JP3175544B2 - Welding line detection device and detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding device for detecting a welding line and providing positional information of the welding line to the automatic machine as a visual sensor for an apparatus for automating arc welding, for example, an arc welding robot or an automatic machine. The present invention relates to a line detection device and a detection method.

[0002]

2. Description of the Related Art Conventionally, as a method of detecting the position of a welding line, a slit light is applied to a groove surface of a welding material, thereby obtaining a light section image crossing the groove portion, and capturing the light section image. There is a method in which an image is taken by an apparatus, and a light-section image obtained by this imaging is processed by an image processing unit to detect a welding line position, which is generally called a welding line detection method by a light-section method.

[0003] A conventional example using the light-section method will be described below with reference to FIG. That is, the sensor unit 91 includes a sensor unit 91 and an image processing unit 92. The sensor unit 91 includes a light projecting unit 93 that emits slit light using a semiconductor laser, and a two-dimensional CCD.
It comprises an imaging unit 94 such as a camera. Further, the imaging unit 94
Are arranged at a certain angle with respect to the light projecting section 93.

[0004] Next, the image processing section 92 is connected to the imaging section 9.
A for converting the image signal output from the digital camera 4 into a digital quantity
A / D converter 95, an image data storage unit 96 for storing the image signal converted into a digital amount from the A / D converter 95, and a synchronizing signal based on the image signal output from the imaging unit 94. A synchronizing signal generating unit 97 for generating a synchronizing signal for controlling the A / D converter 95 and the image data storage unit 96, and controlling the entire image processing unit 92, binarization and thinning And an external communication interface unit 99 for transmitting welding line position data to the outside or communicating with an external device.
It is composed of The welding line position is detected by binarizing the image data in the image data storage unit 96 by the overall control unit 98.
Image processing such as thinning is sequentially performed as shown in FIG. 10, and a bending point (discontinuous point) K1 of the captured slit light is obtained.
After calculating (c, d) and K2 (e, f), the midpoint K
The pixel position of 3 (a, b) is calculated, converted into an absolute position, and transmitted to the robot controller 90 as a welding line position. Then, the position of the welding robot to which the welding line detection device is attached is corrected.

[0005]

However, in the above-mentioned conventional configuration, after the image signal from the sensor section 91 is digitized and taken into the image data storage section 96, the overall control section 98 comprising a microcomputer performs shading. The projection value processing was calculated. Therefore, since the gray level projection value processing adds the gray level values for each pixel in the horizontal direction and the vertical direction, the calculation time becomes enormous and the total welding line detection time becomes long.

[0006] The slit light output from the light projecting section 93 is an output having a predetermined constant value.
Only the control of turning ON / OFF with. For this reason, when the material or shape of the target welding member changes, the detection accuracy deteriorates, and there is also a problem that accurate welding line detection cannot be performed.

[0007] As a problem of the whole system, the mounting position of the sensor section 91 is located near the welding torch mounted on the welding robot, and the image processing section 92 is disposed at a place remote from the sensor section 91. Imaging unit 94 in 91
The image signal cable output from the cable is routed around the welding machine, and is susceptible to external noise and the like, and it is difficult to stably detect the welding line.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems. It greatly reduces the processing time of welding line detection, can detect welding lines of various shapes, and improves detection accuracy and external noise. It is an object of the present invention to provide a welding line detection device and a detection method that are hardly affected by such factors.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned object, the present invention provides a light projecting section for irradiating a welding line portion with slit light having a predetermined line width, On the other hand, an image pickup unit for picking up the slit light from an angle forming a certain angle, a light amount adjusting unit for adjusting the light amount of the light projecting unit, and an A / D for converting an image signal from the image pickup unit into a digital amount.
A converter, a synchronizing signal generator for generating a synchronizing signal for controlling image data based on a synchronizing signal separated from the image signal from the imaging unit, and a digital signal from the A / D converter. An image data storage unit for storing image data based on a synchronization signal from a generation unit; and a horizontal and vertical direction based on a digital image signal from the A / D converter and a synchronization signal from the synchronization signal generation unit. A gray level projection value processing unit having a horizontal direction adder and a horizontal direction projection value storage unit for calculating a gray level projection value and a vertical direction adder and a vertical direction projection value storage unit; and the light amount adjustment unit and the synchronization signal generation unit And the image data storage unit and the like, and are obtained from the processing results of the gradation projection value processing unit according to the size of the gradation projection value and the shape of the gradation projection value based on the image data. Either the inflection point of the horizontal gray scale projection value and the inflection point of the vertical gray scale projection value are detected as welding line positions, or the image data in the image data storage unit is binarized and thinned, and then the bending on the line is performed. The system includes an overall control unit for detecting or selecting a point as a welding line position, and an external communication interface unit for sending welding line detection data calculated by the overall control unit to a robot controller or the like.

Next, as a welding line detecting method using the above configuration, an inflection point of the horizontal density projection value and an inflection point of the vertical density projection value obtained from the processing result in the density projection value processing unit are described. A first method of detecting a welding line by calculating, and a second method of calculating a bending point on the line after binarizing and thinning the image data in the image data storage unit and detecting a welding line.
Is selectively switched by the overall control unit according to the size of the gray-scale projection value and the shape of the gray-scale projection value.

Further, as a welding line detecting method using the above configuration, the light amount of the light projecting section is adjusted according to the magnitude of the gray level projection value calculated by the gray level projection value processing section, and the welding line detecting apparatus is mounted. The detected posture of the welding robot is changed to the front, back, left and right with respect to the welding line, and the light amount of the light projecting unit and the robot's detected posture to obtain a grayscale projection value at which there is a detectable bending point are determined. Is performed based on the welding line.

[0012]

With the above arrangement, the image data from the image pickup unit is A / D converted and stored in real time as image data, and at the same time, the horizontal and vertical adders of the newly provided gradation projection value processing unit are provided. And executes the horizontal and vertical projection value processing, and stores the results in the horizontal direction projection value storage unit and the vertical direction projection value storage unit, respectively. The overall control unit calculates the bending points in the horizontal and vertical directions from the stored gray level projection value data, calculates the welding line position based on the bending points, and sends the welding line position to the robot controller via the external communication interface unit. What to send. Thereafter, the robot controller corrects the tip position of the welding robot based on the welding line position data.

The internal system configuration of the sensor unit is within the same case, and the light amount adjustment unit, A / D converter, synchronization signal generation unit, image data storage unit, overall control unit, external communication interface unit, gray scale projection value processing The image signal sent from the imaging unit is made as short as possible, and the data transmission to the welding robot controller, etc., is made to be strong against noise. It is transmitted after being converted into a possible standard (RS422, RS232C).

Further, the inflection point of the horizontal gradation projection value and the inflection point of the vertical gradation projection value obtained by the gradation projection value processing section are calculated by the overall control section, thereby detecting the welding line. And the second method of binarizing and thinning the image data in the image data storage unit, calculating the bending point on the line, and detecting the welding line, is based on the gray-scale projection value obtained in advance by an experiment or the like. It is possible to perform welding line detection after switching to an optimal detection method in the overall control unit according to the shape of the threshold value and the gray level projection value.

Further, in accordance with the magnitude of the gray-scale projection value calculated by the gray-scale projection value processing unit, the light amount of the light projecting unit is adjusted by the general control unit so that the optimum gray-scale projection value is obtained in advance through experiments or the like. Is performed by the light amount adjustment unit according to the command of
The detection position of the welding robot to which the welding line detection device is attached is changed to the front, back, left and right with respect to the welding line, and the welding line to be detected is the amount of light emitted from the light-emitting unit and the detection position of the robot that can detect the optimum welding line. , It is possible to perform an optimum welding line detection. The threshold value for switching these detection methods, the optimal light amount and the detection posture are determined in advance by experiments or the like based on the target welding line, and stored as a database on the robot controller side memory. By doing so, optimization can be achieved when detecting an experiment.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a welding line detecting apparatus according to the present invention will be described below with reference to FIGS.

As shown in FIG. 1, this embodiment is roughly divided into a sensor unit 1 and an image processing unit 2.

First, the sensor section 1 includes a light projecting section 3 for irradiating slit light having a predetermined line width to a welding line section, and an angle forming a predetermined angle with respect to the irradiation light from the light projecting section 3. The imaging unit 4 is configured to image slit light.

Next, regarding the image processing unit 2, a light amount adjusting unit 5 for adjusting the light amount of the light projecting unit 3 and an A / D converter 6 for converting an image signal from the imaging unit 4 into a digital amount.
A synchronizing signal generator 7 for generating a synchronizing signal for controlling image data based on a synchronizing signal separated from the image signal from the imaging unit 4, and a synchronizing signal generator for converting a digital image signal from the A / D converter 6 And an image data storage unit 8 for storing as image data based on a synchronization signal from the control unit 7, an integrated control of a light amount adjustment unit 5, a synchronization signal generation unit 7, an image data storage unit 8 and the like, and an image processing based on the image data. An external communication interface unit 11 for sending welding line detection data calculated by the overall control unit 9 to the robot control device 10 and the like;
A horizontal adder 12 and a horizontal projection value storage unit 13 for calculating a gray level projection value in the horizontal and vertical directions based on the digital image signal from the / D converter 6 and the synchronization signal from the synchronization signal generation unit 7 And a gray-scale projection value processing unit 16 including a vertical direction adder 14 and a vertical direction projection value storage unit 15.

FIG. 2 shows the internal configuration of the sensor unit 1. The light projecting unit 3 includes a semiconductor laser 17 and a cylindrical lens 18. The imaging unit 4 includes the area CCD 1
9 and an objective lens 20.

The operation of the welding line detecting device configured as described above will be described. First, parallel light is emitted from the semiconductor laser 17 inside the light projecting unit 3, passes through the cylindrical lens 18, is converted into slit light having a certain line width, and is applied to a target work. The shape of the welding line shown in FIGS. 1 and 2 is for a joint where two plates are overlapped. The slit light applied to the welding target passes through the objective lens 20 disposed at a position inclined about 20 degrees with respect to the light projecting unit 3 and is imaged on the area CCD 19. The welding line detection position in this case is a position where the straight line portion of the slit light is bent. The image captured by the area CCD 19 is transmitted from the imaging unit 4 as an image signal combined with a synchronization signal such as a horizontal synchronization signal or a vertical synchronization signal.

The transmitted image signal is input to the A / D converter 6 of the image processing unit 2 and is converted into a digital value. Further, a horizontal synchronizing signal and a vertical synchronizing signal are separated from the image signal, and a synchronizing signal generating section 7 converts the A / D converter 6 and a synchronizing signal for storing image data in an image data storage section 8. And a synchronizing signal for the gray level projection value processing unit 16 to synchronize with the image data.

In the gray-scale projection value processing section 16, the A / D
Based on the image data from the converter 6 and the signal from the synchronizing signal generator 7, the horizontal direction adder 12 and the vertical direction adder 14 add the grayscale data of each pixel in real time, and output the horizontal projection value. The results are stored in the storage unit 13 and the vertical projection value storage unit 15, respectively. FIG. 3 is an explanatory diagram of the grayscale projection value processing data. When the welding line shape is a lap joint, an image 31 as shown in FIG. 3 is obtained, and when the shading projection process is performed, the result in the horizontal direction X becomes a vertical shading value 32 as shown in the horizontal shading projection value 32 on the right side of the welding line image 31. The result in the direction Z is obtained as a vertical gray value projection value 33 below the welding line image 31. Among them, the reason why a peak is formed in the gray-scale projection value is that secondary reflection occurs near the welding line, and scattered light exists near this. Therefore, in the method based on the gray level projection value processing, the pixel position is obtained from the horizontal peak values X1 and X2 and the vertical peak value Z1, and the position is detected as the welding line position.

In the overall control unit 9, the light amount adjusting unit 5
And the integrated control of the synchronizing signal generator 7 and the image data storage 8, and the image processing is executed based on the image data and the result of the gray scale projection processing to finally detect the welding line. The welding line detection data is sent to the robot controller 10 via the external communication interface unit 11. Then, the welding robot corrects the target position of the welding line based on this value.

Next, a method of switching the welding line detection method in the overall control unit 9 will be described. The method is switched to one of the following two methods depending on the shape and surface form of the welding member. First, the first method is based on the result of the horizontal density projection value 32 shown in FIG. 3, and shows the horizontal peak values X1 and X2 and the vertical density projection value 33 peak value Z1.
Is remarkable, and as shown in FIG. 4, a large gray-scale projection value exceeding the values of the vertical threshold value W1 and the horizontal threshold value W2 obtained in advance by experiment is obtained.
The pixel position of the valley between 2 and the pixel position of the peak value Z1 is obtained, and the pixel position (a, b) of the welding line image 31 is obtained. This is converted into an absolute position and transmitted to the robot.

In the case of the result of the horizontal density projection value 32 shown in FIG. 3, when the horizontal peak values X1 and X2 and the vertical density projection value 33 peak value Z1 do not appear remarkably, the second In the case where a light and shade projection value lower than the values of the vertical threshold value W1 and the horizontal threshold value W2 shown in FIG. 4 is obtained, the processing is the same as the method shown in FIG. , Binarize the stored image data,
The bending point is detected after thinning, and the bending point K1 (c, d)
From K2 (e, f) and its midpoint K3 (a, b),
Then, the pixel position of the welding line position is determined. This is converted into an absolute position and transmitted to the robot.

Therefore, the processing contents of the welding line detection method are switched according to the magnitude of the gray level projection value. FIG. 5 is a flowchart showing the flow of the switching of the detection method as described above.
First, image data fetching and horizontal / vertical density shading projection processing are simultaneously executed (step I). Next, the vertical density peak value Z1 and the horizontal density peak values X1, X2
Is calculated (step II). Next, the peak value Z1 is larger than the vertical threshold value W1, and the peak values X1, X2
Is larger than the horizontal threshold value W2, the processing is YES, and if at least one of them is smaller, the processing is NO (step III). If the answer is YES, the first method is performed (step IV). If either of them is smaller, the second method is performed (Step V).

When the shape of the target welding line changes, the shape of the projection value is different, so that the processing contents are partially changed, but the processing contents are basically the same and will not be described.

As for the light quantity adjustment of the light projecting section 3, the light quantity of the light projecting section 3 is adjusted to an optimum value according to the magnitude of the threshold value of the gray level projection value shown in FIG. After simultaneously changing the detection posture of the welding robot 61 to which the welding line detection device is attached, the optimum light amount and the detection posture that can be detected are automatically determined. Then, welding line detection is performed. FIG. 6 is a conceptual diagram showing a case where the welding robot 61 to which the welding line detection device of the present embodiment is mounted detects a welding line by changing the amount of light and the posture. 62 is a welding torch. The above-described detection method first performs the welding line detection by switching between the two types of detection methods depending on the target welding line, and if the detection is still not possible, furthermore, the light amount of the light emitting unit and the detection posture are also determined. After changing the above two types of detection methods to find out the optimal detection conditions,
This is to perform final welding line detection.

FIG. 7 is a configuration diagram of a robot system when the sensor section 1 and the image processing section 2 of the welding line detecting apparatus of the present invention are separated.

In the same case of the sensor unit 1 in which the light projecting unit 3 and the imaging unit 4 are arranged, the light amount adjusting unit 5 and the A / A
When the D converter 6, the synchronizing signal generator 7, the image data storage 8, the overall controller 9, the external communication interface 11, and the gray-scale projection value processor 16 are incorporated, the system configuration is as shown in FIG. . In this case, the entire circuit section is formed into a gate array and replaced with a dedicated LSI, and the substrate on which it is mounted is reduced in size and integrated with the sensor section 1.

As described above, according to the present embodiment, the image data from the imaging unit 4 of the sensor unit 1 is A / D converted and stored as image data in real time, and at the same time, a newly provided gray scale projection value is obtained. The horizontal direction adder 12 and the vertical direction adder 14 of the processing unit 16 execute horizontal and vertical gray scale projection value processing, and the results are stored in the horizontal direction projection value storage unit 13 and the vertical direction projection value storage unit, respectively. Is what you do.

In the same case of the sensor unit 1, the light amount adjusting unit 5, the A / D converter 6, the synchronizing signal generating unit 7, the image data storing unit 8, the overall control unit 9, the external communication interface unit 11, Image processing unit 2 such as projection value processing unit 16
And shortens the signal line of the image signal transmitted from the imaging unit 4 as much as possible.

The welding line is detected by calculating the inflection point of the horizontal gradation projection value and the inflection point of the vertical gradation projection value obtained from the processing result of the gradation projection value processing section 16. And the image data in the image data storage unit
A second method of calculating a bending point on the line after calculating the value and thinning the line to detect a welding line, and selectively welding the whole control unit in accordance with the magnitude and distribution shape of the grayscale projection value The light amount of the light projecting unit is adjusted according to the line detection method and the magnitude of the gradation projection value calculated by the gradation projection value processing unit 16, and the detection posture of the welding robot to which the welding line detection device is attached is welded. Welding line that changes to the front, back, left and right, determines the amount of light in the light projecting unit and the robot's detection posture that can obtain a grayscale projection value that has a detectable bending point, and detects the welding line based on that By implementing the detection method, if the shape of the welding line to be detected or the surrounding environment changes,
The detection is performed by switching to an optimal method.

[0035]

As described above, according to the present invention, the light amount adjusting section, the A / D converter, the synchronizing signal generating section, the image data storing section, the overall control section, the external communication interface section, the gray level projection value processing section, A horizontal direction adder and a horizontal direction projection value storage unit for calculating horizontal and vertical direction gray level projection values, and a gray level projection value having a vertical direction adder and a vertical direction projection value storage unit By providing the processing unit, it is possible to realize an excellent effect that the welding line detection time can be significantly reduced as compared with the related art.

In the same case of the sensor section, a light amount adjusting section, an A / D converter, a synchronizing signal generating section, an image data storing section, an overall control section, an external communication interface section, and a gradation projection value processing section are incorporated. With this configuration, the impedance of the signal line can be reduced, and the resistance to external noise can be greatly improved.

Further, the welding line detection time can be further reduced by switching the welding line detection method in the overall control unit according to the magnitude and distribution shape of the gradation projection value calculated by the gradation projection value processing unit.

Further, the light amount of the light projecting section is adjusted according to the magnitude of the gray level projection value calculated by the gray level projection value processing section, and the detection posture of the welding robot to which the welding line detecting device is attached is simultaneously changed. By doing so, stable welding line detection can be realized even if the shape of the welding line or the surrounding environment changes.

[Brief description of the drawings]

FIG. 1 is a block diagram of a welding line detecting apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing the internal configuration of a sensor unit.

FIG. 3 is an explanatory diagram of gray-scale projection value processing data;

FIG. 4 is an explanatory diagram of a threshold value of gradation projection value processing data;

FIG. 5 is a flowchart showing switching between two detection methods.

FIG. 6 is a conceptual diagram in a case where a welding line is detected by changing a light amount and a posture.

FIG. 7 is a configuration diagram of a robot system when a sensor unit and an image processing unit of the welding line detection device are separated.

FIG. 8 is a configuration diagram of a robot system when a sensor unit and an image processing unit of the welding line detection device are integrated.

FIG. 9 is a block diagram of a conventional welding line detection device.

FIG. 10 is an explanatory diagram of detection of a bending point by binarization and thinning;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sensor part 2 Image processing part 3 Light projection part 4 Image pick-up part 5 Light quantity adjustment part 6 A / D converter 7 Synchronization signal generation part 8 Image data storage part 9 Overall control part 10 Robot controller 11 External communication interface part 12 Horizontal direction Adder 13 Horizontal direction projection value storage unit 14 Vertical direction adder 15 Vertical direction projection value storage unit 16 Shade projection value processing unit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B23K 9/127

Claims (4)

(57) [Claims] 1. A light projecting unit for irradiating a welding line portion with slit light having a predetermined line width, and an imaging for imaging the slit light from an angle forming a constant angle with respect to the irradiation light from the light projecting unit. Unit, a light amount adjusting unit that adjusts the light amount of the light projecting unit, and an A / A that converts an image signal from the imaging unit into a digital amount.
A D converter, a synchronizing signal generator for generating a synchronizing signal for controlling image data based on a synchronizing signal separated from the image signal from the imaging unit, and synchronizing the digital image signal from the A / D converter with the synchronizing signal. An image data storage unit for storing image data based on a synchronization signal from a signal generation unit;
A horizontal adder, a horizontal projection value storage unit, and a vertical adder for calculating horizontal and vertical gradation projection values based on a digital image signal from a converter and a synchronization signal from the synchronization signal generation unit And a gray-scale projection value processing unit having a vertical projection value storage unit, and integrally control the light amount adjustment unit, the synchronization signal generation unit, the image data storage unit, and the like, and determine the magnitude of the gray-scale projection value based on the image data. Depending on the shape of the gradation projection value, whether the inflection point of the horizontal gradation projection value and the inflection point of the vertical gradation projection value obtained from the processing result in the gradation projection value processing unit are detected as the welding line position, or image data binarized by the inflection point of the line on which thinning the image data in the storage unit and the overall control unit for selecting whether to detect the weld line position, the weld line detected data calculated by the overall control unit The welding line detection device and an external communication interface for transmitting to a robot controller. 2. A light amount adjusting section, an A / D converter, a synchronizing signal generating section, an image data storing section, an overall controlling section, and an external device, in the same case of a sensor section in which a light projecting section and an image pickup section are arranged. 2. The welding line detecting device according to claim 1, further comprising a communication interface unit and a shading projection value processing unit. 3. A welding line detecting device according to claim 1,
A first method of detecting a welding line by calculating an inflection point of a horizontal grayscale projection value and an inflection point of a vertical grayscale projection value obtained from a processing result in the grayscale projection value processing unit;
A second method of binarizing image data in the image data storage unit, thinning the image data, calculating a bending point on the line, and detecting a welding line, according to the size of the grayscale projection value and the shape of the grayscale projection value And a welding line detection method for selectively switching between the first method and the second method by an overall control unit. 4. A welding line detecting device according to claim 1,
In accordance with the magnitude of the gray level projection value calculated by the gray level projection value processing unit, the light amount of the light emitting unit is adjusted, and the detection posture of the welding robot equipped with the welding line detection device is adjusted to the front and rear with respect to the welding line. A welding line detection method that determines the amount of light in the light projecting unit and the detection posture of the welding robot that can be changed to the left and right to obtain a shaded projection value that has a detectable bending point, and detects the welding line based on that. .