KR101896915B1 - Sensor for monitoring tendon force, and system for analyzing tendon force using the same - Google Patents

Abstract

The eddy current sensor device includes a coil part and a casing. The coil unit includes an excitation coil for generating a first magnetic field, a second magnetic field generated by eddy current induced in the target structure by the first magnetic field, and a sensing coil for detecting an electric signal corresponding to a synthetic magnetic field of the first magnetic field . The casing accommodates the coil portion inside and surrounds the coil portion to block the outside. And a magnetic force part for holding and fixing the casing and the coil part to the target structure by being magnetically fixed inside the casing. An eddy current sensor is installed on the surface of at least one wedge that is press-fitted between the tendon and the anchor head to provide a varying stress on the basis of the tensile force so that the magnetic permeability changes according to the stress of the tendon. The tension monitoring unit provides an excitation signal to the eddy current sensor while using the electrical signal detected by the eddy current sensor to calculate information about the tension of the tension. If the calculated tension falls below the allowable threshold, a critical alarm is automatically issued. It is possible to provide driving power to the tensional force monitoring unit in a self-induction manner in the inspection vehicle and to collect the tensile tensional force information measured by the eddy current sensor from the tensional force monitoring unit.

Description

TECHNICAL FIELD [0001] The present invention relates to a sensor for monitoring tension force of a tendon, and a system for detecting a tension of the tendon using the same. [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety diagnosis of a structure, and more particularly, to a technique for diagnosing the safety of a structure by monitoring the tensile force of the tendon in a structure provided with a tender.

The post-tensioning (PT) method is a typical method widely used in the design of concrete bridges and high-rise buildings. It uses a tendon composed of tendon bundles to apply pre-stress to the structure Thereby increasing the strength of the structure. Tendon, which is used as a major member of this method, gradually relaxes its tension over time. Due to the relaxation of the strain on the structure, the safety of the structure may be threatened. To prevent this problem, it is necessary to develop a technology to precisely monitor the PT tensile tension and to prevent the damage of the structure due to the weakening of the tension.

Various studies have been conducted to accurately measure the tensile strength of the PT tendon mounted on the structure. Techniques utilizing electromagnetic sensors, fiber optic sensors, or elongation sensors have been proposed as typical techniques for monitoring the tension-reduction. The technique using the electromagnetic sensor is installed in such a manner that the tensile passes through the center of the cylindrical sensor. Generate a strong magnetic field to magnetize the tendon to secure sufficient measurement resolution. At this time, since a power of several hundred watts is required instantaneously to magnetize the tendon, it is large in size, and there is a limit in practicability for use in a practical civil structure construction site. The technique using the optical fiber sensor is applied to the construction of a new type of tendon in which the optical fiber is inserted. Fiber optic sensors are a very expensive sensor, requiring a fairly long fiber to build bridges from several to several tens of kilometers, and cost a lot of initial installation costs. In the method using the elongation sensor, the elongation sensor is attached to the anchor head as a whole, and the tension of the tender is indirectly measured using the elongation state of the anchor head. There is a disadvantage in that it can be monitored for extreme load changes such as tendon cutting rather than tensing tension monitoring of the tendon. In addition, although the price per unit of the elongation sensor is small, the number of sensors required for the multi-tenant measurement is large, so care must be taken in the management and monitoring data processing.

It is an object of the present invention to solve the above problems and to provide a method of monitoring the degree of strain relief of a PT tendon by measuring a change in the magnitude of the eddy current by inducing an eddy current on the wedge of the PT tendon fusing unit. And it is an object of the present invention to provide an eddy current sensor device capable of increasing measurement accuracy by blocking the influence of an external magnetic field.

Another object of the present invention is to provide a system for diagnosing tensile force of a tendon of a structure capable of automatically alarming when the magnitude of the tension is below an allowable threshold by monitoring the tension of the tendon using the eddy current sensor device.

It is still another object of the present invention to provide a method and apparatus for measuring the tension of a tendon by using the eddy current sensor device and providing and collecting information on the power required for driving the eddy current sensor device and the tension force measured by the eddy current sensor device The present invention relates to a system for diagnosing a tension of a tendon.

In order to accomplish one aspect of the present invention, an eddy current sensor device according to embodiments of the present invention includes a coil portion and a casing. The coil unit includes an excitation coil for generating a first magnetic field, a second magnetic field generated by the eddy current induced in the target structure by the first magnetic field, and a second magnetic field for sensing an electric signal corresponding to a synthetic magnetic field of the first magnetic field. Coil. The casing surrounds and encloses the coil portion, and is made of a material having a magnetic shielding ability, thereby blocking a magnetic field from entering the coil portion from the outside.

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

In an exemplary embodiment, the coil unit may be such that the sensing coil is inserted into the excitation coil so that the sensing coil and the excitation coil form a double cylindrical shape.

In the exemplary embodiment, the eddy current sensor device may further include a coil case surrounding the exciting coil and the sensing coil, and having connectors connected to the exciting coil and the sensing coil, respectively.

In an exemplary embodiment, the coil unit may be a form in which the sensing coil and the exciting 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 portions, and a flexible connecting member disposed between the plurality of FPCB type coil portions and connecting the plurality of FPCB type coil portions 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 the exemplary embodiment, the eddy current sensor device may further include a magnetic force part for receiving and fixing the casing and the coil part to the target structure by magnetic force while improving the sensitivity of the eddy current sensor. .

In the exemplary embodiment, a plurality of the coil portions may be provided, and the magnetic force portions may be plural as the coil portions, and one magnetic portion may be provided for each coil portion. Further, the eddy current sensor device further includes a plurality of elastic members for fixing the plurality of magnetic force portions to the inside of the casing, providing elastic forces to the respective permanent magnets, and pushing the respective coil portions toward the target structure so as to fix them .

In order to achieve the above object, according to the present invention, there is provided a system for diagnosing a tensile force of a tendon, comprising: a force sensor for detecting a tensile force of a tendon for providing a varying stress based on a tensile force, For monitoring through at least one wedge in which the magnetic permeability varies according to the stress of the tensen. The tendon tension diagnostic system includes an eddy current sensor and a tension monitor. Wherein the eddy current sensor comprises: an excitation coil installed on a surface of the at least one wedge for generating a first magnetic field based on an excitation signal; and an eddy current generator for generating an eddy current induced in the at least one wedge by the first magnetic field. A coil part including a sensing coil for detecting an electric signal corresponding to a second magnetic field and a synthetic magnetic field of the first magnetic field; And a casing enclosing the coil part and enclosing the coil part, the casing being made of a material having a magnetic shielding ability and blocking a magnetic field from being introduced into the coil part from the outside. The tensional force monitoring unit provides the excitation signal to the eddy current sensor, and calculates information on the tension of the tendon using the electric signal detected by the eddy current sensor.

In an exemplary embodiment, the tensional force monitoring unit comprises: (i) measuring the n electrical signals through the eddy current sensor at an initial tension condition to calculate a first variance value ( ₀ ); (ii) ( _I ) calculating the second variance value ( ₁ ) by performing the same measurement of the electric signal n times through the eddy current sensor even when the tension of the tendon is changed according to the elapse of time, (iii) σ ₀ ) and the second variance value (σ ₁ ), and (iv) if the calculated damage index exceeds the allowable threshold value, an algorithm that automatically generates a risk alarm is implemented. And to perform the program.

In an exemplary embodiment, the tensile stress diagnostic system may include a casing for holding and fixing the casing and the coil portion to the surface of the at least one wedge, and a magnetic force And the like.

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

In an exemplary embodiment, the controller may include a function of issuing a critical alarm if the magnitude of the calculated tractive force falls below an allowable threshold value.

In an exemplary embodiment, the control unit may provide a receive control signal to the digitizer to receive the digital electrical signal to enable use of the transmit control signal and the receive control signal for synchronization between the waveform generator and the digitizer. have.

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

In an exemplary embodiment, the tensional force monitoring unit compares a first digital electric signal obtained during a first time interval of the digital electric signal and a second digital electric signal obtained during a second time interval of the digital electric signal, It may be to determine the damage index of the tendon.

In an exemplary embodiment, the tendon tension diagnostic system may include a primary coil installed in the movable body, a coil installed in the structure in which the eddy current sensor is installed, coupled with the primary coil in a magnetic induction manner, A power and data wireless transmitter including a secondary coil; And a power monitoring unit which is provided on the movable body and is connected to the primary coil to provide power required for driving the eddy current sensor and the tensional force monitoring unit through a power and data wireless transmission unit in a magnetic induction manner, And a wireless transmission and data receiving unit for collecting information on the tension of the mobile terminal 100 in a self-induction manner.

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

The tensing tension monitoring system according to the embodiments of the present invention uses the magnetic force to attach the eddy current sensor to the wedge surface, so that the installation method is very simple. In addition, the eddy current can be efficiently generated on the surface of the wedge by the magnetic force part that provides the magnetic force, thereby improving the sensitivity of the sensor.

By covering the coil part of the eddy current sensor by using a casing having a superior magnetic shielding function, it is possible not only to improve the sensor precision by blocking external magnetic factors, but also to securely protect the coil part from the outside.

In addition, the present invention has an advantage that safety management of a structure can be facilitated by automatically generating a danger warning when the tensile force of the tendon falls below an allowable critical point.

Since the present invention can wirelessly supply driving power to the eddy current sensor and data collection from the eddy current sensor by a magnetic induction method using an inspection vehicle, it is possible to simplify the tensing tension monitoring system and reduce the initial cost In addition, the maintenance cost of the system can be reduced, and the advantage of easy data collection is also provided.

1 is an exploded perspective view showing a configuration of a cylindrical eddy current sensor according to an embodiment of the present invention.
Fig. 2 (a) 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. 2 (b) is a sectional view taken along a cutting line A-A '.
3 shows a state in which a cylindrical eddy current sensor according to an embodiment of the present invention is installed on a wedge surface of an anchor head.
4 is a cross-sectional view taken along line B-B 'in Fig.
5 is a block diagram showing a configuration of a system for monitoring a tension force of a PT tendon using a cylindrical eddy current sensor according to an embodiment of the present invention.
6 is a flowchart illustrating a procedure for measuring a tension force of a PT tendon tension monitoring system according to embodiments of the present invention.
7 (a) and 7 (b) are views for explaining the damage index of the tendency calculated by the tendon tension monitoring system shown in FIG.
FIG. 8 is a flowchart illustrating an algorithm for calculating a damage index through processing of tensions monitoring data of a PT tendon measured in a PT tendon tension monitoring system according to an exemplary embodiment of the present invention, and automatically alerting the risk of mitigation of the tension.
9 shows an example of eddy current graph measured under the initial tension condition.
10 shows an example of the eddy current graph measured under the changed tension condition.
11 shows an example of a graph for performing hypothesis verification using the difference between the initial tension and the changed tension.
12 shows an example of a graph for automatically determining whether the PT tension tendency is lowered by on-line monitoring based on the damage index.
13 shows a coil arrangement of an FPCB eddy current sensor according to another embodiment of the present invention.
14 is a sectional view of the FPCB type eddy current sensor according to the embodiment of the present invention installed on the wedge surface of the anchor head.
15 is a plan view of a coil part for an FPCB eddy current sensor in which three FPCB eddy current sensors shown in FIG. 13 are connected in the form of a circular closed loop through a flexible connecting member according to an embodiment of the present invention.
16 shows a schematic diagram of a wireless sensor node system for tendon tension monitoring employing an eddy current sensor according to an embodiment of the present invention.
FIG. 17 is a flowchart illustrating wireless acquisition of data detected by a sensor node and wireless power supply to a sensor node using the wireless sensor node system for tensing tension monitoring shown in FIG. 16;

For the embodiments of the invention disclosed herein, specific structural and functional descriptions are set forth for the purpose of describing an embodiment of the invention only, and it is to be understood that the embodiments of the invention may be practiced in various forms, The present invention should not be construed as limited to the embodiments described in Figs.

The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It is to be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but on the contrary, is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. 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. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between. Other expressions that describe the relationship between components, such as "between" and "between" or "neighboring to" and "directly adjacent to" should be interpreted as well.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprise", "having", and the like are intended to specify the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, , Steps, operations, components, parts, or combinations thereof, as a matter of principle.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be construed as meaning consistent with meaning in the context of the relevant art and are not to be construed as ideal or overly formal in meaning unless expressly defined in the present application .

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

1 is an exploded perspective view showing a configuration of a cylindrical eddy current sensor 200 according to an embodiment of the present invention. 2 (a) and 2 (b) are a plan sectional view and a side sectional view of the coil portion 210 of the cylindrical eddy current sensor 200 shown in Fig. 3 shows a state in which the cylindrical eddy current sensor 200 shown in FIG. 1 is installed on the surface of the wedge 330 of the anchor head 370. When a part of the casing 260 is opened FIG. 4 is a cross-sectional view taken along line B-B 'in Fig.

Referring to FIGS. 1 and 2, the cylindrical eddy current sensor 200 includes a coil portion 210. According to an embodiment, the coil section 210 includes an excitation coil 220 having a conductive wire wound in a cylindrical shape and a sensing coil 240 having a conductive wire 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 monitoring tendon 310. The sensing coil 240 is inserted into the exciting coil 220 so that the two coils 220 and 240 can be coupled in a double cylindrical shape. The sensing coil 240 and the exciting coil 220 may be bonded together with an adhesive, for example. The double cylindrical coupling body of the excitation coil 220 and the sensing coil 240 is enclosed by a coil case 215 to constitute a cylindrical coil part 210. The coil case 215 may be provided with connectors 217. 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 is disposed inside and the magnetic field change can be monitored efficiently. The exciting coil 220 can form a magnetic field outside.

According to the embodiment, the cylindrical eddy current sensor 200 may include a casing 260 that receives and encloses the coil portion 210 and shields the coil portion from the outside. It is preferable that the casing 260 is made of a material having a high magnetic permeability and a good magnetic shielding ability in order to prevent the magnetic field from entering the inner coil part 210 from the outside. For example, the casing 260 may be made of a ferromagnetic material, a ferromagnetic material, an alloy of permalloy, sendust, ferrite, or the like. The casing 260 may be cylindrical to accommodate the coil portion 210 therein. The upper surface in the axial direction of the cylindrical casing 260 may be open and the lower surface may be a closure surface formed with openings through which the tendons 310 can penetrate.

An adhesive may be used to fix the eddy current sensor 200 to a structure (hereinafter, referred to as a 'target structure') 300 to be fixedly monitored. However, when an adhesive is used, the monitoring result may vary depending on the adhesive. The sensitivity of the eddy current sensor 200 may be influenced by the kind of the adhesive, the thickness of the adhesive, and the position of the adhesive, so that the reliability of the monitoring result may be lowered. In order to overcome this disadvantage of the adhesive, the eddy current sensor 200 can be fixed to the target structure 300 using a magnetic force.

According to the embodiment, the cylindrical eddy current sensor 200 may further include a magnetic force portion. The magnetic force portion can be realized by, for example, permanent magnet 250. The permanent magnet 250 may be of a donut shape whose inner diameter is smaller than the outer diameter of the coil portion 210 and larger than the tendon 310 and whose outer diameter is smaller than the inner diameter of the casing 260. The permanent magnet 250 may be housed 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 into the casing 260. The casing 260 is divided into a portion into which the permanent magnet 250 is press-fitted and the other portion, and the two portions may be coupled by, for example, a screw coupling method. The eddy current sensor 200 can be fixed to the target structure 300 by the magnetic force of the permanent magnet 250 with respect to the target structure 300.

The target structure 300 may include a tendon 310 and a wedge 330. [ The tenton 310 penetrates the anchor head 370 and may be press-fit between the anchor head 370 and the tendon 310 with one or more wedges 330. The tent (310) can be caught by the wedge (330) and fixed to the anchor head (370). Specifically, the 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 whose diameter gradually decreases in a positive first direction D1. The tent 310 is inserted into the tapered wedge insert hole 372 of the anchor head 370 in a state of being firmly engaged with the one or more wedges 330. [ That is, one or more wedges 330 may be sandwiched between the tent (310) and the wedge insertion holes (372) of the anchor head (370). The tendons 310 are held very tightly by the wedges 330 to prevent slippage in the first direction D1. The tent (310) can be firmly fixed to the anchor head (370) through the wedge (330). When the permanent magnets 250 are introduced, the wedges 330 may be made of a material having a strong coupling force with the permanent magnets 250. The wedges 330 may be made of a ferromagnetic material, for example.

3 and 4, the permanent magnet 250 is fixed to the inner bottom surface of the casing 260 and the coil part 210 is fixed on the permanent magnet 250. The cylindrical eddy- Can be disposed. The cylindrical eddy current sensor 200 may be installed on the surface of the wedges 330 while the coil portion 210, the permanent magnet 250 and the casing 260 are extrapolated to the tendon 310. The permanent magnet 250 fixed to the casing 260 is placed on the wedges 330 and the eddy current sensor 200 can be fixed to the surfaces of the wedges 330 by attraction with the wedges 330 . It is shown in the drawing that three wedges 330 are provided, which is exemplary and the number of wedges 330 may be two or four or more. In this installed state, the coil part 210 is parallel to the surface of the wedge 330 and the direction of the central axis of the coil part 210 may be the same as the normal direction of the wedge 330 surface. The casing 260 may be sized to cover all of the wedges 330.

The cylindrical eddy current sensor 200 is installed on the surface of the wedges 330 of the anchor head 370 whose stress is increased in proportion to the magnitude of the tension of the tendon 310 while being extrapolated to the tendon 310, An eddy current is generated on the surfaces of the wedges 330 according to the first magnetic field B1 generated in the exciting coil 220 and the sensing coil 240 detects the second magnetic field B2 generated based on the eddy current The magnitude of the tensile force of the tensile 310 can be detected.

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

5, the tensing 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 control unit 500. The eddy current sensor 200 generates a first magnetic field B1 toward the target structure 300 based on the applied excitation signal ES to induce eddy currents EC on the surfaces of the wedges 330 of the target structure 300 And detects an electric signal VS corresponding to the second magnetic field B2 generated by the eddy current EC. The waveform issuing device 150 provides the excitation 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, The digital electric signal DVS is supplied.

FIG. 6 is a flowchart illustrating a procedure for measuring the tensions of the tensional force monitoring system 100 of the PT tendon 310 in accordance with embodiments of the present invention.

1 to 6, the controller 500 provides a transmission control signal TCS to the waveform generator 150 (S100). The waveform generator 150 provides an 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 be varied in accordance with 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 can be determined in accordance with the transmission control signal TCS. The frequency range of the excitation signal ES can be from 10 Hz to 1 MHz. When using a plurality of frequencies, the tension monitoring system 100 is able to obtain a greater variety of digital voltage signals DVS. When the tension monitoring system 100 acquires more digital voltage signals DVS, it is possible to diagnose the safety of the target structure 300 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. Thereby, an alternating current flows in the exciting coil 220, so that the first magnetic field B1 can be generated around the sensor 200. [ The first magnetic field B1 may be formed along a first direction D1 toward the surface of the wedges 330 as shown in FIG.

An eddy current EC is induced on the surface of the wedge 330 as the first magnetic field B1 is applied to the wedge 330 of the target structure 300. [ The second magnetic field B2 is generated by the eddy current EC and 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 by the eddy current EC induced on the surface of the wedge 330 are linked with the sensing coil 240. [ In the sensing coil 240, these two magnetic fields are synthesized and a voltage signal VS corresponding to the changed magnetic field is induced.

Specifically, the magnetic field of the wedge 330 of the target structure 300 can be changed by the first magnetic field B1 generated from the cylindrical eddy current sensor 200. A swirling eddy current EC may occur on the surface of the wedge 330 of the target structure 300 when the magnetic field is changed in the target structure 300 by the first magnetic field B1. The eddy currents EC can be generated along the second direction D2. A second magnetic field B2 directed toward the sensor 200 may occur due to 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, the first magnetic field B1 and the second magnetic field B2 are applied to the sensing coil 240, and a voltage signal VS corresponding to the change in the resultant magnetic field of the two magnetic fields can be induced. The magnitude of the voltage signal VS can be determined based on the intensity of the eddy current EC. For example, as the magnitude of the eddy current EC increases, the magnitude of the voltage signal VS increases, and as the magnitude of the eddy current EC decreases, the magnitude of the voltage signal VS may decrease.

The digitizer 400 digitizes the voltage signal VS corresponding to the second magnetic field B2 to provide the 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 control unit 500 provides a reception control signal RCS to the digitizer 400 to receive the digital voltage signal DVS. The digitizer 400 outputs the digital voltage signal DVS obtained by digitizing the voltage signal VS corresponding to the second magnetic field B2 to the control unit 500 based on the reception control signal RCS provided from the control unit 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 tensional force monitoring system 100 .

The tensing tension monitoring system 100 according to embodiments of the present invention allows the controller 500 to cause the eddy current sensor 200 to generate a first magnetic field B1 to be applied to the surface of the wedge 330 of the target structure 300 Current sensor EC is generated on the surface of the wedge 330 and the electric current signal induced based on the second magnetic field B2 generated by the eddy current EC is detected by the eddy current sensor 200 And the detection signal is digitized and provided to monitor the change in the tension of the tendon 310.

 The tendon 310 can provide a varying stress SF according to the tension force TF. For example, the tensile 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 the time elapses, the tensile force (TF) of the tendon 310 supporting the target structure 300 may decrease. If the tensile force (TF) of the tendon 310 decreases over time, there may be a problem with the safety of the target structure 300. If the tensile force TF of the tendon 310 decreases with the lapse of time, the stress SF of the tendon 310 may also decrease.

When a tensile force is applied to the tendon 310, stress concentration occurs at a portion of the wedge 330 that contacts the tendon 310. The wedge 330 can 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 periphery of the tendon 310, as shown in FIGS. The wedge 330 may be made of a ferromagnetic material. The wedge 330 may vary in magnetic permeability according to the stress SF. As the stress SF decreases, the magnetic permeability may decrease and the magnetic permeability may increase as the stress SF increases.

In the exemplary embodiment, as the magnetic permeability of the wedge 330 varies, the intensity of the eddy current EC may also vary. For example, as the stress SF increases, the magnetic permeability of the wedge 330 may increase, and in that case, the intensity of the eddy current EC generated on the surface of the wedge 330 by the first magnetic field B1 . Also, as the stress SF decreases, the magnetic permeability of the wedge 330 may decrease, and the intensity of the eddy currents 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 that occurs on the surface of the wedge 330. [ For example, as the intensity of the eddy current EC increases, the intensity of the second magnetic field B2 may increase, and as the intensity of the eddy current EC decreases, the intensity of the second magnetic field B2 may decrease have.

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

In an exemplary embodiment, the tendon tension monitoring system 100 includes a first digital voltage signal DVS1 and a second digital voltage signal DVS1 obtained during a first time period TI1 of the digital voltage signal DVS, The second digital voltage signal DVS2 obtained during the time interval TI2 may be compared to determine the damage index DI of the target structure 300. [ 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 interval TI1, the digitizer 400 may provide the first digital voltage signal DVS1. Also, during the second time interval TI2, the digitizer 400 may provide the second digital voltage signal DVS2.

As time passes, the tensile force (TF) of the tendon 310 may decrease. If the tensile force (TF) of the tendon 310 decreases over time, there may be a problem with the safety of the target structure 300. The first digital voltage signal DVS1 obtained during the first time period TI1 and the second digital voltage signal DVS2 obtained during the second time period TI2 are compared to diagnose the safety of the target structure 300 . The tensile stress monitoring system 100 may compare the first digital voltage signal DVS1 and the second digital voltage signal DVS2 to determine the damage index DI of the target structure 300. [ The safety of the target structure 300 can be diagnosed based on the damage index DI of the target structure 300. [ If the damage index DI of the target structure 300 increases, there may be a problem with the safety of the target structure 300.

In an exemplary embodiment, the tensile stress monitoring system 100 is configured to detect a damage index (e.g., a voltage drop) of the target structure 300 based on a variance value of the first digital voltage signal DVS1 and a variance value of the second digital voltage signal DVS2 Damage Index (DI) can be determined. For example, as the variance 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.

The principle of calculating such a damage index can be actually applied to automatically alert the user of the risk when the tension of the tendon 310 is detected. FIG. 8 is a flow chart illustrating a method of calculating a damage index by processing a tensing force monitoring data of a PT tendon 310 measured in a tensing tension monitoring system 100 of a PT tendon according to embodiments of the present invention, Fig.

It is possible to automatically determine the decrease in the tension of the tendon 310 in the current state by utilizing the tension data of the tendon 310 measured by the eddy current sensor 200. [ The algorithm for this may be implemented by a program and executed by the control unit 500. [ The details of this algorithm are as follows.

First, signal measurement is performed n times at an initial (t = 0) tensional force condition (S200). 9 shows an example of a graph of an eddy current graph measured n times at an initial (t = 0) tensional force condition, that is, a tension signal (i.e., a digital electric signal) of the tension 310. Fig. n signal measurement can be performed through the procedure described in FIG. 6, that is, the procedure from step S100 to step S150 n times. The difference between successive measured signals with the same tension maintained can be assumed to be general noise. Here, the initial (t = 0) means immediately after the installation of the tendon 310 in the target structure 300, but on the other hand, a certain point in time has elapsed since the installation of the tendon 310, When you want to be the time point, the reference time point may be initial (t = 0).

The variance value? 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 ( ₀ ) of the n initial digital electrical signals (DVS) can be calculated using Equation (1).

here,

Is a variance value of n digital electrical signals (DVS) under an initial load (tension) condition,

Under the same load conditions,

Under the initial load (X) condition

The second measurement data (digital electrical signal), and

Represents the average value of the measurement data (digital electric signal) under the initial load (X) condition.

Next, at step S220, the tension force of the tenter 310 is again measured n times under the tension condition at the time point (t = T1) when a predetermined time has elapsed after the signal measurement at the initial time (t = 0). 10 shows an example of a eddy current graph, i.e., a tension signal (i.e., a digital electric signal) of the tension 310 measured at a changed tensional force condition at time t = T1. The measurement of the tension at time t = T1 is performed in the same manner as the measurement of the tension at the initial time (t = 0). That is, the tension measurement signals (n digital electric signals DVS) at time t = T1 can be obtained by performing the procedure from step S100 to step S150 n times. At time t = T1, the tension of the tendon 310 may be changed.

Then, the average value of the measurement data at the initial tension condition is used to calculate a variance value for n measurement signals, i.e., n digital electric signals DVS obtained through n signal measurements performed at time t = T1 (S230). The variance value ( ₁ ) of n digital electric signals (DVS) at time t = T1 can be calculated using Equation (2). At time t = T1, n digital electrical signals (DVS) represent the tension of the tendon 310 at the modified tension conditions.

here,

Is a variance value of n digital electric signals (DVS) under the load (tension) condition at time t = T1,

Under the same load conditions,

(T) under the changed load (tension) (Y) condition

The second measurement data (digital electric signal),

Represents the average value of the measurement data (digital electric signal) under the initial load (X) condition.

Next, the n digital electric signals (n) obtained from the initial dispersion value ( ₀ ) of the n digital electric signals (DVS) obtained at the initial or time t = 0 and the changed load (tension force) The damage index DI ₁ is calculated based on the variance value? ₁ of the DVSs (S240).

11 illustrates a graph for performing hypothesis verification using the difference between the initial tension and the changed tension. 12 shows an example of a graph for automatically determining whether the PT tension tendency is lowered by on-line monitoring based on the damage index. Referring to these two figures, if the change in the tension of the tendon 310 at the time t = T1 is not serious compared with the tension of the tendon 310 at the initial time (t = 0) We can hypothesize that the two variance values σ ₀ and σ ₁ must have the same level. With this hypothesis in mind, we can perform probabilistic / statistical analysis to verify this hypothesis. In carrying out this analysis, a damage index (DI) as shown in the following equation (3) can be utilized.

here

Represents the damage index (DI ₁ ). Once the damage index (DI ₁ ) is calculated, the degree of strain relief of the tendon 310 is monitored based on the calculated damage index (DI ₁ ). For example, the strain relief can be monitored by checking whether the calculated damage index (DI ₁ ) exceeds a preset threshold value (S250).

When a situation in which the damage index (DI ₁₎ calculated in step S250 exceeds a preset threshold value occurs, this means that the safety risk for the target structure 300. If such a situation occurs, a 'danger' warning is automatically generated to notify the structure manager and / or the user (S260).

If it is determined that the damage index (DI ₁₎ calculated in step S250 is not greater than a preset threshold value, and performs steps from which the predetermined time elapses (t = T2) one hours S220, repeat S230, S240. That is, at time t = T2, the digital electrical signal DVC indicating the tension of the tendon 310 is measured n times, and the average value of the initial measured signals

) Was used and that one calculates a variance value (σ ₁₎ of the measurement signal, and then the tendon at the time t = T2 based on the initial variance value previously obtained (σ ₀₎ to the current calculated variance value (σ ₁₎ ( 310) calculates a damage index (DI ₁₎ of. Then do the following, step S250 again, and repeats to check whether or not exceeds the threshold value the calculated damage index (DI _1). Through this process, the tension of the tendon 310 can be continuously monitored.

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

The FPCB eddy current sensor 1200 may include a coil portion such as the cylindrical eddy current sensor 200 and a casing 260 for covering the coil portion and shielding an external magnetic field from entering the coil portion. The FPCB eddy current sensor 1200 may further include a magnetic force portion. The magnetic portion may be embodied as a permanent magnet, for example.

The FPCB eddy current sensor 1200 may include at least one coil part. The coil portion can be provided for each wedge, which is an object to be measured. When there are a plurality of wedges 330a, 330b, ..., the number of the coil parts 1210a, 1210b, ... may be plural. The configuration and design of each coil section 1210 may be the same. The FPCB eddy current sensor 1200 may include a plurality of permanent magnets 250a, 250b, .... One coil section 1210 and one permanent magnet may be installed on each of the plurality of wedges 330a, 330b, ....

The FPCB eddy current sensor 1200 further includes a plurality of permanent magnets 250a, 250b, ... which are fixed to the inside of the casing 260 A plurality of elastic members 255a, 255b, ... for providing an elastic force in a first direction D1 to support the respective coil portions 1210a, 1210b, ... to the wedges 330a, 330b, ...). Each of the elastic members 255a, 255b is fixed to the bottom of the casing 260 and the other side is fixed to one side of the permanent magnets 250a, 250b, It is possible to flexibly adjust the interval between the bottom surfaces.

The configuration and role of the casing 260 in the FPCB type eddy current sensor 1200 to block the introduction of the external magnetic field into the coil part 1210 by accommodating the coil part 1210 therein is the same as the cylindrical eddy current sensor 200, and thus the description thereof will be omitted here.

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

The FPCB type eddy current sensor 1200 differs from the cylindrical eddy current sensor 200 in the configuration of the coil part 1210. The coil portion 1210 includes an FPCB 1230 and an excitation coil 1220 and a sensing coil 1240 laminated in the FPCB 1230 in a two-layer structure. For example, the sensing coil 1240 and the exciting coil 1220 are disposed in the first layer and the second layer, respectively, in the FPCB 1230 of the predetermined shape, and the two coils 1220 and 1240 are disposed in the FPCB 1230 ), As shown in FIG. More precise measurements can be made if the sensing coil 1240 is disposed on a single layer that can be located closer to the surface of the wedges 330a, 330b, .... Of course, the sensing coil 1240 may be arranged in two layers and the exciting coil 1220 in the first layer. The excitation coil 1220 and the sensing coil 1240 may be made of a metal having good conductivity. The FPCB 1230 of the coil part 1210 may be made of a flexible material. If the coil part 1210 is made thin with a soft material, it can be easily handled and can be manufactured in a form that can be directly attached to the wedge surface. The coil part 1210 of the FPCB eddy current sensor 1200 can be designed to have a size that can be attached to the surface of the wedge. The coil section 1210 may be designed in the shape of an arcuate band, for example, like a wedge.

A plurality of wedges may be inserted into the wedge insertion holes 372 between the anchor head 370 and the tent. As illustrated in FIG. 14, depending on the installation state, the surface heights of the plurality of wedges 330a, 330b,... May be different from each other. When the cylindrical eddy current sensor 200 is installed, the coil portion 210 of the cylindrical eddy current sensor 200 has a plurality of wedges 330a, 330b, ...) can not be directly in contact with each other, and a gap can be created. In this case, it may be disadvantageous in terms of the bonding force to the wedges (330a, 330b, ..) of the eddy current sensor 1200 and the accuracy of the measurement signal. The cylindrical eddy current sensor 200 may be more suitably installed when the height of the plurality of wedges 330a, 330b,... Is uniform. In the case where the plurality of wedges 330a, 330b,... Have different surface heights, the FPCB type coil part 1210, which can be provided for each wedge, may be more suitable.

Referring to FIG. 14, a plurality of coil parts 1210a, 1210b,... May be provided on respective surfaces of a plurality of wedges 330a, 330b,. The elastic members 255a and 255b and the permanent magnets 250a and 250b are interposed between the coil parts 1210a and 1210b and the bottom surface of the casing 260. Each of the permanent magnets 250a, 250b, ... is supported by one side of each of the coil parts 1210a, 1210b, ... by the elastic force of the elastic members 255a, 255b, ... provided in the first direction D1. And is pressed against the surface of the wedge (330a, 330b, ...). Whereby the respective coil parts 1210a, 1210b, ... can be attached to the surfaces of the wedges 330a, 330b, .... In this state, attraction is exerted between the permanent magnets 250a, 250b, ... and the wedges 330a, 330b, .... Thus, the entirety of the FPCB eddy current sensor 1200 can be kept fixed to the surfaces of the wedges 330a, 330b, ....

5, the FPCB eddy current sensor 1200 may be used in place of the cylindrical eddy current sensor 200 described above. The operation principle of the tensile force monitoring system 100 constructed using the FPCB type eddy current sensor 1200 is the same as that in the case of using the cylindrical eddy current sensor 200, so that a description thereof will be omitted here to avoid redundancy.

On the other hand, in the cylindrical eddy current sensor 200 or the FPCB type eddy current sensor 1200, the coil part 210 or 1210a, 1210b, .., is fixed to the wedges 330 or 330a, 330b,. .). ≪ / RTI > However, the sensitivity of the eddy current sensor 200 or 1200 may be adversely affected depending on the type of the adhesive, the thickness of the adhesive, and the position of the adhesive. The use of an adhesive can change the result of monitoring the tensile force of the tendon 310 depending on the adhesive, so that the reliability of the monitoring result may be lowered. In order to solve such a problem, the present invention uses a magnetic force part. The magnetic field portion uses, for example, permanent magnet 250 or 250a, 250b,. That is, instead of the adhesive, the coil part 210 or 1210a, 1210b,... Can be fixed to the wedges 330a, 330b, ... using the magnetic force of the permanent magnet 250 or 250a, 250b, To be fixed to the surface. The coil part 210 or 1210a, 1210b, .., of the eddy current sensor 200 or 1200 is magnetized by the magnetic force of the permanent magnet 250 or 250a, 250b, ..) is convenient because it simplifies the installation work of the eddy current sensor.

According to an exemplary embodiment, the plurality of FPCB type coil parts 1210 shown in FIG. 13 may be integrally connected via a flexible connecting member 1250. [ The connection type FPCB type coil portion may be configured as a circular, elliptical, polygonal, or similar closed loop type. For example, FIG. 15 shows an example in which a flexible FPCB type coil part 1200 is arranged between a plurality of FPCB type coil parts 1210 and connected to each other to form a circular FPCB type coil part 1300. 15 shows an example in which three FPCB type coil sections 1210 are connected. However, the number of FPCB type eddy current sensors 1210 to be connected does not necessarily have to be three, but two or four or more It is possible. It is preferable to arrange the FPCB type coil part 1200 in a number corresponding to the number of wedges so as to form a circular FPCB type coil part 1300 by connecting the number of the FPCB type coil parts 1210 corresponding to the number of wedges.

Since the plurality of FPCB coil sections 1210 of the circular FPCB coil section 1300 are connected to each other by the connecting member 1250 having good stretchability, the difference in the surface height of the wedges 330a, 330b, It is easy to install without receiving. Considering the case where a plurality of FPCB type coil parts 1210 are arranged one by one on the surface of 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 can be buffered by the flexible connecting members 1250. Since the plurality of FPCB type coil parts 1210 are integrally connected, they can be installed at the same time, which is advantageous in that handling and installation are easy.

The circular FPCB coil section 1300 can be substantially the same as that described above. That is, the permanent magnets 250a, 250b,... May be provided for each FPCB coil section 1210, one on top of the other. Further, a 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, ... provide elastic forces to the respective permanent magnets 250a, 250b, .. while fixing the plurality of permanent magnets 250a, 250b, ... in the casing. So that the individual FPCB type coil part 1210 is pushed toward the surface of the wedges 330a, 330b, ... so as to be fixed.

Next, a wireless sensor node system for monitoring the tendency of the tensile force reduction according to the present invention will be described. In the case of the PT tendon system, it is mostly buried in concrete, and the fusing part is not easily accessible. Therefore, the sensors and sensor nodes installed in the fusing unit are subjected to the monitoring of the tensions in the state embedded in the concrete. As a method of supplying power to a sensor node, a battery is used or a power is supplied by a wired line. In data acquisition, a sensor node is directly accessed or a wired data transmission method is used. When power and data are transferred using existing methods, problems such as battery replacement and maintenance of power / data wired system occur, which increases the maintenance cost of the sensor.

In order to solve this problem, a concrete wireless power and data transmission technology is required and a system capable of power transmission and data reception at the upper part of the concrete deck is required without directly accessing the sensor node during power supply and data acquisition of the sensor node . As an example of this system, FIG. 16 shows a schematic diagram of a wireless sensor node system 600 for tensile tension monitoring.

Referring to FIG. 16, the system 600 mainly has a configuration combining a wireless power and a data transmission unit and a sensor node for PT tension-reduction monitoring. The wireless sensor node system 600 for tensile tension monitoring wirelessly transmits electric power to a bridge sensor through a pair of coils without a communication module and a power line and simultaneously detects a primary side voltage fluctuation due to a secondary side load fluctuation Data can be transmitted wirelessly.

In particular, the wireless sensor node system 600 for tensing tension monitoring according to the present invention includes a wireless transmission and data receiving unit 620, a wireless receiving and data providing unit 660, and a power and data wireless transmitting unit 650 can do. Wireless charging of sensor battery 664 and wireless transmission of data generated by sensor node 670 may use the same resonator. The resonator may be implemented as a power and data wireless transmitter 650. Here, the sensor node 670 includes 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, for smart bridge implementation . The sensor node 670 may also include other sensors, such as temperature sensors, for measuring the state of the bridge 615, for example, for smart bridge implementation.

The power and data radio transmission unit 650 is connected to a primary side coil 652 provided in a movable body such as a vehicle 610 (hereinafter, the vehicle 610 will be described as an example) And a secondary side coil 654 installed in a fixed structure such as a bridge 615 (hereinafter, the bridge 615 will be described as an example). When the primary side coil 652 is positioned on the secondary side coil 654 by the movement of the vehicle 610 (that is, in the state where the magnetic force can be induced by magnetic flux linkage with each other The primary side coil 652 and the secondary side coil 654 can transfer electric energy from one side to the other side by mutual magnetic induction method.

The wireless transmission and data receiving unit 620 can be installed in the vehicle 610 and can move with the vehicle. And may also be coupled to the primary side coil 652 of the power and data wireless transmitters 650.

The radio receiving and data providing unit 660 may be installed at or around the tendon 310 of a structure such as the bridge 615, for example. And is also coupled to the secondary side coil 654 of the power and data wireless transmission unit 650.

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

More specifically, power is supplied to the primary coil 652 manufactured on the basis of the magnetic induction by the wireless transmission and data receiving unit 620 mounted on the inspection vehicle 610 (S300). To this end, the primary side coil 652 of the power and data radio transmission unit 650 mounted on the vehicle 610 approaches the secondary side coil 654 provided on the bridge 615. An alternating current flows in the primary coil 652 by the supplied power, and a magnetic field is formed around the primary coil 652. The magnetic field is linked with the secondary coil 654. The power source may be a battery for the inspection vehicle 610 or a separate battery.

The secondary coil 654 provided in the structure 615, such as a bridge, is coupled to the primary coil 652 on a magnetic induction basis. Therefore, when the alternating current is supplied to the primary side coil 652, the secondary side coil 654 is coupled to the primary side coil 652 in mutually magnetic induction relationship, do. The secondary coil 654 receives power from the primary coil 652 and supplies the received power to the sensor node 670 for tension-tension monitoring (S310). The induced alternating current can be converted to a direct current through the rectifying process. The direct current can flow into the sensor battery portion 664 and be charged.

The sensor node 670 can perform the operation of measuring the tension of the tendon 310 described above while the power is supplied to the sensor node 670. [ That is, in the eddy current sensor 200 or 1200 connected to the sensor node 670, a current is supplied to the exciting coil 220 or 1220 to generate a constant first magnetic field B1 to form an eddy current on the surface of the wedge 330 S320).

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

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

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

Through the above process, the measurement data collected by the inspection vehicle 610 can be used to determine whether the tensile strength of the tensile 310 is lowered or damaged (S360). The result of the determination as to the decrease in the tensile force of the tendon 310 is transmitted to the specialist so that appropriate follow-up measures can be taken.

In the wireless power transmission system, 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, resulting in a large conduction loss and a low transmission efficiency. Therefore, in order to reduce the magnitude of the circulating current flowing in the primary side coil 652, it is desirable to design the reactive power portion of the input impedance as small as possible. This allows the LC resonance phenomenon to occur, thereby eliminating the reactive power portion. Further, a series-series compensation resonator structure in which the current required for the primary side coil 652 varies depending on the load to minimize the conduction loss can be utilized. According to actual tests, for example, the total power required to acquire and process measurement data is about 10 watts, and the time required to acquire data is about 10 seconds.

The 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 a second magnetic field generated based on the eddy current to the sensor, And can be applied to a structure diagnosis apparatus.

While the present invention has been described with reference to the preferred embodiments thereof, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as defined in the appended claims. It will be understood.

100: Tension tension monitoring system 150: Waveform generator
200: Cylindrical eddy current sensor 210: coil part
220, 1220: exciting coil 240, 1240: sensing coil
250, 250a, 250b: permanent magnets 255a, 255b: elastic member
260: Outer casing 310: Tendon
330, 330a, 330b: Wedge 370: Anchor head
400: digitizer 500: control unit
600: Wireless Sensor Node System for Tension Tension Monitoring
620: Radio transmission and data reception unit 650: Power and data radio transmission unit
660: Radio receiver and data provider 664: Sensor battery
670: Sensor node 1200: FPCB type eddy current sensor
1250: Elastic connecting member 1300: Circular FPCB type eddy current sensor

Claims (15)

Wherein the anchor head is press-fitted between a tendon and an anchor head which provide a varying stress based on a tensile force to firmly hold the tendon and fix it on the anchor head, wedge;
An excitation coil provided on a surface of the at least one wedge for generating a first magnetic field based on an excitation signal applied thereto and a second magnetic field generated by the eddy current induced in the at least one wedge by the first magnetic field, And a sensing coil for detecting an electric signal corresponding to a composite magnetic field of the first magnetic field, wherein a direction of the first magnetic field passing through the sensing coil and a direction of the second magnetic field are opposite to each other; And a casing enclosing the coil portion and enclosing the coil portion, the casing being made of a material having a magnetic shielding ability and preventing a magnetic field from flowing into the coil portion from the outside; And
And a tension monitoring unit for providing the excitation signal to the exciting coil and calculating information on the tension of the tension using the electric signal detected by the sensing coil. The system according to claim 1, further comprising a magnetic force part for receiving and fixing the casing and the coil part to the wedge magnetically by being housed in the casing. The system according to claim 1 or 2, wherein the coil part is inserted into the excitation coil so that the sensing coil and the excitation coil form a double cylindrical shape. 3. The system of claim 1 or 2, further comprising a coil case surrounding the exciting coil and the sensing coil and having connectors connected to the exciting coil and the sensing coil, respectively. [2] The apparatus of claim 1, wherein the coil unit is an FPCB coil unit having the sensing coil and the exciting coil arranged in a two-layer structure via a flexible printed circuit board (FPCB) Tension diagnostic system. The flexible printed circuit board according to claim 1, wherein the coil portion includes a plurality of FPCB coil portions, and a flexible connecting member disposed between the plurality of FPCB coil portions to connect the plurality of FPCB coil portions to form a closed loop, Wherein the FPCB type coil unit has 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) of a predetermined shape. The system according to claim 5 or 6, further comprising a magnetic force part for receiving and fixing the casing and the coil part to the wedge magnetically by being housed in the casing. delete 2. The method of claim 1, wherein the tension monitoring unit comprises: (i) calculating a first variance value ( ₀ ) by performing n measurements of the electrical signal through the eddy current sensor at an initial tension condition, (ii) ( _I ) calculating the second variance value ( ₁ ) by performing the same measurement of the electric signal n times through the eddy current sensor even when the tensile force of the tendon is changed according to the first variance value ₀ ) and the second variance value (σ ₁ ), and (iv) when the calculated damage index exceeds the allowable threshold value, an algorithm is automatically implemented to generate a danger alarm And a program for executing the program. delete The apparatus of claim 1, wherein the tensional force monitoring unit comprises: a waveform generator for providing the excitation signal having a predetermined frequency based on a transmission control signal; A digitizer for digitizing an electrical signal corresponding to the second magnetic field to provide a digital electrical signal; And a control unit for providing the transmission control signal to the waveform generator and receiving the digital electric signal from the digitizer to calculate a tension of the tendon. 12. The system of claim 11, wherein the controller is provided with a function of issuing a critical alarm when the calculated magnitude of the calculated tension falls below an allowable threshold value. The apparatus of claim 1, wherein the tensional force monitoring unit compares a first electrical signal obtained during a first time period of the electrical signal with a second electrical signal obtained during a second time period of the electrical signal, And determining a tensile strength of the tensile force. 2. The apparatus according to claim 1, further comprising: a primary coil installed in the movable body; and a secondary coil provided in the structure provided with the eddy-current sensor and coupled to the primary coil in a magnetic induction manner, And a data wireless transmission unit; And a power monitoring unit which is provided on the movable body and is connected to the primary coil to provide power required for driving the eddy current sensor and the tensional force monitoring unit through a power and data wireless transmission unit in a magnetic induction manner, Further comprising a wireless transmission and data receiving unit for collecting information on a tension force of the tentative tension sensor by a magnetic induction method. 15. The system of claim 14, wherein the movable body is a vehicle and the structure is a road and / or a bridge over which the vehicle can travel.

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