JPH0453623B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a groove detection device that detects a groove shape such as a groove line position. This invention relates to a groove detection device suitable for a fully automatic welding robot that automatically performs welding.

[Prior Art] As a conventional groove detection device, there is one shown in FIG. 7, for example. This example is disclosed in Japanese Patent Application Laid-Open No. 154771/1983.

In FIG. 7, a groove surface 10 of a material to be welded 100 is shown.
2, the forward direction in the traveling direction of the welding torch 104 is
The light is illuminated linearly by the optical system 106.

Further, in front of the welding torch 104, a two-dimensional position detector 108 composed of a CCD or the like is arranged. An interference filter 110 and a neutral density filter 112 are arranged on the light incident side of the position detector 108, respectively.

The optical axis of the position detector 108 is directed toward the arc point P on the groove surface 102 and the portion after the reflection surface on the groove surface 102 of the illumination light output from the optical system 106. That is, the arc light and the reflected illumination light are each incident on the position detector 108.

Next, the operation of the conventional device as described above will be explained. First, the arc light from the arc point P enters the position detector 108 via the attenuation filter 112 and the interference filter 110, respectively. Further, the reflected light from the groove surface 102 of the illumination light of the optical system 106 is
The light enters the position detector 108 via the interference filter 110.

In other words, the arc image and the groove surface image are each observed by the position detector 108.

Among these, the weld line is first detected by observing the groove surface image. Furthermore, by observing the arc image, the degree of bending and the amount of protrusion of the wire during welding can be detected.

Based on this information, welding conditions are controlled and welding line tracing control of the welding torch is performed.

[Problems to be Solved by the Invention] However, the conventional groove detection device as described above requires a light source for illumination;
This has the disadvantage that the device configuration and adjustment become complicated.

In addition, there is a possibility that arc light from welding may be mixed in the illumination light output from such an illumination light source, resulting in uneven illumination and the inconvenience that groove detection cannot be performed well. .

This invention was made in view of this point, and does not require a special light source for illumination.
It is an object of the present invention to provide a groove detection device that can perform highly accurate groove detection while effectively preventing the adverse effects of arc light.

[Means for Solving the Problems] The groove detection device according to the present invention includes an imaging means for capturing an image of the groove using a welding arc as illumination light; a two-dimensional storage means for storing information on each pixel; an integrating means for performing an integral process on each of the pixel information;
The present invention is characterized by comprising a differentiating means for performing differentiation processing on integrated pixel information; and a detecting means for obtaining information regarding the shape of the groove from the differentiated pixel information.

[Function] According to the present invention, arc light is used as illumination light for obtaining a groove image, and no special illumination means is used.

However, since arc light is unstable, the pixel information of the captured groove image is subjected to differential processing after integral processing, and this is used to obtain information regarding the shape of the groove.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Configuration of Embodiment FIG. 1 shows the overall configuration of an embodiment of the groove detection device according to the present invention. Further, FIG. 2 shows a schematic side view.

In these figures, a two-dimensional imaging device 12 such as a CCD camera is arranged in the direction of movement of the welding torch 10, which is indicated by an arrow FA. A filter 14 such as a neutral density filter is provided on the light incident side of the imaging device 12, if necessary.

This imaging device 12 is arranged so that it can image the groove 18 or groove surface 20 of the base material 16 to be welded at a distance L in front of the molten pool directly below the welding torch 10, for example, at a position of 10 to 30 mm. has been done.

Furthermore, the illumination light used when imaging is performed is arc light, and no special illumination means is provided.

Next, the above-mentioned welding torch 10 and imaging device 12
An air nozzle 22 that opens in the direction of the imaging area of the imaging device 12 is provided between the welding section and the welding section.
Good imaging is now possible.

Next, the image signal, which is the imaging output of the imaging device 12 described above, is input to the signal processing device 24. This signal processing device 24 includes a microcomputer 26 and a memory 28, and their operations allow information regarding the groove shape, such as information on the groove position, to be obtained.

Next, the processing results of the signal processing device 24 are connected to be input to a welding control device 30.
This welding control device 30 controls welding conditions, groove line tracing, etc. in the welding torch 10 using input information regarding the groove shape.

Next, the operational block configuration of the signal processing device 24 described above will be explained. FIG. 3 shows an example of the construction of such a working block.

In this figure, an image signal from an imaging device 12 is input to a control section 32.
This control section 32 includes a memory 28 and an arithmetic processing section 3.
4, respectively. This arithmetic processing section 34
The integrating means 36, the differentiating means 38, and the detecting means 4
0 and calculation means 42, respectively. Further, the detection means 38 is provided with a limiter 44 .

Among the above components, the control unit 32 has functions such as A/D converting the input image signal and storing it in the memory 28, reading out data in a predetermined area from the memory 28, and outputting it with a delay. .

Next, the memory 28 has a two-dimensional configuration,
By specifying the coordinate values X and Y, it is possible to check the brightness or amount of light of any pixel.

Next, the integrating means 36 sums up the brightness of the pixels lined up in a predetermined direction in the memory 28 to obtain
It performs integration. The reason why such integration is performed for pixels is to reduce the influence of noise by coordinating the contours of the image.

Next, the differentiating means 38 is for differentiating the integrated image signal and extracting the outline of the image.

Further, the detection means 40 and the calculation means 42 are for obtaining shape information regarding the groove 18 from the differentiated image signal.

The limiter 44 is for suppressing large fluctuations in the detection position due to erroneous detection.

Furthermore, the output of the groove information to the welding control device 30 is delayed by a time corresponding to the distance L shown in FIG.
It is now output to .

To give an overview of the operation of the device configured as described above, a two-dimensional image obtained by the imaging device 12 is input to the signal processing device 24, where predetermined image processing is performed on a specific region. be exposed. Through this processing, the weld line position or groove center, root gap width, etc. are detected.

In this embodiment, since arc light is used as illumination light, the illuminance of the groove 18, which is the subject of the imaging device 12, is not constant and changes from moment to moment. For this reason,
No processing is performed by binarizing the image signal, and integration,
Processing such as differentiation is performed.

Next, the groove information obtained through these processes is processed after a delay corresponding to the distance L shown in FIG.
It is input to the welding control device 30. Welding control device 3
0, welding control such as welding current, arc voltage, welding amount, and welding speed is performed based on the input information.

Effects of the Example Next, the overall effect of the above example will be explained in the fourth section.
This will be explained in detail with reference to FIGS. 6 through 6.
Furthermore, Fig. 4 shows the flow of the operation as a flowchart, Fig. 5 shows the contents of the operation as a time chart, and Fig. 6 shows the contents of the integral and differential operations. has been done.

First, initial settings are made so that the groove 18 is within the field of view of the imaging device 12 (step 4 in FIG.
(See SA). As a result, the imaging device 18 can obtain an image as shown in FIG. 5A of the groove 18 of the base material 16 to be welded shown in FIG. 5B.

That is, the image signal of the groove 18 captured by the imaging device 12 is sent to the A/D by the control unit 32.
It is converted and further stored in the memory 28 (see step SB).

Next, in the control unit 32, for this image,
Only minute areas as shown by the dashed line in FIG. 5A are set or limited as processing areas, and pixel data within these areas are read out from the memory 28 and subsequent signal processing is performed.

First, as shown in step SC, positional integration is performed by the integrating means 36 on the luminance of the pixel. FIG. 5C shows the luminance data of each pixel at an appropriate X coordinate value. As shown in this figure, the brightness is high at the aperture surface 20 and low at other parts. However, due to the influence of optical noise, the root gap ends GA, GB, shoulder KA,
It is difficult to detect the location of KB well.

Therefore, integration as shown in FIG. 6 is performed.
In FIG. 6, A shows an example of luminance data of each pixel corresponding to the shoulder KA portion. Integration is performed by adding the same Y coordinates in the X direction. For example, the integral value of pixel Q1 is the sum of the luminances of pixels _Q11 to _Q15 . The same applies to other pixels Q2, Q3, Q4...

The positional integration in the X direction as described above is performed for the specified area indicated by the dashed line in FIG. 5A, and luminance integral data as shown in FIG. 5D is obtained. Thereby, the outline of the image in the X direction can be coordinated, and the level of optical noise can be relatively suppressed.

Next, the above integral data is differentiated by the differentiating means 38 (see step SD). This differentiation is performed by determining the luminance difference between the pixels located second to the left and right of the pixel for which the differential value is to be determined (see FIG. 6B).

FIG. 5E shows the differential data obtained in the above manner, and the root gap GA,
Peaks corresponding to GB, Sjorda KA, and KB appear clearly.

Next, the detection means 40 detects the positions of the root gaps GA, GB, shoulders KA, KB and measures the root gap width with respect to the differential luminance data obtained as described above (step SE
reference).

In other words, within the specified area shown in FIG. 5A,
The position of the pixel with the maximum differential value is determined and detected as the position of the root gap GA, GB, shoulder KA, KB.

At this time, due to the influence of noise, the maximum pixel of the differential value is the root gap GA, GB, shoulder KA,
A limiter 44 sets a limit within a predetermined range for the detected position so that it does not coincide with the position of KB and causes a large variation in the detected position, and position variation exceeding the set value is absorbed.

Then, the root gap width is measured from the positions of the root gaps GA and GB determined as described above.

Next, using a predetermined conversion formula, the welding current command value and welding speed are calculated from the measured gap width.
This is performed by the calculation means 42 (see step SF). Then, such welding data is once stored in the memory 28, and after a predetermined delay, is output from the control section 32 to the welding control device 30 (step SG).
reference).

This delayed output eliminates the time difference due to the positional difference of L between the imaging position and the welding position,
Current commands and speed commands corresponding to the gap width directly below the welding torch 10 are given, and the welding control device 30 controls the welding torch 10 based on these commands.

The above operations are repeated, and when all welding is completed, the operation of the device also ends (step
(See SH).

Effects of the Example As explained above, this example has the following effects.

(1) Since only a predetermined region of the captured image is processed, it is possible to speed up and stabilize the processing.

(2) Although a welding arc is used as the illumination light for the groove, the signal processing is performed using integration and differentiation, so the influence of noise is effectively reduced and the position of the root gap and shoulder can be detected with high accuracy. It can be performed.

(3) Since the root gap and shoulder positions are detected within a predetermined range and their values are limited, no significant detection errors occur.

(4) Since data is output taking into account the difference between the imaging position and the welding position, the welding conditions correspond well to the gap width.

Note that the present invention is not limited to the above-mentioned embodiment in any way; for example, in the above-mentioned embodiment, positional integration is performed to integrate the luminance of adjacent pixels at the same time as the integration process, but when the same pixel is Time integration may also be performed.

Further, the signal processing described above can be performed using software using a computer, but it may also be performed using hardware by configuring a dedicated circuit.

[Effects of the Invention] As explained above, according to the present invention, it is possible to effectively prevent the adverse effects of arc light and perform highly accurate groove detection without requiring a special illumination light source. There is an effect.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the present invention;
Figure 2 is an explanatory diagram showing the side view of the device in Figure 1;
The figure is an explanatory diagram showing the action blocks of the signal processing part.
FIG. 4 is a flowchart showing the operation of the above embodiment, FIG. 5 is a time chart showing the operation of the above embodiment, FIG. 6 is an explanatory diagram showing the integral and differential operations of the above embodiment, and FIG. 7 is a conventional diagram. FIG. 2 is a perspective view showing an example of the device. 10...Welding torch, 12...Imaging device, 16
... Base material, 18 ... Groove, 20 ... Groove surface, 24
... Signal processing device, 26 ... Microcomputer, 28 ... Memory, 30 ... Welding control device, 3
2... Control unit, 36... Integrating means, 38... Differentiating means, 40... Detecting means, 42... Calculating means.

Claims (1)

[Scope of Claims] 1. In a groove detection device that obtains information regarding a groove necessary for setting welding conditions for maintaining a welding arc in a predetermined state from an image of the groove, the apparatus comprises: , an imaging means for imaging the welding arc as illumination light; a two-dimensional storage means for storing information of each pixel of the groove image taken by the imaging means; and an integral processing for each of these pixel information. An invention characterized by comprising: an integrating means for performing a differential process on the integrated pixel information; and a detecting means for obtaining information regarding the shape of the groove from the differentiated pixel information. Ahead detection device.