JPH07318320A - Method and device for length measurement of long body - Google Patents

Abstract

PURPOSE:To take in an image with proper timing regardless of the function of a camera. CONSTITUTION:A second sensor device 70 is provided near a camera 30. The camera 30 is operated by using two signals, the detection signal of an end part 10t of an object 10 generated by the second sensor device 70 and the detection signal of the other end part 10b thereof generated by multiple sensor devices 50 behind the former.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for measuring a long object such as a metal material used as a material for a tube, and particularly, for measuring such an object while transferring it from one process to another process. The present invention relates to a technique for measuring a long object that can be effectively used for lengthening.

[0002]

BACKGROUND OF THE INVENTION This type of length measurement technique can be roughly divided into two types. One is that each image of both ends of the object to be measured is captured by a camera (image capturing device including an image sensor), and the distance data between each camera at each end and the image captured by each camera are captured. This is a method of knowing the length of an object based on the processed data (see, for example, Japanese Patent Laid-Open No. 4-184205). The other is that one end of the object to be measured is detected by a non-contact type end detecting means such as a photoelectric sensor device, and only the other end is detected by the camera. A method of knowing the length of an object based on the data of the distance between the camera and the edge detection means and the data obtained by image processing of the image captured by the camera (for example, Japanese Patent Laid-Open No. 57-2
2507).

In terms of measurement accuracy, the former technique of taking a camera on both ends is generally superior. However, the cameras must be arranged on both ends, which is a cost disadvantage. In that respect, the latter technique is advantageous in terms of cost, since it is sufficient to dispose the camera only on one end. Therefore, the inventors focused their attention on the latter technique and conducted repeated research. As a result, in the latter technique, it was found that the timing of capturing an image by the camera had a great influence on the measurement accuracy. In particular, in order to improve the efficiency of measurement, the length of the object is measured while moving it. However, even if the same timing shift occurs, the larger the transfer speed, the larger the error in the length measurement.

[0004]

With regard to such a timing of taking a camera, the idea of setting the scanning speed of the camera according to the moving speed of a long object to be measured is disclosed in the above-mentioned Japanese Patent Laid-Open No. 57-22507. (Page 12, upper right column, lines 12 to 14 of the same publication). However, it is difficult to obtain sufficient accuracy with the timing method based on such an idea. Because a long object is
Since it is usually driven by rollers, slips and the like will inevitably occur there, and it cannot be transported at a constant moving speed. Another problem is that the functions of the camera are limited. The shutter speed of the camera used for length measurement is as high as 1/1000 sec, but the synchronizing signal of the image is 1/60 sec, for example, and its period is relatively long. Therefore, the moving speed of the object must be suppressed so as to match the function of the camera side. However, this cannot increase the efficiency of length measurement. It should be noted that it may be considered to enhance the function of the camera itself, but this involves considerable difficulty in terms of cost and technology.

[0005]

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide a technique capable of accurately taking an image capturing timing regardless of the function of a camera. Also,
Another object of the present invention is to provide a technique capable of measuring an object moving at high speed with high accuracy.

[0006]

As shown with reference to FIG. 1 showing an embodiment, the present invention provides a reference point serving as a reference along a transfer line 20 for a long object 10 to be measured. There is the camera 30 in the portion of the sensor unit 50, and the sensor device 50 for detecting the end portion of the object 10 in the portion distant from the reference point by a predetermined distance
There are a plurality of sensor devices 501 to 510, and the respective sensor devices 501 to 510 are arranged at a fixed distance from each other along the transfer line 20, and one of the ends 10b of the object 10 is detected by these sensor devices 501 to 510. , A length measuring technique for measuring the length of the object 10 by capturing an image of the other end 10t of the object 10 with the camera 30.

According to the present invention, the second sensor device 70 is arranged on the transfer line 20 immediately before the camera 30, and the second sensor device 70 is provided.
The sensor device 70 of one of the ends 10 of the object 10.
Using two signals, one end detection signal for detecting t and one end detection signal for detecting the other end 10b of the object 10 by one of the plurality of sensor devices 501 to 510 after that. An image is captured by the camera 30. Each sensor device 5 in the plurality of sensor devices 50
01-510, and the second sensor device 70,
This is for detecting the end portion of 0, and a photoelectric sensor device is generally used. In the case of a photoelectric sensor device, it includes a light emitting element and a light receiving element, and these elements are included in the transfer line
It is arranged so as to sandwich. However, it is also possible to use another non-contact type sensor device such as an electromagnetic type, or a contact type sensor device such as a limit switch or a load cell. However, in order to detect the object 10 being transferred,
A non-contact type, especially a photoelectric sensor device is suitable. The number of the second sensor device 70 may be one, but the plural sensor devices 50 are set appropriately, for example, about 5 to 15 according to the range of the length of the object 10 to be measured. And
The distance between adjacent ones of the sensor devices 501 to 510 is set to an appropriate value within the field of view of the camera 30, for example, 2 m. Usually, each interval is all the same, but it does not have to be. In short, it is only necessary to be able to grasp the distances from the reference point to the sensor devices 501 to 510. However, it is preferable to make each interval the same in order to facilitate the calculation.

As the camera 30 for capturing images, various image capturing devices such as CCD line sensors and video cameras can be used. The camera will be selected in consideration of the required measurement accuracy. In a camera with a field of view of X and the number of pixels is P, one pixel corresponds to the length of X / P (for example, when X is about 2,200 mm and Y is 512, one pixel is about 4 mm long). Equivalent to).

Further, in order to ensure that the image is captured by the camera, the second sensor device 70 is connected to the camera 30.
Must be placed within the field of view. However, when the lengths of the objects 10 to be measured are relatively uniform and there is no large difference between the objects 10, the second sensor device 70 may be arranged outside the field of view of the camera 30. For example, when the field of view of the camera is about 2,200 mm, it is usually arranged inside the field of view, but the distance should be measured in comparison with the interval between the sensor devices 501 to 510 on the sensor device 50 side. When the length range of the object 10 is small, for example, about 100 to 300 mm,
There is no problem even if it goes out of the field of view.

[0010]

When the object 10 to be measured is transferred along the transfer line 20, the camera 30 is moved according to the transfer.
It is assumed that the second sensor device 70 near to detects the one end 10t of the object 10. At that time, the other end 10b of the object 10 is connected to the sensor device 50n on the sensor device 50 side.
And 50 (n−1) adjacent thereto (in the example of FIG. 1, between the sensor devices 507 and 508). Then, the object 10 reaches the sensor device 50n (the sensor device 508 in the example of FIG. 1). At that time, the sensor device 50 n (sensor device 508) is connected to the end portion 10 of the object 10.
b is detected. In the present invention, the camera 30 is operated by using the detection signal of the end portion 10b from the sensor device 50n as a trigger. Therefore, the camera 30 has a small electrical delay time (for example, 2 μsec) to allow the object 10 to move.
The image of the end portion 10t of 10 is captured. Such a delay is small when converted into an error in length measurement. For example, the transfer speed of the object 10 is normally 1.5 m /
When set to sec, the error does not reach 1 mm. One pixel of the image captured by the camera 30 is, for example, several mm
Considering that it corresponds to the length of, the size of the error is negligible.

[0011]

[First Embodiment] FIG. 1 is a diagram showing a configuration of a first embodiment of a length measuring technique according to the present invention, and FIG. 2 is a diagram showing a timing chart thereof. The object 10 to be measured is
This is the material of the tube with a length of around 20m. This object 10
The bottom-side end 10b is cut and made flat, while the top-side end 10t is sharp like a spear. The object 10 is a transfer line 2 such as a roller table.
0, transferred in the direction of arrow R. The transfer line 20 is
It is a known one having a driving roller and a guide roller. A CCD camera 30 is located in the middle of the transfer line 20 at a certain reference point. The camera 30 has one screen 5
It has a 12-pixel image capture function. Camera 30
Maintains a subject distance of 1,600 mm away from the transfer line 20, and its field of view is about 2,200 mm in the direction of the transfer line 20.

A photoelectric sensor device 501 of a non-contact type is provided at a downstream portion of the camera 30 which is separated by a predetermined distance of 6,500 mm from a certain reference point, and 2,0 from the photoelectric sensor device 501.
Photoelectric sensor device 502, photoelectric sensor device 503, ...
There is 0. These photoelectric sensor devices 501 to 510 are
A sensor device 50 that detects the bottom end 10 b of the object 10 is configured. Each photoelectric sensor device 501-510
It is a known device including a light emitting element and a light receiving element. The light emitting element and the light receiving element sandwich the transfer line 20,
For example, they are installed at a distance of 150 to 2,000 mm.

Also note that near the camera 30 is a second sensor device, a photoelectric sensor device 70. This photoelectric sensor device 70 is also the photoelectric sensor device 5 described above.
01 to 510, which includes a light emitting element and a light receiving element. The photoelectric sensor device 70 is located at a position of 1,000 mm upstream of the transfer line 20 from a reference point of the camera 30. The position is within the field of view of the camera 30, but at the full field of view.

On the other hand, a control device 80 is located away from the transfer line 20. The control device 80 uses the camera 30.
In addition to the above operation, the signals from the photoelectric sensor devices 50 and 70, the data obtained by the image processing of the image captured by the camera 30, and the photoelectric sensor devices 50 from the reference point.
Based on the distance data of 1 to 510, the length of the object 10 is calculated and output. The control device 80 is mainly composed of a personal computer, and has an input / output unit and
The calculation means 810 and the display means 820 are provided.

It is assumed that the object 10 is transferred along the transfer line 20 in the direction of arrow R. Depending on the transfer, the object 10
When the pointed top-side end 10t reaches the portion of the second photoelectric sensor device 70, the sensor device 70 detects the top-side end 10t, as shown in FIG. This produces signal 70s. At that time, the bottom end 10b of the object 10 is located between the photoelectric sensor devices 507 and 508. By the subsequent transfer, the bottom end 10b of the object 10 reaches the photoelectric sensor device 508 adjacent to the photoelectric sensor device 507. At that moment, the photoelectric sensor device 508 generates a signal 508s indicating that the bottom end 10b of the object 10 has been detected, as shown in FIG.

When the detection signal 508s from the photoelectric sensor device 50 is output after the detection signal 70s from the second photoelectric sensor device 40 is output, the control device 80 is slightly controlled as shown in FIG. 2 (c). The internal trigger signal 80s is generated with various delay times. The internal trigger signal 80s is
At the same time, it becomes a trigger for the camera 30,
Works. Camera trigger signal 3 shown in (e) of FIG.
The delay time until 0 s occurs and the shutter of the camera 30 opens is, for example, about 2 μsec. Further, the shutter time is, for example, 1 /
It is 1,000 seconds. Therefore, there is a delay of about several μsec from when the photoelectric sensor device 50 generates the detection signal 508s until the shutter of the camera 30 opens.
When converted to length, it is a value that can be almost ignored. By the way, in this type of length measurement, for example, ± 10-2
Considering that an accuracy of about 0 mm is required, the object 1
Even if the transfer speed of 0 is increased by one digit, there is no problem in terms of measurement accuracy. It should be noted that FIG. 2D shows the vertical-synchronization signal of the camera 30, and its cycle is, for example, 1/60 sec.

[0017]

[Second Embodiment] FIG. 3 is a diagram showing the configuration of a second embodiment of the length measuring technique according to the present invention. Also in this second embodiment, the basic components are the same as those in the first embodiment. Therefore, the same reference numerals are given to the corresponding components, and the description thereof will be omitted. In the second embodiment, the transfer direction is opposite to that in the first embodiment, and the object 10 is transferred from the plurality of photoelectric sensor devices 50 side to the camera 30 side as shown by an arrow R '. To be done. Therefore, the second that should be placed upstream of the camera 30
The photoelectric sensor device 70 ′ of FIG.
It is installed near 0. However, also in this second embodiment, after the second photoelectric sensor device 70 ′ detects one end 10b of the object 10, the photoelectric sensor device 50 detects the other end 10t of the object 10. The signal is used to operate the camera 30.

There are a plurality of photoelectric sensor devices 501 to 5
It goes without saying that the intervals of installation of 10 do not necessarily have to be set to be exactly the same. For example, set the interval to 2,0
Even when all the same as 00mm, there are 1
It may be 995 mm, and the other portions may be 2,005 mm. If the information of those positions is correctly input to the control device 80, the control device 80 outputs the same length measurement result for the same object 10. Further, data such as the diameter of the object 80 may be input to the control device 80 in advance, and the calculation unit 810 may perform processing such as correction based on the diameter.

[0019]

According to the present invention, the second camera is provided near the camera 30.
The sensor device 70, 70 'of the
A signal for detecting one end 10t of 0 and the other end 1 of the object 10 generated by a plurality of sensor devices 50 thereafter.
The camera 3 using two signals, a signal for detecting 0b
Since 0 is activated, the camera 30 can be activated with a slight electrical delay. The delay is a value that can be ignored in length measurement, and the transfer speed of the object 10 to be measured can be further increased.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a timing chart according to the first embodiment.

FIG. 3 is a configuration diagram similar to FIG. 1 showing a second embodiment of the present invention.

[Explanation of symbols]

 10 Object to be measured 20 Transfer line 30 Cameras 50, 501-510 Sensor device 70 Second sensor device 80 Control device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigetoshi Hyodo 1st Nishino-cho, Higashimukaijima, Amagasaki City, Hyogo Prefecture Sumitomo Metal Industries Co., Ltd. Steel Pipe Works

Claims (8)

[Claims] 1. A length measuring method for measuring a long object during transfer, wherein a camera is provided at a reference point which is a reference along a transfer line along which the object to be measured is transferred. , There are a plurality of sensor devices for detecting the end portion of the object at a portion distant from the reference point by a predetermined distance, and each sensor device is arranged at a fixed distance from each other along the transfer line, By detecting one of the ends of the object by the sensor device of, while capturing an image of the other end of the object by the camera,
In the object length measuring method for measuring the length of the object, a second sensor device is arranged on the transfer line immediately in front of the camera, and the second sensor device has one end portion of the object. Image by the camera by using two signals, one end detection signal for detecting the other end and another end detection signal for one of the plurality of sensor devices detecting the other end of the object thereafter. A method for measuring the length of a long object, characterized in that 2. The length measuring method according to claim 1, wherein a camera is provided on the upstream side along the transfer direction, a plurality of sensor devices are provided on the downstream side, and a second sensor device is provided on the upstream side of the camera. 3. The length measuring method according to claim 1, wherein a plurality of sensor devices are provided on the upstream side along the transfer direction, a camera is provided on the downstream side, and a second sensor device is provided on the upstream side of the camera. 4. The length measuring method according to claim 1, wherein the second sensor device is within a visual field of the camera. 5. The length measuring method according to claim 1, wherein the plurality of sensor devices have substantially equal intervals between adjacent ones. 6. The length measuring method according to claim 1, wherein each of the plurality of sensor devices and the second sensor device is a non-contact type. 7. A camera arranged at a reference point serving as a reference along a transfer line along which a long object to be measured is transferred, and a plurality of sensors arranged at a part separated from the reference point by a predetermined distance. A plurality of sensor devices for detecting one end of the object, and a plurality of sensor devices arranged upstream of the camera in the transfer direction. A second sensor device that is on the side and detects the other end of the object, and operates the camera in response to a detection signal from the second sensor device and a detection signal from the plurality of sensor devices.
A length measuring device for a long object, comprising: a control device that controls so as to capture an image of an end portion side of the object detected by the second sensor device. 8. The control device, based on distance data from the reference point to the plurality of sensor devices, and data obtained by performing image processing on the image captured by the camera,
The length measuring device according to claim 7, further comprising a calculation unit that calculates a length of the object.