JPH0694071B2 - Welding line scanning detector - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding line profile detecting device, and more particularly, it is suitable for an automatic welding robot and is capable of detecting the position of a welding line at high speed. It relates to the device.

[Background of the Invention]

Since the visual sensor for welding robots follows the position of the groove that changes momentarily due to thermal strain during welding, it continuously captures the input image of the groove image captured by a camera, etc., and performs high-speed processing to track information. Need to get Since this process is also performed while spatters, fumes, etc. appearing randomly during welding, noise is generated, and it is devised to eliminate these noises.

The following documents are known as this type of visual sensor. "WF Crocson, PG Debby, et, al: Progress. In. Visual Feedback Fore
arc. Welding of Thin Sheet Steel: ProSeaching of Conference on Visual and Sensory Controls ,, PP.1
89-200, Staff Cult, 1982 "(WFCloksin, PGDave
y, et, al: Progress in Visual Feedback for Robot Arc-
Welding of Thin Sheet Steel; Proc.Conf.on Vision an
d Sensory Controls, PP.189-200, Stuffgart, 1982).

That is, the system shown in the above-mentioned document divides the light section image obtained from the observation device into 256 × 256 pixels, and the brightness at each pixel is 1-bit information of “0,1”. After conversion to, write to the memory of the computer, and use the information written in the memory to calculate the line by the computer, detect the start point, slope, length of the line, determine the type of welding groove, groove The position was detected.

However, the information processing of the system uses 256 × 256 full screen information, so the groove position cannot be detected at high speed, and spatter or electric noise generated during welding causes There is a noise component mixed in, the information processing procedure for determining the noise component is complicated, and as a result, there is a drawback that it takes time to process.

[Object of the Invention]

The present invention has been made in view of the above-mentioned problems in the conventional technique, and even if the relative positional relationship between the welding member and the detection device changes, a welding line that can detect this change at high speed. An object of the present invention is to provide a copy detection device.

[Outline of Invention]

A welding line scanning detection apparatus according to the present invention is provided with a slit beam irradiation system, an observation optical system, and a welding line scanning detection system which converts an image obtained from the observation optical system into a digital amount and performs a calculation process. In, in the two-dimensional detection area defined by setting the reference welding line position on the basis of the light section image information stored in advance in the processing system or the light section image information obtained immediately before, It is characterized in that the welding line position detection processing is carried out.

Example of Invention

An embodiment of the welding line profile detecting device of the present invention will be described in detail below with reference to the accompanying drawings.

1 and 2 show the construction of the optical system of the welding line profile detecting device, showing the welding torch portion. As shown in FIG. 1 and FIG. 2, the optical system of the detection device includes a welding torch 1
And is attached to the moving support 2. The light sources 3 and 4 are attached at a predetermined angle with respect to the central axis of the welding torch 1, and irradiate sheet-like laser beams 5 and 6 in a plane. The light sources 3 and 4 are the welding members 7
A single slit light beam 8 is formed on the welding line of 1 to irradiate the shadowed portions with each other by the welding torch 1.

The image of the slit light beam 8 projected on the welding line of the welding member 7 is converted into an electric signal by the observation optical device 9 fixed to the torch 1. The observation optical device 9 is, for example,
It incorporates a two-dimensional optical position detector such as an ITV camera and a fixed sensor.

FIG. 3 shows the configuration of an electric circuit for converting the image signal obtained by the observation optical device 9 shown in FIGS. 1 and 2 into digital information and performing a calculation process. The two-dimensional optical position detector 9'constituting the observation optical device 9 is a synchronous circuit.
In synchronization with the sync signal obtained from 10, the light section image on the detector is sequentially scanned and converted into a video signal. The sync signal is
It is generated by dividing the frequency of the clock signal of the clock circuit 11.

Reference numeral 12 denotes an A / D converter, which receives the video signal obtained from the two-dimensional optical position detector 9'as an input and converts the analog input into a digital quantity by a pulse signal given from the clock circuit 11. The pulse signal of the clock circuit 11 is counted by the address counter 13.

Reference numeral 14 indicates a data selector, and 15 indicates an address selector. When the output of the A / D converter 12 and the output of the address counter 13 are selected, the information converted into the video signal digital amount is stored in the memory 16 at any time. Reference numeral 17 represents a calculator, and at the time when one screen has been captured, the chip selector circuit 18 switches the input / output of the data selector 14 and the address register 15, and the calculator 17 respectively.
The position of the welding line is obtained by using the digital information stored in the memory 16 by connecting to the data bus and the address bus.

Further, FIG. 4 shows an example of how to allocate addresses on the screen. In this example, the image is divided vertically and horizontally into “256 × 256”, and the brightness of the input image at each division point is set to 8 After converting to a digital quantity of bits, the memory shown in FIG.
This digital information is stored in 16.

Hereinafter, the processing method will be described step by step using the light section images obtained for the lap joint shown in FIGS. 5 to 10 as an example. 5 to 10 show how the position of the weld line of the lap plate joint is detected by the torch-integrated visual sensor.

When the lap plate joint is the detection target, the upper plate of the work is on the left side with respect to the traveling direction of the welding torch (No. 5).
Figures 7 to 7) and on the right side (Figures 8 to 10)
(Shown in the figure), and in either case, the line where the lower end of the side surface of the upper plate contacts the lower plate is the welding line to be obtained.

Typical light section images obtained in these two cases are shown in FIGS. 7 and 10. Then, in these two cut images, points A and B in each image indicate the position of the welding line.

5 and 6 are views for explaining the torch traveling direction in the light section image of FIG. 7, and are a side view and a front view of the torch portion when the work is on the left hand of the torch traveling direction. .

8 and 9 are views for explaining the torch traveling direction in the light section image of FIG. 10, and are a side view and a front view of the torch portion when the work is on the right hand of the torch traveling direction. .

7 and 10, the scanning detection is exactly the same except that the upper plate of the talk is on the left side or the right side with respect to the direction of travel of the welding torch. explain.

The image detection of the welding line is as described above with reference to FIGS. 1 to 3, but first, the light section image obtained by the two-dimensional optical position detector 9'shown in FIG. 3 is A / D converted. It is converted into a digital quantity by the device 12 and stored in the memory 16. And memory 16
The digital information stored in the computer is compared with the threshold value stored in the computer 17 in advance, and the image data is converted into binary information of "0,1". Next, the address of the point where the binarized image information is switched from “0” to “1” and from “1” to “0” is stored in the memory built in the computer 17.

FIGS. 11 (a) to 11 (e) are for explaining the change point address detection obtained from the light section image of the copy welding line. The address of the point at which the image information is switched, that is, the change point address is It becomes like FIG. 11 (b). In the figure, "○-" indicates switching from "0" to "1", and "x-" indicates switching from "1" to "0". Below, the address of each image is represented by (m, n).
Here, (n × 256 + m) corresponds to the absolute address in FIG.

Next, the standard welding line position (m ₀ , n ₀ ) is determined based on the processing result obtained immediately before or the preset value, and the area of “50 × 50” is centered on the welding line position. Select all the elements that have change points inside and find the center point and line length of the selected line element.

The condition that the m-coordinates of the center points of vertically adjacent line elements do not differ by, for example, 1/4 or more of the line length and the line lengths do not differ by, for example, 1/4 or more belong to the same line group. If the center points of line elements belonging to the same line group are connected using (the same conditions shall be set in advance by a computer),
11 Figure (d) is obtained. Next, the left and right end points are taken for each of these line groups, the change point of the image information is obtained in the vertical direction of this end point, and the center point is similarly obtained for this vertical direction line element. The original 8-bit image data is read out from each of the center points in the horizontal direction thus obtained and the center points in the vertical direction, and the brightness is compared. And
The brighter center point is set as the true center point, the true center points of the left and right end points are obtained in each line group, and the true center points in the line groups are connected to form the center line. Then, finally, the intersection is calculated with respect to the center line of each line group.

In this way, the slope of each line and
It can be determined that the light section image of FIG. 11 (a) corresponds to the case where the welding line is on the right side of the torch traveling direction shown in FIGS. 8 and 9, and the intersection point corresponding to point B in FIG. Coordinates (md, n
Detect d) as the position of the weld line.

By multiplying this coordinate value (md, nd) by the image magnification of the observation optical system, the position in the left and right direction of the welding line; the front and back direction, and the position in the vertical direction when the irradiation angle of the slit light is taken into account, can be obtained by calculation. .

Further, FIG. 12 shows an overall configuration diagram of a welding robot configured by using the copying detection apparatus of the present invention. The robot body 19 has the degrees of freedom of F ₁ , F ₂ , F ₃ , F ₄ , F _5, and F ₆ , and the above-described welding torch-integrated detection device 26 is attached to the movable support body 2 attached to the wrist portion thereof. Is provided. 7 is a welding member work to be welded.

In the drawing, reference numeral 20 denotes a welding wire, and a shield gas is supplied to a conduit tube 25 from a wire supply reel 21 via a guide 22 and a gas cylinder 23 via a tube 24.

In such a welding robot configuration, the processing of the image information from the detection device 26 provided in the torch portion is performed by the image processing device 27 incorporating the control circuit shown in FIG. The robot body 19 is controlled by the robot control circuit.
28. The robot control circuit 28 controls the robot body 19 so as to correct the posture and position of the welding torch-integrated detection device 26 based on the processing result of the image processing device 27. At the same time, the welding power source is turned on / off or the current is controlled.

In this way, the welding robot performs high-precision welding work while tracing the welding torch along the welding line of the welding member.

〔The invention's effect〕

As is apparent from the above-described embodiment, according to the present invention, the area for performing the image detection processing of the welding line is narrowed and the image detection processing of only the welding line is performed, so the welding line detection processing time is short. It takes time and high speed welding can be realized. Also,
There is an effect that it is less likely to be affected by optical noise due to spatter generated during welding.

[Brief description of drawings]

The attached drawings are views for explaining one embodiment of the present invention, and FIGS. 1 and 2 are configuration diagrams of an optical system of a welding line tracing detection device, showing a front view and a side view of a welding torch portion. is there. FIG. 3 is a block diagram of an image processing circuit, FIG. 4 is a diagram for explaining an address allocation example of an image memory, and FIGS. 5, 6, and 7 are cases where a work is on the left side of the torch moving direction. 3 is a side view, a front view and a light section image of the torch part of FIG. FIG. 8, FIG. 9 and FIG. 10 are a side view, a front view and a light section image of the torch when the work is on the right hand of the torch moving direction. FIG. 11 is a diagram for explaining a detection image processing process, and FIG. 12 is a diagram for explaining an overall configuration of a welding robot using the detection device of the present invention. 1 ... Welding torch, 2 ... Moving support, 3,4 ... Slit light source, 5,6 ... Sheet laser light, 7 ... Welding member,
8 ... Slit beam, 9 ... Observation optical system, 9 '... two-dimensional optical position detector, 10 ... Synchronous circuit, 11 ... Clock circuit, 12 ... A / D converter, 13 ... Address Counter, 14 ...
… Data selector, 15 …… Address selector, 16 …… Memory, 17 …… Computer, 18 …… Chip selector, 19 …… Robot body.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsuguo Udagawa 502 Jinritsucho, Tsuchiura-shi, Ibaraki Machinery Research Institute, Hiritsu Seisakusho Co., Ltd. Narashino Factory, Hitachi, Ltd.

Claims (1)

[Claims] 1. A light source for irradiating a welding line of a workpiece to be welded, and an observation light detector for detecting reflected light from a direction at a constant angle with respect to a surface formed by the light emitted from the light source. And a welding line tracing detection device in a welding robot, which comprises a calculator and a calculation system for converting an image formed by reflected light detected by the photodetector into digital information and performing a calculation process, the processing system of the calculation system. The reference welding line position is determined based on the optical cutting image information stored in advance or the optical cutting image processing information obtained immediately before, and the welding line is set within the two-dimensional detection area centered on the reference position. A welding line profile detection device characterized by being configured to perform position detection processing.