KR101765089B1 - method of measuring using FBG sensor - Google Patents
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
- G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
- G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
- G01D5/35306—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement
- G01D5/35309—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement using multiple waves interferometer
- G01D5/35316—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using an interferometer arrangement using multiple waves interferometer using a Bragg gratings
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
- G01B11/18—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge using photoelastic elements
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
- G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
- G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
- G01D5/3537—Optical fibre sensor using a particular arrangement of the optical fibre itself
- G01D5/3538—Optical fibre sensor using a particular arrangement of the optical fibre itself using a particular type of fiber, e.g. fibre with several cores, PANDA fiber, fiber with an elliptic core or the like
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- G—PHYSICS
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- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
- G01K11/32—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres
- G01K11/3206—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres at discrete locations in the fibre, e.g. using Bragg scattering
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- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/24—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
- G01L1/242—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre
- G01L1/246—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre using integrated gratings, e.g. Bragg gratings
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L11/00—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00
- G01L11/02—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00 by optical means
- G01L11/025—Measuring steady or quasi-steady pressure of a fluid or a fluent solid material by means not provided for in group G01L7/00 or G01L9/00 by optical means using a pressure-sensitive optical fibre
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- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
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- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/02057—Optical fibres with cladding with or without a coating comprising gratings
- G02B6/02076—Refractive index modulation gratings, e.g. Bragg gratings
Abstract
The FBG sensor measurement method according to an exemplary embodiment of the present invention selects at least one of information on the number of FBG sensors or characteristics of a center wavelength and an ambient wavelength of each of a plurality of FBG sensors or a difference value between a center wavelength and an ambient wavelength A storage step of storing a spectrum of a Bragg wavelength measured by each of the FBG sensors as data; an input step of inputting a Bragg wavelength of the FBG sensor; a measurement step of measuring a Bragg wavelength in the plurality of FBG sensors; A determination step of determining whether an overlap of a plurality of wavelengths stored in the storage step has occurred by comparing the information input in the input step with the wavelength on the spectrum stored in the storing step; A calculation step of calculating a change amount of a Bragg wavelength of the FBG sensor; and a conversion step of converting the measured wavelength variation amount into a sensor measurement value The determining step may compare the number of the FBG sensors with the number of wavelengths stored in the stored data.
Description
The present invention relates to a measurement method using an FBG sensor, and more particularly, to a measurement method using an FBG sensor capable of increasing the accuracy of sensor measurement by resolving a measurement error due to a wavelength overlap in the measurement of an array type FBG sensor ≪ / RTI >
Radiation-resistant optical fiber is a special optical fiber with radiation-resistant properties with minimal or no optical loss and optical fiber damage in a radiation environment.
In recent years, the generation of nuclear power generation facilities has been increasing due to the rapid population growth worldwide and the increase in energy demand due to the industrialization of developing countries. In this situation, it is necessary to continuously monitor the temperature of nuclear facilities such as nuclear reactor pressure vessel, cooler, etc. in order to judge the safety situation of nuclear power generation facilities in real time and to take appropriate action. Thermocouple, thermistor, or radiation temperature sensor, which is a thermocouple temperature sensor operating at high temperature, is used for temperature measurement of nuclear facilities, but temperature sensor sensitivity, corrosion resistance, sensor probe damage, and drift And a drift phenomenon. Therefore, a sensor technology using an optical fiber is attracting attention.
The most widely used sensor among the optical fiber sensors is an FBG sensor, which is made by inducing a refractive index change in a certain period of a fiber core and measuring the amount of change by the spectrum of incident wave and reflected wave by Bragg condition equation.
Fiber Bragg grating (FBG) is an alternative to conventional electrical and mechanical sensors. It is a sensor technology using fiber Bragg grating (FBG) in optical fiber. It has high accuracy, small size, electromagnetic interference (EMI) Performance and so on. Studies on the radiation effects of FBG have shown that they are resistant to radiation and have suitable properties as temperature sensors in nuclear reactors and space environments.
This FBG has a characteristic of reflecting only the wavelength satisfying the Bragg condition of the following equation (1), and transmitting the other wavelengths as it is.
[Equation 1]
Λ r = 2n eff Λ
In Equation (1),? R denotes the reflection wavelength of the optical fiber grating, n eff denotes an effective refractive index of the optical fiber core, and? Denotes a grating period.
1 is a schematic diagram of a fiber Bragg grating.
Referring to FIG. 1, when a traveling wave meets an optical fiber grating, a specific wavelength component propagates to a reflected wave. That is, when a broadband light source is incident on the optical fiber grating, a specific wavelength component is reflected and returned to the input end as shown in FIG. 1, and the remaining components are transmitted through the optical fiber grating. Through such changes in the reflected wavelength, various physical changes such as temperature, variation, and pressure can be measured.
Currently, the instrument that measures the characteristics of the FBG sensor uses Optical Spectrum Analyzer (OSA), Otical Sensing Interrogator (OSI), etc., and uses OSI as a device to monitor information of multiple FBG sensors at the same time.
FIG. 2 is a graph showing a measurement waveform of the array type FBG sensor, and FIG. 3 is a graph showing a wavelength overlap phenomenon of the array type FBG sensor.
The conventional array type FBG sensor measures the physical change based on the variation of the central wavelength for each sensor as shown in FIG. However, as shown in FIG. 3, when a plurality of array type FBG sensors are used in the same line, when a sensor is measured, an overlap phenomenon of a central wavelength may occur as a Bragg wavelength is changed. In the case of a lap phenomenon, A measurement error occurs.
In particular, when the initial FBG sensor is installed, it is output in order of wavelength and the installation point is determined by the initial wavelength value. However, if the wavelength changes greatly due to sudden physical changes (temperature, pressure, variation, etc.) of the installation point, the wavelength value becomes larger or smaller than the surrounding FBG sensor.
That is, in the case where the Bragg wavelength change is severe, the wavelength of the FBG sensor overlaps with the wavelength of the FBG sensor installed around, or the order of the wavelength may be changed. In this case, it is difficult to distinguish the FBG sensor, there is a problem.
A method of measuring an FBG sensor according to an embodiment of the present invention has the following problems in order to solve the above-mentioned problems.
The present invention provides a measurement method using an FBG sensor capable of improving the accuracy of sensor measurement by solving measurement errors due to wavelength overlap in an array type FBG sensor measurement.
The solution to the problem of the present invention is not limited to those mentioned above, and other solutions not mentioned can be clearly understood by those skilled in the art from the following description.
The FBG sensor may measure at least one of the FBG sensor number, the center wavelength and the peripheral wavelength of each of the plurality of FBG sensors, or the difference between the center wavelength and the surrounding wavelength. A storage step of storing a spectrum of a Bragg wavelength measured by each of the FBG sensors as data; an input step of inputting a Bragg wavelength of the FBG sensor; a measurement step of measuring a Bragg wavelength in the plurality of FBG sensors; A determination step of determining whether an overlap of a plurality of wavelengths stored in the storage step has occurred by comparing the information input in the input step with the wavelength on the spectrum stored in the storing step; A calculation step of calculating a change amount of a Bragg wavelength of the FBG sensor; and a conversion step of converting the measured wavelength variation amount into a sensor measurement value The determining step may compare the number of the FBG sensors with the number of wavelengths stored in the stored data.
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If the number of the FBG sensors is equal to the number of the wavelengths stored in the stored data, the determining step determines that no overlapping of wavelengths occurs.
If the number of the FBG sensors is different from the number of the wavelengths stored in the stored data, the determining step may determine that an overlap of wavelengths occurs.
The determining step may further determine whether the order of the stored plurality of wavelengths is changed.
If it is determined that the overlapping of the wavelength has occurred, the difference value between the center wavelength and the neighboring neighboring wavelength with the center wavelength is compared with the difference value between the center wavelength and the surrounding wavelength inputted in the input step, A comparison step for distinguishing the sensors may be further performed.
In the comparison step, if the FBG sensor is not distinguished, the difference between the center wavelength and the center wavelength and the nth neighboring neighboring wavelength is compared with the center wavelength and the center wavelength input from the input step, A second comparison step of distinguishing the FBG sensor from the wavelength difference value may be further performed.
If the FBG sensor is classified in the comparison step, an addition / subtraction step of adding or subtracting the difference between the center wavelength and the surrounding wavelength inputted in the input step to display the sensor center wavelength value may be further included.
The sensor measurement value may be selected from pressure, temperature, or displacement.
In an FBG sensor according to an embodiment of the present invention, an FBG sensor installed in an array in an extreme environment such as a nuclear reactor has an overlap phenomenon in which a center wavelength is overlapped due to a sudden change in temperature and pressure It is possible to distinguish the FBG sensors overlapping with each other and to grasp the center wavelength of the corresponding FBG sensor, thereby increasing the measurement accuracy of the FBG sensor.
The effects of the present invention are not limited to those mentioned above, and other effects not mentioned may be clearly understood by those skilled in the art from the following description.
1 is a schematic diagram of a fiber Bragg grating.
2 is a graph showing a measured waveform of the array type FBG sensor.
3 is a graph showing a wavelength overlapping phenomenon of the array type FBG sensor.
4 is a graph showing the waveform of the reflected wave of the FBG sensor.
FIG. 5 is a flowchart illustrating a method of measuring a FBG sensor according to an embodiment of the present invention.
FIG. 6 is a flowchart showing a time-series measurement method using an FBG sensor according to another embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout.
In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. It is to be noted that the accompanying drawings are only for the purpose of facilitating understanding of the present invention, and should not be construed as limiting the scope of the present invention with reference to the accompanying drawings.
Hereinafter, a measurement method using the FBG sensor according to an embodiment of the present invention will be described in detail with reference to FIGS. 4 to 5. FIG.
FIG. 4 is a graph showing a reflected wave waveform of the FBG sensor, and FIG. 5 is a flow chart showing a time-series measurement method using the FBG sensor according to an embodiment of the present invention.
The measuring method using the FBG sensor according to an embodiment of the present invention may include an input step S100, a measuring step S200, a storing step S300, a determining step S400, a calculating step S500, Conversion step S600.
First, the input step S100 includes the number of FBG sensors installed to measure temperature, pressure, displacement, etc., the characteristics of the center wavelength and the peripheral wavelength of each of the plurality of FBG sensors, or the difference value between the center wavelength and the surrounding wavelength .
The information of the center wavelength and the surrounding wavelength inputted in the input step S100 is used to determine whether overlapping of the bragg wavelength is performed in the decision step S400 and whether or not the order of the Bragg wavelengths is changed And is used as information for matching the overlapped wavelength with the FBG sensor in the comparison step S700.
The conventional FBG sensor measurement method measures the change of the sensor characteristic by recognizing the change of the central wavelength value. However, in the present invention, not only the center wavelength but also the intrinsic characteristics of the peripheral wavelength formed around the central wavelength, the initial values of the center wavelength and the peripheral wavelength, and the difference value between the center wavelength and the peripheral wavelength, It is possible to distinguish which wavelength is the wavelength of the FBG sensor.
The measuring step S200 is a step of measuring the Bragg wavelength in the plurality of FBG sensors. The array FBG sensor can be used in a radiation environment and can be used in an extreme environment having a high temperature and a high pressure condition, Temperature, pressure, acceleration, and displacement.
Specifically, when a traveling wave passing through an optical fiber meets a Bragg grating, a specific wavelength component propagates to a reflected wave. That is, when a broadband light source is incident on the Bragg grating, a specific wavelength component is reflected back to the input stage, and the remaining components are transmitted through the Bragg grating. Through these changes in reflected wavelength, various physical changes such as temperature, variation, and pressure can be measured.
The storing step S300 is a step of storing the spectrum of the Bragg wavelength measured by each of the FBG sensors as data. At this time, a plurality of Bragg wavelengths are simultaneously stored, and wavelength overlapping may occur in this process.
The determination step S400 compares the information input in the input step S100 with the wavelength of the spectrum stored in the storage step S300 and overlaps the plurality of wavelengths stored in the storage step S300 Or not.
In the present exemplary embodiment, the determining step S400 may include comparing the number of FBG sensors input in the input step S100 with the number of wavelengths displayed in the spectral data stored in the storing step S300, in particular, the number of central wavelengths It is possible to determine whether the wavelengths overlap or not.
For example, when the number of FBG sensors input in the input step S100 and the number of wavelengths displayed in the spectral data stored in the storage step S300 are the same, the wavelengths of all the FBG sensors are displayed, It can be determined that no overlap occurs.
As another example, if the number of FBG sensors inputted in the input step S100 differs from the number of wavelengths displayed in the spectral data stored in the storage step S300, in particular, the number of central wavelengths, it is not displayed on the wavelengths of all the FBG sensors It can be determined that an overlap of wavelengths has occurred.
If it is determined in step S400 that the overlapping of the wavelength has occurred, the difference between the center wavelength and the neighboring neighboring wavelengths with respect to the center wavelength is calculated from the center wavelength input from the input step S100 A comparison step (S710) for distinguishing the FBG sensors from the wavelength difference values is further performed.
In the comparison step S710, if the FBG sensor is not distinguished, the difference between the center wavelength and the center wavelength and the nth neighboring neighboring wavelength is calculated as the center wavelength and the center wavelength in the input step S100, (S720, S730) for distinguishing the FBG sensor from the difference between the wavelength and the n-th neighboring wavelength. (Where n is an integer of 2 or more).
More specifically, when an overlapping phenomenon occurs, a peak-intensity wavelength (λ L ) and a peak-intensity wavelength (λ) of a center wavelength and a neighboring left neighboring wavelength comparing whether the Bragg matching) the center of peak-to-peak value to the difference value around the peak wavelength of the wavelength input from the difference value (Δλ CL1) the input step (S100) may be divided in to the FBG sensor.
In this case, if there is overlap at the neighboring left-hand side of the center wavelength, the peak-intensity (λ R ) and peak-intensity (center wavelength) of the center wavelength and the neighboring right- It is possible to distinguish the FBG sensor by comparing whether the difference value? CR1 of the wavelength? Bragg matches the difference value between the peak value of the center wavelength inputted in the input step S100 and the peak value of the surrounding wavelength.
If it is difficult to distinguish the FBG sensor by the difference (Δλ CL1 , Δλ CR1 ) between the central wavelength and the neighboring left and right neighboring wavelengths due to the overlapping of the center wavelength and the neighboring neighboring left and right neighboring wavelengths, The FBG sensor can be distinguished by the difference between the center wavelength and the second neighboring wavelength and the center wavelength. This process can be repeatedly performed until the FBG sensor can be identified.
If it is determined in step S400 that the overlapping of the wavelength has occurred, the peak value of the surrounding wavelength displayed on the spectrum stored in step S300 is stored in the input step S100 It is also possible to distinguish the FBG sensor by comparing it with the peak value of the inputted ambient wavelength.
In addition, if it is determined that the overlapping of the wavelengths has occurred, various characteristics of the peripheral wavelengths displayed on the stored spectrum in the storage step S300 are compared with various characteristics of the peripheral wavelengths input in the input step S100, It is also possible to distinguish the sensors.
FIG. 6 is a flowchart showing a time-series measurement method using an FBG sensor according to another embodiment of the present invention.
Alternatively, the determining step S400 may further determine whether the order of the plurality of stored wavelengths is changed. This can also be checked as much as possible through the difference between the peripheral wavelength and the center wavelength, as described above.
The comparison of the number of FBG sensors inputted in the input step S100 with the number of wavelengths indicated in the spectral data stored in the storing step S300, particularly the number of central wavelengths, determines whether overlapping of the wavelengths is overlapped Of course, it is necessary to judge whether or not the order of the wavelengths has changed even if overlapping of wavelengths does not occur.
Accordingly, in the storage step (S300), the wavelengths and the FBG sensors are matched with each other based on the characteristics of the central wavelength and the peripheral wavelength of the FBG sensors input in the input step S100 and / or the difference between the center wavelength and the peripheral wavelength matching. Also, matching the wavelengths with the FBG sensor can determine whether the order of the wavelengths displayed in the stored spectral data has changed.
In the present embodiment, if the FBG sensor is classified in the comparison step (S400), an addition / subtraction step (S820) for displaying the sensor center wavelength value by adding or subtracting the difference between the center wavelength and the surrounding wavelength inputted in the input step (S100) As shown in FIG. When a phenomenon that a plurality of wavelengths overlap occurs, the central wavelength may be deformed in the process.
Referring to FIG. 4, when an error occurs in which the center wavelengths of the different FBG sensors overlap in the entire spectrum data, the FBG sensor is discriminated in the comparison step (S400), and the center wavelengths inputted in the input step (S100) The actual center wavelength of the FBG sensor can be inferred by adding or subtracting the difference value of the ambient wavelength to or from the ambient wavelengths (? L ,? R ) on the stored data in the storage step S300.
The calculation step S500 is a step of calculating a change amount of a Bragg wavelength of the FBG sensor based on the determination result, and the conversion step S600 is a step of converting the measured wavelength variation amount into a sensor measurement value.
In the present embodiment, the sensor measurement value may be any one selected from pressure or temperature, or displacement or acceleration. However, the sensor measurement value of the present invention is not limited thereto, and various measurement values that can be measured through the FBG sensor are applicable.
Hereinafter, an embodiment of a measurement method using an FBG sensor according to the present invention will be described according to circumstances.
In the first embodiment, a case where no overlapping of wavelengths occurs will be described.
[Example 1]
First, the number of the FBG sensors, the waveform of each of the FBG sensors, and / or the difference between the center wavelength and the surrounding wavelength are input to the storage means and the Bragg wavelength reflected from the plurality of FBG sensors is measured. The spectrum of the Bragg wavelength measured by each of the FBG sensors is stored as data.
Thereafter, it is determined whether or not an overlap of the stored plurality of wavelengths occurs by comparing the number of initially input FBG sensors with the number of stored wavelengths (in particular, the center wavelength). If it is determined that the number of FBG sensors initially input is equal to the number of stored wavelengths (in particular, the center wavelength) by the data and there is no overlapping of wavelengths, a change amount of the Bragg wavelength of the FBG sensor is calculated, The wavelength change amount can be converted into a sensor measurement value to measure temperature, pressure, displacement, acceleration, and the like.
In the second embodiment, a case where a wavelength is overlapped will be described.
[Example 2]
First, the number of the FBG sensors, the waveform of each of the FBG sensors, and / or the difference between the center wavelength and the surrounding wavelength are input to the storage means and the Bragg wavelength reflected from the plurality of FBG sensors is measured. The spectrum of the Bragg wavelength measured by each of the FBG sensors is stored as data.
Thereafter, the number of initially inputted sensors and the number of stored wavelengths are compared with each other to determine whether overlapping of the stored plurality of wavelengths has occurred. At this time, it is judged whether or not the wavelength order is changed in addition to whether or not the overlap of the wavelength has occurred. If it is determined that the wavelengths overlap or the order of the wavelengths is changed, the peak wavelength (λ L ) of the center wavelength and the neighboring left neighboring wavelength (λ L ) and the peak value of the center wavelength -intensity The FBG sensor is discriminated by comparing whether the difference value? CL1 of the wavelength? Bragg matches the information of the difference between the center wavelength and the surrounding wavelength inputted in the input step S100.
If there is overlap at the neighboring left-hand side of the central wavelength, the peak-intensity (λ R ) and peak-intensity (center) wavelengths of the center wavelength and the neighboring right- It is possible to distinguish the FBG sensor by comparing whether the difference value? CR1 of the wavelength? Bragg matches the information of the difference between the center wavelength and the surrounding wavelength inputted in the input step S100.
If it is difficult to distinguish the FBG sensors by the difference (Δλ CL1 , Δλ CR1 ) between the center wavelength and the neighboring left and right neighboring wavelengths due to the overlapping of the center wavelength and the neighboring left and right neighboring wavelengths, The FBG sensor can be distinguished by the difference between the center wavelength and the second neighboring wavelength and the center wavelength. This process can be repeatedly performed until the FBG sensor can be identified.
Once the classification of the FBG sensor is completed, the amount of change in the Bragg wavelength of the FBG sensor can be calculated, and the measured wavelength change amount can be converted into the sensor measurement value to measure the temperature, pressure, displacement, and acceleration.
In general, the FBG sensor can monitor the internal accident environment from the outside even when power supply is not possible in case of nuclear emergency, unlike the nuclear temperature sensor currently installed and used. It can cope with various characteristics suitable for the original sensor. However, when used as a distribution sensor in an extreme environmental condition such as a nuclear power plant, an FBG sensor should be installed in an array, and the FBG Bragg wavelength is overlapped due to a sudden change in temperature or pressure at a certain point. And a sensor measurement error may occur. However, it is possible to prevent overlapping phenomenon of each FBG sensor wavelength and to improve the accuracy of the sensor measurement through each step of the present invention.
The embodiments and the accompanying drawings described in the present specification are merely illustrative of some of the technical ideas included in the present invention. Therefore, it is to be understood that the embodiments disclosed herein are not intended to limit the scope of the present invention but to limit the scope of the present invention. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents. It should be interpreted.
S100: input step
S200: Measurement step
S300: storage step
S400: Judgment step
S500: Calculation step
S600: Conversion step
S710: Comparison step
S720: Secondary comparison step
S820:
Claims (9)
A measurement step of measuring a Bragg wavelength in the plurality of FBG sensors;
Storing a spectrum of Bragg wavelength measured by each of the FBG sensors as data;
A determination step of determining whether an overlap of a plurality of wavelengths stored in the storage step occurs by comparing the information inputted in the input step with the wavelength on the spectrum stored in the storing step;
A calculating step of calculating a change amount of a Bragg wavelength of the FBG sensor based on a result of the determining step; And
And a conversion step of converting the measured wavelength change amount into a sensor measurement value,
Wherein the determining step compares the number of the FBG sensors with the number of wavelengths stored in the stored data.
Wherein the determining step determines that an overlap of wavelengths does not occur when the number of FBG sensors is equal to the number of wavelengths stored in the stored data.
Wherein the determining step determines that an overlap of wavelengths occurs when the number of FBG sensors is different from the number of wavelengths stored in the stored data.
Wherein the determining step further determines whether the order of the stored plurality of wavelengths is changed.
If it is determined that the overlapping of the wavelength has occurred, the difference value between the center wavelength and the neighboring neighboring wavelength with the center wavelength is compared with the difference value between the center wavelength and the surrounding wavelength inputted in the input step, A measurement method using an FBG sensor in which a comparison step for distinguishing the sensors is further performed.
In the comparison step, if the FBG sensor is not distinguished, the difference between the center wavelength and the center wavelength and the nth neighboring neighboring wavelength is compared with the center wavelength and the center wavelength input from the input step, A method of measuring using an FBG sensor in which a secondary comparison step for distinguishing an FBG sensor is performed by comparing with a wavelength difference value.
A measurement step of measuring a Bragg wavelength in the plurality of FBG sensors;
Storing a spectrum of Bragg wavelength measured by each of the FBG sensors as data;
A determination step of determining whether an overlap of a plurality of wavelengths stored in the storage step occurs by comparing the information inputted in the input step with the wavelength on the spectrum stored in the storing step;
A calculating step of calculating a change amount of a Bragg wavelength of the FBG sensor based on a result of the determining step; And
A conversion step of converting the measured wavelength change amount into a sensor measurement value;
Lt; / RTI >
If it is determined that the overlapping of the wavelength has occurred, the difference value between the center wavelength and the neighboring neighboring wavelength with the center wavelength is compared with the difference value between the center wavelength and the surrounding wavelength inputted in the input step, A further comparative step of separating the sensors is carried out,
Wherein the FBG sensor further comprises an addition / subtraction step of adding / subtracting a difference between a center wavelength and an ambient wavelength inputted in the input step to display a sensor center wavelength value when the FBG sensor is classified in the comparison step .
Wherein the sensor measurement value is selected from pressure, temperature, or displacement.
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| KR102228641B1 (en) | 2020-09-25 | 2021-03-17 | (주)에프비지코리아 | Measuring system using fbg sensor |
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