CN110243934A - A kind of ultrasonic weld seam detection method based on wavelet convolution neural network - Google Patents

A kind of ultrasonic weld seam detection method based on wavelet convolution neural network Download PDF

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CN110243934A
CN110243934A CN201910461584.5A CN201910461584A CN110243934A CN 110243934 A CN110243934 A CN 110243934A CN 201910461584 A CN201910461584 A CN 201910461584A CN 110243934 A CN110243934 A CN 110243934A
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neural network
weld
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朱俊江
濮玉
严天宏
陈源
何雨辰
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Shangyu Institute Of Advanced Studies China University Of Metrology Co Ltd
China Jiliang University Shangyu Advanced Research Institute Co Ltd
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/04Analysing solids
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/44Processing the detected response signal, e.g. electronic circuits specially adapted therefor
    • G01N29/4481Neural networks
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00Indexing codes associated with group G01N29/00
    • G01N2291/26Scanned objects
    • G01N2291/267Welds
    • G01N2291/2675Seam, butt welding

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Abstract

The invention discloses a kind of ultrasonic weld seam detection methods based on wavelet convolution neural network, comprising the following steps: step 1: obtaining weld data;Step 2: weld data pretreatment;Step 3: training wavelet convolution neural network;Step 4: weld data to be detected is obtained;Step 5: weld data pretreatment to be detected;Step 6: testing result is calculated;Step 7;Judge whether weldment to be detected is qualified.Cannot accurately it classify when the present invention is for the weld seam detection of different defect types in the prior art, influence of the different scale to testing result of signal is not accounted for when detection, the technical problems such as the accuracy rate of detection is low improve, the high accuracy for examination that there is the present invention weld seam for different defect types can accurately classify when detecting, detect, detect for different signal scales.

Description

A kind of ultrasonic weld seam detection method based on wavelet convolution neural network
Technical field
The present invention relates to weld seam detection technical field more particularly to a kind of supersonic weldings based on wavelet convolution neural network Stitch detection method.
Background technique
Welded unit refers to the metal structure formed by welding, in numerous necks such as building, automobile manufacture, ship, bridge There is the figure of welded unit in domain, welded unit quality it is good with it is bad not only largely affect its use it is safe Property, or even very big hidden danger caused to the safety of the person, and insufficient (incomplete) penetration or it is lack of penetration be the most danger for causing welding structure to fail Dangerous factor.In order to prevent the accident as caused by problems of welded quality, economic loss caused by welding point failure and really is reduced The normal operation for protecting welded unit just seems extremely urgent and important with the presence or absence of the detection of defect to weld seam nugget, has pole Big practical meaning in engineering.
In the welding process, defect is frequently found in inside weld seam.It is exactly to cut that most direct detection method is carried out to it Interior tissue is observed later, but this belongs to destructive test, it is difficult to meet the needs of automatic online detection.? In lossless detection method, ultrasound detection has advantage at low cost and can detecte internal structure, therefore uses ultrasonic butt welding It connects quality and carries out detection as a kind of natural good method.But ultrasonic detecting technology still has technological deficiency at present, it is existing Supersonic detection method cannot accurately classify when being detected for the weld seams of different defect types, when detection, does not examine Consider influence of the signal of different scale to testing result, the accuracy rate of detection is low.
Against the above technical problems, the ultrasonic weld seam detection based on wavelet convolution neural network that the invention discloses a kind of There is the weld seam for different defect types can accurately classify, when detecting for different signals by method, the present invention The high accuracy for examination that scale is detected, detected.
Summary of the invention
It is super based on wavelet convolution neural network that it is an object of the invention to overcome the deficiencies of the prior art and provide a kind of Sound wave weld inspection method, cannot be accurate when solving the weld seam detection of different defect types in the prior art Classify, the technologies such as when detection does not account for influence of the different scale to testing result of signal, and the accuracy rate of detection is low Problem improves, and there is the present invention weld seam for different defect types can accurately classify when detecting, for not The high accuracy for examination that same signal scale is detected, detected.
The invention is realized by the following technical scheme: the invention discloses a kind of ultrasounds based on wavelet convolution neural network Wave weld inspection method, comprising the following steps:
Step 1: weld data is obtained, defect weldment and zero defect weldment are scanned using ultrasonic sensor, obtained Weld data is obtained, weld data includes defective data and normal data;
Step 2: weld data pretreatment pre-processes weld data according to Preprocessing Algorithm, obtains pretreatment weldering Data are stitched, pre-processing weld data includes pretreatment defective data and pretreatment normal data, first to weld data progress bar Te Wozi filtering;Then mean filter is carried out to the weld data after butterworth filter using mean filter;Finally Weld data after mean filter is normalized;
Step 3: training wavelet convolution neural network, using weld data and pretreatment weld data according to training algorithm Training wavelet convolution neural network;
Step 4: obtaining weld data to be detected, is scanned using ultrasonic sensor to weldment to be detected, obtain to Detect weld data;
Step 5: weld data pretreatment to be detected pre-processes weld data to be detected according to Preprocessing Algorithm, It obtains pre-processing weld data to be detected, butterworth filter is carried out to weld data to be detected first;Then it is filtered using mean value Wave device carries out mean filter to the weld data to be detected after butterworth filter;Finally to after the mean filter to Detection weld data is normalized;
Step 6: calculating testing result, will pre-process weld data to be detected and is input to trained wavelet convolution nerve It is calculated in network, obtains testing result;
Step 7;Judge whether weldment to be detected is qualified, will test result and 0.5 comparison, if testing result is greater than 0.5, Then the weld seam of weldment to be detected is defective, if testing result less than 0.5, the weld seam zero defect of weldment to be detected.
Further, in order to improve the accuracy of data acquisition, in step 1, the frequency of the center probe of ultrasonic sensor Rate is 5MHz.
Further, in order to improve the accuracy of weld defect type classification, in step 1, defect weldment includes in weld seam Has the lack of penetration weldment of leachy weldment, weld seam with the weldment being mingled with, in weld seam, in the weldment and weld seam that weld seam does not merge Weldment with crackle.
Further, in order to improve the accuracy of testing result, in step 2 and step 5, Preprocessing Algorithm is specifically wrapped It includes:
Butterworth filter is carried out to data first;The characteristics of butterworth filter is the frequency response curve in passband It is flat to greatest extent, do not rise and fall, and being then gradually reduced in suppressed frequency band is zero.In the Bode diagram of the logarithm diagonal frequencies of amplitude On, since a certain boundary angular frequency, amplitude is gradually reduced with the increase of angular frequency, tends to minus infinity.
Then mean filter is carried out to the data after butterworth filter using mean filter;Mean filter is allusion quotation The linear filtering algorithm of type, it refers to that the template includes surrounding closes on the image to object pixel to a template Pixel (8 pixels, constitute a Filtering Template, that is, remove object pixel itself around centered on object pixel), then use The average value of entire pixels in template replaces original pixel value;
Finally the data after mean filter are normalized, data are become 0~1 by normalized Between decimal.
Further, in order to improve the effect of data prediction, the window of mean filter is dimensioned to 0.0002s.
Further, in order to improve the training effect of wavelet convolution neural network, in step 3, training algorithm includes random Gradient descent algorithm, Adam algorithm, RMSProp algorithm, Adagrad algorithm, Adadelta algorithm or Adamax algorithm.
Further, in order to improve the training effect of wavelet convolution neural network, the accuracy that data calculate, step are improved In three, wavelet convolution neural network successively includes the first convolutional layer, the first pond layer, the second convolutional layer, the second pond layer, third Convolutional layer, third pond layer, Volume Four lamination, the 4th pond layer, the 5th convolutional layer, the 5th pond layer, the first full articulamentum and Second full articulamentum.Every layer of convolutional layer is made of several convolution units, and the parameter of each convolution unit is to pass through backpropagation What algorithm optimized.The purpose of convolution algorithm is to extract the different characteristic of input, and first layer convolutional layer can only extract The rudimentary feature such as levels such as edge, lines and angle, the convolutional layer of more layers can from low-level features iterative extraction it is more complicated Feature, therefore wavelet convolution neural network is designed to five layers of convolutional layer by the present invention, can extract the more complicated spy of weld seam Sign improves the accuracy of weld classification detection.In wavelet convolution neural network, a pond is often added between convolutional layer Layer.Pond layer can effectively reduce the size of parameter matrix, to reduce the number of parameters finally connected entirely in layer.It uses Pond layer, which can accelerate calculating speed, also prevents over-fitting, and in field of image recognition, image is too big sometimes, we Need to reduce the quantity of training parameter, it is required periodically to introduce pond layer between subsequent convolutional layer.Pond is only One the purpose is to reduce the space sizes of image.Pond is completed alone in each depth dimension, therefore the depth of image is kept It is constant.In wavelet convolution neural network structure, after multiple convolutional layers and pond layer, be connected to 1 or 1 or more entirely connect Layer is connect, each node of full articulamentum is connected with upper one layer of all nodes, for the characteristic synthetic that front is extracted Get up.
Further, in order to improve the training effect of wavelet convolution neural network, the first convolutional layer, the second convolutional layer, The number of three convolutional layers, Volume Four lamination and the filter in the 5th convolutional layer is followed successively by 11, seven, five, three, three It is a, the first convolutional layer, the second convolutional layer, third convolutional layer, Volume Four lamination and the 5th convolutional layer convolution kernel size be followed successively by (39,1), (27,11), (23,7), (17,5), (13,3), convolution kernel is also referred to as Filter, is with one group of fixed power The neuron of weight, the two-dimensional matrix of usually n*m, n and m are also the receptive field of neuron.What is deposited in n*m matrix is to receptive field The coefficient of middle data processing.The filtering of one convolution kernel can be used to extract specific feature (such as can extract contour of object, Shade etc.).The process for extracting new feature from initial data by convolutional layer becomes featuremap again (feature is reflected Penetrate), multiple characteristic patterns of former weld image are obtained by the convolution of convolution kernel, improve the accuracy of image recognition, the first convolution The step-length of layer, the second convolutional layer, third convolutional layer, Volume Four lamination and the 5th convolutional layer is 1, the first convolutional layer, volume Two Lamination, third convolutional layer, Volume Four lamination and the 5th convolutional layer excitation function be LeakyReLUctant function, the first pond Change layer, the second pond layer, third pond layer, the 4th pond layer and the 5th pond layer and is all made of maximization pond method, the first pond The size for changing the pond window of layer, the second pond layer, third pond layer, the 4th pond layer and the 5th pond layer is disposed as 2, first The number of the neuron of full articulamentum output is ten, and the excitation function of the first full articulamentum is wavelet function, the second full connection The number of the neuron of layer output is one, and the excitation function of the second full articulamentum is sigmoid function.It is every in neural network A node receives input value, and input value is passed to next layer, and attribute value can be directly passed to next by input node Layer (hidden layer or output layer) has letter between hidden layer and output the outputting and inputting of node layer in wavelet convolution neural network Number relationship, this function are known as excitation function, and without using if excitation function, every layer of neural network all only does linear change It changes, also still linear transformation after multilayer input superposition.Because the ability to express of linear model is inadequate, excitation function can introduce non- Linear factor improves the recognition capability of image.
Further, in order to improve the accuracy of the first full articulamentum output result, wavelet function are as follows:
y1For output, it be α is 0.7, β 0.5 that x, which is input,.α and β is that variable element, α and β are obtained by test of many times. The accuracy that the second full articulamentum exports result is improved by the calculating of wavelet function.
Further, in order to improve the accuracy of the first full articulamentum output result, wavelet function are as follows:
y2For output, x is input, α 0.9, β 0.4.α and β is that variable element, α and β are obtained by test of many times.It is logical The calculating for crossing wavelet function improves the accuracy of the second full articulamentum output result.
The invention has the following advantages that the present invention is based on the ultrasonic waves of wavelet convolution neural network to be directed to different defect types Weld seam and different signal scales detected, obtain the weld seam of different defect types and the data of normal weld first, Then it is calculated by pretreatment, initial data and calculated result training wavelet convolution neural network, then obtains weld seam to be detected Data are sent in wavelet convolution neural network after pretreatment and are calculated as a result, finally comparing judgement to result Weld seam is obtained with the presence or absence of defect, the present invention can accurately classify when detecting for the weld seam of different defect types, can It is high with the accuracy rate for being detected, being detected for different signal scales.
Detailed description of the invention
Fig. 1 is flow chart of the present invention;
Fig. 2 is wavelet convolution neural network structure schematic diagram.
Specific embodiment
It elaborates below to the embodiment of the present invention, the present embodiment carries out under the premise of the technical scheme of the present invention Implement, the detailed implementation method and specific operation process are given, but protection scope of the present invention is not limited to following implementation Example.
Embodiment 1
Embodiment 1 discloses a kind of ultrasonic weld seam detection method based on wavelet convolution neural network, as shown in Figure 1, The following steps are included:
The following steps are included:
Step 101: weld data is obtained, defect weldment and zero defect weldment are scanned using ultrasonic sensor, Weld data is obtained, weld data includes defective data and normal data;
Step 102: weld data pretreatment pre-processes weld data according to Preprocessing Algorithm, is pre-processed Weld data, pretreatment weld data include pretreatment defective data and pretreatment normal data;
Step 103: training wavelet convolution neural network, using weld data and pretreatment weld data according to training algorithm Training wavelet convolution neural network;
Step 104: obtaining weld data to be detected, weldment to be detected is scanned using ultrasonic sensor, obtain Weld data to be detected;
Step 105: weld data pretreatment to be detected locates weld data to be detected according to Preprocessing Algorithm in advance Reason, obtains pre-processing weld data to be detected;
Step 106: calculating testing result, weld data to be detected will be pre-processed and be input to trained wavelet convolution nerve It is calculated in network, obtains testing result;
Step 107;Judge whether weldment to be detected is qualified, will test result and 0.5 comparison, if testing result is greater than 0.5, Then the weld seam of weldment to be detected is defective, if testing result less than 0.5, the weld seam zero defect of weldment to be detected.
In step 101, the frequency of the center probe of ultrasonic sensor is 5MHz, and defect weldment includes having folder in weld seam Have the lack of penetration weldment of leachy weldment, weld seam in miscellaneous weldment, weld seam, have in the weldment and weld seam that weld seam does not merge and split The weldment of line.
In step 102 and step 105, Preprocessing Algorithm is specifically included:
Butterworth filter is carried out to data first;
Then mean filter is carried out to the data after butterworth filter using mean filter;
Finally the data after mean filter are normalized.
The window of mean filter is dimensioned to 0.0002s.
In step 103, training algorithm includes stochastic gradient descent algorithm, Adam algorithm, RMSProp algorithm, Adagrad calculation Method, Adadelta algorithm or Adamax algorithm.
As shown in Fig. 2, wavelet convolution neural network successively includes the first convolutional layer, the first pond layer, the second convolutional layer, Two pond layers, third convolutional layer, third pond layer, Volume Four lamination, the 4th pond layer, the 5th convolutional layer, the 5th pond layer, One full articulamentum and the second full articulamentum, every layer of convolutional layer are made of several convolution units, and the parameter of each convolution unit is It is optimized by back-propagation algorithm.The purpose of convolution algorithm is to extract the different characteristic of input, first layer convolutional layer Can only extract some rudimentary features such as levels such as edge, lines and angle, the convolutional layer of more layers can from low-level features iteration More complicated feature is extracted, therefore wavelet convolution neural network is designed to five layers of convolutional layer by the present invention, can extract weld seam More complicated feature, improve weld classification detection accuracy.In wavelet convolution neural network, between convolutional layer often In addition a pond layer.Pond layer can effectively reduce the size of parameter matrix, finally connect in layer entirely to reduce Number of parameters.Can accelerate calculating speed using pond layer also prevents over-fitting, in field of image recognition, sometimes Image is too big, it would be desirable to reduce the quantity of training parameter, it is required periodically to introduce pond between subsequent convolutional layer Change layer.The sole purpose in pond is to reduce the space size of image.Pond is completed alone in each depth dimension, therefore is schemed The depth of picture remains unchanged.In wavelet convolution neural network structure, after multiple convolutional layers and pond layer, it is connected to 1 or 1 A above full articulamentum, each node of full articulamentum is connected with upper one layer of all nodes, for front is extracted To characteristic synthetic get up.
Of first convolutional layer, the second convolutional layer, third convolutional layer, Volume Four lamination and the filter in the 5th convolutional layer Number is followed successively by 11, seven, five, three, three, the first convolutional layer, the second convolutional layer, third convolutional layer, Volume Four product The convolution kernel size of layer and the 5th convolutional layer is followed successively by (39,1), (27,11), (23,7), (17,5), (13,3), convolution kernel Referred to as Filter is with the neuron of one group of fixed weight, the two-dimensional matrix of usually n*m, and n and m are also nerve The receptive field of member.What is deposited in n*m matrix is the coefficient to data processing in receptive field.The filtering of one convolution kernel can be used to mention Take specific feature (such as contour of object, shade can be extracted etc.).It is extracted from initial data by convolutional layer new The process of feature become feature map (Feature Mapping) again, the multiple of former weld image are obtained by the convolution of convolution kernel Characteristic pattern improves the accuracy of image recognition, the first convolutional layer, the second convolutional layer, third convolutional layer, Volume Four lamination and the 5th The step-length of convolutional layer is 1, and the first convolutional layer, the second convolutional layer, third convolutional layer, Volume Four lamination and the 5th convolutional layer swash Encouraging function is LeakyReLUctant function, the first pond layer, the second pond layer, third pond layer, the 4th pond layer and Five pond layers are all made of the pond method that maximizes, the first pond layer, the second pond layer, third pond layer, the 4th pond layer and the The size of the pond window of five pond layers is disposed as 2, and the number of the neuron of the first full articulamentum output is ten, and first connects entirely The excitation function for connecing layer is wavelet function, and the number of the neuron of the second full articulamentum output is one, the second full articulamentum Excitation function is sigmoid function.Each node in neural network receives input value, and input value is passed to next layer, Attribute value can be directly passed to next layer (hidden layer or output layer) by input node, hidden in wavelet convolution neural network There is functional relation between layer and output the outputting and inputting of node layer, this function is known as excitation function, without using excitation letter If number, every layer of neural network all only does linear transformation, also still linear transformation after multilayer input superposition.Because of linear mould The ability to express of type is inadequate, and excitation function can introduce non-linear factor, improves the recognition capability of image.
Wavelet function are as follows:
y1For output, it be α is 0.7, β 0.5 that x, which is input,.α and β is that variable element, α and β are obtained by test of many times. By the way that the weld data of various defect types and normal weld data to be brought into wavelet function calculate respectively, and will Calculated result is compared, and repeatedly carries out bringing test into, the final optimal value for obtaining α and β, α 0.7, β 0.5.
Embodiment 2
Embodiment 2 discloses a kind of ultrasonic weld seam detection method based on wavelet convolution neural network, including following step It is rapid:
Step 101: weld data is obtained, defect weldment and zero defect weldment are scanned using ultrasonic sensor, Weld data is obtained, weld data includes defective data and normal data;
Step 102: weld data pretreatment pre-processes weld data according to Preprocessing Algorithm, is pre-processed Weld data, pretreatment weld data include pretreatment defective data and pretreatment normal data;
Step 103: training wavelet convolution neural network, using weld data and pretreatment weld data according to training algorithm Training wavelet convolution neural network;
Step 104: obtaining weld data to be detected, weldment to be detected is scanned using ultrasonic sensor, obtain Weld data to be detected;
Step 105: weld data pretreatment to be detected locates weld data to be detected according to Preprocessing Algorithm in advance Reason, obtains pre-processing weld data to be detected;
Step 106: calculating testing result, weld data to be detected will be pre-processed and be input to trained wavelet convolution nerve It is calculated in network, obtains testing result;
Step 107;Judge whether weldment to be detected is qualified, will test result and 0.5 comparison, if testing result is greater than 0.5, Then the weld seam of weldment to be detected is defective, if testing result less than 0.5, the weld seam zero defect of weldment to be detected.
In step 101, the frequency of the center probe of ultrasonic sensor is 5MHz, and defect weldment includes having folder in weld seam Have the lack of penetration weldment of leachy weldment, weld seam in miscellaneous weldment, weld seam, have in the weldment and weld seam that weld seam does not merge and split The weldment of line.
In step 102 and step 105, Preprocessing Algorithm is specifically included:
Butterworth filter is carried out to data first;
Then mean filter is carried out to the data after butterworth filter using mean filter;
Finally the data after mean filter are normalized.
The window of mean filter is dimensioned to 0.0002s.
In step 103, training algorithm includes stochastic gradient descent algorithm, Adam algorithm, RMSProp algorithm, Adagrad calculation Method, Adadelta algorithm or Adamax algorithm.
Wavelet convolution neural network successively include the first convolutional layer, the first pond layer, the second convolutional layer, the second pond layer, Third convolutional layer, third pond layer, Volume Four lamination, the 4th pond layer, the 5th convolutional layer, the 5th pond layer, the first full connection Layer and the second full articulamentum, every layer of convolutional layer are made of several convolution units, and the parameter of each convolution unit is by reversed What propagation algorithm optimized.The purpose of convolution algorithm is to extract the different characteristic of input, and first layer convolutional layer can only extract Some rudimentary features such as levels such as edge, lines and angle, the convolutional layer of more layers can from low-level features iterative extraction it is more multiple Miscellaneous feature, therefore wavelet convolution neural network is designed to five layers of convolutional layer by the present invention, can extract the more complicated of weld seam Feature, improve weld classification detection accuracy.In wavelet convolution neural network, one is often added between convolutional layer Pond layer.Pond layer can effectively reduce the size of parameter matrix, to reduce the number of parameters finally connected entirely in layer. Can accelerate calculating speed using pond layer also prevents over-fitting, and in field of image recognition, image is too big sometimes, We need to reduce the quantity of training parameter, it is required periodically to introduce pond layer between subsequent convolutional layer.Chi Hua Sole purpose be reduce image space size.Pond is completed alone in each depth dimension, therefore the depth of image It remains unchanged.In wavelet convolution neural network structure, after multiple convolutional layers and pond layer, it is connected to 1 or 1 or more Full articulamentum, each node of full articulamentum is connected with upper one layer of all nodes, for the feature that front is extracted It integrates.
Of first convolutional layer, the second convolutional layer, third convolutional layer, Volume Four lamination and the filter in the 5th convolutional layer Number is followed successively by 11, seven, five, three, three, the first convolutional layer, the second convolutional layer, third convolutional layer, Volume Four product The convolution kernel size of layer and the 5th convolutional layer is followed successively by (39,1), (27,11), (23,7), (17,5), (13,3), convolution kernel Referred to as Filter is with the neuron of one group of fixed weight, the two-dimensional matrix of usually n*m, and n and m are also nerve The receptive field of member.What is deposited in n*m matrix is the coefficient to data processing in receptive field.The filtering of one convolution kernel can be used to mention Take specific feature (such as contour of object, shade can be extracted etc.).It is extracted from initial data by convolutional layer new The process of feature become feature map (Feature Mapping) again, the multiple of former weld image are obtained by the convolution of convolution kernel Characteristic pattern improves the accuracy of image recognition, the first convolutional layer, the second convolutional layer, third convolutional layer, Volume Four lamination and the 5th The step-length of convolutional layer is 1, and the first convolutional layer, the second convolutional layer, third convolutional layer, Volume Four lamination and the 5th convolutional layer swash Encouraging function is LeakyReLUctant function, the first pond layer, the second pond layer, third pond layer, the 4th pond layer and Five pond layers are all made of the pond method that maximizes, the first pond layer, the second pond layer, third pond layer, the 4th pond layer and the The size of the pond window of five pond layers is disposed as 2, and the number of the neuron of the first full articulamentum output is ten, and first connects entirely The excitation function for connecing layer is wavelet function, and the number of the neuron of the second full articulamentum output is one, the second full articulamentum Excitation function is sigmoid function.Each node in neural network receives input value, and input value is passed to next layer, Attribute value can be directly passed to next layer (hidden layer or output layer) by input node, hidden in wavelet convolution neural network There is functional relation between layer and output the outputting and inputting of node layer, this function is known as excitation function, without using excitation letter If number, every layer of neural network all only does linear transformation, also still linear transformation after multilayer input superposition.Because of linear mould The ability to express of type is inadequate, and excitation function can introduce non-linear factor, improves the recognition capability of image.
In the present embodiment, wavelet function are as follows:
y2For output, x is input, α 0.9, β 0.4.α and β is that variable element, α and β are obtained by test of many times.It is logical It crosses and the weld data of various defect types and normal weld data is brought into wavelet function calculates respectively, and will meter It calculates result to be compared, repeatedly carries out bringing test into, the final optimal value for obtaining α and β, α 0.9, β 0.4.

Claims (10)

1. a kind of ultrasonic weld seam detection method based on wavelet convolution neural network, which comprises the following steps:
Step 1: weld data is obtained, defect weldment and zero defect weldment are scanned using ultrasonic sensor, welded Data are stitched, the weld data includes defective data and normal data;
Step 2: weld data pretreatment pre-processes the weld data according to Preprocessing Algorithm, obtains pretreatment weldering Data are stitched, the pretreatment weld data includes pretreatment defective data and pretreatment normal data;
Step 3: training wavelet convolution neural network, using the weld data and the pretreatment weld data according to training Algorithm trains wavelet convolution neural network;
Step 4: obtaining weld data to be detected, is scanned using the ultrasonic sensor to weldment to be detected, obtain to Detect weld data;
Step 5: weld data pretreatment to be detected carries out the weld data to be detected according to the Preprocessing Algorithm pre- Processing, obtains pre-processing weld data to be detected;
Step 6: calculating testing result, and the pretreatment weld data to be detected is input to the trained wavelet convolution It is calculated in neural network, obtains testing result;
Step 7;Judge whether the weldment to be detected is qualified, by the testing result and 0.5 comparison, if the testing result Greater than 0.5, then the weld seam of the weldment to be detected is defective, if the testing result less than 0.5, the weldment to be detected Weld seam zero defect.
2. as described in claim 1 based on the ultrasonic weld seam detection method of wavelet convolution neural network, which is characterized in that step In rapid one, the frequency of the center probe of the ultrasonic sensor is 5MHz.
3. as described in claim 1 based on the ultrasonic weld seam detection method of wavelet convolution neural network, which is characterized in that step In rapid one, the defect weldment includes having that the weldment being mingled with, to have leachy weldment, weld seam in weld seam lack of penetration in weld seam With the weldment of crackle in the weldment and weld seam that weldment, weld seam do not merge.
4. as described in claim 1 based on the ultrasonic weld seam detection method of wavelet convolution neural network, which is characterized in that step Rapid two and step 5 in, the Preprocessing Algorithm specifically includes:
Butterworth filter is carried out to data first;
Then mean filter is carried out to the data after butterworth filter using mean filter;
Finally the data after mean filter are normalized.
5. as claimed in claim 4 based on the ultrasonic weld seam detection method of wavelet convolution neural network, which is characterized in that institute The window for stating mean filter is dimensioned to 0.0002s.
6. as described in claim 1 based on the ultrasonic weld seam detection method of wavelet convolution neural network, which is characterized in that step In rapid three, the training algorithm include stochastic gradient descent algorithm, Adam algorithm, RMSProp algorithm, Adagrad algorithm, Adadelta algorithm or Adamax algorithm.
7. as described in claim 1 based on the ultrasonic weld seam detection method of wavelet convolution neural network, which is characterized in that step In rapid three, the wavelet convolution neural network successively includes the first convolutional layer, the first pond layer, the second convolutional layer, the second pond Layer, third convolutional layer, third pond layer, Volume Four lamination, the 4th pond layer, the 5th convolutional layer, the 5th pond layer, first connect entirely Connect layer and the second full articulamentum.
8. as claimed in claim 7 based on the ultrasonic weld seam detection method of wavelet convolution neural network, which is characterized in that institute State the number of the first convolutional layer, the second convolutional layer, third convolutional layer, Volume Four lamination and the filter in the 5th convolutional layer It is followed successively by 11, seven, five, three, three, first convolutional layer, the second convolutional layer, third convolutional layer, Volume Four The convolution kernel size of lamination and the 5th convolutional layer is followed successively by (39,1), (27,11), (23,7), (17,5), (13,3), institute The step-length for stating the first convolutional layer, the second convolutional layer, third convolutional layer, Volume Four lamination and the 5th convolutional layer is 1, described First convolutional layer, the second convolutional layer, third convolutional layer, Volume Four lamination and the 5th convolutional layer excitation function be LeakyReLUctant function, first pond layer, the second pond layer, third pond layer, the 4th pond layer and the described 5th Pond layer be all made of maximize pond method, first pond layer, the second pond layer, third pond layer, the 4th pond layer and The size of the pond window of the 5th pond layer is disposed as 2, and the number of the neuron of the first full articulamentum output is ten A, the excitation function of the first full articulamentum is wavelet function, and the number of the neuron of the second full articulamentum output is One, the excitation function of the second full articulamentum is sigmoid function.
9. as claimed in claim 8 based on the ultrasonic weld seam detection method of wavelet convolution neural network, which is characterized in that institute State wavelet function are as follows:
The y1For output, the x is input, and described be α is 0.7, and the β is 0.5.
10. as claimed in claim 8 based on the ultrasonic weld seam detection method of wavelet convolution neural network, which is characterized in that The wavelet function are as follows:
The y2For output, the x is input, and the α is 0.9, and the β is 0.4.
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