JPS6230874B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an industrial television camera (hereinafter referred to as ITV).
The present invention relates to a method for detecting weld lines.

There are various methods for detecting weld lines in automatic welding machines, but one method for detecting weld lines using ITV is to project slit light from a light source through a slit, capture the image with ITV, and detect weld lines. A method to do this is generally known.

In other words, a slit light is projected onto the joint of two workpieces that are joined almost orthogonally to each other, and the image is
A slit light pattern is formed on the image taken by ITV in a roughly dogleg shape, and the rising point (the point where the dark area changes to the bright area) and the falling point (the point where the bright area changes to the dark area) at each line number. In this method, the outline of the slit light pattern is detected based on each position, and the welding line is detected based on the line number bent in a substantially doglegged shape on the outline.

However, since this method detects the outline of the slit light pattern based on the brightness and darkness of the image and detects the welding line, a clear image cannot be obtained even if there is a disturbance such as a poor surface condition of the workpiece. The problem is that the outline of the slit light pattern is distorted and the correct welding line cannot be detected.

The present invention has been made in view of the above circumstances, and its purpose is to detect a weld line that can detect the correct weld line even if a clear image cannot be obtained due to various disturbances and the outline of the slit light pattern is distorted. The purpose is to provide a method.

Embodiments of the present invention will be described below with reference to the drawings.

When two works 1 and 2 are joined so that they are perpendicular to each other, and a slit light is projected from the light source 3 onto the joint, captured by the ITV 4 and the video signal of the ITV 4 is processed, a slit light pattern is obtained as shown in Figure 2. An image is obtained in which portions A' and B' corresponding to A and B are bright and the rest is dark.

Here, if the surface condition of each workpiece 1 and 2 is excellent and no disturbance occurs, a clear image as shown in Fig. 2 will be obtained and the outline of the slit light pattern will not collapse, but the surface of workpieces 1 and 2 If the conditions are bad, disturbances will occur, resulting in an image as shown in FIG. 3, and the outline of the slit light pattern will collapse as shown in FIG. 4, resulting in a problem that a correct weld line cannot be detected.

In other words, since a dark part C occurs within a bright part A', the level number TFi has a rising point a (the point where the dark part changes to a bright part) and a falling point b.
(the point where the bright part changes to the dark part) occurs twice, and the correct outline of the slit light pattern cannot be obtained, making it impossible to detect the correct welded part.

Therefore, in the present invention, it is possible to check whether the distance from the rising point to the falling point is within a predetermined width of the slit light, and to capture only the good ones as data so that the weld line can be detected correctly as the correct contour. I made it.

The details will be explained below with reference to FIG. 5 and subsequent figures.

The video signal R obtained by the ITV 4 is input to a comparator 5 and a synchronization signal separation circuit 6, and the comparator 5 converts it into a binary signal R' using a threshold value VF, and the synchronization signal separation circuit 6 converts it into a binary signal R', and the synchronization signal separation circuit 6 converts it into a vertical synchronization signal r. ₁ and horizontal synchronization signal _r2 .

The separated horizontal synchronization signal _r2 is input to the first and second counters 7 and 8 as a reset signal for the first counter (horizontal synchronization signal counter) 7 and a count-up signal for the second counter (vertical synchronization signal counter) 8, respectively. , the vertical synchronizing signal _r1 is input as a reset signal to the second counter 8, and a count-up signal from the oscillator 9 is input to the first counter 7.

As a result, the first counter 7 counts the clock from the oscillator 9 and is reset by the horizontal synchronizing signal _r2 to detect the horizontal position, and the second counter 8 counts the horizontal synchronizing signal _r2 and detects the vertical position. The line number is detected by resetting with a synchronization signal.

On the other hand, the binarized signal R' is sent to the differentiating circuit 10 and differentiated into first and second rising pulses P ₁ , P ₂
and the first and second falling pulses P ₁ ′ and P ₂ ′. The first and second rising pulses P ₁ and P ₂ are sent to one input side of the first and second AND circuits 11 ₁ and 11 ₂ , respectively, and are passed through the one-shot delay circuit 12 to the other input side of the first AND circuit 11 ₁ . and is sent to the other input side of the second AND circuit ₁₁₂ via the inverter 13. In addition, the first and second falling pulses
Similarly, P ₁ ′ and P ₂ ′ are the third and fourth AND circuits 11 ₃ ,
11 to one input side of ₄ , and are sent to one input side of the third AND circuit 11 to 3 through the one-shot delay circuit ₁₄ .
The _{timing shown} in FIG _. TR ₁ , TR ₂ ,
TF ₁ and TF ₂ signals are output. And the first
The outputs TR ₁ , TR 2 , TF ₁ , TF ₂ of the second, third and fourth AND circuits 11 ₁ to 11 ₄ are _the outputs of the first to fourth latches 1
6 ₁ to 16 ₄ , respectively, and the first to fourth
The latches 16 ₁ to 16 ₄ are latched by the output signal (horizontal position) of the first counter 7 to determine the first and second rising points a ₁ , a ₂ at a predetermined line number.
horizontal positions R ₁ , R ₂ and the first and second falling points b ₁ ,
Outputs the horizontal positions F ₁ and F ₂ of b ₂ .

The horizontal position R ₁ of this first rising point a ₁ is the first and second
The second rising point is input to the subtracters 17 ₁ and 17 ₂ .
The horizontal position R ₂ of a ₂ is input to the third subtractor 17 ₃ , and the horizontal position F ₁ of the first falling point b ₁ is input to the first subtractor 17 ₁ of the second falling point b _2. The horizontal position F ₂ is input to the second and third subtracters 17 ₂ , 17 ₃ , and in the first subtracter 17 ₁ (R ₁ to F ₂ ), the second subtracter 17
₂ is (R ₁ − F ₂ ), and the third subtractor ₁₇ is (R ₂ − F 2 ).
F ₂ ), and calculate the calculation result (i.e., the distance from the first rising point a ₁ to the first falling point b ₁
L ₁ , distance L ₂ from _the first rising point a ₁ to the second falling point b ₂ , distance L ₃ from the second rising point a ₂ to the second falling point b 2 Third comparator 18 ₁ , 18
₂ , ₁₈₃ and is compared with a predetermined slit light width B set by the setting device 19, and if it is larger than B, a signal is output.

Then, the output of the first comparator ₁₈₁ is the first and second
First switch 2 of data select 19 ₁ , 19 ₂
0 ₁ directly as an ON signal T ₁ and passes through the inverter 21 to the first AND circuit 22 ₁ and the second
is input to the AND circuit ₂₂₂ , and the second comparator _181
The output _of
The output of the third comparator ₁₈₃ is input to the second AND circuit 222, and the output of each first comparator ₁₈₃ is inputted to the second AND circuit 222.
When ₈₁ outputs a signal {(R ₁ −F ₁ )≧B}, the first and second AND circuits 22 ₁ and 22 ₂ do not output,
The first comparator 18 ₁ does not output a signal {(R ₁ −F ₁ )
<B}, the second and third comparators 18 ₂ and 18 ₃ output signals {(R ₁ −F ₂ )≧B, (R ₂ −F ₂ )≧B} and the first AND circuit 22 ₁ The signal is inputted as the ON signal _T2 of the first and second switches ₂₀₁ and ₂₀₂ of the first and second data selectors ₁₉₁ and ₁₉₂ , and only the third comparator ₁₈₃ receives the signal. Output {(R ₂ −F ₂ )≧B} and the second AND circuit 22
₂ outputs a signal, and the signal is sent to the second switch 20 2 , ₂ of the first and second data selector 19 ₁ , ₁₉ 2
It is input as the ON signal _T3 of ₀₂ .

The first data selector ₁₉₁ is
Either one of R ₁ and R ₂ is input to the computing device 24 as rise data R ₁ and the second data selector 19 ₂
Input either F ₁ or F ₂ as full data F ₁ to the computer 24 and calculate the rising and falling points of the actual image to create a corrected slit light pattern as shown in FIG. You can draw an outline.

As described above, even if a clear image cannot be obtained due to various disturbances and the outline of the slit light pattern is distorted, the correct weld line can be detected.

Since the present invention is constructed as described above, even if a clear image cannot be obtained due to various disturbances and the outline of the slit light pattern is distorted, the correct weld line can be detected.

[Brief explanation of the drawing]

Figure 1 is a schematic perspective view of the weld line detection device, Figure 2 is a schematic perspective view of the weld line detection device;
3 are explanatory diagrams of the image, FIG. 4 is an explanatory diagram of the conventional slit light pattern outline when disturbance occurs, and FIG. 5 is a diagrammatic configuration explanatory diagram showing an embodiment of the present invention. , FIG. 6 is an operation timing chart, and FIG. 7 is an explanatory diagram of the outline of the slit light pattern according to the present invention. 1 and 2 are workpieces, 3 is a light source, 4 is an ITV, 5 is a comparator, 6 is a synchronizing signal separation circuit, 7 and 8 are first and second counters, 9 is an oscillator, 10 is a differential circuit, 11
is an AND circuit, 16 is a latch, 17 is a subtracter, 1
8 is a comparator, 19 is a setting device, 19 is a data select, 20 is a switch, 22 is an AND circuit, and R is a video signal.

Claims (1)

[Claims] 1 In a method in which a slit light is projected onto the joint of two works 1 and 2 that are joined at a predetermined angle to each other, and an image thereof is taken by an ITV 4 to detect a welding line, each line of the video signal R of the ITV 4 is Detect the rising and falling points in the number, calculate the distance from each rising point to the falling point, and compare each distance with a predetermined slit light width B to calculate the distance from the slit light width B. Select only the line numbers with a large value, determine the outline of the slit light pattern based on the rising and falling points of the slit light pattern at the selected line number, and determine the bending position of the outline of the slit light pattern. A weld line detection method, characterized in that the weld line is detected by.