CN104990668A - Fiber bragg grating tension sensor calibration method - Google Patents

Abstract

A fiber bragg grating tension sensor calibration method includes: performing preloading on a fiber bragg grating tension sensor; judging whether fiber bragg grating tension sensor preloading processes reach 3; judging whether the number of times of preloading K is equal to or greater than 3; recording an output wavelength value of a working state of the fiber bragg grating tension sensor; selecting detection points, progressively increasing fiber bragg grating tension, recording wavelength values of corresponding processes and tension indicating values till the detection points remain stable; judging whether the number of times of measurement is equal to or greater than the number of the detection points; progressively decreasing an unloading standard force value point by point, and recording wavelength values of corresponding return strokes and tension indicating values till the detection points remain stable; judging whether the number of times of measurement is equal to or greater than the number of the detection points. The detection processes are performed for three times continuously, and an indication error, a zero returning error and repeatability of the fiber bragg grating tension sensor are calculated. The fiber bragg grating tension sensor calibration method provided by the invention improves precision of a calibration result of the fiber bragg grating sensor.

Description

A kind of fiber grating pull force sensor caliberating method

Technical field

The present invention relates to a kind of fiber grating pull force sensor caliberating system, belong to photoelectron measuring element technical field.

Background technology

China carries out the research work of fiber grating from the middle and later periods nineties 20th century, due to time meet development of the national economy climax, therefore, from the starting stage, fiber grating just links together with sensing detection.At present, the application of fiber grating in electric power, building, petrochemical industry, biologic medical has become the important motivity promoting China's Fibre Optical Sensor industry development.Fibre Optical Sensor is based on fiber optic materials, and have difference in essence with traditional electric-type sensor, therefore, the promotion of China's fiber optic sensor technology is based on colleges and universities, scientific research institutions.

Current studies in China mechanism to the research of fiber-optic grating sensor mainly in fiber-optic grating sensor material property, engineering survey application etc., demarcation aspect major part is detected for fiber-optic grating sensor accuracy and is in manual operations, demarcation mode limits its large-scale application to a great extent, lack the detection of unified sensor production standard and poor efficiency, staking-out work become restriction its development key factor.

Domesticly at present realize fiber-optic grating sensor accuracy automatically to detect the mechanism of demarcation fewer, as: " fiber-optical grating temperature sensor signal receiving and the automatic calibration system design thereof " of Shandong University mainly realizes automatic Calibration for fiber-optical grating temperature sensor; " the distributed fiberoptic sensor calibration experiment based on BOTDR is studied " of Nanjing University is mainly for the automatic Calibration of optical fiber grating temperature, pulling force sensor.Pertinent literature report is yet there are no for the automatic detection of the many reference amounts such as optical fiber grating temperature, pressure, pulling force, stress pulling force, displacement, obliquity sensor and calibration system.

Summary of the invention

Object of the present invention provides a kind of scaling method and process thereof of fiber grating pulling force sensor to overcome defect that above-mentioned prior art exists just, solves the problem of calibrating of fiber grating pulling force sensor.

Technical scheme of the present invention is as follows:

A scaling method for fiber grating pulling force sensor, comprises the steps:

Step S1, preloads fiber grating pulling force sensor, first with force standard machines, fiber grating pulling force sensor is pre-loaded into full scale F _n, be then down to zero load;

Step S2, judges that whether fiber grating pulling force sensor preload process is more than 2 times;

Step S3, judges comparative result, namely preloads number of times K and whether is more than or equal to 3 times; If so, then carry out step 4; Otherwise, return step S1;

Step S4, installs fiber grating pulling force sensor, and becomes duty, with the output wave long value λ of Multi-wavelength meter record fiber grating pulling force sensor _i;

Step S5, selects check point, and be detect starting point with measurement lower limit, (M-1) % measuring the upper limit is generally got at its check point interval, and in measurement range, at least detect M the point comprising zero-bit, each point should roughly be uniformly distributed;

Step S6, the stressed axis pointwise of fiber grating pulling force sensor increases progressively standard force value F _i, keep stablizing 10min postscript picture recording to each check point and answer process wavelength value λ _iwith the pulling force indicating value X of fiber grating pulling force sensing instrument _i;

Step S7, judges whether pendulous frequency N is more than or equal to check point number M-1; If so, then step S8 is carried out; Otherwise, return step S6;

Step S8, pointwise is successively decreased unloading standard force value, keeps stablize 10min postscript record respective backhaul wavelength value λ to each check point _iwith the pulling force indicating value X of fiber grating pulling force sensing instrument _i;

Step S9, judges whether pendulous frequency N is more than or equal to check point number M-1; If so, then terminate to measure; Otherwise, return step S8;

Step S10, this testing process carries out 3 times continuously, calculates the error of indication, the back to zero error of fiber grating pulling force sensing instrument, repeatability, sensitivity, error of fitting and the linearity.

2. a kind of fiber grating pull force sensor caliberating method according to claim 1, is characterized in that, in described step S10,

A) sensitivity

In formula: s is the sensitivity of fiber-optic grating sensor, and sensitivity is calculated by least square method; F _ifor demarcating the standard value of standard of i-th; λ _iit is the centre wavelength value that the i-th calibration point Multi-wavelength meter is measured; N is pendulous frequency;

B) error of fitting

Wherein:

In formula: Δ λ _iit is the difference of the error of fitting of the i-th calibration point, measured value and match value; λ i is the centre wavelength value that the i-th calibration point Multi-wavelength meter is measured; it is the match value of the i-th calibration point; F _ifor demarcating the standard value of standard of i-th; B is reference point;

C) linearity

In formula: ζ _lfor the linearity, error of fitting Δ λ _imaximal value and export the ratio of full scale; Δ λ _maxfor error of fitting Δ λ _imaximal value; λ _fSfor the range of fiber-optic grating sensor output wavelength.

The invention has the beneficial effects as follows: the physical parameter cross validation mode of Decoder read number and magnitude calculation is measured the static demarcating coefficient of sensor by this caliberating device by least square method, and carries out error analysis and analysis on Uncertainty.Adopt optical wavelengthmeter to demarcate fiber Bragg grating (FBG) demodulator and stated accuracy is traceable to national standard, detect foundation accurately for optical fiber grating sensing instrument provides, substantially increase work efficiency and the stated accuracy of instrument calibration.

Accompanying drawing explanation

Fig. 1 is demarcation process flow diagram of the present invention.

Embodiment

Below by way of embodiment, and the invention will be further described by reference to the accompanying drawings.

A scaling method for fiber grating pulling force sensor, comprises the steps:

Step S1, preloads fiber grating pulling force sensor, first with force standard machines, fiber grating pulling force sensor is pre-loaded into full scale F _n, be then down to zero load;

Step S2, judges that fiber grating pulling force sensor is from full scale F _nwhether meet 3 times to this preload process unloaded;

Step S3, judges comparative result, and whether namely preload number of times K is 3; If so, then carry out step 4; Otherwise, return step S1;

Step S4, installs fiber grating pulling force sensor, and becomes duty, with the output wave long value λ of Multi-wavelength meter record fiber grating pulling force sensor _i;

Step S5, selects check point, and be detect starting point with measurement lower limit, (M-1) % measuring the upper limit is generally got at its check point interval, and in measurement range, at least detect M point (comprising zero-bit), each point should roughly be uniformly distributed;

Step S6, the stressed axis pointwise of fiber grating pulling force sensor increases progressively standard force value F _i, keep stablizing 10min postscript picture recording to each check point and answer process wavelength value λ _iwith the pulling force indicating value X of fiber grating pulling force sensing instrument _i;

Step S7, judges whether pendulous frequency N is more than or equal to check point number M; If so, then step S8 is carried out; Otherwise, return step S6;

Step S8, pointwise is successively decreased unloading standard force value, keeps stablize 10min postscript record respective backhaul wavelength value λ to each check point _iwith the pulling force indicating value X of fiber grating pulling force sensing instrument _i;

Step S9, judges whether pendulous frequency N is more than or equal to check point number M; If so, then terminate to measure; Otherwise, return step S8;

Step S10, this testing process carries out 3 times continuously, calculates the error of indication of fiber grating pulling force sensing instrument, back to zero error and repeatability; Its each index calculate mode is as follows:

A) sensitivity

In formula: s is the sensitivity (unit: nm/kN) of fiber-optic grating sensor, and sensitivity is calculated by least square method; F _ifor demarcating the standard value (unit: kN) of standard of i-th; λ _iit is the centre wavelength value (unit: nm) that the i-th calibration point Multi-wavelength meter is measured; N is pendulous frequency;

B) error of fitting

Wherein:

In formula: Δ λ _ibe the error of fitting (unit: nm) of the i-th calibration point, the difference of measured value and match value; λ i is the centre wavelength value (unit: nm) that the i-th calibration point Multi-wavelength meter is measured; it is the match value (unit: nm) of the i-th calibration point; F _ifor demarcating the standard value (unit: kN) of standard of i-th; B is reference point (unit: nm);

C) linearity

In formula: ζ _lfor the linearity, error of fitting Δ λ _imaximal value and export the ratio of full scale; Δ λ _maxfor error of fitting Δ λ _imaximal value (unit: nm); λ _fSfor the range (unit: nm) of fiber-optic grating sensor output wavelength.

By reference to the accompanying drawings the specific embodiment of the present invention is explained in detail above, but the present invention is not limited to above-mentioned embodiment, in the ken that those of ordinary skill in the art possess, various change can also be made under the prerequisite not departing from present inventive concept.

Claims (2)

1. a scaling method for fiber grating pulling force sensor, is characterized in that, comprises the steps:

Step S1, preloads fiber grating pulling force sensor, first with force standard machines, fiber grating pulling force sensor is pre-loaded into full scale F _n, be then down to zero load;

Step S2, judges that whether fiber grating pulling force sensor preload process is more than 2 times;

Step S3, judges comparative result, namely preloads number of times K and whether is more than or equal to 3 times; If so, then carry out step 4; Otherwise, return step S1;

Step S4, installs fiber grating pulling force sensor, and in duty, with the output wave long value λ of Multi-wavelength meter record fiber grating pulling force sensor _i;

Step S5, selects check point, and be detect starting point with measurement lower limit, (M-1) % measuring the upper limit is generally got at its check point interval, and in measurement range, at least detect M the point comprising zero-bit, each point should roughly be uniformly distributed;

Step S6, the stressed axis pointwise of fiber grating pulling force sensor increases progressively standard force value F _i, keep stablizing 10min postscript picture recording to each check point and answer process wavelength value λ _iwith the pulling force indicating value X of fiber grating pulling force sensing instrument _i;

Step S7, judges whether pendulous frequency N is more than or equal to check point number M-1; If so, then step S8 is carried out; Otherwise, return step S6;

Step S8, pointwise is successively decreased unloading standard force value, keeps stablize 10min postscript record respective backhaul wavelength value λ to each check point _iwith the pulling force indicating value X of fiber grating pulling force sensing instrument _i;

Step S9, judges whether pendulous frequency N is more than or equal to check point number M-1; If so, then terminate to measure; Otherwise, return step S8;

Step S10, this testing process carries out 3 times continuously, calculates the error of indication, the back to zero error of fiber grating pulling force sensing instrument, repeatability, sensitivity, error of fitting and the linearity.

2. a kind of fiber grating pull force sensor caliberating method according to claim 1, is characterized in that, in described step S10,

A) sensitivity

$S=\[n\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{F}_i{\mathrm{\λ}}_i-\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{F}_i\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\λ}}_i\]/\[n\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{F_i}^2-{\left(\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{F}_i\right)}^2\]---\left(1\right)$

In formula: s is the sensitivity of fiber-optic grating sensor, and sensitivity is calculated by least square method; F _ifor demarcating the standard value of standard of i-th; λ _iit is the centre wavelength value that the i-th calibration point Multi-wavelength meter is measured; N is pendulous frequency;

B) error of fitting

${\mathrm{\Δ\λ}}_i={\mathrm{\λ}}_i-\stackrel{\‾}{{\mathrm{\λ}}_f}---\left(2\right)$

Wherein: $\stackrel{\‾}{{\mathrm{\λ}}_f}={\mathrm{SF}}_i+b---\left(3\right)$

$b=\[\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{F_i}^2\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{\mathrm{\λ}}_i-\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{F}_i\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{F}_i{\mathrm{\λ}}_i\]/\[n\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{F_i}^2-{\left(\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{F}_i\right)}^2\]---\left(4\right)$

In formula: Δ λ _iit is the difference of the error of fitting of the i-th calibration point, measured value and match value; λ i is the centre wavelength value that the i-th calibration point Multi-wavelength meter is measured; it is the match value of the i-th calibration point; F _ifor demarcating the standard value of standard of i-th; B is reference point;

C) linearity

${\mathrm{\ξ}}_L=\±\frac{{\mathrm{\Δ\λ}}_{max}}{{\mathrm{\λ}}_{FS}}---\left(5\right)$

In formula: ζ _lfor the linearity, error of fitting Δ λ _imaximal value and export the ratio of full scale; Δ λ _maxfor error of fitting Δ λ _imaximal value; λ _fSfor the range of fiber-optic grating sensor output wavelength.