CN102706955A - Pipeline defect characteristic extraction method and device based on uniaxial magnetic leakage data - Google Patents

Pipeline defect characteristic extraction method and device based on uniaxial magnetic leakage data Download PDF

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CN102706955A
CN102706955A CN2012101778251A CN201210177825A CN102706955A CN 102706955 A CN102706955 A CN 102706955A CN 2012101778251 A CN2012101778251 A CN 2012101778251A CN 201210177825 A CN201210177825 A CN 201210177825A CN 102706955 A CN102706955 A CN 102706955A
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defect
single shaft
data
pipeline
processing module
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CN102706955B (en
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张化光
刘金海
冯健
马大中
汪刚
殷宇殿
高丁
卢森骧
谭亮
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Northeastern University China
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Northeastern University China
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Abstract

The invention discloses a pipeline defect characteristic extraction method and a pipeline defect characteristic extraction device based on uniaxial magnetic leakage data. The device comprises an internal detection device main body, a magnet, a uniaxial Hall sensor and a control unit circuit board, wherein the control unit circuit board comprises an analog switch, a voltage follower, a low-pass filter, an analog to digital (A/D) conversion module, a data signal processing (DSP) module, a field programmable gate array (FPGA) and a defect characteristic memory. The pipeline defect characteristic extraction method comprises the following steps of: converting the uniaxial magnetic leakage data of a pipeline internal detection device, which serve as characteristic extraction data, into an image according to a mapping relation between magnetic field intensity and pixels, and filtering the image; and determining the possible position of a defect by judgment, binarizing the image by using a detection threshold value, determining the boundary of the defect by connection and chain codes, and determining the type of the defect according to the distribution of sensors of an internal detector.

Description

Defect of pipeline feature extracting method and device based on the single shaft magnetic flux leakage data
Technical field
The invention belongs to input and area of pattern recognition, be specifically related to defect of pipeline feature extracting method and device based on the single shaft magnetic flux leakage data.
Background technology
China is located in the Western Pacific bank; The submarine surface ground is unstable; Subsea pipeline and underwater structure suffer the influence that dielectric corrosion, ocean current dash naughty and marine accident for a long time simultaneously, and sea-bottom oil-gas pipeline is easy to generate defective and damage, when serious booster, oil and gas leakage or platform can take place also and collapse; Cause enormous economic loss, also cause marine environmental pollution simultaneously.For fear of the generation of similar accidents such as oil and gas leakage, should regularly detect and safeguard in-service pipeline, detect the latent defect in the duct wall.China has carried out oil exploitation at shallow sea area in the nineties in last century, and many subsea pipelines have been on active service more than ten years, and detection and repair are imperative.
Feature extraction is a notion in computer vision and the Flame Image Process, and it refers to the extraction image information that uses a computer, and determines whether the point of each image belongs to a characteristics of image.The result of feature extraction is divided into different subsets to the point on the image, and these subclass often belong to isolated point, continuous curve or continuous zone.
The tentative application that China Petroleum Pipeline company has cooperated to carry out three high definition flux leakage detectors with external certain company; These three high definition flux leakage detectors utilize four three-dimensional Hall elements to replace 4 traditional coil pickoffs, can write down the magnetic leakage signal of three discrete axial.The metal that in detecting data, has characteristic feature increases defective and three axis signals.Through to detection signal analysis and excavation checking interpretation of result, find that this signal characteristic is obvious, significantly strengthened the accuracy that flaw size is judged, improved accuracy of detection, high with the excavation testing result goodness of fit.This detecting device can well analyze the defective in the pipeline, but because the sensor that uses is many, the image data amount is big; Capacity requirement to memory module is also just bigger; And because of being that device can generate heat, therefore because data volume is big, so heating is more serious in processing.Be compared to above-mentioned detecting device, littler based on the defective extraction element of single shaft data, also littler for the memory module capacity requirement.
Summary of the invention
To the deficiency of prior art, the present invention proposes defect of pipeline feature extracting method and the device based on the single shaft magnetic flux leakage data, to reach simple in structure, only uses the single shaft data to carry out feature extraction, only stores characteristic, reduces the purpose of storage space greatly.
Defect of pipeline feature deriving means based on the single shaft magnetic flux leakage data comprises: interior pick-up unit main body, magnet, single shaft Hall element and control unit circuit plate, and described control unit circuit plate comprises analog switch, voltage follower, low-pass filter, AD modular converter, DSP data processing module, FPGA and defect characteristic storer; Interior pick-up unit main body is right cylinder; Be provided with first magnet at the one of which end, its other end is provided with second magnet, and first magnet and second magnet are torus; And be placed on the interior pick-up unit main body; Between described first magnet and second magnet, be provided with cell body, described cell body is a torus, is provided with groove uniformly on this cell body outside surface; In described groove, be provided with the single shaft Hall element, the front of described single shaft Hall element perpendicular to pipeline radially.
The number of described groove is 10~40.
The number that is provided with the single shaft Hall element in the described groove is 1~12.
Adopt the defect characteristic storer as data-carrier store, a storage defect characteristic.
A kind of defect characteristic method for distilling that adopts based on the defect of pipeline feature deriving means of single shaft magnetic flux leakage data, it is characterized in that: step is following:
Step 1, DSP data processing module read the transition single shaft stray field signal data that collect from in-pipeline detection device, and through data fusion and interpolation data are handled formation leakage field curve;
Step 2, in the DSP data processing module, detected single shaft stray field signal data are removed noise, the signal enhancement process;
Step 3, in the DSP data processing module, convert field signal into picture element signal through mapping, be converted into gray level image;
Step 4, in the DSP data processing module, judge in the current single shaft stray field signal data whether have defective zone; It is poor that value that promptly this moment detects and previous sampled value are done; If difference greater than setting value, is then carried out feature extraction to defect area, execution in step 5; If difference is less than setting value, then execution in step 9;
Step 5, in the DSP data processing module, pixel image being carried out filtering once more, set a pixel threshold through calculating, through this pixel threshold image is carried out two-value and handle, is black and white two color images with image transitions;
Step 6, in the DSP data processing module, image is operated, confirmed the border of single shaft magnetic flux leakage data image deflects through using chain code;
Step 7, in the DSP data processing module, obtain length and width, girth, area and the degree of depth of defective respectively according to the sampling interval of image that has drawn the defective border and leakage field curve;
Step 8, in the DSP data processing module, defect characteristic is classified according to criteria for classification, and saving result;
Step 9, in the DSP data processing module if proceed signature analysis, get back to step 4 and continue to carry out; If do not proceed signature analysis, then finish.
Advantage of the present invention:
That defect of pipeline feature extracting method and the device that the present invention is based on the single shaft magnetic flux leakage data has is simple in structure, only use the single shaft data to carry out feature extraction, only store characteristic, advantage that storage space is little.
Description of drawings
Fig. 1 is the defect of pipeline feature deriving means structural drawing of an embodiment of the present invention based on the single shaft magnetic flux leakage data;
Among the figure, pick-up unit main body in the 1-; 2-first magnet; 3-second magnet; The 4-groove; The 5-cell body; 6-single shaft Hall element; 7-control unit circuit plate;
Fig. 2 is an embodiment of the present invention magnetization characteristic figure;
Fig. 3 is that an embodiment of the present invention single shaft Hall element is at ducted synoptic diagram;
Among the figure, the 601-tube wall; 602-iron brush; The 603-defective; 604-single shaft Hall element; 605-first magnet; 606-second magnet; The 607-yoke;
Fig. 4 is the structural representation of an embodiment of the present invention control unit circuit plate;
Fig. 5 is an embodiment of the present invention data acquisition circuit schematic diagram;
Fig. 6 is an embodiment of the present invention control unit circuit schematic diagram;
Fig. 7 is an embodiment of the present invention Magnetic Flux Leakage Inspecting process flow diagram;
Fig. 8 is an embodiment of the present invention leakage field curve map;
Fig. 9 is an embodiment of the present invention four connected sums eight connected graphs, and among the figure, A figure is four connected graphs, and B figure is eight connected graphs;
Figure 10 is an embodiment of the present invention defect of pipeline border and areal map, and among the figure, A figure is former areal map, and B figure is the border and the areal map of four connections, and C figure is the border and the areal map of eight connections;
Figure 11 is the connectivity diagrams of an embodiment of the present invention chain code, and among the figure, A figure is four connection synoptic diagram, and B figure is eight connection synoptic diagram, and C figure is four connection chain code synoptic diagram, and D figure is eight connection chain code synoptic diagram.
Embodiment
Below in conjunction with figure embodiments of the invention are done and to further describe.
Fig. 1 is the defect of pipeline feature deriving means structural drawing of an embodiment of the present invention based on the single shaft magnetic flux leakage data; This device comprises based on the defect of pipeline feature extraction of single shaft magnetic flux leakage data: interior pick-up unit main body, magnet, single shaft Hall element and control unit circuit plate, and described control unit circuit plate comprises analog switch, voltage follower, low-pass filter, AD modular converter, DSP data processing module, FPGA and defect characteristic storer; Interior pick-up unit main body is right cylinder; Be provided with first magnet at the one of which end, its other end is provided with second magnet, and first magnet and second magnet are torus; And be placed on the interior pick-up unit main body; Between described first magnet and second magnet, be provided with cell body, described cell body is a torus, is provided with groove uniformly on this cell body outside surface; In described groove, be provided with the single shaft Hall element, the front of described single shaft Hall element perpendicular to pipeline radially.The number of described groove is 10~40.The number that is provided with the single shaft Hall element in the described groove is 1~12.
The reason that stray field produces is that the magnetic flux density in the flux path changes, the magnetic line of force bends, and the generation of this phenomenon is based upon on the ferrimagnet high magnetic permeability characteristic basis, utilizes Hall element to detect stray field and can know that there is situation in defective.Ferrimagnet in the closed magnetic circuit is after being magnetized under the effect of driving source, if ferrimagnet is even continuous isotropic medium, most of magnetic line of force will be constrained on material internal, and material surface does not almost have the magnetic line of force to pass.When there are defective in the inside of material or top layer, because there is very big-difference in the magnetic permeability of the high magnetic permeability of ferromagnetic material and the medium (generally being air) of fault location filling.Under unsaturated situation still, and the ratio that defective occupies is less, and the remaining continuous part of material still can hold whole magnetic flux, and magnetic flux will preferentially pass through in the magnetic resistance materials with smaller so, and just the magnetic flux density of material internal becomes big.Under the situation of nearly saturated magnetization, when the size of defective was big, near the magnetic flux density the defective was difficult to increase, and the part magnetic flux can overflow from rejected region, passes through the defective ambient air and gets into material again, thereby form leakage flux.
For example: be to have defective on the steel plate of S in the area of section, the sectional area of defective is Δ S, and then the residual area of defect area steel plate is S-Δ S.If the magnetic field intensity of magnetizing field is definite value H, the magnetic induction density at zero defect place is B in the steel plate.Total magnetic flux through the steel plate cross section is: Φ=BS; In the defect processing strain be: Φ=B'* (S-Δ S); Promptly the magnetic induction density of <img file=" BDA00001711264800041.GIF " he=" 120 " img-content=" drawing " img-format=" jpg " inline=" no " orientation=" portrait " wi=" 276 " /> fault location increases because of the existence of defective; But because material is closely saturated; From magnetization curve figure, can draw: magnetic permeability μ is tending towards descending, and the variation range of Δ B=B '-B is very little.Actual magnetic flux is that < Φ is so inevitable some magnetic flux is leaked to from material in the medium on every side Φ '=B'* (S-Δ S) ≈ B* (S-Δ S).According to the continuous principle of border magnetic flux, the magnetic flux B of steel plate outside surface<sub >s</sub>For:<img file="BDA00001711264800042.GIF" he="117" img-content="drawing" img-format="GIF" inline="no" orientation="portrait" wi="207" />In the formula, μ<sub >s</sub>Be the relative permeability of air, μ is the relative permeability of steel plate, and B is the magnetic induction density in the steel plate.Its magnetization characteristic is as shown in Figure 1.Fig. 3 is that embodiment of the invention single shaft Hall element is at ducted synoptic diagram, through the field signal between the probe detection device two ends magnet of single shaft Hall element.
Fig. 4 is the structural representation of embodiment of the invention control unit circuit plate; The single shaft Hall element is selected ss495 for use; Supply voltage is 5VDC in this instance, and the representative value of supply current when supply voltage is 5VDC is 7.0mA, so low in energy consumption; The way of output is that ratio is linear, can react on positive or negative magnetic field.Be evenly distributed with 22 grooves on the cell body in the embodiment of the invention, and be provided with 4 single shaft Hall elements in each groove, 88 single shaft Hall elements perpendicular to pipeline are radially promptly used altogether in each single shaft Hall element front.Each single shaft Hall element ss495 has 3 pins, is connected 5VDC and simulation ground respectively with No. 2 pins No. 1, and No. 3 pin is an output pin, is connected to the input end of analog switch.
The signal that the single shaft Hall element collects gets into the AD modular converter through analog switch after voltage follower and the low-pass filter.Because what the AD modular converter required input is one-channel signal, be the field signal of multichannel and the single shaft Hall element collects.Therefore need carry out the conversion from the multichannel to the single channel to signal through analog switch.
Analog switch is selected CD4067 for use, and CD4067 is digital control analog switch, has low conduction impedance, the characteristic of low cut-off leakage current and home address decoding.In addition, in whole input reference signal, conducting resistance keeps relative stability.CD4067 is 16 channel switchs, and each sheet CD4067 has these 16 input channels of I0~I15, and four scale-of-two input end A0~A3 and control end C are arranged, and any combined optional of input is selected a way switch, when C=1, representes closeall passage.In the embodiment of the invention, use 6 CD4067, can allow port number is 96; The 1st~5 CD4067, every I0~I14 connects the output terminal of 15 single shaft Hall element ss495, and last passage I15 input end of every is through a resistance eutral grounding; As zero point, prevent the zero point drift that the thermal characteristics of device causes, the I0 of the 6th CD4067~I12 connects 13 single shaft Hall element output terminals; Last three input end I3~I15 link together, and through a resistance eutral grounding.
The output terminal of each analog switch connects a voltage follower, plays the effect of buffering, isolation, raising load capacity.Constitute voltage follower by operational amplifier TL082 in the present embodiment, the output terminal O of 6 CD4067 connects No. 3 pins of TL082, the i.e. in-phase input end of TL082.
Each voltage follower output terminal connects a RC low-pass filter, and the high frequency noise in the filtered signal, No. 1 pin of TL082 connect resistance one end of RC low-pass filter as output pin.
The AD sampling module is selected the AD7606 of U.S. ADI company for use; AD7606 is 16,6 passage synchronized sampling analog to digital converters, built-in analog input clamping protection, second order frequency overlapped-resistable filter, follows the tracks of hold amplifier, 16 electric charge reallocation successive approximation type a/d C, digital filter, 2.5V reference voltage source, reference voltage buffering and high speed serialization and parallel interface flexibly.Adopt 6 sampling modules in the embodiment of the invention; Each AD7606 adopts the 5V single power supply; Electric capacity one end of RC low-pass filter is connected to six input end of analog signal V1 ~ V6 (the electric capacity one end V1 of the 1st AD sampling module is connected to six input end of analog signal V1 of AD7606, by that analogy, until the 6th AD sampling module) of AD7606; Digital signal after the analog-converted adopts the 16 bit parallel way of outputs, holds output by DB0 ~ DB15 of AD7606.
Fig. 6 is an embodiment of the invention control unit circuit schematic diagram, and control module adopts the FPGA+DSP mode.FPGA is responsible for controlling the AD sampling module, carries out operations such as feature extraction at DSP through the algorithm routine that writes.In inventive embodiments, the handled data volume of lower layer signal Preprocessing Algorithm is big, and is high to the rate request of handling, but the computing structure is relatively simple, is applicable to the realization of FPGA hardware, takes into account speed and dirigibility so simultaneously.The characteristics of high-rise Processing Algorithm are that handled data volume lower level algorithm is few, but the control structure of algorithm is complicated, are applicable to the dsp chip that arithmetic speed is high, addressing mode is flexible, communication mechanism is powerful to realize.
FPGA adopts the EP3C25F324C8N model of CycloneIII series.By FPGA control AD conversion, 16 bit parallel data DB0 ~ DB15 after the AD conversion give the DB0 ~ DB15 in the IO interface of FPGA.It is master controller that the DSP data acquisition module is selected the TMS320C6713 of TI company for use; In embodiments of the present invention; DSP (is ED0~ED31) be connected with FPGA, SDRAM respectively through the EMIF interface; DSP, FPGA and SDRAM together use data bus ED0 ~ ED31, and address bus EA2 ~ EA21.Signal data gets into DSP; Program through downloading in the DSP is carried out denoising; The figure image intensifying; With of the conversion of the detected voltage signal of single shaft Hall element, and carry out the feature extraction and the classification of defects operation of defective, at last defect of pipeline characteristic and classification of defects situation are saved in the storer to pixel map.
At data width of the inner generation of FPGA is 32bit; The degree of depth is 512 asynchronous FIFO module, as the data output buffers, and the data of buffer memory after the AD conversion; Half-full sign HALF_FULL (being the INT4 mouth) is connected to the interrupt INT 4 of TMS320C6713; When FIFO was half-full, DSP read data in buffer through data bus ED0 ~ ED31 from the IO mouth of FPGA, carry out feature extraction after; Through data bus ED0 ~ ED31 characteristic is stored among the SDRAM again, therefore need be with EMIF interface ED0 ~ ED31 pin of TMS320C6713 and DQ0 ~ DQ31 pin of SDRAM.
Data-carrier store SDRAM selects MT48LC2M32B2TG for use, and capacity is the SDRAM of 64Mb:x32, and MT48LC2M32B2TG is 512Kx32x4banks.Just store characteristic in the present embodiment, so reduced storage space greatly.
This paper invention provides a kind of defect of pipeline feature extracting method based on the single shaft magnetic flux leakage data; This method is the single shaft data in the defect and magnetic leakage data that obtain when utilizing in-pipeline detection device in pipeline, to patrol and examine; Its magnetic field branch is analyzed; And through simple algorithm the characteristic of defective is extracted, and finally pass through the defect characteristic that extracted, defective is classified.Fig. 7 is an embodiment of the invention Magnetic Flux Leakage Inspecting process flow diagram, and this method is carried out as follows:
Step 1, DSP data processing module read the transition single shaft stray field signal data that collect from in-pipeline detection device, and through data fusion and interpolation data are handled formation leakage field curve;
Fig. 8 is an embodiment of the present invention leakage field curve map; The embodiment of the invention adopts the data fusion technology; Utilize the some observation information of computing machine, under certain criterion, analyze automatically, comprehensive in addition, the information processing technology of carrying out to accomplish required decision-making and evaluation tasks to obtaining chronologically.Space when the embodiment of the invention adopts the method for interpolation to be used for filling image transformation between the pixel.On the basis of discrete data, mend and insert continuous function, make this continuous curve through whole given discrete data points.Utilize this method to estimate the approximate value of function through the value situation of function at limited some place at other some places.
Step 2, in the DSP data processing module, detected single shaft stray field signal data are removed noise, the signal enhancement process;
Step 3, in the DSP data processing module, convert field signal into picture element signal through mapping, be converted into gray level image;
The characteristic of arranging according to sensor; Obtain the arrangement pitches of per two detecting sensors; Because what use is along evenly the distribute pipe leakage internal detector of probe of right cylinder outside surface circumference pipeline to be detected, so detecting device is (d along sampling interval of each probe of pipeline axial 0=the girth of arranging/Hall element number); Draw the interval d' that each sampled point of data is detected on each road according to the detecting device fltting speed 0Owing to the sensor reason of arranging causes having spacing d between the magnetic line of force in the image I in the step 3 0, the space the when embodiment of the invention adopts the method for interpolation to be used for filling image transformation between the pixel is d according to the degree reference axis of interpolation to the new spacing of magnetic flux leakage data 1If between the Monitoring Data of per two groups of Hall elements, insert n group new data, so new spacing through interpolation algorithm
Step 4, in the DSP data processing module, judge in the current single shaft stray field signal data whether have defective zone; It is poor that value that promptly this moment detects and previous sampled value are done; If difference greater than setting value 25.6, is then carried out feature extraction to defect area, execution in step 5; If difference is less than setting value 25.6, then execution in step 9; Setting value is wherein decided according to field condition.
Step 5, the image in the step 4 is carried out black and white two-value Filtering Processing: set a pixel threshold P 0, if original pixel P<p 0, the pixel that then will locate is changed to 0; If original pixel P>P 0, the pixel that then will locate is changed to 1, is designated as the image II.
If the gray-scale value of piece image is 0 ~ m level, the pixel of gray-scale value i is n i, be divided into two groups of c with k then 0={ 0 ~ k} and c 1={ k+1 ~ m}, the variance between two groups does
Figure BDA00001711264800071
Wherein:
Figure BDA00001711264800072
is the mean value of entire image gray scale;
Figure BDA00001711264800073
is elected threshold value of going average gray when being k;
Figure BDA00001711264800074
Be c 0The probability that produces;
μ 0, μ 1Be c 0, c 1Selected threshold is the average gray that k is;
Figure BDA00001711264800075
Be group c 0, c 1The probability that produces.
Change k between 0 ~ m, the k when asking following formula to be maximal value (works as k=k *The time), promptly ask δ 2(k) pairing k *Value is a threshold value, δ 2(k) be exactly the threshold value choice function.
Step 6, in the DSP data processing module, image is operated, confirmed the border of single shaft magnetic flux leakage data image deflects through using chain code;
The defective border is confirmed: for the point and the frontier point of defined range inside, need to consider each through the neighbouring relations between the pixel after the Filtering Processing once more, these relations can be described by being communicated with rule.Usually the connection method of definition has two kinds: four connected sums eight are communicated with, and Fig. 9 is the embodiment of the invention four connected sums eight connected graphs.Four are communicated with the pixel connected relation only analyze direct neighbor point, and eight to be communicated with what analyze be the target pixel points connected relation between eight pixels on every side.The border can use this connection of two types to define with the zone, and they are complementary, promptly; If the border is four connections, the zone is exactly eight connections so, and Figure 10 is embodiment of the invention defect of pipeline border and areal map; The figure Oxford gray is represented the border, light grey expression zone.In order to express profile, coordinate that can the memory image pixel sequence also can only be stored the relation between the contiguous pixels.Suppose to have a border completely, promptly one group of tie point from a pixel, finds next pixel in the direction of the clock.Be that next pixel is in the consecutive point on certain main assigned direction.Then, only need just form chain code to the numeric string of the continuous direction of specifying next pixel together.
Figure 11 is the connectivity diagrams of embodiment of the invention chain code, and among the figure, A figure is four connection synoptic diagram, and B figure is eight connection synoptic diagram, and C figure is four connection chain code synoptic diagram, and D figure is eight connection chain code synoptic diagram.As scheme among the D, the pixel on defective border is traveled through, find out the rightmost point of first row, be labeled as starting point P0, be made as and be labeled.Definite relation according to eight connection chain codes is carried out picture element scan to adjacent 8 pixels of a P0 in the direction of the clock; The point that scans first pixel value and be black is labeled as the consecutive point of P0; Be the point on the P0 direction 3 shown in the figure, be designated as P1, the while is made as some P1 and is labeled.Again P1 as starting point, in the direction of the clock to the scanning one by one of adjacent 8 points of a P1, the some P2 on the outgoing direction 4 is first black color dots, it is designated as another adjacent frontier point of P1, will put P2 simultaneously and be made as and be labeled.By that analogy, till a P0 is confirmed as last adjacent frontier point, just can the defective border be confirmed.
Step 7, in the DSP data processing module, obtain length and width, girth, area and the degree of depth of defective respectively according to the sampling interval of image that has drawn the defective border and leakage field curve;
Through the resulting boundary curve of step 6, according to the movement velocity of internal detector, sampling rate and axially the interval of data can obtain length axial length, girth, area and the degree of depth of defective.
The major axis of defective is got on the border maximal value of distance between any two pixels (like the L1 among the D figure among Figure 11);
Minor axis is perpendicular to long axis direction, computing method similar (like the L2 among the D figure among Figure 11);
The defective girth is exactly the length around all pixels of defective, with representing apart from sum between the pixel in twos adjacent on the defective edge.Because the length of chain code is fixed, be d' in 0,4 direction chain code lengths 0In 2,6 direction chain code lengths is d 1; 1,3,5,7 direction chain code lengths do
Figure BDA00001711264800081
The defective edge is traveled through, begin scanning, add up the d' between each edge pixel in eight connected regions then from first pixel that is labeled 0, d 1With the chain code number of d, multiply by length value again and just obtain perimeter value.
Defect area has been represented the size of defect area, can try to achieve through the number of inner (comprising the defective border) all pixels of statistical shortcomings.
Depth of defect has been represented the thickness that pipeline is corroded, and the difference of defect magnetic flux leakage field maximum intensity and defect magnetic flux leakage field minimum intensity can obtain the stray field signal depth D in the defect area through calculating.
Step 8, step 8, in the DSP data processing module to defect characteristic according to criteria for classification classify (criteria for classification is confirmed according to field condition in advance) and saving result;
Step 9, in the DSP data processing module, judge whether to proceed signature analysis,, get back to step 4 and continue to carry out if continue; If do not continue, then finish.

Claims (5)

1. based on the defect of pipeline feature deriving means of single shaft magnetic flux leakage data; Comprise: interior pick-up unit main body, magnet, single shaft Hall element and control unit circuit plate; Described control unit circuit plate comprises analog switch, voltage follower, low-pass filter, AD modular converter, DSP data processing module, FPGA and defect characteristic storer, it is characterized in that: interior pick-up unit main body is right cylinder, is provided with first magnet at the one of which end; Its other end is provided with second magnet; First magnet and second magnet are torus, and are placed on the interior pick-up unit main body, between described first magnet and second magnet, are provided with cell body; Described cell body is a torus; Be provided with groove uniformly on this cell body outside surface, in described groove, be provided with the single shaft Hall element, the front of described single shaft Hall element perpendicular to pipeline radially.
2. the defect of pipeline feature deriving means based on the single shaft magnetic flux leakage data according to claim 1 is characterized in that: the number of described groove is 10~40.
3. the defect of pipeline feature deriving means based on the single shaft magnetic flux leakage data according to claim 1 is characterized in that: the number that is provided with the single shaft Hall element in the described groove is 1~12.
4. the defect of pipeline feature deriving means based on the single shaft magnetic flux leakage data according to claim 1 is characterized in that: adopt the defect characteristic storer as data-carrier store, a storage defect characteristic.
5. an employing is based on the defect characteristic method for distilling of the defect of pipeline feature deriving means of single shaft magnetic flux leakage data, and it is characterized in that: step is following:
Step 1, DSP data processing module read the transition single shaft stray field signal data that collect from in-pipeline detection device, and through data fusion and interpolation data are handled formation leakage field curve;
Step 2, in the DSP data processing module, detected single shaft stray field signal data are removed noise, the signal enhancement process;
Step 3, in the DSP data processing module, convert field signal into picture element signal through mapping, be converted into gray level image;
Step 4, in the DSP data processing module, judge in the current single shaft stray field signal data whether have defective zone; It is poor that value that promptly this moment detects and previous sampled value are done; If difference greater than setting value, is then carried out feature extraction to defect area, execution in step 5; If difference is less than setting value, then execution in step 9;
Step 5, in the DSP data processing module, pixel image being carried out filtering once more, set a pixel threshold through calculating, through this pixel threshold image is carried out two-value and handle, is black and white two color images with image transitions;
Step 6, in the DSP data processing module, image is operated, confirmed the border of single shaft magnetic flux leakage data image deflects through using chain code;
Step 7, in the DSP data processing module, obtain length and width, girth, area and the degree of depth of defective respectively according to the sampling interval of image that has drawn the defective border and leakage field curve;
Step 8, in the DSP data processing module, defect characteristic is classified according to criteria for classification, and saving result;
Step 9, in the DSP data processing module if proceed signature analysis, get back to step 4 and continue to carry out; If do not proceed signature analysis, then finish.
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CN103343885B (en) * 2013-06-20 2015-10-14 西南石油大学 Pipeline Magnetic Flux Leakage Inspection online data compression method
CN106537134A (en) * 2014-05-18 2017-03-22 查尔斯斯塔克德雷珀实验室有限公司 System and method of measuring defects in ferromagnetic materials
CN104063588A (en) * 2014-06-12 2014-09-24 东北大学 Multi-source data fusion-based system and method for predicting pipeline corrosion defect size
CN104063588B (en) * 2014-06-12 2017-03-22 东北大学 Multi-source data fusion-based method for predicting pipeline corrosion defect size
CN104075735A (en) * 2014-07-03 2014-10-01 湖北航天技术研究院总体设计所 Self diagnosis method and self diagnosis device for inertia measurement device
CN104075735B (en) * 2014-07-03 2017-02-15 湖北航天技术研究院总体设计所 Self diagnosis method and self diagnosis device for inertia measurement device
US11888242B2 (en) 2016-05-10 2024-01-30 Novatel Inc. Stacked patch antennas using dielectric substrates with patterned cavities
US10985467B2 (en) 2016-05-10 2021-04-20 Novatel Inc. Stacked patch antennas using dielectric substrates with patterned cavities
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CN106442707A (en) * 2016-12-14 2017-02-22 中国计量大学 Metal pipeline defect detecting device based on low-frequency electromagnetism
CN106404893B (en) * 2016-12-16 2019-05-03 北京华航无线电测量研究所 A kind of axial direction pipeline magnetic flux leakage defect automatic signal detection method
CN106404893A (en) * 2016-12-16 2017-02-15 北京华航无线电测量研究所 Automatic axial magnetic flux leakage defect signal detection method
CN110320222A (en) * 2018-03-29 2019-10-11 波音公司 Backscatter X-ray for pipeline checks system
CN108982522A (en) * 2018-08-09 2018-12-11 北京百度网讯科技有限公司 Method and apparatus for detecting defect of pipeline
WO2020073407A1 (en) * 2018-10-09 2020-04-16 河海大学 Gate detection robot based on giant magnetoresistance element and detection method
CN109697714B (en) * 2018-11-26 2021-08-17 联想(北京)有限公司 Information detection method, equipment and computer storage medium
CN109697714A (en) * 2018-11-26 2019-04-30 联想(北京)有限公司 A kind of information detecting method, equipment and computer storage medium
CN109765292A (en) * 2019-02-18 2019-05-17 西南石油大学 A kind of defect of pipeline accurate-location device
CN109765292B (en) * 2019-02-18 2024-03-26 西南石油大学 Accurate positioning method for pipeline defects
CN110006338A (en) * 2019-04-28 2019-07-12 哈尔滨工业大学(深圳) A kind of damage of steel cable area detecting method
CN110307796A (en) * 2019-06-27 2019-10-08 南京理工大学 A kind of FBG strain gauge means of high dynamic response
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CN114354741A (en) * 2022-03-21 2022-04-15 广东海洋大学 Pipeline defect detection method and system

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