the controller 500. to provide. For example, the transmission control signal TCS and the reception control signal RCS provided by the control unit 500 may be used for synchronization between the waveform generator 150 and the digitizer 400 included in the tension monitoring system 100. Can be.

As such, the tendon tension monitoring system 100 according to the embodiments of the present invention may allow the controller 500 to generate an first magnetic field B1 by causing the eddy current sensor 200 to surface the wedge 330 of the target structure 300. The eddy current sensor 200 generates an eddy current EC on the surface of the wedge 330 and detects an electric signal induced based on the second magnetic field B2 generated by the eddy current EC. The change in the tension force of the tendon 310 can be monitored by receiving the digitized detection signal.

 The tendon 310 may provide a stress SF that varies with the tension force TF. For example, the tension force TF of the tendon 310 may be formed along the first direction D1, and the stress SF of the tendon 310 may be formed along the second direction D2. As time passes, the tension force TF of the tendon 310 supporting the target structure 300 may decrease. When the tension force TF of the tendon 310 decreases with time, a problem may arise in the safety of the target structure 300. When the tension force TF of the tendon 310 decreases with time, the stress SF of the tendon 310 may also decrease.

When tension is applied to the tendon 310, stress concentration occurs at the portion of the wedge 330 in contact with the tendon 310. The wedge 330 may generate the eddy current EC and the second magnetic field B2 based on the magnetic permeability that varies with the stress SF. For example, the wedge 330 may surround the tendon 310 as shown in FIGS. 3 and 4. The wedge 330 may be made of a ferromagnetic material. The wedge 330 may vary its magnetic permeability according to the stress SF. As the stress SF decreases, the magnetic permeability may decrease, and as the stress SF increases, the magnetic permeability may increase.

In an exemplary embodiment, the intensity of the eddy current EC may also change as the magnetic permeability of the wedge 330 changes. For example, as the stress SF increases, the magnetic permeability of the wedge 330 may increase, in which case the intensity of the eddy current EC generated on the surface of the wedge 330 by the first magnetic field B1 may be Can increase. In addition, as the stress SF decreases, the magnetic permeability of the wedge 330 may decrease, and in this case, the intensity of the eddy current EC generated on the surface of the wedge 330 may decrease.

In an exemplary embodiment, the intensity of the second magnetic field B2 may vary based on the intensity of the eddy current EC occurring on the surface of the wedge 330. For example, the intensity of the second magnetic field B2 may increase as the intensity of the eddy current EC increases, and the intensity of the second magnetic field B2 may decrease as the intensity of the eddy current EC decreases. have.

Next, FIG. 7 is a diagram for explaining the damage index of the tendon 310 calculated by the tendon tension monitoring system 100.

In an exemplary embodiment, the tendon tension monitoring system 100 may include a first digital voltage signal DVS1 and a second one of the digital voltage signal DVS acquired during the first time interval TI1 of the digital voltage signal DVS. The damage index DI of the target structure 300 may be determined by comparing the second digital voltage signal DVS2 acquired during the time interval TI2. For example, the first time interval TI1 may be from the first time T1 to the second time T2. In addition, the second time interval TI2 may be from the third time T3 to the fourth time T4. During the first time period TI1, the digitizer 400 may provide the first digital voltage signal DVS1. In addition, the digitizer 400 may provide the second digital voltage signal DVS2 during the second time period TI2.

As time passes, the tension force TF of the tendon 310 may decrease. When the tension force TF of the tendon 310 decreases with time, a problem may arise in the safety of the target structure 300. In order to diagnose the safety of the target structure 300, the first digital voltage signal DVS1 acquired during the first time interval TI1 and the second digital voltage signal DVS2 acquired during the second time interval TI2 may be compared. Can be. The tendon tension monitoring system 100 may determine the damage index DI of the target structure 300 by comparing the first digital voltage signal DVS1 and the second digital voltage signal DVS2. The safety of the target structure 300 may be diagnosed based on the damage index DI of the target structure 300. When the damage index DI of the target structure 300 increases, a problem may occur in the safety of the target structure 300.

In an exemplary embodiment, the tendon tension monitoring system 100 may determine the damage index of the target structure 300 based on the dispersion value of the first digital voltage signal DVS1 and the dispersion value of the second digital voltage signal DVS2. Damage Index (DI) can be determined. For example, as the dispersion value of the difference between the first digital voltage signal DVS1 and the second digital voltage signal DVS2 increases, the damage index DI of the target structure 300 may increase.

By applying such a damage index calculation principle in practice, when the tension relaxation of the tendon 310 is detected, the risk can be automatically alerted. FIG. 8 illustrates a damage index through processing tension monitoring data of PT tendon 310 measured in the tension monitoring system 100 of PT tendon according to the embodiments of the present invention, and automatically alarms a risk due to tension relaxation. A flowchart showing the algorithm.

By using the tension data of the tendon 310 measured by the eddy current sensor 200, it is possible to automatically determine the decrease in the tension of the tendon 310 in the current state. An algorithm for this may be implemented as a program and executed by the controller 500. Details of this algorithm are as follows:

First, signal measurement is performed n times in the initial (t = 0) tension condition (S200). 9 shows an example of a graph of an eddy current graph measured n times under an initial (t = 0) tension condition, that is, a graph of a tension signal (ie, a digital electric signal) of tendon 310. Signal measurement of n times may be performed by performing the procedure described with reference to FIG. 6, that is, the procedure from step S100 to step S150 n times. It can be assumed that the difference between successively measured signals while the tension is kept the same is general noise. Here, the initial (t = 0) may mean immediately after the tendon 310 is installed in the target structure 300, but on the other hand, a specific time point has passed since the tendon 310 was installed. The reference time point may be the initial time (t = 0) when the view point is used.

A variance value σ ₀ is calculated for n initial measurement signals, i.e., n initial digital electrical signals DVS, obtained through n signal measurements performed in step S200 (S210). The variance value σ ₀ of the n initial digital electrical signals DVS may be calculated using Equation 1.

Where σ ₀ is the variance of the n digital electrical signals DVS under the initial load (tension), n is the number of measurements under the same load conditions, and X _i (t) is the i-th measurement under the initial load (X) conditions Data (digital electrical signals), and

Denotes the average value of the measurement data (digital electric signal) under the initial load (X) conditions, respectively.

Next, the tension force of the tendon 310 is measured n times again under the tension force condition at a time point t = T1 after a predetermined time elapses after the initial signal measurement (t = 0) (S220). FIG. 10 shows an example of an eddy current graph measured under a changed tension force condition at time t = T1, that is, a tension force signal (ie, a digital electric signal) of tendon 310. The tension measurement at time t = T1 is performed in the same manner as the tension measurement at the initial stage (t = 0). That is, by performing the procedure from step S100 to step S150 n times, it is possible to obtain a tension force measurement signal (n digital electrical signals DVS) at time t = T1. At time t = T1, the tension force of tendon 310 may be changed.

Then, a variance value is calculated for n measurement signals, i.e., n digital electrical signals (DVS), obtained by measuring n signals performed at time t = T1 using the average value of the measurement data under the initial tension force condition. (S230). The variance value σ ₁ of the n digital electrical signals DVS at time t = T1 may be calculated using Equation 2. The n digital electrical signals DVS at time t = T1 represent the tension force of tendon 310 at the changed tension condition.

Where σ ₁ is the variance of the n digital electrical signals DVS under load (tension) conditions at time t = T1, n is the number of measurements under the same load conditions, and Y _i (t) is the changed load (tension) I measurement data (digital electrical signal) under (Y)

Denotes the average value of the measurement data (digital electric signal) under the initial load (X) conditions, respectively.

Next, the initial dispersion value (σ ₀ ) of the n digital electrical signals DVS obtained at the time t = 0, and the n digital electrical signals obtained under the changed load (tension) condition obtained at t = T1 after the elapse of time. The damage index DI ₁ is calculated based on the variance value σ ₁ of the DVSs (S240).

11 illustrates a graph for performing hypothesis testing using the difference between an initial tension force and a modified tension force. 12 shows an example of a graph for automatically determining whether PT tendon tension is lowered through damage index-based online monitoring. When referring to these two figures, if the change in the tension force of tendon 310 at time t = T1 compared to the tension force of tendon 310 at the initial (t = 0) is not a serious level, it is calculated in the previous process. It can be hypothesized that the two variances, σ ₀ and σ ₁ , should have the same level. With this hypothesis in place, we can perform probabilistic / statistical analysis to verify this. In performing this analysis, the damage index (DI) as shown in Equation 3 below may be utilized.

Where X ² _stat represents the damage index (DI ₁ ). After calculating a damage index (DI _1), on the basis of the calculated damage index (DI ₁₎ and monitors the tensile force relaxation degree of the tendon 310. The For example, the tension reduction may be monitored by checking whether the calculated damage index DI ₁ exceeds a preset threshold (S250).

When the damage index DI ₁ calculated in step S250 exceeds a preset threshold value, it means that the safety of the target structure 300 is in a dangerous state. If such a case occurs, automatically generate a 'danger' warning to be notified to the structure manager and / or user (S260).

If it is determined that the damage index DI ₁ calculated in step S250 does not exceed a preset threshold, steps S220, S230, and S240 are repeatedly performed at a time point t = T2 after that. That is, the digital electrical signal (DVC) indicating the tension force of the tendon 310 is measured n times at time t = T2, and the average value of the initial measurement signals (

) Is then used to calculate the variance value (σ ₁ ) of the measured signals, and then the tendon at time t = T2 based on the previously obtained initial dispersion value (σ ₀ ) and the presently obtained dispersion value (σ ₁ ). 31

Calculate the damage index DI ₁ of 0). Then, step S250 is again performed to check whether the calculated damage index DI ₁ has exceeded the threshold. Through this process, it is possible to continuously monitor the tension relaxation of the tendon (310).

Next, FIG. 13 illustrates a coil arrangement of a flexible printed circuit board (FPCB) type eddy current sensor 1200 according to another embodiment of the present invention. 14 is a cross-sectional view of the FPCB type eddy current sensor 1200 according to the embodiment of the present invention installed on the wedge surface of the anchor head 360.

The FPCB type eddy current sensor 1200, like the cylindrical eddy current sensor 200, may include a coil part and a casing 260 to surround the coil part and shield the external magnetic field from flowing into the coil part. The FPCB type eddy current sensor 1200 may further include a magnetic force part. The magnetic part may be implemented by, for example, a permanent magnet.

The FPCB type eddy current sensor 1200 may include at least one coil unit. One coil part can be provided for every wedge which is a measurement object. When there are a plurality of wedges 330a, 330b, ..., a plurality of coil parts 1210a, 1210b, ... may also be provided. The configuration or design of each coil unit 1210 may be the same. The FPCB type eddy current sensor 1200 may include a plurality of permanent magnets 250a, 250b,... One coil unit 1210 and one permanent magnet may be installed in each of the plurality of wedges 330a, 330b,...

The FPCB type eddy current sensor 1200 also secures a plurality of permanent magnets 250a, 250b,... To each of the permanent magnets 250a, 250b,... A plurality of elastic members 255a, 255b, which provide elastic force in the first direction D1 to support the coil parts 1210a, 1210b, .. by pressing them toward the wedges 330a, 330b, ... ..) may further include. Each elastic member 255a, 255b, .... one side is fixed to the bottom of the casing 260 and the other side is fixed to one side of the permanent magnets (250a, 250b, ...), the bottom and the permanent magnet of the casing 260 The gap between the bottom of the can be adjusted elastically.

The configuration and role of the casing 260 in the FPCB type eddy current sensor 1200, that is, the coil part 1210 is accommodated therein so as to block an external magnetic field from flowing into the coil part 1210, the cylindrical eddy current sensor described above ( Since it is substantially the same as that of 200, the description thereof is omitted here.

Each of the permanent magnets 250a, 250b,... May have a size and a shape capable of covering the coil part 1210. For example, each of the permanent magnets 250a, 250b,... May be shaped like the coil part 1210. The role of each permanent magnet 250a, 250b, ... is substantially the same as that of the cylindrical eddy current sensor 200 described above.

The FPCB type eddy current sensor 1200 has a different configuration than that of the cylindrical eddy current sensor 200. The coil unit 1210 includes an FPCB 1230, an excitation coil 1220 and a sensing coil 1240 stacked in a two-layer structure on the FPCB 1230. For example, the sensing coil 1240 is preferably disposed on one layer and the excitation coil 1220 is disposed on two layers, respectively, within the FPCB 1230 having a predetermined shape, and the two coils 1220 and 1240 are arranged on the FPCB 1230. It can be configured in the form of a united through. When the sensing coil 1240 is disposed on the first floor which may be located closer to the surface of the wedges 330a, 330b,..., More accurate measurement may be performed. Of course, the sensing coil 1240 may be disposed on two layers, and the excitation coil 1220 may be disposed on one layer, respectively. The excitation coil 1220 and the sensing coil 1240 may be made of a metal having good conductivity. The FPCB 1230 of the coil unit 1210 may be made of a flexible material. If the coil part 1210 is made thin in a flexible material, it is easy to handle and can be manufactured in the form which can be directly attached to the wedge surface. The coil part 1210 of the FPCB type eddy current sensor 1200 may be designed to be sized to attach to the surface of the wedge. The coil portion 1210 may be designed in the shape of an arc-shaped band, for example shaped like a wedge.

There may be a plurality of wedges inserted into the wedge insertion holes 372 between the anchor head 370 and the tendon 310. As illustrated in FIG. 14, the surface heights of the plurality of wedges 330a, 330b,... If the surface height of the plurality of wedges (330a, 330b, ...) is different, when the cylindrical eddy current sensor 200 is installed, the coil portion 210 of the cylindrical eddy current sensor 200 is the plurality of wedges (330a, 330b, Some of them may not be in direct contact with each other and may create gaps. In this case, it may be disadvantageous in terms of the bonding force to the wedges (330a, 330b, ...) of the eddy current sensor 1200 or the accuracy of the measurement signal. The cylindrical eddy current sensor 200 may be more suitable to be installed when the surface height of the plurality of wedges (330a, 330b, ...) is uniform. When the surface heights of the plurality of wedges 330a, 330b,... Are different from each other, the FPCB-type coil part 1210 that can be installed one for each wedge may be more suitable.

Referring to FIG. 14, a plurality of coil parts 1210a, 1210b,... May be installed on each surface of the plurality of wedges 330a, 330b,... Between the coil parts 1210a, 1210b,... And the bottom surface of the casing 260, elastic members 255a, 255b,... And permanent magnets 250a, 250b,... Each of the permanent magnets 250a, 250b, .. is provided on one side of each coil part 1210a, 1210b, ... by the elastic force provided by the elastic members 255a, 255b, .. in the first direction D1. Contact with the surface of the wedge (330a, 330b, ...). As a result, each of the coil parts 1210a, 1210b,... Can be attached to the surface of the wedges 330a, 330b,... In addition, the attraction force between the permanent magnet (250a, 250b, ...) and the wedge (330a, 330b, ...) in the state. As a result, the entire FPCB type eddy current sensor 1200 may be fixed to the surfaces of the wedges 330a, 330b...

In constructing the tendon tension monitoring system 100 shown in FIG. 5, the FPCB type eddy current sensor 1200 may be used in place of the cylindrical eddy current sensor 200 described above. Since the operation principle of the tendon tension monitoring system 100 configured using the FPCB type eddy current sensor 1200 is the same as the case of using the cylindrical eddy current sensor 200, a description thereof will be omitted here to avoid duplication.

On the other hand, in the cylindrical eddy current sensor 200 or FPCB type eddy current sensor 1200, the coil portion 210 or 1210a, 1210b, ... using the adhesive to the wedge 330 or (330a, 330b,. It can also be fixed to the surface of. However, the sensitivity of the eddy current sensor 200 or 1200 may be adversely affected depending on the type of adhesive, the thickness of the adhesive, and the position of the adhesive. When the adhesive is used, the tension monitoring result of the tendon 310 may be changed according to the adhesive, and thus the reliability of the monitoring result may be lowered. The present invention uses a magnetic force as a way to solve this problem. The magnetic portion uses, for example, permanent magnet 250 or (250a, 250b, ...). That is, the coil portion 210 or 1210a, 1210b, ... by using the magnetic force of the permanent magnet 250 or (250a, 250b, ...) instead of the adhesive of the wedges (330a, 330b, ...) Make sure it's fixed to the surface. The coil portion 210 or 1210a, 1210b, .. of the eddy current sensor 200 or 1200 may generate wedges 330a, 330b, Direct attachment to the surface of ..) simplifies the installation of the eddy current sensor.

According to an exemplary embodiment, the plurality of FPCB type coil units 1210 illustrated in FIG. 13 may be integrally connected through the flexible connecting member 1250. The connected FPCB type coil part may be configured as a closed loop of a circular, elliptical, polygonal, or similar form. For example, an example in which the flexible connection member 1250 is disposed between the plurality of FPCB type coil units 1210 and connected to each other to form a circular FPCB type coil unit 1300 is illustrated in FIG. 15. However, FIG. 15 exemplarily shows that three FPCB-type coil units 1210 are connected. The number of FPCB-type eddy current sensors 1210 to connect may not necessarily be three, but may be two or four or more. It may be. Since it is preferable to arrange one for each surface of the wedge, it may be desirable to configure the circular FPCB type coil part 1300 by connecting the FPCB type coil part 1210 corresponding to the number of wedges.

Since the circular FPCB type coil part 1300 is connected to each other by a flexible connecting member 1250, the plurality of FPCB type coil parts 1210 are limited to the difference in the surface height of the wedges 330a, 330b,... Can be installed easily without receiving. Considering the case where the plurality of FPCB-type coil parts 1210 are arranged one by one on the surfaces of the wedges 330a, 330b, .. having different surface heights, the heights of the plurality of FPCB-type coil parts 1210 are different from each other. The height difference may cushion the flexible connecting members 1250. Since a plurality of FPCB-type coil units 1210 are integrally connected, they can be installed at a time, so there is an advantage of easy handling and installation.

The circular FPCB coil unit 1300 may be installed in substantially the same manner as described above. That is, permanent magnets 250a, 250b,... May also be installed on each individual FPCB type coil unit 1210. In addition, the plurality of elastic members 255a, 255b,... May be disposed between the permanent magnet 250 and the bottom surface of the casing 260. The plurality of elastic members (255a, 255b, ...) provides elastic force to each permanent magnet (250a, 250b, ...) while fixing the plurality of permanent magnets (250a, 250b, ...) inside the casing The individual FPCB type coil unit 1210 is supported by being pushed to the surface of the wedges (330a, 330b, ...) to be fixed.

Next, a wireless sensor node system for monitoring tendon drop force reduction according to the present invention will be described. In the case of PT tendon systems, most of them are embedded in concrete and are not easily accessible. Therefore, in the case of the sensor and the sensor node installed in the fixing unit is to monitor the tension force embedded in the concrete. As a method of supplying power to a sensor node, a battery is used or power is supplied by wire, and data acquisition is performed by directly accessing a sensor node or by using a wired data transmission method. Using existing methods, power and data transfers can lead to problems such as battery replacement and power / data wired system maintenance, increasing the maintenance costs of the sensor.

In order to solve this problem, there is a need for a system that can transmit power and receive data on the concrete deck without direct access to the sensor node by applying concrete wireless power and data transmission technology. . As an embodiment of this system, FIG. 16 shows a schematic conceptual diagram of a wireless sensor node system 600 for tendon tension monitoring.

Referring to FIG. 16, the system 600 has a configuration in which a wireless power and data transmission unit and a PT node's tension drop monitoring sensor node are largely combined. The tendon tension monitoring wireless sensor node system 600 wirelessly transmits power to the bridge sensor through a pair of coils without a communication module and a power line, and simultaneously changes the primary side voltage caused by the secondary side load variation. Data can be transmitted wirelessly.

Specifically, the wireless sensor node system 600 for tendon tension monitoring according to the present invention includes a wireless power transmission and data receiving unit 620, a wireless power receiving and data providing unit 660, and a power and data wireless transmission unit 650. can do. Wireless charging of the sensor battery 664 and wireless transmission of data generated by the sensor node 670 may use the same resonator. The resonator may be implemented by the power and data wireless transmission unit 650. Here, the sensor node 670 is a tendon tension monitoring system 100 including an eddy current sensor 200, or 1200 for measuring the tension of the tendon 310 inserted into the bridge 615, for example to implement a smart bridge. It may include. The sensor node 670 may also include other sensors, such as temperature sensors, for measuring the condition of the bridge 615, such as for example for smart bridge implementations.

The power and data radio transmitter 650 is, for example, a primary side coil 652 installed on a movable body such as the vehicle 610 (hereinafter described with the vehicle 610 as an example) and for example, a road or a bridge 615. It includes a secondary side coil 654 which is installed in a fixed structure (hereinafter described as an example of the bridge 615). The power and data radio transmitter 650 is capable of magnetic induction when the primary side coil 652 is positioned above the secondary side coil 654 due to the movement of the vehicle 610 (ie, magnetic flux linkage with each other). ), It is possible to transfer electrical energy from one side to the other in a mutual magnetic induction method between the primary side coil 652 and the secondary side coil 654.

The wireless power transmission and data receiver 620 may be installed in the vehicle 610 to move with the vehicle. It may also be coupled to the primary side coil 652 of the power and data wireless transfer unit 650.

The wireless faucet and data provider 660 may be installed at or near tendon 310 of a structure, such as a bridge 615, for example. It is also connected to the secondary side coil 654 of the power and data radio transmitter 650.

FIG. 17 is a flowchart illustrating wireless power transmission to the sensor node 670 and wireless reception of data detected by the sensor node 670 using the tendon tension monitoring wireless sensor node system 600. In the system 600, for wireless power transmission to the sensor node 670, the wireless transmission and data receiver 620 transmits power wirelessly so that the power passes through the concrete for the bridge so that the sensor node 670 is located. The power supply and the data provider 660 are supplied. At the same time, in order to transfer the data detected by the sensor node 670 to the wireless power transmission and data receiving unit 620, the physical information of the bridge 615 is converted into a digital signal and then wirelessly based on the converted digital signal. The magnitude of the load of the power receiving and data providing unit 660 is varied. The wireless power transmission and data receiving unit 620 recovers the data detected by the sensor 670 by detecting a circulating current appearing on the primary side or a physical quantity corresponding thereto according to a large change in the load. The wireless charging and data collection of the bridge sensor node 670 may be performed through the inspection vehicle 610 equipped with the power transmission and data receiver 620.

In more detail, the wireless power transmission and data receiver 620 mounted on the inspection vehicle 610 supplies power to the primary coil 652 manufactured based on magnetic induction (S300). To this end, the primary side coil 652 of the power and data wireless transmission unit 650 mounted in the vehicle 610 approaches so as to be positioned on the secondary side coil 654 installed in the bridge 615. An alternating current flows through the primary coil 652 by the supplied electric power, and a magnetic field is formed around the primary coil. The magnetic field is bridged with the secondary coil 654. The power supply may use a battery for the test vehicle 610 or a separate battery.

The secondary coil 654 installed in the structure 615 such as a bridge is coupled to the primary coil 652 on a magnetic induction basis. Therefore, when an alternating current flows to the primary side coil 652, the secondary side coil 654 is coupled to the secondary side coil 654 because the primary side coil 652 is coupled in a mutual magnetic induction relationship. do. Through this, the secondary coil 654 receives power from the primary coil 652 and supplies the received power to the tendon tension monitoring sensor node 670 (S310). The induced alternating current can be converted to direct current while undergoing rectification. The direct current may flow into the sensor battery unit 664 and be charged.

While power is supplied to the sensor node 670, the sensor node 670 may perform an operation of measuring the tension force of the tendon 310 described above. That is, in the eddy current sensor 200 or 1200 connected to the sensor node 670, an eddy current is generated on the surfaces of the wedges 330 by generating a constant first magnetic field B1 by flowing a current through the excitation coil 220 or 1220 ( S320).

The magnetic field in the eddy current sensor 200 changes due to the influence of the secondary magnetic field B2 generated in the formed eddy current, and is measured through the sensing coil 240 or 1240 (S330).

The measured signal is digitized, and the tension force is calculated by applying the above-mentioned tension force automatic alarm algorithm based on the digital measurement data (S340).

The calculated tension data of the tendon 310 is transferred to the primary coil mounted in the inspection vehicle 610 through the secondary coil 654 in a magnetic induction manner (S350).

Through this process, it is possible to determine the lowering force or damage of the tendon 310 by using the measurement data collected by the inspection vehicle 610 (S360). The determination result of the lowering of the tension force of the tendon 310 is transmitted to the expert to take appropriate follow-up.

In the wireless power transmission scheme, the lower the coupling coefficient, the larger the circulating current that is not transmitted from the primary side coil 652 to the secondary side coil 654, which results in large conduction loss and low transmission efficiency. Therefore, in order to reduce the magnitude of the circulating current flowing through the primary side coil 652, it is desirable to design the reactive power portion of the input impedance as small as possible. This makes it possible to eliminate the reactive power portion by allowing LC resonance to occur. In addition, it is possible to use a series-series compensation resonator structure in which the current required for the primary side coil 652 varies according to the load, thereby minimizing the conduction loss relatively. In actual testing, for example, the total power required to acquire and process measurement data is about 10 watts and the time to acquire data is about 10 seconds.

Structure diagnosis system according to embodiments of the present invention can improve the performance by generating an eddy current in the target structure according to the first magnetic field generated from the sensor, and providing the sensor with a second magnetic field generated based on the eddy current It can be applied to the structure diagnosis apparatus.

While the invention has been described above with reference to preferred embodiments, those skilled in the art will be able to make various modifications and changes to the invention without departing from the spirit and scope of the invention as set forth in the claims below. I will understand.

Claims (15)

1. An excitation coil for generating a first magnetic field, and a sensing coil for detecting an electrical signal corresponding to the second magnetic field generated by the eddy current induced by the first magnetic field in the target structure and the composite magnetic field of the first magnetic field. Coil part; And

   And surrounding the housing while accommodating the coil unit and having a magnetic shielding capability to block a magnetic field from entering the coil unit from the outside.
2. The eddy current sensor device of claim 1, further comprising: a magnetic force unit accommodating and fixed in the casing to magnetically fix the casing and the coil unit to the target structure.
3. The eddy current sensor device of claim 1, wherein the coil part is interpolated into the excitation coil so that the sensing coil and the excitation coil have a double cylindrical shape.
4. The eddy current sensor device of claim 1 or 2, further comprising a coil case surrounding the combination of the excitation coil and the sensing coil and provided with connectors connected to the excitation coil and the sensing coil, respectively.
5. The eddy current of claim 1, wherein the coil part is an FPCB type coil part in which the sensing coil and the excitation coil are arranged in a two-layer structure via a flexible printed circuit board (FPCB) having a predetermined shape. Sensor device.
6. The coil unit of claim 1, wherein the coil unit includes a plurality of FPCB coil units and an elastic connecting member disposed between the plurality of FPCB coil units to connect the plurality of FPCB coil units to form a closed loop. The FPCB type coil unit is an eddy current sensor device, characterized in that the sensing coil and the excitation coil is arranged in a two-layer structure via a flexible printed circuit board (FPCB) of a predetermined shape.
7. 7. The eddy current sensor device according to claim 5 or 6, further comprising a magnetic force unit accommodating and fixed to the inside of the casing to magnetically fix the casing and the coil unit to the target structure.
8. For monitoring a tension force of a tendon that provides a fluctuating stress based on the tension force through at least one wedge that is press-fitted between the tendon and the anchor head to vary the magnetic permeability according to the stress of the tendon,

   An excitation coil provided on a surface of the at least one wedge, the excitation coil for generating a first magnetic field based on an excitation signal, and a second magnetic field generated by an eddy current induced in the at least one wedge by the first magnetic field; A coil unit including a sensing coil detecting an electrical signal corresponding to the synthesized magnetic field of the first magnetic field; And an eddy current sensor surrounding and enclosing the coil unit therein, the casing being made of a material having a magnetic shielding capability to block a magnetic field from entering the coil unit from the outside. And

   And a tension force monitoring unit for providing the excitation signal to the eddy current sensor and calculating information on the tension force of the tendon using the electrical signal detected by the eddy current sensor.
9. The method of claim 8, wherein the tension monitoring unit (i) performs the measurement of the electrical signal n times through the eddy current sensor in the initial tension force conditions to calculate a first dispersion value (σ ₀ ), (ii) the passage of time The second dispersion value (σ ₁ ) is calculated by performing the same measurement of the electrical signal n times through the eddy current sensor even when the tension force of the tendon is changed, and (iii) the calculated first dispersion value (σ). ₀ ) and the second variance value (σ ₁ ) are calculated by probability statistical analysis, and (iv) an algorithm is generated that automatically generates a risk alarm when the calculated damage index exceeds the acceptable threshold. A tendon tension diagnosis system, characterized in that it has a function of executing a program.
10. 9. The tendon tension diagnosis system according to claim 8, further comprising a magnetic force unit accommodating and fixed inside the casing to magnetically fix the casing and the coil unit to a surface of the at least one wedge.
11. The apparatus of claim 8, wherein the tension monitoring unit comprises: a waveform generator configured to provide the excitation signal having a predetermined frequency based on a transmission control signal; A digitizer for digitizing the electrical signal corresponding to the second magnetic field to provide a digital electrical signal; And a control unit providing the transmission control signal to the waveform generator and receiving the digital electrical signal from the digitizer to calculate the tension force of the tendon.
12. 12. The tendon tension diagnosis system according to claim 11, wherein the control unit has a function of alerting a danger when the magnitude of the calculated tension force falls below an allowable threshold value.
13. The tendon force monitoring device of claim 8, wherein the tension monitoring unit compares the first digital electrical signal acquired during the first time interval of the digital electrical signal with the second digital electrical signal acquired during the second time interval of the digital electrical signal. Tendon tension diagnosis system, characterized in that for determining the damage index of.
14. The electric power of claim 8, further comprising a primary coil installed in the movable body, and a secondary coil installed in the structure in which the eddy current sensor is installed, coupled to the primary coil in a magnetic induction manner, and connected to the tension monitoring unit. And a data radio transmission unit; And installed in the movable body and connected to the primary side coil to provide power necessary for driving the eddy current sensor and the tension monitoring unit through the power and data wireless transmission unit in a magnetic induction manner and from the tension monitoring unit. Tendon tension diagnosis system, characterized in that it further comprises a wireless transmission and data receiving unit for collecting information about the tension of the magnetic induction method.
15. 15. A tendon tension diagnosis system according to claim 14, wherein the movable body is a vehicle and the structure is a road and / or a bridge that the vehicle can carry.

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