CN110814465A - Universal method for automatically extracting welding seam contour - Google Patents

Universal method for automatically extracting welding seam contour Download PDF

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CN110814465A
CN110814465A CN201911194751.0A CN201911194751A CN110814465A CN 110814465 A CN110814465 A CN 110814465A CN 201911194751 A CN201911194751 A CN 201911194751A CN 110814465 A CN110814465 A CN 110814465A
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welding
weld
slope
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CN110814465B (en
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余卓骅
胡艳梅
何银水
龚平华
蒋吴曦
张国涛
吴谣
黄怡彬
金书强
涂亮
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INSTITUTE OF TECHNOLOGY EAST CHINA JIAOTONG UNIVERSITY
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00Arc welding or cutting
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00Arc welding or cutting
    • B23K9/24Features related to electrodes
    • B23K9/28Supporting devices for electrodes
    • B23K9/287Supporting devices for electrode holders
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B23MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23KSOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00Arc welding or cutting
    • B23K9/32Accessories

Abstract

The invention discloses a general method for automatically extracting a welding seam outline, which relates to the technical field of welding and comprises the following steps: collecting a welding seam image which is not subjected to arc striking before welding as a reference image, and automatically determining a filtering angle and an interested area of Gabor filtering by using the reference image; collecting a welding image, carrying out self-adaptive Gabor filtering on the welding image to obtain a multi-direction characteristic diagram, and simultaneously obtaining a reference image and an interested area part of the direction characteristic diagram; processing the two interested area parts by using a scale invariant feature transform algorithm to obtain the matching positions of the similar points of the two images; and (3) carrying out self-adaptive local threshold segmentation processing on the region of interest of the multidirectional characteristic diagram to obtain a binary image, and extracting the weld seam contour according to the obtained coordinates of the matching position and the clustering result. The invention is effective to typical butt joint and angle joint joints, can be popularized to the extraction of welding seams of other joint outlines, and is beneficial to the integration of a welding information acquisition and processing system.

Description

Universal method for automatically extracting welding seam contour
Technical Field
The invention relates to the technical field of welding, in particular to a general method for extracting a typical butt joint and angle joint GMAW (gas metal arc welding) automatic welding seam profile of a thick plate under laser vision sensing.
Background
At present, in the GMAW (gas metal arc welding) automatic welding of a robot thick plate, a laser vision sensing system is mostly used for detecting characteristic information of a welding seam profile to guide a welding gun to complete welding seam tracking, so that the online effective extraction of the welding seam profile is the premise of realizing the automatic welding. At present, different welding seam contour extraction methods are proposed by a plurality of researches aiming at the GMAW automatic welding of thick plates with different joints. The methods are provided aiming at the profile appearance of the welding seam under the specific application background, and the application range is not wide. As is well known, developing a set of efficient algorithms to achieve online extraction of a certain weld profile requires considerable cost and is not conducive to popularization. Therefore, the universal welding seam outline extraction method not only can save the welding production cost, but also is beneficial to the popularization of the automatic welding technology, and has practical significance.
Disclosure of Invention
Aiming at the problems, the invention provides a general method for automatically extracting the welding seam outline.
The technical scheme adopted by the invention is as follows: a general method for automatic weld seam profile extraction includes the following steps:
collecting a welding seam image which is not subjected to arc striking before welding as a reference image, and automatically determining a filtering angle and an interested area of Gabor filtering by using the reference image; collecting a welding image, carrying out self-adaptive Gabor filtering on the welding image to obtain a multi-direction characteristic diagram, and simultaneously obtaining a reference image and an interested area part of the direction characteristic diagram; processing the two interested area parts by using a scale invariant feature transform algorithm to obtain the matching positions of the similar points of the two images; and (3) carrying out self-adaptive local threshold segmentation processing on the region of interest of the multidirectional characteristic diagram to obtain a binary image, carrying out nearest neighbor clustering on data points with the gray value of 255 in the binary image, and extracting the weld seam contour according to the obtained coordinates of the matching position and the clustering result.
Further, the automatic determination of the filtering angle and the region of interest of the Gabor filtering by using the reference image comprises the following steps:
s11, the welding gun is in the initial welding position, the laser vision sensor is in the working state, and a welding seam image without arc light and with laser stripes is collected without arc striking and is used as a reference image for extracting the contour of the welding seam at this time;
s12, performing self-adaptive local threshold segmentation processing on the reference image to obtain a binary strip-shaped weld seam outline;
s13, determining 80 pixel boundaries respectively from top to bottom by taking the center line of the strip-shaped welding seam contour as a reference, and taking the boundaries as the top and bottom boundaries of the region of interest; the left and right boundaries of the region of interest are the left and right boundaries of the reference center line;
s14, calculating the slope of the data where the central line is located:
Figure DEST_PATH_IMAGE001
(1)
wherein
Figure 100002_DEST_PATH_IMAGE002
A footer to represent the data is indicated,
Figure DEST_PATH_IMAGE003
indicating foot markThe data points of the surrounding neighbors are,
Figure 100002_DEST_PATH_IMAGE004
coordinates representing the row on which the laser stripe data point lies,
Figure DEST_PATH_IMAGE005
coordinates representing a column in which the laser stripe data point is located;
s15, obtaining monotonously increasing and decreasing slope intervals by using formulas (2) and (3), respectively:
(2)
Figure DEST_PATH_IMAGE007
(3)
where t represents the angle of slope;
s16, obtaining the length of the slope monotone interval by adopting the following method: subtracting the subscript of the first slope from the subscript of the last slope of each slope monotonic interval;
s17, calculating the average length of all slope monotonous intervals, and acquiring the part of the slope monotonous interval with the length larger than the average length;
s18, carrying out segmentation by an Otsu threshold segmentation method on the numerical value of the slope monotonic interval with the length larger than the average length to obtain a threshold, wherein the interval with the length numerical value larger than the threshold represents the characteristic point of the weld contour at the position, and the position of the midpoint of the interval corresponding to the position in the image is taken as the position of the characteristic point;
s19, dividing the weld contour central line extracted from the reference image into a plurality of sections by the identified characteristic points, and determining the arctangent angle of the slope of each section by the coordinates of the first data point and the last data point of each section from left to right as follows:
Figure 100002_DEST_PATH_IMAGE008
(4)
wherein
Figure DEST_PATH_IMAGE009
Indicates the number of segments of the above-mentioned segment,
Figure 100002_DEST_PATH_IMAGE010
andrespectively the ordinate and abscissa of the first data point of each segment,and
Figure DEST_PATH_IMAGE013
respectively, the ordinate and abscissa of the last data point of the segment.
Further, the step S2 includes:
acquiring a local threshold:
Figure 100002_DEST_PATH_IMAGE014
(5)
whereinAn image of the weld is represented,
Figure 100002_DEST_PATH_IMAGE016
which represents the number of lines of the image,
Figure DEST_PATH_IMAGE017
indicating the position of the line on which the image is looped each time,
Figure 100002_DEST_PATH_IMAGE018
which represents the number of columns of the image,
Figure DEST_PATH_IMAGE019
indicating the area covered by each circular column,
Figure 100002_DEST_PATH_IMAGE020
indicating that the interval of the columns is 2 per cycle,
Figure DEST_PATH_IMAGE021
the number of rows representing the weld image,
Figure 100002_DEST_PATH_IMAGE022
the number of columns representing the weld image.
Further, the acquiring of the reference image and the region of interest of the directional feature map specifically includes:
s21, using the above
Figure DEST_PATH_IMAGE023
Respectively carrying out Gabor filtering on the welding seam images collected in welding, and obtaining a direction characteristic diagram with the same size as the original image every time, wherein the Gabor filtering formula is as follows:
Figure 100002_DEST_PATH_IMAGE024
(6)
Figure DEST_PATH_IMAGE025
(7)
wherein the content of the first and second substances,
Figure 100002_DEST_PATH_IMAGE026
and
Figure DEST_PATH_IMAGE027
is the coordinate of each pixel point in the collected welding seam image,
Figure 100002_DEST_PATH_IMAGE028
is the frequency of the filtering of the signal,
Figure DEST_PATH_IMAGE029
is said filteringThe angle of the angle is set to be,
Figure 100002_DEST_PATH_IMAGE030
is the standard deviation, and set
Figure DEST_PATH_IMAGE031
S22, dividing the welding seam image into a plurality of welding seam images by taking the vertical coordinate of the obtained characteristic points as a boundary line
Figure 100002_DEST_PATH_IMAGE032
Sequentially intercepting the direction characteristic diagrams of all the areas to form a multidirectional characteristic diagram;
and S23, respectively intercepting the multi-direction feature map and the reference image according to the region of interest to obtain the regions of interest of the direction feature map and the reference image.
Further, the extracting the weld seam profile according to the obtained coordinates of the matching position and the clustering result specifically comprises:
s31, performing self-adaptive local threshold segmentation processing on the region of interest of the multidirectional feature map to obtain a binary image, setting Euclidean distance of 5 pixels as a clustering threshold, and performing nearest neighbor clustering on data points with the gray value of 255 to generate a certain number of classes;
s32, in the scale invariant feature transformation algorithm, the coordinates of the matching positions generated in the two input interested areas are superposed on the binary image;
and S33, extracting the class which is closest to the coordinates of each matching position and is less than 5 pixels away, wherein all the extracted classes form the weld seam outline.
The invention has the advantages that:
the invention relates to a general method for extracting a weld contour of GMAW (gas metal arc welding) automatic welding of a typical joint of a thick plate under laser vision sensing, which is characterized in that a weld image that a welding gun is at an initial welding position and a laser vision sensing system is not arcing under a working state is collected and used as a reference image, adaptive local threshold segmentation processing is carried out on the image to obtain the weld contour, and an interested area is determined according to the weld contour; filtering a weld image acquired in real time in welding by adopting a Gabor filter with a self-adaptive filtering angle to generate a multidirectional characteristic diagram; respectively acquiring a reference image F1 and a multidirectional feature map F2 in the region by using the acquired region of interest; processing the F1 and the F2 by using a scale invariant feature transform algorithm to obtain the coordinates (xi, yi) of the similar point of the two images (i =1,2, …); performing self-adaptive local threshold segmentation processing on the F2 to obtain a binary weld image; and (3) carrying out nearest neighbor clustering on data points in the binary image, and extracting classes belonging to the weld seam contour according to coordinates (xi, yi) (i =1,2, …), wherein the classes form the whole weld seam contour. The invention is effective to typical butt joint and angle joint joints, can be popularized to the extraction of welding seams of other joint outlines, is beneficial to reducing the software development cost in welding and is beneficial to the integration of a welding information acquisition and processing system.
In addition to the objects, features and advantages described above, other objects, features and advantages of the present invention are also provided. The present invention will be described in further detail below with reference to the drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention.
FIG. 1 is a flow chart of a general method of automatic weld profile extraction of the present invention;
FIG. 2 is a diagram of the information provided by the T-junction reference image of the present invention;
FIG. 3 is a schematic representation of the multi-directional multi-zone profile determination of the present invention;
FIG. 4 is a reference image and feature map region of interest transformed based on scale invariant features of the present invention
A matching graph of domain affinity locations;
FIG. 5 is an extracted graph of weld profiles based on matching locations and nearest neighbor clustering in accordance with the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Referring to fig. 1, as shown in fig. 1, a general method for automatic weld profile extraction includes the following steps:
collecting a welding seam image which is not subjected to arc striking before welding as a reference image, and automatically determining a filtering angle and an interested area of Gabor filtering by using the reference image; collecting a welding image, carrying out self-adaptive Gabor filtering on the welding image to obtain a multi-direction characteristic diagram, and simultaneously obtaining a reference image and an interested area part of the direction characteristic diagram; processing the two interested area parts by using a scale invariant feature transform algorithm to obtain the matching positions of the similar points of the two images; and (3) carrying out self-adaptive local threshold segmentation processing on the region of interest of the multidirectional characteristic diagram to obtain a binary image, carrying out nearest neighbor clustering on data points with the gray value of 255 in the binary image, and extracting the weld seam contour according to the obtained coordinates of the matching position and the clustering result.
The method for automatically determining the filtering angle and the region of interest of the Gabor filtering by utilizing the reference image comprises the following steps:
s11, the welding gun is in the initial welding position, the laser vision sensor is in the working state, and a welding seam image without arc light and with laser stripes is collected without arc striking and is used as a reference image for extracting the contour of the welding seam at this time;
s12, performing self-adaptive local threshold segmentation processing on the reference image to obtain a binary strip-shaped weld seam outline;
s13, determining 80 pixel boundaries respectively from top to bottom by taking the center line of the strip-shaped welding seam contour as a reference, and taking the boundaries as the top and bottom boundaries of the region of interest; the left and right boundaries of the region of interest are the left and right boundaries of the reference center line;
s14, calculating the slope of the data where the central line is located:
Figure 271825DEST_PATH_IMAGE001
(1)
wherein
Figure 401455DEST_PATH_IMAGE002
A footer to represent the data is indicated,
Figure 74882DEST_PATH_IMAGE003
indicating foot mark
Figure 631765DEST_PATH_IMAGE002
The data points of the surrounding neighbors are,
Figure 633219DEST_PATH_IMAGE004
coordinates representing the row on which the laser stripe data point lies,
Figure 425595DEST_PATH_IMAGE005
coordinates representing a column in which the laser stripe data point is located;
s15, obtaining monotonously increasing and decreasing slope intervals by using formulas (2) and (3), respectively:
Figure 828894DEST_PATH_IMAGE006
(2)
Figure 556679DEST_PATH_IMAGE007
(3)
where t represents the angle of slope;
s16, obtaining the length of the slope monotone interval by adopting the following method: subtracting the subscript of the first slope from the subscript of the last slope of each slope monotonic interval;
s17, calculating the average length of all slope monotonous intervals, and acquiring the part of the slope monotonous interval with the length larger than the average length;
s18, carrying out segmentation by an Otsu threshold segmentation method on the numerical value of the slope monotonic interval with the length larger than the average length to obtain a threshold, wherein the interval with the length numerical value larger than the threshold represents the characteristic point of the weld contour at the position, and the position of the midpoint of the interval corresponding to the position in the image is taken as the position of the characteristic point;
s19, dividing the weld contour central line extracted from the reference image into a plurality of sections by the identified characteristic points, and determining the arctangent angle of the slope of each section by the coordinates of the first data point and the last data point of each section from left to right as follows:
Figure 45429DEST_PATH_IMAGE008
(4)
wherein
Figure 641495DEST_PATH_IMAGE009
Indicates the number of segments of the above-mentioned segment,and
Figure 63567DEST_PATH_IMAGE011
respectively the ordinate and abscissa of the first data point of each segment,and
Figure 173791DEST_PATH_IMAGE013
respectively, the ordinate and abscissa of the last data point of the segment.
The step S2 includes:
acquiring a local threshold:
Figure 286103DEST_PATH_IMAGE014
(5)
wherein
Figure 355691DEST_PATH_IMAGE015
An image of the weld is represented,
Figure 943667DEST_PATH_IMAGE016
which represents the number of lines of the image,
Figure 756902DEST_PATH_IMAGE017
indicating the position of the line on which the image is looped each time,
Figure 989300DEST_PATH_IMAGE018
which represents the number of columns of the image,
Figure 495368DEST_PATH_IMAGE019
indicating the area covered by each circular column,
Figure 305061DEST_PATH_IMAGE020
indicating that the interval of the columns is 2 per cycle,
Figure 921987DEST_PATH_IMAGE021
the number of rows representing the weld image,
Figure 8892DEST_PATH_IMAGE022
the number of columns representing the weld image.
The obtaining of the reference image and the region of interest of the direction feature map specifically includes:
s21, using the above
Figure 685861DEST_PATH_IMAGE023
Respectively carrying out Gabor filtering on the welding seam images collected in welding, and obtaining a direction characteristic diagram with the same size as the original image every time, wherein the Gabor filtering formula is as follows:
Figure 985780DEST_PATH_IMAGE024
(6)
Figure 140817DEST_PATH_IMAGE025
(7)
wherein the content of the first and second substances,
Figure 347808DEST_PATH_IMAGE026
and
Figure 54733DEST_PATH_IMAGE027
is the coordinate of each pixel point in the collected welding seam image,
Figure 714384DEST_PATH_IMAGE028
is the frequency of the filtering of the signal,
Figure 673113DEST_PATH_IMAGE029
is the angle of the filtering, and is,
Figure 469031DEST_PATH_IMAGE030
is the standard deviation, and set
Figure 612436DEST_PATH_IMAGE031
S22, dividing the welding seam image into a plurality of welding seam images by taking the vertical coordinate of the obtained characteristic points as a boundary line
Figure 759383DEST_PATH_IMAGE032
Sequentially intercepting the direction characteristic diagrams of all the areas to form a multidirectional characteristic diagram;
and S23, respectively intercepting the multi-direction feature map and the reference image according to the region of interest to obtain the regions of interest of the direction feature map and the reference image.
The extracting of the weld seam profile according to the obtained coordinates of the matching position and the clustering result specifically comprises:
s31, performing self-adaptive local threshold segmentation processing on the region of interest of the multidirectional feature map to obtain a binary image, setting Euclidean distance of 5 pixels as a clustering threshold, and performing nearest neighbor clustering on data points with the gray value of 255 to generate a certain number of classes;
s32, in the scale invariant feature transformation algorithm, the coordinates of the matching positions generated in the two input interested areas are superposed on the binary image;
and S33, extracting the class which is closest to the coordinates of each matching position and is less than 5 pixels away, wherein all the extracted classes form the weld seam outline.
The invention provides a general method for extracting a weld contour based on laser vision sensing, which is based on typical butt joint and fillet joint weld contour of thick plate welding. The method fully utilizes the non-arc welding seam outline image collected before each welding, and combines a direction detection algorithm and a scale invariant feature transformation algorithm to position the welding seam outline in the welding. The specific technical scheme is as follows:
step 1: before each welding, the laser vision sensor is in a working state, the welding gun is in a welding state, and an outline image of a welding seam which is not subjected to arcing is collected and used as a reference image;
step 2: adopting self-adaptive local threshold segmentation processing to the reference image to obtain a banded weld outline in the binary image, and obtaining a central line of the banded weld outline by calculating an average coordinate value of each row of banded weld outlines, wherein a calculation method for determining a threshold in the self-adaptive local threshold segmentation processing is a formula (1);
Figure 100002_DEST_PATH_IMAGE034
(1)
wherein
Figure 256224DEST_PATH_IMAGE015
An image of the weld is represented,
Figure 296861DEST_PATH_IMAGE016
which represents the number of lines of the image,
Figure 220955DEST_PATH_IMAGE017
indicating the position of the line on which the image is looped each time,
Figure 589619DEST_PATH_IMAGE018
which represents the number of columns of the image,
Figure 14784DEST_PATH_IMAGE019
indicating the area covered by each circular column,
Figure 50873DEST_PATH_IMAGE020
indicating that the interval of the columns is 2 per cycle,
Figure 411448DEST_PATH_IMAGE021
the number of rows representing the weld image,
Figure 532987DEST_PATH_IMAGE022
the number of columns representing the weld image.
And step 3: determining an interested area by taking the central line as a reference and 80 pixels above and below the central line, extracting a part of an original reference image in the interested area for subsequent matching processing, and calling the part to be F1;
and 4, step 4: obtaining the slope of the central line of the weld seam outline by using a formula (2):
Figure 100002_DEST_PATH_IMAGE036
(2)
whereinA footer to represent the data is indicated,
Figure 855701DEST_PATH_IMAGE003
indicating foot mark
Figure 387177DEST_PATH_IMAGE002
The data points of the surrounding neighbors are,
Figure 855067DEST_PATH_IMAGE004
coordinates representing the row on which the laser stripe data point lies,
Figure 762980DEST_PATH_IMAGE005
coordinates representing a column in which the laser stripe data point is located;
and 5: obtaining monotone increasing and decreasing slope intervals by respectively adopting formulas (3) and (4):
Figure 508083DEST_PATH_IMAGE006
(3)
Figure 210459DEST_PATH_IMAGE007
(4)
step 6: obtaining length values of slope intervals which are monotonically increased and decreased, processing the length values by utilizing an Otsu threshold segmentation method to obtain a threshold of the length value, and determining the interval with the length value larger than the threshold, which is called as a large interval;
and 7: determining the position of the middle position of the large region in the image, wherein the position is the position of the feature point;
and 8: dividing the central line of the welding seam contour in the reference image into m segments by the characteristic points, and determining the arctangent values of the slopes corresponding to the m segments by using a formula (5), wherein the values are the filtering angles of Gabor filtering:
Figure 100002_DEST_PATH_IMAGE038
(5)
and step 9: carrying out m times of Gabor filtering on the collected images in welding by using formulas (6) and (7) to obtain m different direction characteristic graphs, wherein the filtering angle at each time is
Figure 100002_DEST_PATH_IMAGE040
Figure 100002_DEST_PATH_IMAGE042
(6)
Figure 100002_DEST_PATH_IMAGE044
(7)
Wherein x and y are coordinates of elements in the grayscale image,
Figure 100002_DEST_PATH_IMAGE046
is the frequency of the filtering of the signal,
Figure 100002_DEST_PATH_IMAGE048
is the angle of the filtering, and,
Figure 100002_DEST_PATH_IMAGE050
is a standard deviation, and
Figure 100002_DEST_PATH_IMAGE052
step 10: according to the segmentation in the step 8, sequentially intercepting the corresponding direction feature maps in the step 9 from left to right to form a final multidirectional feature map;
step 11: intercepting a multi-directional feature map portion in the region of interest, referred to as "F2";
step 12: performing self-adaptive local threshold segmentation processing on the F2 to obtain a binary image;
step 13: setting Euclidean distance as 5 pixel values as a threshold value in clustering, and performing nearest neighbor clustering on data points with the gray value of 255 in the binary image in the step 12 to obtain different classes;
step 14: processing the F1 in the step 3 and the F2 in the step 11 by adopting a scale invariant feature transform algorithm to obtain the positions of matching points at which the two images are similar;
step 15: superposing the coordinates of the matching points obtained in the two images on the binary image in the step 12;
step 16: and (3) calculating the distance between each class in the step (13) and all the matching points in the step (14), and if the distance between a certain class and one of the matching points is less than 5 pixels, extracting the class as a part of the weld contour, and accordingly extracting all the classes, wherein the classes form the final weld contour.
Example 1:
1. the welding gun is in a welding posture and is positioned at an initial welding position, the laser vision sensing system is in a working state, and an image of a welding seam which is not subjected to arcing before welding is collected and used as a reference image, as shown in the leftmost image of the image in FIG. 2;
2. the reference image is processed as shown in fig. 2, that is, adaptive local threshold segmentation processing and strip weld contour center acquisition processing are respectively performed, and then an area of interest, a feature point and a filtering angle are respectively acquired
Figure 15911DEST_PATH_IMAGE048
(m=1,2,…);
3. Using the obtained filter angle
Figure 461936DEST_PATH_IMAGE048
(m =1,2, …) carrying out Gabor filtering, processing a welding seam image acquired in the welding process, and determining a final multidirectional feature map by combining the region of interest and the region segmented by the feature points, as shown in FIG. 3;
4. taking the interesting region part of the reference image and the multidirectional feature map as input, and processing by using a scale-invariant feature transformation algorithm to obtain the coordinates of similar matching points, as shown in FIG. 4;
5. performing self-adaptive local threshold segmentation processing on the multidirectional feature map, performing nearest neighbor clustering on data points with a segmented gray value of 255, wherein Euclidean distance threshold for clustering is 5 pixels, and circles with different radiuses in the graph 5 represent classes in a clustering result;
6. according to the nearest principle, classes which are nearest to the matching point in Euclidean distance and within 5 pixels are obtained, and the classes are weld contour data, and are shown in a right diagram in FIG. 5.
The invention relates to a general method for extracting a weld contour of GMAW (gas metal arc welding) automatic welding of a typical joint of a thick plate under laser vision sensing, which is characterized in that a weld image that a welding gun is at an initial welding position and a laser vision sensing system is not arcing under a working state is collected and used as a reference image, adaptive local threshold segmentation processing is carried out on the image to obtain the weld contour, and an interested area is determined according to the weld contour; filtering a weld image acquired in real time in welding by adopting a Gabor filter with a self-adaptive filtering angle to generate a multidirectional characteristic diagram; respectively acquiring a reference image F1 and a multidirectional feature map F2 in the region by using the acquired region of interest; processing the F1 and the F2 by using a scale invariant feature transform algorithm to obtain the coordinates (xi, yi) of the similar point of the two images (i =1,2, …); performing self-adaptive local threshold segmentation processing on the F2 to obtain a binary weld image; and (3) carrying out nearest neighbor clustering on data points in the binary image, and extracting classes belonging to the weld seam contour according to coordinates (xi, yi) (i =1,2, …), wherein the classes form the whole weld seam contour. The invention is effective to typical butt joint and angle joint joints, can be popularized to the extraction of welding seams of other joint outlines, is beneficial to reducing the software development cost in welding and is beneficial to the integration of a welding information acquisition and processing system.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (5)

1. A general method for automatically extracting welding seam outline is characterized by comprising the following steps
The method comprises the following steps:
collecting a welding seam image which is not subjected to arc striking before welding as a reference image, and automatically determining a filtering angle and an interested area of Gabor filtering by using the reference image; collecting a welding image, carrying out self-adaptive Gabor filtering on the welding image to obtain a multi-direction characteristic diagram, and simultaneously obtaining a reference image and an interested area part of the direction characteristic diagram; processing the two interested area parts by using a scale invariant feature transform algorithm to obtain the matching positions of the similar points of the two images; and (3) carrying out self-adaptive local threshold segmentation processing on the region of interest of the multidirectional characteristic diagram to obtain a binary image, carrying out nearest neighbor clustering on data points with the gray value of 255 in the binary image, and extracting the weld seam contour according to the obtained coordinates of the matching position and the clustering result.
2. The general method for automatic weld profile extraction according to claim 1, characterized in that
In that, the automatic determination of the filtering angle and the region of interest of the Gabor filtering by using the reference image comprises the following steps:
s11, the welding gun is in the initial welding position, the laser vision sensor is in the working state, and a welding seam image without arc light and with laser stripes is collected without arc striking and is used as a reference image for extracting the contour of the welding seam at this time;
s12, performing self-adaptive local threshold segmentation processing on the reference image to obtain a binary strip-shaped weld seam outline;
s13, determining 80 pixel boundaries respectively from top to bottom by taking the center line of the strip-shaped welding seam contour as a reference, and taking the boundaries as the top and bottom boundaries of the region of interest; the left and right boundaries of the region of interest are the left and right boundaries of the reference center line;
s14, calculating the slope of the data where the central line is located:
(1)
wherein
Figure DEST_PATH_IMAGE004
A footer to represent the data is indicated,
Figure DEST_PATH_IMAGE006
indicating foot mark
Figure 787808DEST_PATH_IMAGE004
The data points of the surrounding neighbors are,
Figure DEST_PATH_IMAGE008
coordinates representing the row on which the laser stripe data point lies,
Figure DEST_PATH_IMAGE010
coordinates representing a column in which the laser stripe data point is located;
s15, obtaining monotonously increasing and decreasing slope intervals by using formulas (2) and (3), respectively:
Figure DEST_PATH_IMAGE012
(2)
Figure DEST_PATH_IMAGE014
(3)
where t represents the angle of slope;
s16, obtaining the length of the slope monotone interval by adopting the following method: subtracting the subscript of the first slope from the subscript of the last slope of each slope monotonic interval;
s17, calculating the average length of all slope monotonous intervals, and acquiring the part of the slope monotonous interval with the length larger than the average length;
s18, carrying out segmentation by an Otsu threshold segmentation method on the numerical value of the slope monotonic interval with the length larger than the average length to obtain a threshold, wherein the interval with the length numerical value larger than the threshold represents the characteristic point of the weld contour at the position, and the position of the midpoint of the interval corresponding to the position in the image is taken as the position of the characteristic point;
s19, dividing the weld contour central line extracted from the reference image into a plurality of sections by the identified characteristic points, and determining the arctangent angle of the slope of each section by the coordinates of the first data point and the last data point of each section from left to right as follows:
Figure DEST_PATH_IMAGE016
(4)
whereinIndicates the number of segments of the above-mentioned segment,
Figure DEST_PATH_IMAGE020
and
Figure DEST_PATH_IMAGE022
respectively the ordinate and abscissa of the first data point of each segment,
Figure DEST_PATH_IMAGE024
and
Figure DEST_PATH_IMAGE026
respectively, the ordinate and abscissa of the last data point of the segment.
3. The general method for automatic weld profile extraction according to claim 2, characterized in that
In that, the step S2 includes:
acquiring a local threshold:
Figure DEST_PATH_IMAGE028
(5)
wherein
Figure DEST_PATH_IMAGE030
An image of the weld is represented,which represents the number of lines of the image,
Figure DEST_PATH_IMAGE034
indicating the position of the line on which the image is looped each time,
Figure DEST_PATH_IMAGE036
which represents the number of columns of the image,
Figure DEST_PATH_IMAGE038
indicating the area covered by each circular column,
Figure DEST_PATH_IMAGE040
indicating that the interval of the columns is 2 per cycle,
Figure DEST_PATH_IMAGE042
the number of rows representing the weld image,
Figure DEST_PATH_IMAGE044
the number of columns representing the weld image.
4. The general method for automatic weld profile extraction according to claim 1 or 2, which is based on the following claims
The method is characterized in that the obtaining of the reference image and the region of interest of the direction feature map specifically comprises the following steps:
s21, using the above
Figure DEST_PATH_IMAGE046
Respectively carrying out Gabor filtering on the welding seam images collected in welding, and obtaining a direction characteristic diagram with the same size as the original image every time, wherein the Gabor filtering formula is as follows:
Figure DEST_PATH_IMAGE048
(6)
Figure DEST_PATH_IMAGE050
(7)
wherein the content of the first and second substances,
Figure DEST_PATH_IMAGE052
and
Figure DEST_PATH_IMAGE054
is the coordinate of each pixel point in the collected welding seam image,
Figure DEST_PATH_IMAGE056
is the frequency of the filtering of the signal,is the angle of the filtering, and is,
Figure DEST_PATH_IMAGE060
is the standard deviation, and set
Figure DEST_PATH_IMAGE062
S22, dividing the welding seam image into a plurality of welding seam images by taking the vertical coordinate of the obtained characteristic points as a boundary line
Figure DEST_PATH_IMAGE064
Sequentially intercepting the direction characteristic diagrams of all the areas to form a multidirectional characteristic diagram;
and S23, respectively intercepting the multi-direction feature map and the reference image according to the region of interest to obtain the regions of interest of the direction feature map and the reference image.
5. The general method for automatic weld profile extraction according to claim 1, characterized in that
The step of extracting the weld contour according to the obtained coordinates of the matching position and the clustering result specifically comprises the following steps:
s31, performing self-adaptive local threshold segmentation processing on the region of interest of the multidirectional feature map to obtain a binary image, setting Euclidean distance of 5 pixels as a clustering threshold, and performing nearest neighbor clustering on data points with the gray value of 255 to generate a certain number of classes;
s32, in the scale invariant feature transformation algorithm, the coordinates of the matching positions generated in the two input interested areas are superposed on the binary image;
and S33, extracting the class which is closest to the coordinates of each matching position and is less than 5 pixels away, wherein all the extracted classes form the weld seam outline.
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