CN102564643A - Method for automatic calibration and variable separation sensing for quasi-distributed fiber grating sensing network and device thereof - Google Patents
Method for automatic calibration and variable separation sensing for quasi-distributed fiber grating sensing network and device thereof Download PDFInfo
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Abstract
The utility model discloses a method for automatic calibration and variable separation sensing for a quasi-distributed fiber grating sensing network, and a device thereof. Aiming at the problems of initial wavelength mismatching in a matching fiber grating sensing network combined with time-division multiplexing and wave-division multiplexing and drift error due to different ambient temperatures, a matching grating array is automatically calibrated by a temperature control method, the influences of temperature drift and wavelength mismatching are eliminated, and meanwhile, the control parameter is used as a reference for sensing the separation of temperature and strain (stress) parameters in the result. Used as the key technology for a sensing network, an Internet of Things and other application systems, the method is used in different fields of track traffic, new energy resources, etc.
Description
Technical field
The present invention relates to Fibre Optical Sensor and field of measurement, realize perception, also can be used as the gordian technique of application systems such as sensing net and Internet of Things temperature, ess-strain etc. through quasi-distributed sensing network.
Background technology
Fiber grating (Fiber Bragg Grating-FBG) is present sensory field research and uses one of focus.Because it has anti-electromagnetic interference (EMI), precision is high, adverse environment resistant, and the life-span is long and be easy to advantage such as networking, obtains widespread use in a lot of fields.
Can realize (standard) distributed sensing network through a plurality of gratings being made up (multiplexing), and adopt different technologies to carry out the perception analysis of different parameters.The multiplex mode of optical fiber grating sensing network mainly concentrates on the technology of wavelength-division multiplex or wavelength-division multiplex combination space division multiplexing, in these systems, is limited by mechanical tunable (scanning) wave filter in the demodulation speed of optical fiber grating sensing and serviceable life.The networking capacity be can improve in conjunction with the empty technology (different fiber grating or the combination of a plurality of grating being placed in the different fiber, then not on the same group) of dividing, but still the speed and the life-span of wave filter and photoswitch are subject to through the photoswitch gating.
Also have in the recent period through time division multiplex is combined with the coupling grating and improve perception velocities and life-span; Realize the solution of (standard) distributed sensing, confirm the size of current parameter sensing (pressure, strain, temperature etc.) through the Wavelength matched relation between perception sensing grating or sequence and coupling grating or the sequence.Yet as far as sensing and matched fiber grating (sequence), in practical application, face two important problem: the difference of reasons such as (1) manufacturing process; (2) actual environment for use environment temperature of living in prestress (strain) different and that possibly exist influences; All possibly cause the centre wavelength of sensing and coupling grating (sequence) can't realize coupling; Measurement result is caused bigger uncertainty, directly influence sensing accuracy.
The present invention is directed to this problem,, proposed a kind of automatic calibration method, realize sensing and the accurate perception of coupling grating (sequence) under different situations, guarantee the reliability of perception data in conjunction with time division multiplex matched fiber grating sensing network structure.
Summary of the invention
In view of having the cross influence that the sensing means can't guarantee the accuracy of perception data and eliminate the perception parameter fully now; The present invention is intended to proposition and realizes a kind of intelligent demarcation and analytical approach; Can either eliminate initial error, can in monitoring in real time, realize separation perception again different parameters.
This purpose of the present invention realizes through following means.
A kind of quasi-distributed fiber grating sensing network is demarcated automatically and is separated cognitive method with variable; On wideband light source, fiber optical circulator, the two group switching centre wavelength equipment that sensing grating array and reference light grid array, photodetector, temperature adjusting module array, electric control module and main control module are formed one to one; Adopt following mode to realize that High Precision Automatic demarcation separates perception with variable: the light that wideband light source sends gets into the different sensing grating array of centre wavelength after through first optical circulator, and the light of sensing grating array reflected back gets into the reference light grid array behind second optical circulator; The light of reference light grid array reflected back is delivered to main control module after photodetector detects; Each grating in the reference light grid array all has separate temperature sensing and adjustment module; Electric control module by same is handled; And carry out exchanges data with main control module, formation can be eliminated initial error and can in monitoring in real time, realize the sensor-based system to the separation perception of different parameters again.
The present invention will control through the thermal tuning method with reference to grating; Realize the coupling fully of two sequences in original state; And then in the actual perceived process; Through the thermal tuning with reference to grating being obtained the influence (when two sequences be in different temperature environment under) of temperature, and then realize the separating of temperature and strain parameters such as (stress) thoroughly eliminated cross influence to sensing grating.
Like this; Two groups of coupling grating sequences are installed in perceptive object and control and treatment end as sensor array and referential array respectively; Each sequence is made up of N wavelength different fibers grating, but the grating initial center wavelength (on the ideal situation) of same sequence number is identical in two sequences.Through wideband light source is modulated, the signal after the modulation (by means of optical circulator) preface successively carries out check and analysis at last respectively through sensor array and referential array.Eliminate because the influences such as prestress that possibly exist in the uncertainty of manufacture craft and the installation process.
The present invention also aims to, the device that is achieved is provided for above method.
The quasi-distributed fiber grating sensing network is demarcated the device that separates cognitive method with variable automatically; Sensing grating array and reference light grid array, photodetector, temperature adjusting module array, electric control module and main control module are formed one to one by wideband light source, fiber optical circulator, two group switching centre wavelength; Said temperature adjusting module array changes the centre wavelength of this grating by many through the temperature of regulating refrigerator and realizes forming with the real Wavelength matched semiconductor cooler with the adjustable output of high low temperature of sensing grating, and the independent correspondence of each semiconductor cooler is matched with a fiber grating in the said sensing grating array; Said electric control module is by ARM chip, MAX1978 and the incompatible realization of high precision DAC chipset, and the output voltage of ARM control DAC chip drives the change that the MAX1978 chip is realized electric current size and Orientation on the semiconductor cooler.
Measure of the present invention can guarantee the grating realization coupling under the various mismatch conditions simultaneously; Help to eliminate the preparatory mismatch problems that the optical fiber Bragg grating sensing technology is brought because of manufacture craft and installation process; And can make sensing grating and coupling grating be operated in same equivalent temperature or obtain temperature information accurately through measures ambient temperature; Thereby thoroughly eliminate temperature and stress cross sensitivity problem, realize the separating treatment of perception variable grating sensing.
Description of drawings is following:
Fig. 1 is a principle of the invention structured flowchart;
Fig. 2 is that the present invention realizes the schematic diagram demarcated;
Fig. 3 the present invention is based on the schematic diagram that time division multiplex realizes quasi-distributed perception;
Fig. 4 is that the present invention demarcates the process flow diagram with perception;
Fig. 5 is the sensing technology system schematic of the embodiment of the invention based on matched fiber grating;
Fig. 6 is an automatic temperature-adjusting control circuit system structural drawing of forming electric control module;
Fig. 7 is that the present invention provides x group coupling grating to accomplish correct match measurement process flow diagram one time;
Fig. 8 is that the present invention provides the TEC cooling piece to accomplish once automatic temperature-controlled process flow diagram flow chart.
Embodiment
Below in conjunction with accompanying drawing enforcement of the present invention is done further to describe.But should be emphasized that following embodiment is exemplary, rather than in order to limit scope of the present invention and application.
Fig. 1 is a theory structure block diagram of the present invention.The light that wideband light source 101 sends gets into the sensing grating array later on through first optical circulator 102 and (has comprised 103
11, 103
12103
1N), the centre wavelength of these gratings is all different, satisfies corresponding sensor monitoring dynamic range.The light of sensing grating reflected back gets into the reference light grid array and (has comprised 103 after second optical circulator 104
21, 103
22103
2N).In fact still be that the detection of transmitted light can be selected according to actual conditions to carry out reflected light with reference to grating and sensing grating array.Light signal is delivered to main control module 108 after photodetector 105 detects.Each grating in the reference light grid array all has separate temperature sensing and adjustment module, and promptly 106
1, 106
2106
NThese modules are carried out control and treatment by same circuit module 107, and 107 also carry out exchanges data with main control module 108, can eliminate initial error and can in monitoring in real time, realize the sensor-based system to the separation perception of different parameters again thereby constitute.
In original state; Because problems such as technology and prestrains, sensing grating array and reference light grid array can't be realized good coupling, the spectrum situation shown in Fig. 2 (a); And this mismatch is at random for different gratings; Unpredictable, therefore, caused very big problem to realizing accurate sensing.Through the control of main control module 108,107 pairs of temperature adjusting module 106 arrays of control treatment module, can be with the fully coupling of each grating in the reference light grid array, shown in Fig. 2 (b) according to the corresponding sequence number grating of its actual conditions realization with the sensing grating array.
Fig. 3 has explained the principle of this time division multiplex system, also is how we control demarcation automatically according to the sensing detection result principle.Because wideband light source is modulated, after the sensing grating and coupling grating of modulation signal through diverse location, will there be the different result of detections on the sequential like this at the photodetector end.We can obtain relevant position (sequence number) sensing grating and (mate corresponding peak power fully with matching status with reference to grating through the high speed circuit analysis; The reduction of the corresponding detection power of spectrum mismatch); The detection signal of correspondence different amplitudes on sequential (height of different time signal is different among Fig. 3), thus realize the quasi-distributed perception of high speed.
Fig. 4 has provided Typical control flow process of the present invention, and just the pictute of above-mentioned principle of work can combine conventional means to select further to optimize its logic and algorithm according to the working control circuit that adopts during practical implementation.
Fig. 5 is the sensing technology system embodiment synoptic diagram of the present invention one based on matched fiber grating.Its cardinal principle is to come information such as demodulation stress and temperature through the sensing grating array with the center wavelength variation of the corresponding grating of coupling grating array.System constructing mainly is made up of a wideband light source (SLED), two groups of fiber gratings (sensing grating array and coupling grating array), two groups of circulators and follow-up demodulating system.Wherein, FBG1 to FBGx is an x bragg grating, and its centre wavelength is respectively λ 1 to λ x, is called the sensing grating array, mainly is affixed on the object under test, like track, bridge, blade etc.; FGB1 ' to FBG ' x be and the corresponding x of sensing grating the coupling grating, be called the reference light grid array.The temperature adjusting module array is served as reasons many and through the temperature of regulating refrigerator the centre wavelength of this grating is changed to realize the Wavelength matched semiconductor cooler and thermistor array composition with high low temperature adjustable output real with sensing grating, and the independent correspondence of each semiconductor cooler and thermistor is matched with a fiber grating in the said sensing grating array; Electric control module is by ARM chip, MAX1978 and the incompatible realization of high precision DAC chipset, and the output voltage of ARM control DAC chip drives the change that the MAX1978 chip is realized electric current size and Orientation on the semiconductor cooler.
Fig. 6 is an automatic temperature-adjusting control circuit system structural drawing of forming electric control module.Circuit mainly is made up of MAX1978 control module 1, semiconductor chilling plate interface 2, thermistor interface 3, high precision DA chip 4, ARM digital control unit 5, power circuit 6.Wherein, semiconductor chilling plate interface 2 and thermistor interface 3 link to each other respectively with thermistor with semiconductor chilling plate among Fig. 3; ARM digital control circuit 5 links to each other with high precision DA chip 4, to control the voltage of every road TEC; Power circuit 6 provides various required voltages for whole temperature conditioning unit.The conversion accuracy that high precision DA chip 4 adopts is 14, can realize 0.001 ℃ accuracy of temperature control in theory.
Fig. 7 is the process flow diagram that x group coupling grating provided by the invention is accomplished a correct match measurement.System as feedback signal, through digital command system control grating temperature, to search out the maximal value of optical grating reflection spectral power, has promptly realized the real coupling of sensing grating with the coupling grating this moment with the optical grating reflection spectral power under the desired temperature each time.
Fig. 8 is the process flow diagram that TEC cooling piece provided by the invention is accomplished an automatic temperature-adjusting control procedure.At first send corresponding instruction control DA chip every group of pairing TEC of coupling grating carried out the temperature setting by the ARM chip; MAX1978 can come to regulate automatically the size and Orientation of TEC two ends injection current through the feedback that is attached to the thermistor on the TEC then; Thereby change the temperature of TEC, make the setting value of itself and system reach balance.
During actual the use, its concrete demarcation automatically separates perception with variable and comprises following operation steps:
Step 1: the sensing grating that will post (track, bridge, blade etc.) inserts an end of coupling grating with circulator; Start the automatic temperature-adjusting control system; Be set to the normal temperature situation to the temperature of TEC1, measure the reflectance spectrum power (W01) of first group of sensing grating and FBG1, if the difference of the reflectance spectrum power (W1) under the reflectance spectrum power ratio theoretical case that records is more; Then explanation is not mated, otherwise explanation is near coupling;
Step 2: regulate the temperature (earlier to the low temperature direction) of TEC1, treat that low temperature T11 measures the reflectance spectrum power W11 of grating after constant again.If W11＞W01, the temperature that then continues to reduce TEC1 is to T21 and measure its reflective power W21, so repeatedly up to W occurring
N-11＜W
N1＞W
N+11, then TN1 is exactly the required compensation temperature value of current sensing grating and FBG1; If W11＜W01, the temperature that then should increase TEC1 is to T21 ' and measure its reflective power W21 ', so repeatedly up to W occurring
N-11 '＜W
N1 '＞W
N+11 ', then TN1 ' is exactly the required compensation temperature value of current sensing grating and FBG1;
Step 3: repeating step 1-2 makes second group to obtain the TN value under its match condition to X group sensing grating respectively;
Step 4: the more little then temperature control effect of temperature step value Δ T=TNn-T (N-1) n is good more, and the grating of being surveyed matees well more, but implementation complexity and match time also need manyly more;
Step 5: reliably a kind of and efficiently embodiment be that first design temperature step value Δ T is a higher value; As 5 ℃; Find out the approximate match wavelength of each sensing grating through step 1 to step 4; Corresponding then each TN value set temperature step value Δ T little again as 0.5 ℃ do fine setting, thereby obtain matching effect more accurately;
Step 6: with an above-mentioned measured X TN value record, it can be used as the reference value of temperature compensation algorithm between sensing grating and the coupling grating;
Wherein, the temperature control process flow diagram of realizing an X group grating matching effect is seen Fig. 4; Realize that the temperature control process flow diagram of automatic temperature-adjusting control sees Fig. 8.Each parameter in the process flow diagram is chosen only for reference, specifically can decide according to the reality situation of debugging.
The present invention can be applied to many occasions, the health monitoring of for example heavy construction structure; The monitoring of high speed railway track state; Therefore status monitoring of blade or the like in the large-sized wind-driven generator, has good application prospects, as the gordian technique of application systems such as sensing net and Internet of Things, is used for different field such as track traffic, new forms of energy.
Claims (5)
1. a quasi-distributed fiber grating sensing network is demarcated automatically and is separated cognitive method with variable; It is characterized in that; On wideband light source, fiber optical circulator, the two group switching centre wavelength equipment that sensing grating array and reference light grid array, photodetector, temperature adjusting module array, electric control module and main control module are formed one to one; Adopt following mode to realize that High Precision Automatic demarcation separates perception with variable: the light that wideband light source sends gets into the different sensing grating array of centre wavelength after through first optical circulator, and the light of sensing grating array reflected back gets into the reference light grid array behind second optical circulator; The light of reference light grid array reflected back is delivered to main control module after photodetector detects; Each grating in the reference light grid array all has separate temperature sensing and adjustment module; Electric control module by same is handled; And carry out exchanges data with main control module, formation can be eliminated initial error and can in monitoring in real time, realize the sensor-based system to the separation perception of different parameters again.
2. demarcate automatically according to the said quasi-distributed fiber grating sensing network of claim 1 and separate cognitive method with variable; It is characterized in that; Said sensing grating array and reference light grid array are installed in perceptive object and control and treatment end respectively; Each grating array is made up of N wavelength different sequences fiber grating, and the grating of same sequence number has identical initial center wavelength in two grating array on ideal situation.
3. demarcate automatically according to the said quasi-distributed fiber grating sensing network of claim 1 and separate cognitive method with variable; It is characterized in that; Through the temperature adjusting module array; Realization is eliminated the mismatch problems that manufacturing process and prestressed etc. cause with reference to the coupling of corresponding grating in grating and the sensing grating array.
4. demarcate automatically according to the said quasi-distributed fiber grating sensing network of claim 1 and separate cognitive method with variable; It is characterized in that; Through the temperature adjusting module array; Under actual working environment, realize compensation, eliminate the cross influence between temperature and strain and the stress in real time, realize multivariate separation perception temperature contrast between sensing grating array and the reference light grid array.
5. realize that claim 1 or 2 or the 3 or 4 said automatic demarcation of quasi-distributed fiber grating sensing networks separate the device of cognitive method with variable; It is characterized in that; Sensing grating array and reference light grid array, photodetector, temperature adjusting module array, electric control module and main control module are formed one to one by wideband light source, fiber optical circulator, two group switching centre wavelength; Said temperature adjusting module array changes the centre wavelength of this grating by many through the temperature of regulating refrigerator and realizes forming with the real Wavelength matched semiconductor cooler with the adjustable output of high low temperature of sensing grating, and the independent correspondence of each semiconductor cooler is matched with a fiber grating in the said sensing grating array; Said electric control module is by ARM chip, MAX1978 and the incompatible realization of high precision DAC chipset, and the output voltage of ARM control DAC chip drives the change that the MAX1978 chip is realized electric current size and Orientation on the semiconductor cooler.
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Cited By (9)
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| CN103630276A (en) * | 2013-12-18 | 2014-03-12 | 哈尔滨理工大学 | Stress sensing system based on wide-sideband and narrowband fiber grating matching demodulation |
| CN104034471A (en) * | 2014-06-25 | 2014-09-10 | 西南交通大学 | Separately measuring method for basic temperature stress and expansion additional force of continuous welded rails |
| CN105180978A (en) * | 2015-05-26 | 2015-12-23 | 马平 | Optical sensor based on narrow-band light source and filtering characteristic adjustable element and method thereof |
| CN106918414A (en) * | 2015-11-24 | 2017-07-04 | 波音公司 | The system and method that tactile sensing is carried out using Film Optics sensor network |
| CN107255540A (en) * | 2017-06-16 | 2017-10-17 | 北京航空航天大学 | Based on fiber-optic grating sensor temperature stress decoupling method in apertures metal structure |
| CN110806234A (en) * | 2019-10-28 | 2020-02-18 | 中广核核电运营有限公司 | Optical fiber grating sensing equipment |
| WO2021228273A1 (en) * | 2020-05-09 | 2021-11-18 | 武汉理工大学 | Optical fiber grating sensing method applied to small-size fire source monitoring |
| WO2022095615A1 (en) * | 2020-11-09 | 2022-05-12 | 南京南瑞继保电气有限公司 | Distributed optical fiber temperature measurement apparatus and method used for transformer temperature measurement |
| CN114923419A (en) * | 2022-05-05 | 2022-08-19 | 西安应用光学研究所 | Self-calibration grating positioning device based on spatial light path and calibration method |
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Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103630276A (en) * | 2013-12-18 | 2014-03-12 | 哈尔滨理工大学 | Stress sensing system based on wide-sideband and narrowband fiber grating matching demodulation |
| CN104034471A (en) * | 2014-06-25 | 2014-09-10 | 西南交通大学 | Separately measuring method for basic temperature stress and expansion additional force of continuous welded rails |
| CN105180978A (en) * | 2015-05-26 | 2015-12-23 | 马平 | Optical sensor based on narrow-band light source and filtering characteristic adjustable element and method thereof |
| CN105180978B (en) * | 2015-05-26 | 2018-09-18 | 马平 | Optical sensor based on narrow-band light source and filtering characteristic adjustable element and its method |
| CN106918414A (en) * | 2015-11-24 | 2017-07-04 | 波音公司 | The system and method that tactile sensing is carried out using Film Optics sensor network |
| CN107255540A (en) * | 2017-06-16 | 2017-10-17 | 北京航空航天大学 | Based on fiber-optic grating sensor temperature stress decoupling method in apertures metal structure |
| CN107255540B (en) * | 2017-06-16 | 2019-10-18 | 北京航空航天大学 | Based on fiber-optic grating sensor temperature stress decoupling method in apertures metal structure |
| CN110806234A (en) * | 2019-10-28 | 2020-02-18 | 中广核核电运营有限公司 | Optical fiber grating sensing equipment |
| WO2021228273A1 (en) * | 2020-05-09 | 2021-11-18 | 武汉理工大学 | Optical fiber grating sensing method applied to small-size fire source monitoring |
| WO2022095615A1 (en) * | 2020-11-09 | 2022-05-12 | 南京南瑞继保电气有限公司 | Distributed optical fiber temperature measurement apparatus and method used for transformer temperature measurement |
| CN114923419A (en) * | 2022-05-05 | 2022-08-19 | 西安应用光学研究所 | Self-calibration grating positioning device based on spatial light path and calibration method |
| CN114923419B (en) * | 2022-05-05 | 2024-02-27 | 西安应用光学研究所 | Self-calibration grating positioning device and calibration method based on spatial light path |
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Application publication date: 20120711 |