KR101505037B1 - Multiple component reaction force meter using optical bragg gratings and method for measuring reaction force using the same - Google Patents

Abstract

The multi-component reaction force system according to the present invention includes a reaction force lower plate acting together with the ground, a reaction force upper plate acting integrally with the vertical structure, a plurality of two-dimensionally arranged reaction force lower plate and reaction force upper plate, Rigid pillars, fiber optic cables having at least one optical Bragg grating sensor mounted on each of these rigid pillars, and an interrogator. The interrogator is designed to receive incident light of a predetermined spectrum at the input end of the optical fiber cable and to detect the spectrum of the reflected light reflected by the optical Bragg grating sensors at the input end of the optical fiber cable, The strain of each of the rigid columns can be measured by detecting the spectrum of the transmitted light at the output end of the optical fiber cable and by changing the lattice spacing of the optical Bragg grating sensors measured based on the change of the reflected light spectrum or the transmitted light spectrum of the optical Bragg grating sensors have.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-component reaction force measuring method and a reaction force measuring method using a photonic-

The present invention relates to a reaction force measuring apparatus, and more particularly, to a reaction force system capable of measuring a moment reaction force.

Reaction force refers to the force generated in the structure to balance the structure when the structure receives an external force. The vertical reaction force component restricting the vertical displacement at the support is referred to as a vertical reaction force, and the reaction force for restricting the rotational displacement is referred to as a moment reaction force.

The reaction force system for measuring the reaction force is used in the construction site to measure the reaction force from the caisson, pile, foundation, pillar, etc. However, the conventional reaction force system has a very small sectional area compared to the foundation or large column and provides the vertical reaction force measured at a specific point as a representative value Only.

In the conventional reaction force system, only the vertical reaction force component of a specific point is measured, and moment reaction force component, which is one of important components of the reaction force, can not be measured. For this reason, sufficient information about the reaction force can not be obtained in the case of a base having a large area.

Using a plurality of independent reaction systems, the vertical reaction force can be measured at various points. In such a case, since the signal line and the power line are required for each reaction force system, the wiring becomes complicated and the cost is increased. It is difficult to back.

Therefore, there is a need for economical and effective means for measuring the vertical reaction force component and the moment reaction force component by measuring the stress at various points of a large-area elastic body with low cost, low complexity, high reliability and long life.

A problem to be solved by the present invention is to provide a multi-component reaction force system and a reaction force measurement method using an optical Bragg grating.

The multi-component reaction force meter according to one aspect of the present invention

Reaction force lower plate acting together with the ground;

A reaction force system top plate acting integrally with a vertical structure;

A plurality of rigid pillars arranged two-dimensionally between the reaction force lower plate and the reaction force upper plate in parallel with the ground; And

And an optical fiber cable having at least one optical fiber Bragg grating sensor mounted on each of the rigid columns.

According to one embodiment, the plurality of rigid columns may be arranged in a regular arrangement on a two-dimensional plane between the reaction force lower plate and the reaction force upper plate.

According to one embodiment, the rigid column is a square column having a square cross section, and one to four optical Bragg grating sensors may be mounted on at least one side surface of the rigid column in parallel with the normal of the ground have.

According to one embodiment, the reaction force system lower plate and the reaction force system upper plate may be equal to or smaller than the cross section of the vertical structure to be measured.

According to one embodiment, different optical fiber Bragg grating sensors mounted on different rigid pillars are arranged such that each of the plurality of rigid pillars is uniquely identified as each of the local peaks appearing in the reflected light spectrum by the optical Bragg grating sensors, And can have different grating structures, respectively.

According to one embodiment, a plurality of optical Bragg grating sensors mounted on the same rigid column may have the same grating structure.

According to one embodiment, by a change in the lattice spacing of the optical Bragg grating sensors measured based on changes in the reflected swath spectrum or transmitted light spectrum reflected by the plurality of optical Bragg grating sensors, The vertical reaction force component P and the two-way moment reaction force components M _X and M _Y with respect to the ground of the vertical structure are expressed by the following equations

, Which is obtained by the solution of the simultaneous equations of

Where A is the sum of the cross-sectional area of all the rigid pillars, E is the elastic modulus of the body pillar, I _X and I _Y are deulyigo each total moment of inertia component of every rigid body pillar, N is the number of optical Bragg grating sensor, ξ _k and η _k are the two-dimensional coordinates of the k-th optical Bragg grating sensor, and e _k may be an error in the strain measurement.

According to one embodiment, the cross-section of the rigid column is rectangular,

The total cross-sectional moment of inertia components I _X and I _Y can be _calculated by the following equations

And

Lt; / RTI >

Where n is the number of rigid columns in the two-dimensional plane corresponding to the two-dimensional array of the rigid columns, m is the number of rigid columns in the Y axis, i is the index of the number of rigid pillars in the X axis, j is the number of rigid pillars in the Y axis index, x _ij and y _ij is the center coordinate of the i-specific bodies in the second row and the j-th column pole, S is the cross-sectional area of the respective rigid-body pillar, a and b are the horizontal and vertical length of the rigid pillars, i _x, I _y can be the moment of inertia of each rigid body.

According to one embodiment, the cross-section of the rigid column is circular,

The total cross-sectional moment of inertia components I _X and I _Y can be _calculated by the following equations

And

Lt; / RTI >

Where n is the number of rigid columns in the two-dimensional plane corresponding to the two-dimensional array of the rigid columns, m is the number of rigid columns in the Y axis, i is the index of the number of rigid pillars in the X axis, j is the number of rigid pillars in the Y axis Index, x _ij and y _ij are the coordinates of the center of the specific rigid column located in the ith row and jth column, S is the cross sectional area of each rigid column, D is the diameter of the rigid column, I _x And I _y may be the moment of inertia of each rigid column.

A multi-component reaction force system according to another aspect of the present invention includes:

Reaction force lower plate acting together with the ground;

A reaction force system top plate acting integrally with a vertical structure;

A plurality of rigid pillars arranged two-dimensionally between the reaction force lower plate and the reaction force upper plate in parallel with the ground;

An optical fiber cable having at least one optical fiber Bragg grating sensor mounted on each of the rigid columns; And

Wherein a spectrum of incident light of a predetermined spectrum is incident on an input end of the optical fiber cable and a spectrum of reflected light reflected by the optical Bragg grating sensors is detected at an input end of the optical fiber cable, Wherein a strain of each of the rigid columns is detected by a change in the lattice spacing of the optical Bragg grating sensors measured on the basis of changes in the reflected light spectrum or the transmitted light spectrum of the optical Bragg grating sensors And may include an interrogator to measure.

According to another aspect of the present invention, there is provided a reaction force measuring method using a multi-component reaction force system having a plurality of optical Bragg gratings,

A plurality of rigid pillars arranged two-dimensionally in parallel with the ground, and a plurality of rigid pillars arranged in parallel with the ground, and at least one rigid pillars mounted on each of the rigid pillars between a reaction force system lower plate acting integrally with the ground and a reaction force system upper plate acting integrally with a lower end of the vertical structure, Forming a multi-component reaction force system composed of an optical fiber cable having optical Bragg grating sensors of a vertical structure between the lower end of the vertical structure and the ground;

The method comprising the steps of: the interrogator inputting incident light having a predetermined incident light spectrum to an input end of an optical fiber cable of the multi-component reaction force system;

Wherein the interrogator detects a spectrum of reflected light reflected by the optical Bragg grating sensors at an input end of the optical fiber cable or a spectrum of transmitted light partially suppressed by the optical Bragg grating sensors, ;

Measuring the strain of each of the rigid columns by the change of the grating structure of the optical Bragg grating sensors measured by the interrogator based on changes in the reflected light spectrum or the transmitted light spectrum of the optical Bragg grating sensors; And

The total moment of inertia of the rigid columns arranged in a two-dimensional array, the sum of the cross-sectional areas of the rigid columns, the modulus of elasticity of the rigid columns, the total moment of inertia components of the rigid columns, And calculating the vertical reaction force component P, the two-way moment reaction force components M _X and M _Y based on the coordinates of the detected rigid body columns and the strain of each of the detected rigid columns.

According to one embodiment, the plurality of rigid columns may be arranged in a regular arrangement on a two-dimensional plane between a reaction force lower plate and a reaction force upper plate.

According to one embodiment, the rigid column is a square column having a square cross section, and one to four optical Bragg grating sensors are mounted on the side faces of at least one of the side faces of the rigid column in parallel with the normal line of the ground And can have a plurality of optical Bragg gratings.

According to one embodiment, the reaction force system lower plate and the reaction force system upper plate may be equal to or smaller than the cross section of the vertical structure to be measured.

According to one embodiment, different optical fiber Bragg grating sensors mounted on different rigid pillars are arranged such that each of the plurality of rigid pillars is uniquely identified as each of the local peaks appearing in the reflected light spectrum by the optical Bragg grating sensors, And can have different grating structures, respectively.

According to one embodiment, a plurality of optical Bragg grating sensors mounted on the same rigid column may have the same grating structure.

According to one embodiment, the step of calculating the vertical reaction force component P, the two-way moment reaction force components M _X and M _Y ,

The vertical reaction force component P and the two-way moment reaction force components M _X and M _Y with respect to the ground of the vertical structure are expressed by the following equations

From the solution of the simultaneous equations according to < RTI ID = 0.0 >

Where A is the sum of the cross-sectional area of all the rigid pillars, E is the elastic modulus of the body pillar, I _X and I _Y are deulyigo each total moment of inertia component of every rigid body pillar, N is the number of optical Bragg grating sensor, ξ _k and η _k are the two-dimensional coordinates of the k-th optical Bragg grating sensor, and e _k may be an error in the strain measurement.

According to one embodiment, the cross-section of the rigid column is rectangular,

The total cross-sectional moment of inertia components I _X and I _Y can be _calculated by the following equations

And

Lt; / RTI >

Where n is the number of rigid columns in the two-dimensional plane corresponding to the two-dimensional array of the rigid columns, m is the number of rigid columns in the Y axis, i is the index of the number of rigid pillars in the X axis, j is the number of rigid pillars in the Y axis index, x _ij and y _ij is the center coordinate of the i-specific bodies in the second row and the j-th column pole, S is the cross-sectional area of the respective rigid-body pillar, a and b are the horizontal and vertical length of the rigid pillars, i _x, I _y can be the moment of inertia of each rigid body.

According to one embodiment, the cross-section of the rigid column is circular,

The total cross-sectional moment of inertia components I _X and I _Y can be _calculated by the following equations

And

Lt; / RTI >

Where n is the number of rigid columns in the two-dimensional plane corresponding to the two-dimensional array of the rigid columns, m is the number of rigid columns in the Y axis, i is the index of the number of rigid pillars in the X axis, j is the number of rigid pillars in the Y axis Index, x _ij and y _ij are the coordinates of the center of the specific rigid column located in the ith row and jth column, S is the cross sectional area of each rigid column, D is the diameter of the rigid column, I _x And I _y may be the moment of inertia of each rigid column.

According to the multi-component reaction force system and the reaction force measurement method using the optical Bragg grating of the present invention, it is possible to obtain not only the vertical reaction force but also the moment reaction force by being installed in a wide area elastic body.

According to the multi-component reaction force system and reaction force measurement method using the optical Bragg grating of the present invention, since only one optical cable is required, the wiring is not complicated at the time of installation and calibration may be unnecessary.

According to the multi-component reaction force system and the reaction force measurement method using the optical Bragg grating of the present invention, the advantage of high reliability and long lifetime characteristics of the optical Bragg grating can be utilized as it is.

FIG. 1 is a view illustrating a reaction force unit using a photonic bandgap according to an embodiment of the present invention. Referring to FIG.
FIG. 2 is a view illustrating a reaction force unit using a photo-induced Bragg grating according to another embodiment of the present invention.
FIG. 3 is a conceptual diagram illustrating the installation of a multi-component reaction force system using the optical Bragg grating according to an embodiment of the present invention.
FIG. 4 is a conceptual diagram illustrating measurement components obtained from a multi-component reaction force system using a photo-induced Bragg grating according to an embodiment of the present invention.
5 is a flowchart illustrating a reaction force measurement method using a multi-component reaction force system having a plurality of optical Bragg gratings according to an embodiment of the present invention.

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.

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 and 2 are views illustrating a reaction force unit using an optical Bragg grating according to an embodiment of the present invention.

1, the reaction force measuring unit 10 using the optical Bragg grating may include a fiber optic cable 12 having a rigid post 11 and at least one optical Bragg grating sensor 121, 122, have.

Generally, a fiber Bragg grating (FBG) sensor is a sensor capable of detecting a deformation of a structure in which a grating is fixed by measuring a variation of a reflection wavelength generated according to a Bragg's law.

The Bragg's law is based on Bragg diffraction, which is a phenomenon in which constructive interference occurs at a specific angle of reflection depending on the wavelengths, incidence angles, and lattice spacings of incident electromagnetic or particle waves when atoms in a crystal have a specific interval lattice structure. , The angle of incidence, and the spacing of the gratings.

Bragg conditions refer to conditions of incident light, incident angle and lattice spacing for constructive interference to occur in accordance with Bragg law.

On the other hand, the optical fiber cable utilizes the principle that total reflection takes place at the interface when light travels from a material having a high refractive index to a material having a low refractive index. The optical fiber cable is structured such that a core having a high refractive index is wrapped with a cladding having a low refractive index. The light incident on the core of the optical fiber cable is totally reflected between the core and the cladding, do.

The core is prepared by adding a small amount of germanium (Ge), for example, as a material for increasing the refractive index in silica glass, and structural defects may occur during the process in which germanium is deposited on the silica glass. When such a defect is irradiated with strong ultraviolet rays, the coupling structure of germanium is deformed and the refractive index of the optical fiber changes at the corresponding point.

The optical Bragg grating sensor positively utilizes this phenomenon and is an optical fiber based sensor having at least one grating section whose refractive index differs from the normal point in the core of a section of the optical fiber cable.

Since the optical Bragg grating sensor reflects the wavelengths satisfying the Bragg conditions of the optical Bragg grating at the boundary points at which the refractive index is changed, that is, the dielectronic mirror, as a result, Only the light of the other wavelength except the light of the specific wavelength reflected in the light is outputted from the optical Bragg grating sensor cable.

The optical Bragg grating sensor can have a plurality of optical Bragg gratings within a predetermined length, for example, several grating sections within a range of about 10 mm, to more reliably reflect a wavelength satisfying the Bragg condition, You can have a thousand grids.

The relationship between the wavelength of the reflected light and the lattice interval is given by the following equation (1).

Where λ _B is the wavelength of the reflected light, n is the effective refractive index of the optical fiber core, and Λ is the spacing between neighboring grating sections.

The Bragg conditions of each of these lattice sections may be the same, but it may be easier to analyze the spectrum of the reflected light if the respective Bragg conditions are made to be different from each other.

When such a fiber Bragg grating sensor cable is mounted on a compacted, stretched or twisted structure, a subtle change in lattice spacing occurs in the lattice structure of the optical Bragg grating sensor due to compression, tensile or warping of the structure, The wavelength of light also changes. Therefore, by analyzing the change in the spectrum of the light reflected or transmitted by the optical Bragg grating sensor cable, it is possible to precisely detect the minute deformation of the structure.

The relationship between the elastic deformation of the germanium silica glass due to the strain or stress applied to the optical Bragg grating sensor and the change of the wavelength of the reflected light can be expressed by the following equation (2).

Where λ _B is the wavelength of the reflected light, Δλ _B is the wavelength variation of the reflected light, Pe is the photoelastic constant, which is about 0.22 for the germanium silica glass, and ε is the fiber- The applied stress.

On the other hand, the wavelength of the reflected light of the optical Bragg grating sensor is influenced by the expansion according to the temperature, and although the description thereof is omitted in the description of the present invention with respect to this point, it can be easily considered as necessary.

Returning to FIG. 1, the optical fiber cable 12 has at least one optical fiber Bragg grating sensor 121, 122, 123. The optical Bragg grating sensors 121, 122 and 123 are formed on the optical fiber cable 12 with proper spacing therebetween.

The optical Bragg grating sensors 121, 122 and 123 are respectively fixed to the central portions of the respective side surfaces of the rigid column 11 so as to detect the stress in the vertical direction generated in the rigid column 11. [

In FIG. 1, the rigid column 11 is exemplified by a polygonal column having a square bottom, and each of the optical Bragg grating sensors 121, 122, and 123 has a side surface Respectively.

On the other hand, in Fig. 2, each of the optical Bragg grating sensors 121, 122, and 123 is disposed and mounted on the side surface of the rigid column 11 so that the incidence directions of the light are the same each time.

After the optical Bragg grating sensors 121, 122 and 123 are mounted on the object to be deformed such as the rigid column 11, an interrogator externally transmits the incident light having a predetermined incident light spectrum to the optical fiber cable 12 The spectrum of the reflected light reflected along the lattice spacing of the optical Bragg grating sensors 121, 122 and 123 is detected by the interrogator at the input of the optical fiber cable 12 or the optical Bragg grating sensors 121, 122 and 123 can be detected by the interrogator at the output end of the optical fiber cable 12. [

By measuring the change in the lattice spacing of the optical Bragg grating sensors 121, 122, 123 based on the change in the reflected light or the transmitted light spectrum of the optical Bragg grating sensors 121, 122, 123 detected by the interrogator, As a result, the degree of deformation of the rigid column 11 can be known.

The central wavelength values of the reflected light reflected by the respective grating structures of the optical Bragg grating sensors 121, 122 and 123 may be equal to each other and may be different according to the embodiment.

It is preferable that the rigid column 11 should be deformed within a linear elastic range, and the linearity of the elastic modulus within the elastic range is also maintained.

The rigid column 11 may be a polygonal column or a cylinder.

FIG. 3 is a conceptual diagram illustrating the installation of a multi-component reaction force system using the optical Bragg grating according to an embodiment of the present invention.

3, the multi-component reaction force system 100 includes a reaction force lower plate 20 inserted between a lower end of a vertical structure 31 such as a column or foundation of a building and a ground 21 and a reaction force upper plate 30 And a plurality of reaction force unit units 10 arranged in the reaction chamber.

It is preferable that the reaction force lower plate 20 and the reaction force upper plate 30 are equal to or slightly smaller than the cross section of the vertical structure 31 to be measured.

If the multi-component reaction force system 100 is installed on the ground 21, the reaction force lower plate 20 behaves integrally with the ground 21 and the reaction force upper plate 30 is integrally formed with the lower end of the vertical structure 31 It is preferable to be installed so as to behave.

Each of the reaction force-based units 10 using the optical Bragg grating includes an optical fiber cable 12 having a rigid post 11 and at least one optical Bragg grating sensor 121, as illustrated in Fig. 1 or Fig. . ≪ / RTI >

The plurality of rigid pillars 11 may be arranged between the reaction force lower plate 20 and the reaction force upper plate 30 in a constant arrangement, for example, in the form of an array of squares of the same size which are in contact with a circle of a predetermined radius, In the form of a checkerboard.

At least one optical fiber Bragg grating sensor 121 may be mounted on each of the plurality of rigid columns 11. For example, if the rigid column 11 is a square column having a square cross section, One to four optical Bragg grating sensors 121 may be mounted on the side faces of at least one of the side faces of the substrate 11 in parallel with the normal line of the ground 21.

For example, in the case of a quadrangular rigid column corresponding to the top edge of a checkerboard shape, three quadrangular rigid pillars are provided on four side faces of the quadrilateral rigid pillars, one on each of three side faces except for the side face contacting the outer boundary of the multi- Optical Bragg grating sensors 121 may be mounted. In the case of a quadrangular rigid column corresponding to an inner point of a checkerboard shape, four optical Bragg grating sensors 121 may be mounted on each of four side surfaces of a rectangular rigid column.

Thus, one multi-component reaction force system 100 may have N optical Bragg grating sensors 121, for example, n x m? N? 4n x m.

At this time, since the degrees of deformation of the respective side faces are different at each of the rigid columns 11, it can be considered that the grating changes of the optical Bragg grating sensors 121 are different from each other on the side surfaces of the rigid column 11. [ However, the rigid columns 11 are uniformly distributed over a large area between the reaction force lower plate 20 and the reaction force upper plate 30, and the sectional area of each rigid column 11 is smaller than the reaction force lower plate 20 The degree of deformation detected on the different side surfaces of the rigid column 11 when one rigid column 11 is deformed due to the slight inclination of the vertical structure 31 is very small compared to the area of the upper plate 30. [ There is no difference or is negligible.

Therefore, the center wavelengths of the reflection bands due to the plurality of optical Bragg grating sensors 121 of the same lattice spacing mounted on one rigid column 11 are also substantially the same.

Furthermore, if each of the reaction force units 10 is such that each of the reflected light spectra of the optical Bragg grating sensors 121 can uniquely distinguish each of the rigid columns 11 on which the optical Bragg grating sensors 121 are mounted , Each of the reaction force gauges 10 can also be distinguished as local peaks or local valleys appearing in the reflected light spectrum or in the spectrum of the transmitted light so long as each of the optical Bragg grating sensors 121 has a different grating structure .

In other words, each of the local peaks or local valleys appearing in the detected spectrum can be matched one-by-one with each of the rigid columns 11.

To this end, each optical Bragg grating sensor belonging to different reaction force unit (s) 10 may each have a grating structure in which the reflected light spectrum is distinguished from each other.

However, the optical Bragg grating sensors 121 belonging to one reaction force unit 10 may have the same lattice structure.

In order to obtain a reflected light spectrum or a transmitted light spectrum from the multi-component reaction force system 100, the interrogator 200 causes incident light having a predetermined incident light spectrum to enter the input end of the optical fiber cable 12 of the multi-component reaction force meter 100 , The spectrum of the reflected light reflected by the optical Bragg grating sensors 121, 122 and 123 is detected at the input of the optical fiber cable 12 or is detected by the optical Bragg grating sensors 121, 122 and 123 The spectrum of the transmitted light can be detected at the output terminal of the optical fiber cable 12. [

The interrogator 200 detects changes in the lattice spacing of the optical Bragg grating sensors 121, 122 and 123 based on changes in the reflected light spectrum or the transmitted light spectrum of the detected optical Bragg grating sensors 121, As a result, the strain of the rigid column 11 can be measured.

Thus, since the strain of the rigid column 11 is detected at each designated position, the second-order moment reaction force can be obtained by matching the detected strain values to the two-dimensional array corresponding to the arrangement of reaction force units 10 .

FIG. 4 is a conceptual diagram illustrating measurement components obtained from a multi-component reaction force system using an optical Bragg grating according to an embodiment of the present invention to obtain such a second moment reaction force.

Referring to FIG. 4, the arrangement of reaction force units 10 of the multi-component reaction force system 100 may correspond to a two-dimensional rectangular coordinate system having an X-axis and a Y-axis. For the sake of convenience of explanation, the arrangement of the reaction force units 10 is a checkerboard of width n x height m, and the crosswise side and the longitudinal side are respectively parallel to the X and Y axes of the orthogonal coordinate system, An orthogonal coordinate system may be set such that the neutral point of the multi-component reaction force system 100 is at a neutral point.

On the other hand, the secondary moment of inertia of the rigid column 11 is determined according to the cross-sectional shape of the rigid column 11. For example, if the rigid column 11 is a rectangle having a width a and a length b, the moment of inertia ( I _x , I _y ) of one rigid column 11 is given by the following equation (3).

For example, if the rigid column 11 is a circle having a diameter D, the moment of inertia ( I _x , I _y ) of one rigid column 11 is given by the following equation (4).

_{Assuming that} the centers of the rigid pillars C _ij are provided at positions corresponding to (x _ij , y _ij ) on the two-dimensional Cartesian coordinate system, The total moment of inertia ( I _X , I _Y ) of the total cross-sectional moments ( I _X , IOO)

Where i is the index of the number of rigid columns in the X axis, j is the index of the number of rigid columns in the Y axis, x _ij and y _ij are the indexes of the i-th row and the j-th column, The coordinates of the center of the rigid column C _{ij in} the column, S is the cross-sectional area of each rigid column. The total cross-sectional moment of inertia ( I _X , I _Y ) in Equation (5) is based on predetermined values and can therefore be treated as a constant.

Assuming that the total number N of optical Bragg grating sensors 121 and, more precisely, the strain value obtained from any kth optical Bragg grating sensor 121k is ε _k , the strain ε _k is given by the following equation (6). Since the vertical reaction force component P and the moment reaction force components M _X and M _Y occur on the foundation and the ground as a whole, they act on all the rigid columns 11 equally, but the strain 竜 _k May vary from location to location.

Here, A is the sum of the cross-sectional areas of all the rigid columns 11, E is the modulus of elasticity of the rigid column 11, I _X and I _Y are the total moment of inertia components of all the rigid columns 11 Ξ _k and η _k are the coordinates of the kth optical Bragg grating sensor 121k and P, M _X and M _Y are the vertical reaction force components finally obtained by the multi-component reaction force system 100 of the present invention, And the true values of the two-way moment reaction force components. Here, the two-way moment reaction force component means that the moment reaction force component is considered in two directions corresponding to the two coordinate axes of the two-dimensional plane coordinate system in which the reaction force units 10 are arranged. Also, e _k is a realistic and inevitable error at the time of measurement.

According to the heuristic assumption that the statistical mean value of the measurement errors e _k will be close to 0 when the number of strain sensors is increased, the total measurement error R of the total N optical Bragg grating sensors 121 is defined by the following Equation 7 .

It can be seen from Equation (7) and the rational reasoning about it that there exists P, M _X and M _Y which make this total measurement error R 0 or the minimum value close to zero. There are three unknowns in equation (7), and if equation (7) is differentiated by P, M _X and M _Y , respectively, three simultaneous equations as in equation (8) can be established. P, M _X, and M _Y can be obtained by solving the simultaneous equations of Equation (8).

Thereby, not only the vertical reaction force component P but also the two-way moment reaction force components M _X and M _Y can be obtained.

5 is a flowchart illustrating a reaction force measurement method using a multi-component reaction force system having a plurality of optical Bragg gratings according to an embodiment of the present invention.

5, in the reaction force measuring method using a multi-component reaction force system having a plurality of optical fiber Bragg gratings, first, in step S51, a reaction force system lower plate 20 and a vertical structure A plurality of rigid columns 11 and two rigid columns 11 arranged two-dimensionally in parallel with the ground 21 between the reaction force system upper plate 30 acting integrally with the lower ends of the rigid columns 11, Component reaction system 100 composed of an optical fiber cable 12 having one optical Bragg grating sensor 121 may be formed between the lower end of the vertical structure 31 and the ground 21.

It is preferable that the reaction force lower plate 20 and the reaction force upper plate 30 are equal to or slightly smaller than the cross section of the vertical structure 31 to be measured.

Each of the reaction force units 10 may comprise a fiber optic cable 12 having a rigid post 11 and at least one optical fiber Bragg grating sensors 121.

The plurality of rigid pillars 11 may be arranged between the reaction force lower plate 20 and the reaction force upper plate 30 in a constant arrangement, for example, in the form of an array of squares of the same size which are in contact with a circle of a predetermined radius, In the form of a checkerboard.

At least one optical Bragg grating sensor 121 may be mounted on each of the plurality of rigid columns 11.

The optical Bragg grating sensors 121 mounted on each reaction force unit 10 are arranged such that the reaction force unit 10 and the rigid column 11 are distinguished from each other by respective local peaks appearing in the reflected light spectrum, Respectively.

In this case, each of the local peaks appearing in the reflected light spectrum or each of the local valleys appearing in the transmitted light spectrum can be associated with each of the reaction force units 10 and the rigid columns 11 on a one-to-one basis.

However, the optical Bragg grating sensors 121, 122, 123 belonging to one reaction force unit 10 may have the same lattice structure.

Subsequently, in step S52, the interrogator 200 causes incident light having a predetermined incident light spectrum to be incident on the input end of the optical fiber cable 12 of the multicomponent reaction force meter 100.

At step S53 the interrogator 200 detects the spectrum of the reflected light reflected by the optical Bragg grating sensors 121, 122 and 123 at the input of the optical fiber cable 12, The spectrum of the transmitted light partially suppressed by the optical fibers 121, 122, and 123 is detected at the output end of the optical fiber cable 12. [

In step S54, the interrogator 200 detects the optical Bragg grating sensors 121, 122, 123 measured based on changes in the reflected light spectrum or the transmitted light spectrum of the optical Bragg grating sensors 121, 122, The strain rate of each of the rigid columns 11 is measured by the change of the lattice spacing of the rigid columns 11.

In step S55, the total moment of inertia of the rigid columns 11 arranged in a two-dimensional array, the sum of the cross-sectional areas of all the rigid columns 11, the modulus of elasticity of the rigid columns 11, (11), the coordinates of each of the optical Bragg grating sensors, and the strain of each of the detected rigid columns (11) to obtain a solution of the simultaneous equations (8) P, the two-way moment reaction force components M _X and M _Y.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, Modification is possible. Accordingly, the spirit of the present invention should be understood only in accordance with the following claims, and all of the equivalent or equivalent variations will fall within the scope of the present invention.

100 multi-component reaction force system
10 Reaction force unit using optical Bragg grating
11 Rigid column 12 Fiber optic cable
121, 122, 123 Optical Bragg Grating Sensor
20 Reaction force lower plate 21 Ground
30 Reaction system Top plate 31 Vertical structure
200 Interrogator

Claims (19)

Reaction force lower plate acting together with the ground;
A reaction force system top plate acting integrally with a vertical structure;
A plurality of rigid pillars arranged two-dimensionally in a regular arrangement on a two-dimensional plane parallel to the ground between the reaction force lower plate and the reaction force upper plate; And
And a fiber optic cable having at least one fiber Bragg grating sensor mounted on each of the rigid pillars. delete [Claim 2] The method according to claim 1, wherein the rigid column is a quadrangular column having a square cross section and one to four optical Bragg grating sensors are mounted on side faces of at least one side face of the rigid column in parallel with the normal line of the ground A multi-component reaction force system. The multi-component reaction force meter according to claim 1, wherein the reaction force lower plate and the reaction force system upper plate are equal to or smaller than a cross section of a vertical structure to be measured. The system of claim 1, wherein the different optical fiber Bragg grating sensors mounted on different rigid pillars are arranged such that each of the plurality of rigid pillars is uniquely identified as each of the local peaks appearing in the reflected light spectrum by the optical Bragg grating sensors Each having different grating structures. 6. The multicomponent reaction force meter according to claim 5, wherein a plurality of optical Bragg grating sensors mounted on the same rigid column have the same lattice structure. Reaction force lower plate acting together with the ground;
A reaction force system top plate acting integrally with a vertical structure;
A plurality of rigid pillars arranged two-dimensionally between the reaction force lower plate and the reaction force upper plate in parallel with the ground; And
And an optical fiber cable having at least one optical fiber Bragg grating sensor mounted on each of the rigid columns,
When the strain of each of the rigid columns is measured by a change in the lattice spacing of the optical Bragg grating sensors measured based on a change in the reflected light spectrum or the transmitted light spectrum reflected by the plurality of optical Bragg grating sensors, The vertical reaction force component P and the two-way moment reaction force components M _X and M _Y with respect to the ground satisfy the following equations

, Which is obtained by the solution of the simultaneous equations of
Where A is the sum of the cross-sectional area of all the rigid pillars, E is the elastic modulus of the body pillar, I _X and I _Y are deulyigo each total moment of inertia component of every rigid body pillar, N is the number of optical Bragg grating sensor, ξ _k and η _k are two-dimensional coordinates of the k-th optical Bragg grating sensor, and e _k is an error in measuring the strain. [Claim 8] The method of claim 7, wherein the rigid column has a rectangular cross-
The total cross-sectional moment of inertia components I _X and I _Y can be _calculated by the following equations

And

Lt; / RTI >
Where n is the number of rigid columns in the two-dimensional plane corresponding to the two-dimensional array of the rigid columns, m is the number of rigid columns in the Y axis, i is the index of the number of rigid pillars in the X axis, j is the number of rigid pillars in the Y axis index, x _ij and y _ij is the center coordinate of the i-specific bodies in the second row and the j-th column pole, S is the cross-sectional area of the respective rigid-body pillar, a and b are the horizontal and vertical length of the rigid pillars, i _x, And I _y is the moment of inertia of each rigid column. [Claim 8] The method of claim 7, wherein the rigid column has a circular cross-
The total cross-sectional moment of inertia components I _X and I _Y can be _calculated by the following equations

And

Lt; / RTI >
Where n is the number of rigid columns in the two-dimensional plane corresponding to the two-dimensional array of the rigid columns, m is the number of rigid columns in the Y axis, i is the index of the number of rigid pillars in the X axis, j is the number of rigid pillars in the Y axis Index, x _ij and y _ij are the coordinates of the center of the specific rigid column located in the ith row and jth column, S is the cross sectional area of each rigid column, D is the diameter of the rigid column, I _x And I _y are the moment of inertia of each rigid column. Reaction force lower plate acting together with the ground;
A reaction force system top plate acting integrally with a vertical structure;
A plurality of rigid pillars arranged two-dimensionally between the reaction force lower plate and the reaction force upper plate in parallel with the ground;
An optical fiber cable having at least one optical fiber Bragg grating sensor mounted on each of the rigid columns; And
Wherein a spectrum of incident light of a predetermined spectrum is incident on an input end of the optical fiber cable and a spectrum of reflected light reflected by the optical Bragg grating sensors is detected at an input end of the optical fiber cable, Wherein a strain of each of the rigid columns is detected by a change in the lattice spacing of the optical Bragg grating sensors measured on the basis of changes in the reflected light spectrum or the transmitted light spectrum of the optical Bragg grating sensors The total moment of inertia of the rigid columns arranged in a two-dimensional array, the sum of the cross-sectional areas of the rigid columns, the modulus of elasticity of the rigid columns, the total moment of inertia components of the rigid columns, Coordinates of each of the sensors and the angle of the detected rigid pillars On the basis of the strain, a reaction force vertical component P, 2 direction moment reaction force components in M _X and M _Y interrogating the multi-component reaction-based system, comprising a step of including the gaiter to calculate. A plurality of rigid pillars arranged two-dimensionally in parallel with the ground, and a plurality of rigid pillars arranged in parallel with the ground, and at least one rigid pillars mounted on each of the rigid pillars between a reaction force system lower plate acting integrally with the ground and a reaction force system upper plate acting integrally with a lower end of the vertical structure, Forming a multi-component reaction force system composed of an optical fiber cable having optical Bragg grating sensors of a vertical structure between the lower end of the vertical structure and the ground;
The method comprising the steps of: the interrogator inputting incident light having a predetermined incident light spectrum to an input end of an optical fiber cable of the multi-component reaction force system;
Wherein the interrogator detects a spectrum of reflected light reflected by the optical Bragg grating sensors at an input end of the optical fiber cable or a spectrum of transmitted light partially suppressed by the optical Bragg grating sensors, ;
Measuring the strain of each of the rigid columns by the change of the grating structure of the optical Bragg grating sensors measured by the interrogator based on changes in the reflected light spectrum or the transmitted light spectrum of the optical Bragg grating sensors; And
The total moment of inertia of the rigid columns arranged in a two-dimensional array, the sum of the cross-sectional areas of the rigid columns, the modulus of elasticity of the rigid columns, the total moment of inertia components of the rigid columns, And calculating a vertical reaction force component P and a two-way moment reaction force components M _X and M _Y on the basis of the coordinates of each of the detected rigid pillars and the strain of each of the detected rigid columns, . 12. The system of claim 11, wherein the plurality of rigid columns are arranged in a regular arrangement on a two-dimensional plane between a reaction force lower plate and a reaction force upper plate. Measurement method. [Claim 14] The method according to claim 11, wherein the rigid column is a rectangular column having a square cross section, and one to four optical Bragg grating sensors are mounted on at least one side surface of the rigid column in parallel to the normal line of the ground And a plurality of optical Bragg gratings are provided. 12. The reaction force measuring method according to claim 11, wherein the reaction force lower plate and the reaction force upper plate are equal to or smaller than a cross section of a vertical structure to be measured. The system of claim 11, wherein the different optical Bragg grating sensors mounted on different rigid posts are arranged such that each of the plurality of rigid columns is uniquely identified as each of the local peaks appearing in the reflected light spectrum by the optical Bragg grating sensors And each of the plurality of optical Bragg gratings has different grating structures. 16. The reaction force measuring method according to claim 15, wherein a plurality of optical Bragg grating sensors mounted on the same rigid column have the same grating structure. 12. The method of claim 11, wherein the step of calculating the vertical reaction force component P, the two-way moment reaction force components M _X and M _Y comprises:
The vertical reaction force component P and the two-way moment reaction force components M _X and M _Y with respect to the ground of the vertical structure are expressed by the following equations

From the solution of the simultaneous equations according to < RTI ID = 0.0 >
Where A is the sum of the cross-sectional area of all the rigid pillars, E is the elastic modulus of the body pillar, I _X and I _Y are deulyigo each total moment of inertia component of every rigid body pillar, N is the number of optical Bragg grating sensor, wherein ξ _k and η _k are two-dimensional coordinates of a k-th optical Bragg grating sensor, and e _k is an error in measuring strain. [18] The method of claim 17, wherein the rigid column has a rectangular cross-
The total cross-sectional moment of inertia components I _X and I _Y can be _calculated by the following equations

And

Lt; / RTI >
Where n is the number of rigid columns in the two-dimensional plane corresponding to the two-dimensional array of the rigid columns, m is the number of rigid columns in the Y axis, i is the index of the number of rigid pillars in the X axis, j is the number of rigid pillars in the Y axis index, x _ij and y _ij is the center coordinate of the i-specific bodies in the second row and the j-th column pole, S is the cross-sectional area of the respective rigid-body pillar, a and b are the horizontal and vertical length of the rigid pillars, i _x, And I _y is the second-order moment of inertia of each rigid column. A method of measuring reaction force using a multi-component reaction force meter having a plurality of optical Bragg gratings. 18. The method of claim 17, wherein the rigid column has a circular cross-
The total cross-sectional moment of inertia components I _X and I _Y can be _calculated by the following equations

And

Lt; / RTI >
Where n is the number of rigid columns in the two-dimensional plane corresponding to the two-dimensional array of the rigid columns, m is the number of rigid columns in the Y axis, i is the index of the number of rigid pillars in the X axis, j is the number of rigid pillars in the Y axis Index, x _ij and y _ij are the coordinates of the center of the specific rigid column located in the ith row and jth column, S is the cross sectional area of each rigid column, D is the diameter of the rigid column, I _x And I _y are the moment of inertia of each rigid column, wherein the reaction force measurement is performed using a multi-component reaction force system having a plurality of optical Bragg gratings.

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