JPS61128107A - Detection of welded wire, etc. - Google Patents

Abstract

PURPOSE:To enable a correct operation of welding, etc., by correcting a window displacement direction by the center of gravity of inside-window profile image element line set in a digital image, by recognizing a deviated position of a counted value of the number of image elements from the set reference value as the end point of the profile line, etc. CONSTITUTION:Above a specimen, a TV camera 1 is set and prior to measurement, window size 3, detection starting position 11, direction by detection 11, allowable limit of change of number of images of the profile line inside the window 14 are set beforehand. Measurements are conducted with the initial setting of the window in this position 11 and by counting the inside-window areas and by allowing displacements by the specified quantity up to the time when the allowable level of area change of the set area. Similarly a displacement in the direction 6 is conducted, the displacement at this time being such that a correction is made to the effect that the position of center of gravity of the inside-window profile image line falls in the window center perpendicular to the direction 6 and when it gets out of the allowable limit of area change, the displacement is stopped. This position corresponds to either of terminal point, bending point, branch-off point of the line 14 and the central position of the window position thus defined can be issued out as an output as starting and terminating points of the operation.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention detects misalignment of welding lines, glue material application lines, etc. of workpieces in automated welding machines, sealing machines, etc. using industrial robots etc. This article relates to a method for detecting weld lines, etc.

Generally, in welding and sealing work, there are accuracy errors in the workpiece and the jig used to fix it, and if an industrial robot is used to perform the work without making any corrections for this, defective products may occur. very likely to occur. The present invention provides a method for detecting weld lines, etc., which can be used to detect positional deviations of workpieces caused by accuracy errors, etc., and have an industrial robot correct the positional deviations, thereby eliminating the occurrence of defective products. Concerning what to do.

(Prior Art) For example, the following is a well-known technique for optically detecting the displacement of a workpiece in a non-contact manner in an automated welding machine, sealing machine, etc. using a robot or the like. 1st
is JP-A-58-157513111 and JP-A-59
-No. 184816 Some optical displacement meters, such as those described in various publications, are used to detect distance based on the difference in detected angles. When doing so, it was necessary to move the displacement meter using a separate swinging machine. Secondly, in JP-A-5
6-67703 and Japanese Patent Application Laid-Open No. 59-93293, there is a light cutting method, that is, a method in which a slit light is applied to read the step, and a method in which a ring light is applied instead of the slit light to read the step. (Unexamined Japanese Patent Publication No. 58-17407
1), but in this case as well, in the case of a TV camera attached to a robot or the like, it was necessary to move the TV camera itself by mechanical means in addition to the movement of the crobot. Furthermore, thirdly, Japanese Patent Application Laid-Open No. 59-11468
No. 9, JP-A-59-154578, JP-A-59-13
No. 5579, as shown in Japanese Patent Application Laid-Open No. 59-98286,
Some methods track the contour based on the relationship between the pixel of interest and adjacent pixels, or approximate the contour line with line segments. However, in this case, although it is easy to read the shape of the object to be measured, it is not suitable for reading weld lines and the like at high speed. Fourthly, there are known devices that measure the center of gravity of moving small objects and automatically track the objects, but like the third method, they are not suitable for reading weld lines etc. at high speeds. .

(Problems to be Solved by the Invention) The purpose of the present invention is to accurately and quickly detect misalignment of the tangent line of the workpiece, sealing material application line, etc. in automated welding and thinning operations using industrial robots, etc. However, it is an object of the present invention to provide a method for detecting a weld line, etc., which can be used to correct the amount of deviation and an industrial robot.

(Means for Solving the Problem) Therefore, the present invention captures an image of a stationary object to be measured as a two-dimensional image using a TV camera, and detects it via a φ conversion device, an image memo IJ+, and a contour extraction unit. Set a window in the digital image into which a part of the contour line fits in the contour pixel row of the digital image, move it in the specified direction while correcting the window movement direction based on the center of gravity of the contour pixel row in the window, and calculate the number of contour pixels in the window. This is a method for detecting weld lines, etc., in which a position detecting section recognizes the position where the count value deviates from the set range as the end point, bending point, or branching point of the contour line.

(Example) The main structure of the method of the present invention is shown in FIG. The image of the stationary object to be measured (2) is captured as a two-dimensional image by the TV camera (1), converted from analog to digital by the BA, /D converter (6), and stored in the image memo IJ (13). (Divide the image into 256 x 256 points,
The nth point is set as the IBYTE of the image memory and has a value corresponding to its brightness. ) The digital image in the image memory is turned into a contour image αO by a known method in a contour extraction unit αe. From this contour image, the position detection unit αQ uses the method of the present invention to determine the starting point, end point (7), and bending point (
8) Detect and output the branch point (9) position.

FIG. 2 shows a flowchart of the processing of the position detection unit αθ. The implementation method will be described by taking as an example the case of finding the point P2 in the object to be measured (2) in FIG. 3. A TV camera (1) is installed above the object to be measured (2) shown in FIG. 3, and FIG. 4 shows the outline α4 of the image. Prior to measurement, the size of the window (3) and the exploration start position αυ are determined in advance.
(Figure 6), 1st exploration direction (5), 2nd exploration direction (6)
, the allowable level for change in the number of pixels (surface, @) of the contour line U within the window is set. The contour line a< to be searched is shown in FIG. Initialize the Ic window (position Ql shown in Figure 6) and move the window to the first search direction (Ql as shown in Figure 7) while counting the area inside the window.
5) Move Ic by a certain amount.

In this manner, the first search is performed until the area within the window exceeds the previously set area change tolerance level. After that, the window is moved by a fixed amount in the second search direction (6) while counting the area inside the window (Figure 9).

At this time, the center of gravity of the contour pixel row within the window is calculated, and the center of gravity is moved while being corrected in a direction perpendicular to the second search direction (6) so that the center of gravity is at the center of the window (center of gravity correction, FIG. 9).

This correction of the center of gravity allows the contour line sword 4 to follow even if it is diagonal or curved. This method also stops the exploration operation when the area inside the window exceeds a preset area change tolerance level (Fig. 1O). This is
When capturing the starting point and ending point (7) of the capacitive tangent line, etc., welding line (
4) as the contour line α4, it becomes the end point (7) of the contour line Q4 as shown in Fig. 11, the bending point (8) as shown in Fig. 12, or the branching point ( Either it becomes a man or it becomes a man.Using the property that the area inside the window changes greatly around it even if it becomes a man (effects of the invention) Conventional methods for detecting welding lines are as described earlier. Various methods have been devised for this purpose. For example, optical detection methods measure the distance to the object with an optical displacement meter and recognize the detected position as a welding line, or Using the cutting method, irradiate the slit light and cut the stepped part.
The part where the light bends is recognized as a weld line. In the case of Izuko, only one point on the weld line can be detected, but that point is not necessarily the start point (end point) of the weld line. Therefore, in order to find the starting point (ending point) of the weld line, it is necessary to move the sensor over the object to be measured.

This poses a problem in high-speed processing. According to the present invention, since processing is performed using two-dimensional information (plane information), it is only necessary to capture an image once near the start point (end point) of the weld line of the object to be measured, and therefore high-speed processing is possible.

In conventional contour processing, the contour line is approximated by line segments based on the relationship between one point on the contour pixel array and its neighboring pixels,
However, in the present invention, the shape of the contour line does not matter, and the starting point (end point)
, bending points, and branching points are controlled using simple parameters such as area and center of gravity, making high-speed processing possible.

According to the present invention, displacements of the object to be measured within the range that can be captured by the TV right camera can be detected at high speed, not only due to parallel movement but also rotational movement. Since the deviation can be corrected, accurate welding and/or material application work becomes possible.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the main configuration of the method of the present invention, Fig. 2 is a flowchart showing the processing performed by the position detection section of Fig. 1, and Fig. 3 is a TV right camera when the method of the present invention is fully implemented. A schematic perspective view showing the arrangement of the object to be measured and the welding line, etc.;
4 to 13 each show the contour lines extracted by the contour extraction section of FIG. 1. 1...TV right camera 2...Object to be measured 3...Window 4...Welding line 5.6...Specified direction 7.・・・・・・
Starting point/end point 8...Bending point 9...
... Branch point 12 ... A/D conversion section 13.
... Image memory 14 ... Contour line
15...Contour extraction unit 16...Position detection unit Agent Patent attorney Jun Kawauchi 2 Figure 2 Izuγ1O1? J Nishi 7℃ 7%-) Comparison 3
Mouth I TV Camera

Claims (1)

[Claims] A window into which a part of the contour line is inserted in the contour pixel row of the digital image, which is captured by a TV camera as a two-dimensional image of a stationary object and detected via the A/D converter, image memory, and contour extraction unit. is set in the digital image, and the window is moved in the specified direction while correcting the window movement direction based on the center of gravity of the row of contour pixels within the window.The position where the count value of the number of contour pixels within the window deviates from the set range is the end point and bending point of the contour line. , a method for detecting weld lines, etc. output by a position detection unit that recognizes them as branch points.