CN110286145A - A kind of Metal Crack electromagnetic test imager - Google Patents
A kind of Metal Crack electromagnetic test imager Download PDFInfo
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- CN110286145A CN110286145A CN201910748915.3A CN201910748915A CN110286145A CN 110286145 A CN110286145 A CN 110286145A CN 201910748915 A CN201910748915 A CN 201910748915A CN 110286145 A CN110286145 A CN 110286145A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/8851—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
- G01N27/041—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body
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- G—PHYSICS
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
- G01N27/82—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N21/88—Investigating the presence of flaws or contamination
- G01N21/8851—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges
- G01N2021/8887—Scan or image signal processing specially adapted therefor, e.g. for scan signal adjustment, for detecting different kinds of defects, for compensating for structures, markings, edges based on image processing techniques
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Abstract
The present invention provides a kind of Metal Crack electromagnetic test imager, comprising: exciting circuit, for generating and sending pumping signal；Signal switching circuit applies pumping signal to excitation coil for selecting one of coil as excitation coil from multiple coils according to preset order；Signal acquisition circuit, comprising: at least one detection coil of induced voltage is generated for receiving within the scope of secondary magnetic field, the detection voltage that signal amplification circuit receives detection coil simultaneously amplifies, and obtains amplification result；Controller, the amplification result of voltage is collected when receiving each coil as excitation coil in detection coil, calculate distribution of conductivity value, it is converted into gray matrix image, it is obtained after normalized, then to Binary Sketch of Grey Scale Image processing, seeks the boundary rectangle of connected region in image, and rectangular dimension is measured, obtain crackle；Display module receives and shows acquired split.It is intended to change the detection for realizing metal crack by the voltage of coil.
Description
Technical field
The present invention relates to metal defect detection technical fields, more particularly to a kind of Metal Crack electromagnetic test imager.
Background technique
It always will appear either large or small defect in the whole life cycle of metal material, although apparent a wide range of defect
It can be found in time, but blind crack and internal vacuole defects detection difficulty are larger, be easy ignored, such defect can be with
Time integral is gradually increased, and therefore, it is necessary to the defects to metal to detect in time.
There are Liquid penetrant testing, Magnetic testing etc. to metal defect detection method at present, need to handle metal surface, imitates
Rate is lower.
Therefore it provides a kind of metal defect detection scheme easy to operate is a technical problem to be solved urgently.
Summary of the invention
In view of the foregoing deficiencies of prior art and practical application request, the purpose of the present invention is to provide a kind of metals
Crack electromagnetical flaw detection imager and device, it is intended to change the detection for realizing metal crack by the voltage of coil, and can show,
Convenient for giving user intuitive viewing experience.
In order to achieve the above objects and other related objects, the present invention provides a kind of Metal Crack electromagnetic test imager, packet
It includes:
Exciting circuit, for generating and sending pumping signal；
Signal switching circuit, for selecting one of coil as excitation line from multiple coils according to preset order
Circle, and pumping signal is applied to the excitation coil, successively it regard other coils in the multiple coil as excitation coil；
Signal acquisition circuit, comprising: at least one detection of induced voltage is generated for receiving within the scope of secondary magnetic field
Coil, wherein the secondary magnetic field is metal flat to be detected generated magnetic field under the influence of Primary field, and is obtained
The detection voltage of the detection coil, wherein the axis of each coil is each perpendicular to metal flat to be detected；
Signal amplification circuit obtains amplification result for receiving the detection voltage of the detection coil and amplifying；
Controller collects the amplification of voltage as a result, so in detection coil when receiving each coil as excitation coil
Afterwards to the result normalized, obtain measuring vector sum sensitivity matrix accordingly, and using image reconstruction algorithm find out by
Gained distribution of conductivity value is converted gray matrix image by the spatial distribution for surveying conductivity metal, after normalized
It arrives, then to Binary Sketch of Grey Scale Image processing, seeks the boundary rectangle of connected region in image, and measure rectangular dimension, obtain
Take crackle；
Display module receives and shows acquired crackle.
Further, the signal switching circuit, comprising: pumping signal selection circuit,
The pumping signal selection circuit includes: the first driving chip, multiple relays, first driving chip it is defeated
Enter end to be connected with the controller, each output end of first driving chip and a voltage of each relay coil
Input terminal is connected, and another voltage input end of relay coil is high level, and the pumping signal is connected with one end of switch, often
One coil one end ground connection, the other end of coil are connected with the normally opened contact of relay；
Wherein, when a voltage input end of relay coil connection is low level, relay common end is adsorbed to often
Open contact, switch conduction, the model ULN2003 of first chip.
Further, the signal acquisition circuit includes: the second driving chip, multiple relays, the second driving core
The input terminal of piece is connected with the controller, each output end of second driving chip and the one of each relay coil
A voltage input end is connected, and another voltage input end of relay coil is high level；
The input terminal of the amplifying circuit is connected with relay common end, each coil one end ground connection, coil it is another
End is connected with the normally opened contact of relay；
Wherein, when a voltage input end of relay coil is low level, relay common end is adsorbed to normally opened touching
Point, the model ULN2003 of second chip.
Further, the amplifying circuit includes: logic switch chip, amplification chip, multiple variable resistances；
The selection pin of the logic switch chip is connected with the controller, is determined according to the signal of the selection pin
The switch resistance of gating, one end of variable resistance are connected with the amplification chip, and the other end of variable resistance passes through logic switch
Chip (U5) is connected with the amplification chip (U3), and the receiving end of the amplification chip is connected with one end of coil；
The output end of the amplification chip is input to the controller after being converted to direct current signal.
Further, described according to detection sensitivity matrix, obtain the gray value of pixel corresponding to plane to be detected
The formula of matrix is expressed are as follows:
B=SG
Wherein, B is measurement vector；S is sensitivity matrix, and G is distribution of conductivity vector；
The initial value G of distribution of conductivity is obtained using Tikhonov regularization algorithm according to the gradient of data residual error0, reuse
Landweber iterative algorithm obtains final distribution of conductivity G, converts gray matrix image for G.
Further, the exciting circuit includes sinusoidal signal generation circuit, signal amplification circuit；
The sinusoidal signal generation circuit is connected with the signal amplification circuit, wherein the sinusoidal signal generation circuit
Used chip model is AD9833, and chip model used by the signal amplification circuit is INA114.
It further, further include main body frame, handle；
The display module is set to the first side of the main body frame；
The exciting circuit, the signal switching circuit, the signal acquisition circuit, the signal amplification circuit and described
Controller is placed in the main body frame, second side of the coil close to the main structure, the second side and described the
One side is oppositely arranged；
Power module is provided in the handle, the power module switches with the exciting circuit, the signal respectively
Circuit, the signal acquisition circuit, the signal amplification circuit, the controller are connected with the display module；
The power switch being connected with the power module is provided on the handle；
And the charging interface being connected with the power module.
As described above, a kind of Metal Crack electromagnetic test imager provided in an embodiment of the present invention, a coil are being passed through
In the case where pumping signal, electromagnetic induction generates vortex, the secondary magnetic field generated by vortex, and detection coil swashs secondary magnetic field
Lower generation induced voltage is encouraged, and after the voltage for acquiring multiple coils amplifies, it is normalized to obtain corresponding
Vector sum sensitivity matrix is measured, the spatial distribution of tested conductivity metal is then found out using image reconstruction algorithm, finally will
Obtained distribution of conductivity vector is converted into gray matrix image, and to Binary Sketch of Grey Scale Image processing, seeks connection in image
The boundary rectangle in region, and measure rectangular dimension, as crack size.
A kind of electromagnetic test imager convenient for holding is provided, can hold and be detected, and carry out metal surface automatically
The display in crack improves the convenience of electromagnetic test.
Detailed description of the invention
Fig. 1 is a kind of result schematic diagram of the Metal Crack electromagnetic test imager of the embodiment of the present invention.
Fig. 2 is the first circuit connection diagram of the Metal Crack electromagnetic test imager of the embodiment of the present invention.
Fig. 3 is second of circuit connection diagram of the Metal Crack electromagnetic test imager of the embodiment of the present invention.
Fig. 4 is the coil connection schematic diagram of the Metal Crack electromagnetic test imager of the embodiment of the present invention.
Fig. 5 is the coil schematic top plan view of the Metal Crack electromagnetic test imager of the embodiment of the present invention.
Fig. 6 is the third circuit connection diagram of the Metal Crack electromagnetic test imager of the embodiment of the present invention.
Fig. 7 is the 4th kind of circuit connection diagram of the Metal Crack electromagnetic test imager of the embodiment of the present invention.
Fig. 8 is the 5th kind of circuit connection diagram of the Metal Crack electromagnetic test imager of the embodiment of the present invention.
Fig. 9 is the structure connection diagram of the Metal Crack electromagnetic test imager of the embodiment of the present invention.
Figure 10 is the Gray Moment system of battle formations of the Metal Crack electromagnetic test imager of the embodiment of the present invention.
Figure 11 be the Metal Crack electromagnetic test imager of the embodiment of the present invention binaryzation after crackle figure.
Specific embodiment
Illustrate embodiments of the present invention below by way of specific specific example, those skilled in the art can be by this specification
Other advantages and efficacy of the present invention can be easily understood for disclosed content.The present invention can also pass through in addition different specific realities
The mode of applying is embodied or practiced, the various details in this specification can also based on different viewpoints and application, without departing from
Various modifications or alterations are carried out under spirit of the invention.
Please refer to Fig. 1-11.It should be noted that diagram provided in the present embodiment only illustrates this hair in a schematic way
Bright basic conception, only shown in schema then with related component in the present invention rather than component count when according to actual implementation,
Shape and size are drawn, when actual implementation kenel, quantity and the ratio of each component can arbitrarily change for one kind, and its component
Being laid out kenel may also be increasingly complex.
As shown in Figure 1, the embodiment of the present invention provides a kind of Metal Crack electromagnetic test imager, comprising:
Exciting circuit, for generating and sending pumping signal.
As shown in Fig. 2, U1 is that circuit chip AD9833 occurs for sinusoidal signal, by capacitor C1 for filtering, make to control core
The power supply of piece is more stable, can make module output frequency 30kHz, volt value by controlling tri- pins of FSYNC, SCLK, SDATA
For the sinusoidal signal AD9833out of 0.6V, the U2 reverse phase that signal conditioning circuit is input to after capacitor C4 filters out DC component is defeated
Enter end, positive input ground connection is that amplification factor can be changed by adjusting adjustable resistance POT1, adjusted resistance POT1, finally
Obtain the sinusoidal excitation signal Stimulate of frequency 30kHz, volt value 4.5V.
Signal switching circuit, for selecting one of coil as excitation line from multiple coils according to preset order
Circle, and pumping signal is applied to the excitation coil, successively it regard other coils in the multiple coil as excitation coil.
Specifically, the pumping signal selection circuit includes: the first driving chip, multiple relays, first driving
The input terminal of chip is connected with the controller, each output end and each relay coil of first driving chip
One voltage input end is connected, and another voltage input end of relay coil is high level, the pumping signal and the one of switch
End is connected, each coil one end ground connection, the other end of coil is connected with the normally opened contact of relay；Wherein, in relay line
When one voltage input end of circle is low level, the common end of switch is adsorbed to normally opened contact, the model of first chip
ULN2003。
In the embodiment of the present invention, by taking 6 coils as an example, as shown in Figure 3 and Figure 4, coil 8- coil 13.Any one coil
Driving source be can receive as excitation coil, at this point, other coils are as detection coil.
Illustratively, there are 6 coils according to circular arrangement, adjacent windings are separated by 60 degree, and coil axis is parallel to each other but not
It is overlapped, axis is perpendicular to tested planar metal, and in the same plane, the inside of test side 14 is close to simultaneously in bottom surface for all coils bottom surface
It is fixed.
As shown in figure 5, controller is connected with the pin 1- pin 6 of driving chip U6, driving signal RelayOut0- is sent
RelayOut5, corresponding output signal be Stimulate0-Stimulate5, Stimulate0-Stimulate5 respectively with hair
Optical diode D2, light emitting diode D4, light emitting diode D6, light emitting diode D8, light emitting diode D10, light emitting diode D12
It is connected；The other end of light emitting diode D2 is connected by resistance R3 with 5V voltage, the other end of light emitting diode D4 passes through resistance
R5 is connected with 5V voltage, the other end of light emitting diode D6 is connected by resistance R7 with 5V voltage, light emitting diode D9 it is another
End is connected by resistance R7 with 5V voltage, the other end of light emitting diode D11 is connected by resistance R9 with 5V voltage, light-emitting diodes
The other end of pipe D12 is connected by resistance R13 with 5V voltage.
It is assumed to be 6 coils, Coil0-Coil5 is respectively one end of this 6 coil, this 6 other end is grounded.It is each
The normally opened contact of the corresponding relay of a coil, for example, relay K1, K3, K5, K7, K9, K11 normally opened contact respectively with it is each
A coil is corresponding.When coil is powered, corresponding normally opened contact can be adsorbed,.Common end and pumping signal in relay
Stimulate be connected, and when normally opened contact be coil ungrounded end when, the coil be powered in the case where, coil it is ungrounded
End is connected to pumping signal Stimulate.
As shown in fig. 6, controller is connected with the pin 1- pin 6 of driving chip U6, driving signal RelayIn0- is sent
RelayIn5, corresponding output signal be Detect0-Detect5, Detect0-Detect5 respectively with light emitting diode D1, hair
Optical diode D3, light emitting diode D5, light emitting diode D7, light emitting diode D9, light emitting diode D11 are connected；Each hair
Optical diode is connected by resistance with 5V voltage.
Principle identical with Fig. 5, when Detect0-Detect5 is low level, coil is powered, and control relay is adsorbed to
Normally opened contact obtains the DetectSignal of the ungrounded point of each coil.
As shown in fig. 7, due to when gating this coil, one voltage signal of ungrounded correspondence of the coil
DetectSignal has 8 kinds of possibility so being combined by A2, A1, A0, EN for ADG408, for each coil into
Row coding, when controller is sent corresponding coding to U5, then it represents that the coil has been gated, so that selection is corresponding with the coil
Amplification factor, that is, select corresponding resistance value such as schemes POT2-POT7 and corresponds to different resistance values, that is, different puts
Big multiple.
As shown in table 1, with only one primary excitation coil, other 5 are used as detection coil, corresponding 30 kinds of excitations
The amplification factor of other coils is arranged according to the distance relation of coil and excitation coil in mode, thus formed the coil of table 1 with
The corresponding relationship of amplification factor.
Table 1
Such as A2, A1, A0, EN 0101, wherein 0 represents low level, 1 represents high level, indicates gating AMP3, then right
Amplification factor corresponding to the selection resistance POT3 answered, at this point, the both ends of resistance are respectively connected to amplification chip INA114's
AMP_RG+, AMP_RG- realize the amplification to the DetectSignal inputted.
Amplified AC signal AdcSignal is obtained directly by Schottky diode SS34 halfwave rectifier and capacitor filtering
Signal ADC is flowed, then is input to control chip and is AD converted.
Controller collects the amplification of voltage as a result, so in detection coil when receiving each coil as excitation coil
Afterwards to the result normalized, obtain measuring vector sum sensitivity matrix accordingly, and using image reconstruction algorithm find out by
Gained distribution of conductivity value is converted gray matrix image by the spatial distribution for surveying conductivity metal, after normalized
It arrives, then to Binary Sketch of Grey Scale Image processing, seeks the boundary rectangle of connected region in image, and measure rectangular dimension, obtain
Take crackle；
Display module receives and shows acquired crackle.
As shown in figure 8, the connection pin between controller and other devices.T_SCK,T_MOSI,T_MISO,T_CS,
T_PEN, RSET, FSMC_NEW, FSMC_EN4, FSMC_A6, FSMC_NOE, FSMC_D0-FSMC_D15 are that display screen control is drawn
Foot.
Specifically, the model of electromagnetic chromatographic imaging system such as formula (1):
V=F (σ) (1)
Wherein σ indicates the distribution situation of conductivity or magnetic conductivity, and v indicates the voltage in detection coil, F be electromagnet chromatography at
As the ill posed functional relation of system unintentional nonlinearity, if known F and σ, it is easy to obtain calculating voltage v.Formula (1) can be used
Pei Yanuo type Taylor's formula indicates, as shown in formula (2):
S represents sensitivity matrix in formula, i.e. the variation of testee conductivity or magnetic conductivity leads to voltage in detection coil
Change rate, σ0The distribution for indicating the conductivity or magnetic conductivity when tested metal does not have defect, when conductivity or magnetic conductivity change
When sufficiently small, the Pei Yanuo type remainder part of Taylor's formula be can be omitted, and formula (2) can simplify as formula (3).
v-F(σ0)=S (σ-σ0) (3)
WhereinThat is sensitivity matrix, further abbreviation obtain formula (4).
B=SG (4)
Wherein, B indicates that the variation of tested conductivity metal or magnetic conductivity causes detection coil voltage as measurement vector
Variable quantity and metal do not have to detect the ratio of voltage when crackle, and G indicates distribution of conductivity vector, and image reconstruction is i.e. according to sensitivity
Matrix S and measurement vector B obtains distribution of conductivity vector G by Tikhonov regularization algorithm and Landweber iterative algorithm.
Landweber iterative algorithm is from steepest descent method, and with criterion of least squares for main foundation, cardinal principle is
Solution is modified on the negative gradient direction of data residual error, the gradient of data residual error is expressed as follows formula (5):
Shown in corresponding iterative formula such as following formula (6):
Gk+1=Gk-αkST(SGk-B) (6)
Wherein, αkIt is positive relaxation factor, αk▽ f (G can be passed throughk+1) and ▽ f (Gk) it is orthogonal acquire, because selecting each αk
Calculation amount it is larger, usually given αk, it is assumed that αkDefinite value be α, then Landweber iterative formula is represented by such as formula (7) institute
Show:
Gk+1=Gk-αST(SGk-B) (7)
Specifically, measuring sensitivity matrix using model disturbance method, i.e., tested metal is split into 20*20 element mesh
Lattice, each grid cell indicates a pixel, and records sense of the detection coil in each pixel on imaging space
Voltage value is answered, sensitivity matrix is thus obtained.
The initial value G of distribution of conductivity0It is obtained by Tikhonov regularization method.Firstly, making to the induced voltage measured
Normalized, as shown in (9) formula.Then the normalization sensitivity matrix S as shown in (8) formula is obtained, wherein xi,jIt is i-th
The contribution that detection coil value does j-th of pixel, as the element in sensitivity matrix S.
Vi,jThe voltage that j-th of pixel detects when for i-th kind of incentive mode, Vi,emUnder the conditions of barnyard, i-th kind is swashed
The voltage detected when encouraging mode, barnyard voltage is only related with incentive mode, to obtain each xi,jValue, formed it is sensitive
Matrix S is spent, so sensitivity matrix S is known.
Sensitivity matrix S is obtained by above formula (8), and in a program by S solidification, only needs to pass through during actually detected
Measurement vector B is calculated in detection data, for example, one of them is as excitation coil, other 5 in the case where coil is 6
It is a to be used as detection coil, then in the case where a coil is as excitation coil, voltage corresponding to available 5 detection coils
Value is switched to according to signal acquisition circuit and acquires on the corresponding voltage of the coil, then using pumping signal selection circuit will under
For one coil as excitation coil, other 5 are used as detection coil, acquire the coil pair again by signal acquisition circuit switching
This 30 voltage values are formed square in this way, in a cycle, then can obtain 5*6=30 voltage value by the voltage value answered
Battle array, formula are as follows:
By taking first pixel as an example, when No. 8 coils are passed through pumping signal, which generates Primary field, under coil
The testee of side is because electromagnetic induction generates vortex, the material properties, several of size, phase and the liquid form of vortex by test specimen
The influence of what shape and its internal structure is known as secondary magnetic field by the magnetic field that vortex generates, and No. 9-No. 13 coils are as detection line
Circle generates induced voltage due within the scope of secondary magnetic field, and the induced voltage is related with tested metal defect situation, examines respectively
No. 9-No. 13 coil voltages are surveyed, are then successively individually passed through pumping signal to No. 9-No. 13 coils, detect the voltage of remaining coil
Totally 30 detection voltages are one group of acquisition data.
Controller control excitation channel selection circuit, pumping signal Stimulate and coil 8 is connected, controller is controlled again
The signal of coil 9 to coil 13 is sent into signal conditioning circuit respectively, by the logic of ADG408 by sense channel selection circuit processed
The programmable amplification of INA114 is realized in selection, rectification, filtering part is input to after different amplification is amplified, what is obtained is straight
Stream signal ADC is input to control circuit again and is AD converted, and obtains first group of data.Then control circuit is by pumping signal
Stimulate is according to being respectively turned on remaining coil shown in table 1 and acquire the voltage signal of corresponding coil, all data that will be obtained
Image reconstruction is carried out using Tikhonov regularization algorithm and Landweber iterative algorithm.
U in above formula (11)iFor the voltage detected when i-th kind of incentive mode in actual use, Vi,emIt is i-th kind in formula (9)
The barnyard voltage detected when incentive mode obtains the measurement vector B within the scope of current detection by above formula (10) and (11), so
Initial value G is obtained using Tikhonov regularization method afterwards0, calculation formula is as follows:
G0=(STS+μI)-1SB (12)
Wherein, I is unit matrix, and μ is regularization parameter, is chosen in most cases by experience.By G0Substitute into formula (7) into
Row iteration calculates, and acquires end value G, finally converts gray matrix image for distribution of conductivity G, as shown in Figure 10, and will be grey
Spend image binaryzation processing, as shown in figure 11, in image procossing 8 connection refer to a pixel, if with other pixels it is upper,
Under, the left and right, upper left corner, the lower left corner, the upper right corner or lower right corner gray value it is identical be in succession, then it is assumed that they are connections.
Using image connectivity region after bwlabel function acquisition binaryzation in Matlab, by regionprops function
BoundingBox field obtains the minimum circumscribed rectangle of corresponding region, such as the wire in Figure 10 and Figure 11, and measures rectangle ruler
It is very little, as crack size.To achieve the purpose that tested metal defect situation is presented in real time, image refreshing 5 times or more in 1 second.
Further, as shown in figure 9, further including main body frame 14, handle 17；The display module 15 is set to the master
The first side of body frame 14；The exciting circuit, the signal switching circuit, the signal acquisition circuit, the signal are put
Big circuit and the controller are placed in the main body frame 14, coil close to the main structure second side, described the
Two side faces are oppositely arranged with the first side；Be provided with power module in the handle 17, the power module respectively with institute
State exciting circuit, the signal switching circuit, the signal acquisition circuit, the signal amplification circuit, the controller and institute
Display module is stated to be connected；The power switch 16 being connected with the power module is provided on the handle；And with the power supply
The connected charging interface 18 of module.
When measurement, detector switch is opened, the handle 17 of detector lower end is held, will test end 14 and be close to tested metal,
Control circuit 2 makes exciting circuit 3 generate sinusoidal signal, amplifies after filtering out DC component, obtains the sine of 4.5V, 30kHz
Signal Stimulate, control circuit control motivate the driving chip ULN2003 in channel selection circuit, and the control of the chip is patrolled
It collects as shown in table 2, corresponding channel is connected in control relay, such as motivates No. 8 coils first, and control circuit controls driving chip
U7 sequentially turns on relay K4, K6, K8, K10, K12, and No. 9 coil voltage signals are sent into signal conditioning circuit when K4 is connected.It is first
It first passes through INA114 chip to amplify, while the amplification factor of each signal, the control of ADG408 can be changed in ADG408 chip
Logic is as shown in table 3, and the relationship in pumping signal channel, detection signal path and amplification factor is as shown in table 1, amplified signal
AdcSignal obtains direct current signal by the halfwave rectifier and capacitor filtering of D14 Schottky diode.The direct current signal is sent into control
Circuit processed is AD converted, and main control chip is STM32F407ZGT6, obtains one group of signal in this way, successively motivates No. 9-No. 13 lines
Circle, and detect the voltage of corresponding remaining coil.It obtains after all signals further according to Tikhonov regularization algorithm and Landweber
Iterative algorithm carries out image reconstruction, obtains a frame image, continues to repeat above-mentioned detecting step, continuous refreshed image is realized online
The purpose of detection.When low battery, charged using charger from 17 lower end charge port 18 of instrument handle.
Table 2
Table 3
Firstly, the present invention can detect metal surface and shallow-layer underbead crack simultaneously, there is higher sensitivity.Then, originally
Detector carries display screen, and testing result is presented in real time.Secondly detector is lithium battery power supply, need to only be charged on time, operation letter
It is single, it is easy to carry.Finally, detector generally " 7 " font, when use, holds bottom, the sensor of front end is close to tested flat
Face metallic surface, handle upper end are display screen
The above-described embodiments merely illustrate the principles and effects of the present invention, and is not intended to limit the present invention.It is any ripe
The personage for knowing this technology all without departing from the spirit and scope of the present invention, carries out modifications and changes to above-described embodiment.Cause
This, institute is complete without departing from the spirit and technical ideas disclosed in the present invention by those of ordinary skill in the art such as
At all equivalent modifications or change, should be covered by the claims of the present invention.
Claims (7)
1. a kind of Metal Crack electromagnetic test imager characterized by comprising
Exciting circuit, for generating and sending pumping signal；
Signal switching circuit, for selecting one of coil as excitation coil from multiple coils according to preset order, and
Pumping signal is applied to the excitation coil, successively regard other coils in the multiple coil as excitation coil；
Signal acquisition circuit, comprising: for receiving within the scope of secondary magnetic field and generating at least one detection coil of induced voltage,
Wherein, the secondary magnetic field is metal flat to be detected generated magnetic field under the influence of Primary field, and obtains the inspection
The detection voltage of test coil, wherein the axis of each coil is each perpendicular to metal flat to be detected；
Signal amplification circuit obtains amplification result for receiving the detection voltage of the detection coil and amplifying；
Controller collects the amplification of voltage as a result, then right in detection coil when receiving each coil as excitation coil
The result normalized obtains measuring vector sum sensitivity matrix accordingly, and finds out tested gold using image reconstruction algorithm
The spatial distribution for belonging to conductivity converts gained distribution of conductivity value to gray matrix image, obtains after normalized, so
Afterwards to Binary Sketch of Grey Scale Image processing, the boundary rectangle of connected region in image is sought, and measure rectangular dimension, acquisition is split
Line；
Display module receives and shows acquired crackle.
2. Metal Crack electromagnetic test imager according to claim 1, which is characterized in that the signal switching circuit,
It include: pumping signal selection circuit,
The pumping signal selection circuit includes: the first driving chip (U6), multiple relays, first driving chip (U6)
Input terminal be connected with the controller, each output end of first driving chip (U6) and each relay coil
One voltage input end is connected, and another voltage input end of relay coil is high level, the pumping signal and relay
Common end is connected, each coil one end ground connection, the other end of coil is connected with the normally opened contact of relay；
Wherein, when a voltage input end of relay coil connection (U6) is low level, relay common end is adsorbed to often
Open contact, switch conduction, the model ULN2003 of first chip (U6).
3. Metal Crack electromagnetic test imager according to claim 2, which is characterized in that the signal acquisition circuit packet
Include: the input terminal of the second driving chip (U7), multiple relays, second driving chip (U7) is connected with the controller,
Each output end of second driving chip (U7) is connected with a voltage input end of each relay coil, relay
Another voltage input end of coil is high level；
The input terminal of the amplifying circuit is connected with relay common end, each coil one end ground connection, the other end of coil with
The normally opened contact of relay is connected；
Wherein, when a voltage input end of relay coil is low level, relay common end is adsorbed to normally opened contact,
The model ULN2003 of second chip (U7).
4. Metal Crack electromagnetic test imager according to claim 3, which is characterized in that the amplifying circuit includes:
Logic switch chip (U5), amplification chip (U3), multiple variable resistances；
The selection pin of the logic switch chip (U5) is connected with the controller, is determined according to the signal of the selection pin
The switch resistance of gating, one end of variable resistance are connected with the amplification chip (U3), and the other end of variable resistance passes through logic
Switch chip (U5) is connected with the amplification chip (U3), and the receiving end of the amplification chip (U3) is connected with one end of coil；
The output end of the amplification chip (U3) is input to the controller after being converted to direct current signal.
5. Metal Crack electromagnetic test imager according to claim 1-4, which is characterized in that described according to inspection
Sensitivity matrix is surveyed, the formula expression of the gray scale value matrix of pixel corresponding to plane to be detected is obtained are as follows:
B=SG
Wherein, B is measurement vector；S is sensitivity matrix, and G is distribution of conductivity vector；
The initial value G of distribution of conductivity is obtained using Tikhonov regularization algorithm according to the gradient of data residual error0, reuse
Landweber iterative algorithm obtains final distribution of conductivity G, converts gray matrix for G.
6. Metal Crack electromagnetic test imager according to claim 5, which is characterized in that the exciting circuit includes just
Circuit, signal amplification circuit occur for string signal；
The sinusoidal signal generation circuit is connected with the signal amplification circuit, wherein the sinusoidal signal generation circuit is adopted
Chip model is AD9833, and chip model used by the signal amplification circuit is INA114.
7. Metal Crack electromagnetic test imager according to claim 6, which is characterized in that further include main body frame, hand
Handle；
The display module is set to the first side of the main body frame；
The exciting circuit, the signal switching circuit, the signal acquisition circuit, the signal amplification circuit and the control
Device is placed in the main body frame, second side of the coil close to the main structure, the second side and first side
Face is oppositely arranged；
Be provided with power module in the handle, the power module respectively with the exciting circuit, the signal switching circuit,
The signal acquisition circuit, the signal amplification circuit, the controller are connected with the display module；
The power switch being connected with the power module is provided on the handle；
And the charging interface being connected with the power module.
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Application publication date: 20190927 |