JPH0464111B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for positioning an object using an image processing device, and in particular, a method for positioning a weld bead for inspecting the weld bead of an electric resistance welded pipe. It is suitable for a device that detects and positions.

[Conventional technology]

To inspect the welded part of an ERW pipe, place the ERW pipe on a pair of turning rollers, and operate the turning rollers so that the welded part of the ERW pipe faces the detector that inspects the weld part. . (Hitachi Review No. 67
(Figure 4 on page 55 of Vol. 9) Furthermore, a device using an image processing device as a means for positioning an electric resistance welded tube is described on pages 75 to 80 of the above-mentioned document.

2. Description of the Related Art In image processing, it is known to set a frame called a window in order to recognize a target object among image data obtained by imaging, and to process only the area within the frame to make a determination. (Japanese Patent Publication No. 59-35064) [Problems to be Solved by the Invention] In inspecting a weld bead, it is necessary to accurately match the weld bead to a detector.

The size of the weld bead decreases in proportion to the wall thickness, and accurate positioning becomes difficult for small weld beads.

An object of the present invention is to enable accurate positioning relative to an object.

[Means for solving problems]

In the present invention, the size of the object occupied in the partial first window for recognizing the object is the first.
outputs a signal instructing deceleration of the movement of the object when the value of When the sum of the sizes of the objects is greater than or equal to a second predetermined value, and the difference in the sizes of the objects occupying each of the second window and the third window is less than a third predetermined value. outputs a signal to stop the movement of the object, and then, after a predetermined period of time, the difference in the size of the object occupying each of the second window and the third window is determined as a fourth predetermined value. It is characterized by outputting a signal indicating that the object is stopped at a predetermined position when the value is less than the value.

[Effect]

Since the deceleration command is given in the first window, accurate positioning is possible even when the object is moving at high speed. In addition, by using the second and third windows, it is determined whether or not the object is a true object based on the sum of the areas of the object in each window, and the center position of the object is determined based on the difference in the area of the object in each window. Since it determines whether the object is present at the center of the object and outputs a stop signal when both conditions are established, it is possible to stop the true object at the center position. and,
After a predetermined period of time, it is determined whether the vehicle has stopped at the center position using the second and third windows.

〔Example〕

Hereinafter, a case where the present invention is used for positioning for inspection of an electric resistance welded pipe will be explained with reference to FIGS. 1 to 4.

In FIG. 1, the electric resistance welded tube 20 is placed on a pair of turning rollers 25. As shown in FIG. The electric resistance welded tube 20 is rotated by a turning roller and positioned by stopping the rotation. A camera 1 for an image processing device and a detector 26 for an inspection device for inspecting the condition of the weld bead 20a of the electric resistance welded tube 20 are installed on the upper part. The center of camera 1 and the center of detector 26 are on the same line.

The image processing device will be explained. The video signal output from the camera 1 is converted into a digital signal of "1" or "0" by the image input section 2.The video signal of the image input section 2 is sent to the image memory 5 via the switching circuit 3. is input. When the input for one screen is completed, the input from the camera 1 to the image memory 5 is cut off by the switching circuit 3, and the image memory 5 is switched to allow access from the arithmetic processor 6.

The timing circuit 4 generates various timings necessary for the apparatus, such as timing for storing image data in the image memory 5 in accordance with the scanning timing of the camera 1.

A memory (RAM) 8 stores various data necessary for data processing by the arithmetic processor 6.

Based on the image data processing program stored in the memory (ROM) 7, the arithmetic processor 6 takes in the image data stored in the image memory 5, calculates the feature amount (area) of the electric resistance welded tube 10,
As will be described later, various commands and the like for determining the position of the electric resistance welded tube 20 are outputted to the input/output circuit 9 and the like. In addition, the arithmetic processor 6 performs preprocessing for recognition (for example, processing such as noise removal and edge enhancement).
This is also done as a step in the recognition process.

The input/output circuit 9 outputs a deceleration signal and a stop signal to the turning roller 25. After stopping, the stopping accuracy is measured, and an OK or NG signal indicating whether it is within the allowable range is output to the next process device, that is, the inspection device.

Next, the operation of the configuration shown in FIG. 1 will be explained with reference to FIGS. 2 to 4.

Figures a and b in Figure 3 and Figure 4 show the weld bead 20.
This is an image when a is captured. In FIGS. 3 and 4, the left-right direction is the direction of rotation of the electric resistance welded tube 20, that is, the direction of movement of the weld bead 20a due to rotation.

When the electric resistance welded tube 20 is placed on the turning roller 25, the electric resistance welded tube 20 is placed on the turning roller 25.
rotate at a predetermined speed. Also, the positioning operation shown in FIG. 2 is started. The field of view of the camera 1 is illuminated by a lighting lamp 12.

Camera 1 captures an image within the field of view of camera 1,
An image signal corresponding to the brightness of each pixel is output. This process is the process of step F1 in FIG. 2, and the image processing is shown in FIG. 3a. This image signal (analog signal) is converted into a digital signal (“0” or “1”) by the image input section 2 and stored in the image memory 5. This process is the step in Figure 2.
This is the processing of F2 and F3, and the image is shown in Figure 3b.
It is. The weld bead 20a is white and the other parts are black.

WS1 and WS2 in FIG. 3c are windows for deceleration, and W1 and W2 are windows for stopping (positioning).

As shown in Fig. 4a, when the weld bead 20a moves from the left side and the weld bead area (white) SS1 occupied within the window WS1 exceeds the preset threshold value K1, the input/output circuit A deceleration signal is output to 9 to cause the turning roller 25 to operate at deceleration. This process is performed in steps F4 and F5 in Figure 2.
It is. The window WS2 is a window for deceleration when the ERW tube 20 is rotating in reverse,
SS2 is the area (white) of the weld bead 20a occupying in WS2.

Next, when the deceleration operation starts, always calculate the white area in each of the windows W1 and W2, and if the sum of the respective values S1 and S2 is greater than or equal to the preset value KA, | When S1−S2|≦KB (preset threshold), a stop signal is output from the input/output circuit 9 to stop the rotation.

Here, the reason for adding the condition S1+S2≧A is
This is because noise (white) may occur within W1 and W2, so there is a possibility that a stop signal may be output even though the weld bead is not within the window.

The above processing is steps F6, F7, and F8 in FIG.

Next, after a predetermined time t (after the ERW pipe 20 has stopped), calculate "|S1-S2|" again, and use that value and a preset tolerance KC (however, KC<
KB), and if it is within the tolerance KC, send an OK signal.
If the error is outside the tolerance, an NG signal is output from the input/output circuit 9. This process is performed at steps F10, F11, and
They are F12, F13, and F14.

If the NG signal is output, a repositioning operation step F17 is performed. That is, for example, the rotation is started again in the same direction as described above, and after a predetermined period of time, execution is performed from the step F1.

According to this, since the center of the weld bead 20a is located at the center between the windows W1 and W2, accurate positioning can be achieved by providing the detector 26 at the center.

Further, if the welding bead 20a is detected in the window WS1, the deceleration operation starts, so that accurate positioning can be determined and the required time can be shortened.

Further, according to this, when the diameter and speed of the electric resistance welded tube change, it can be easily handled by changing the window position and each threshold value.

In addition, in the above embodiment, the detector 20 is installed in the center of the window W1 and the window W2, but
It is preferable to determine the position by taking into account the delay from when the stop signal is output until the electric resistance welded tube 20 actually stops. This is also related to the size of the threshold KB.

A gap is provided between windows W1 and W2, but it is unnecessary.

In the above embodiment, the electric resistance welded tube is used, but other materials may be used, and the material may be moved in a straight line. Alternatively, the detector or camera may be movable.

〔Effect of the invention〕

In the present invention, since a deceleration command is given in the first window, accurate positioning is possible even when the object is moving at high speed. Also, the second
Using the third window, it is determined whether the object is a real object based on the sum of the areas of the objects in each window, and if it is a real object, this window is used to determine whether or not it is at the center position. Since the stop signal is output at the same time, the object can be stopped at the center position. After a predetermined period of time, it is determined whether the vehicle has stopped at the center position using the second and third windows. Therefore, even if the moving speed of the object is high, it is possible to accurately stop the object.

[Brief explanation of the drawing]

Fig. 1 is a system configuration diagram showing an embodiment of the present invention, Fig. 2 is an operation flowchart in Fig. 1, Fig. 3 a, b, c, and Fig. 4 a, b are diagrams showing image output. . 1... Camera, 20... ERW pipe, 20a... Welding bead, 25... Turning roller, 26...
Inspection instrument detector.

Claims (1)

[Claims] 1. When an object moving relative to a camera is imaged by the camera, and the object is located at a specific position according to the image data, the relative In a positioning method that outputs a signal to stop movement of an object, when the size of the object occupying a partial first window for recognizing the object is equal to or larger than a first predetermined value, the movement of the object is stopped. A signal instructing deceleration is output, and then the sum of the sizes of objects occupying each of a second window and a third window sequentially set on the downstream side of the first window is determined as a second predetermined window. output a signal to stop the movement of the object when the difference in size of the object occupying each of the second window and the third window is less than a third predetermined value; , Next, after a predetermined period of time, if the difference in size of the object in each of the second window and the third window is less than a fourth predetermined value, the object is in the predetermined position. A positioning method characterized by outputting a signal indicating that it is stopped.