JPH04132907A - Optical inspecting apparatus for piping - Google Patents

Abstract

PURPOSE:To quantitatively evaluate the damage inside a tube or the degree of delamination of scales by adjusting the detecting amount of light of a two-dimensional camera on the basis of the comparing result of a reference value and the luminance of an image of a reflecting body by the two-dimensional camera. CONSTITUTION:A value indicating a predetermined area centering a peak value is determined as a reference value from the luminance distribution obtained corresponding to an input image. The quantity of light generated from an illuminating device at that time (power voltage), the opening degree of an aperture or the like data are stored in a memory device 34. At the inspecting time, when a robot 10 runs to reach an inspecting position, a TV camera 13 is switched to the side viewing state and, the quantity of light and the opening degree of the aperture are adjusted to the values preset for inspection purpose. Then, a target 17 is photographed. At this time, if the peak value of the luminance distribution of the image is within the reference area stored beforehand, an inner peripheral surface of the pipe is photographed. If the peak value is outside the reference area, the aperture is changed at 16 so as to accommodate the luminance of the image of the target 17 within the reference area. The target 17 is photographed thereafter. In this manner, the processing conditions of the image of the inner peripheral surface of the pipe can be held approximately constant, so that the inspecting accuracy is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an optical inspection device for piping used for detecting defects such as scratches occurring in piping, peeling of scale attached to piping, and the like.

B. Prior Art This type of optical inspection apparatus for piping has been known, for example, as shown in FIG. 7. In the same figure, wheel 1
The robot 1, which can travel by rotating a, is connected to the piping 2.
It is movable inside. This robot 1 has
A TV camera 3 that photographs the front or side of the pipe, and a lighting device 4 that illuminates the front or side of the pipe are provided. Switching between front F and side photography by the TV camera 3 is performed by switching the photography optical axis of the TV camera 3 to the front or side using an optical system (not shown). Then, monitor T the image from TV camera 3.
Operator monitors with V5.

While remotely controlling the position of the robot 1, the direction of monitoring, etc. using the control device 6, the general situation of the inner peripheral surface of the pipe is grasped on the monitor TV 5.

Problems to be Solved by the C0 Invention In the conventional optical inspection equipment described above, the image on the monitor TV5 is simply visually monitored by the operator, and it is not possible to quantitatively determine the size of defects or scale peeling on the inner surface of the pipe. I couldn't figure it out.

Therefore, the present applicant and others have previously proposed an inspection device equipped with an image processing function. According to this device, image data obtained with a TV camera is binarized using a predetermined threshold value, and feature extraction calculations are performed to obtain an image as shown in Figure 3. The degree can be quantitatively evaluated.

However, in that case, in order to be able to accurately detect scale peeling, etc., it is necessary for the feature extraction image to faithfully reflect the actual state of the inner circumferential surface of the pipe, and the brightness of the image taken by the TV camera must be moderate. Must be. Therefore, we captured images with a TV camera at any position inside the pipe, and while watching the TV monitor, we set the temperature to the optimum brightness.
Adjusting the aperture of the V camera or the amount of light from the illumination light source. However, if the amount of light received by the TV camera changes due to dirt on the optical system while the vehicle is running or deterioration of the light source, the accuracy may deteriorate. Furthermore, since there is no objective standard for adjusting the brightness and the operator relies on his or her intuition, the reliability of the measurement results is low.

The purpose of the present invention is to provide a pipe that can obtain basic image data and always set the amount of light received by a two-dimensional camera at an appropriate value in order to quantitatively evaluate the degree of damage and scale peeling inside the pipe. An object of the present invention is to provide an optical inspection device for use in the industry.

00 Means for Solving the Problems The present invention mounts a reference reflector on a traveling body, and determines the appropriate brightness based on an image obtained by a two-dimensional camera when this reflector is illuminated with an arbitrary amount of light. and a reference value setting means for setting a reference value.

2 of the above reflector illuminated by this reference value and the illumination device.
Based on the comparison results with the brightness of the image taken by the dimensional camera.
The above-mentioned problem is solved by providing an adjusting means for adjusting the amount of light received by the dimensional camera to obtain appropriate brightness.

E1 action: For example, a portion of the scale where the peeling state is known is photographed in advance, and the amount of received light is adjusted so that the peeling rate obtained from the feature amount extraction image matches the actual peeling rate. To adjust the amount of light received, you can adjust the amount of light emitted by changing the power supply voltage of the lighting device, or you can adjust the aperture inserted between the light source and the subject or between the subject and the camera. .

In this state, the reflector is illuminated, and the luminance value of the image of the reflector obtained at that time, or the allowable range centered thereon, is set as a reference value.

In the actual inspection, prior to photographing the inner peripheral surface of the pipe at each stop position, or at any time, the reflector is photographed and its brightness is compared with the above reference value. If it is within the standard value, the inner peripheral surface of the pipe will be photographed. If it does not meet the standard value, the adjustment function operates and resets the amount of received light to the original value.

F. Example An embodiment of the present invention will be described using FIGS. 1 to 6.

FIG. 1 is a schematic configuration diagram showing, for example, a robot 10 that inspects the inside of a cylindrical pipe 2 while traveling therein, a control device 20 thereof, and a detection result analysis device 30.

The robot 10 is provided so that it can travel within the pipe 2 by rotating its axle 11 with a travel motor 12, and can stop at a predetermined position. There is a T at the tip of the robot 1o.
A V-camera 13 and a lighting device 14 that illuminates the inside of the tube are installed. This illumination device 14 has a light source 14a, and is rotatable by a motor 15 about the central axis of the pipe 2 together with a mirror 14b. The mirror 14b takes the position shown in the figure when photographing the inner peripheral surface of the piping on the side of the robot with the TV camera 13, and directs the photographing optical axis of the TV camera 13 to the side. When photographing, the TV camera 13 is swung counterclockwise from the illustrated position, and the photographing optical axis of the TV camera 13 is directed in the direction of the tube axis, so that the TV camera 13 captures an image of the front of the robot. Therefore, with the imaging optical axis facing the side of the tube, the light source 1
By rotating the mirror 4a and the mirror 14b, the photographing optical axis faces a plurality of viewing areas on the inner peripheral surface of the tube, and each viewing area can be photographed.

The robot 10 is a robot control device 2 installed outside the piping.
Controlled by 0.

This control device 20 includes a travel motor drive circuit 21 that remotely controls the travel motor 12 so as to move the robot 10 at predetermined pitches, and a travel motor drive circuit 21 that remotely controls the travel motor 12 so as to move the robot 10 at predetermined pitches, and a travel motor drive circuit 21 that remotely controls the travel motor 12 to move the robot 10 at predetermined intervals. The lighting device motor drive circuit 22 remotely controls the lighting device motor 15, and the aperture adjustment motor drive circuit 23 remotely controls the aperture adjustment motor 16 for adjusting the aperture of the TV camera 13.

The robot 10 also has a target 17 as a reflector placed at a certain distance from the TV camera 13.

The analysis device 30 receives the video signal sent from the TV camera 13, performs predetermined calculations, and outputs various information to the monitor TV 5 and printer 41.

The analysis device 3o includes an A/D converter 31 that converts an analog signal sent from the TV camera 13 into a digital signal, and stores image data that is digitized by the A/D converter 31 and input via an input interface. In addition to performing binarization and noise removal on the image memory 32 and the image data stored in this image memory 32,
A feature extraction device 33 that calculates the area of an extraction region such as a defective part or a part where scale has peeled off, a storage device 34 that stores the calculated area, etc., and calculation of data that quantitatively indicates the situation inside the pipe. a printer drive circuit 36 for outputting information such as the area, area ratio, and inspection position of an extraction area such as a defective part or a part where scale has peeled off to a printer 41; and a CPU 3 for controlling these.
It has 7.

As shown in FIG. 2, the feature extraction circuit 33 takes in the image data in the image memory 32 for each field of view of the TV camera 13 (step 5ll), binarizes it using a predetermined threshold (step 512), and further A feature value extraction calculation is performed on the binarized image to obtain an image as shown in Figure 3, and the area Ai of a mountain mass or an outlying area (hereinafter referred to as a mountain mass) with an area greater than a predetermined value and within one field of view are The center of gravity position (Xi, Yi) of the mountain mass indicated by the coordinate values of the X, Y coordinate system at is stored in the storage device 34 (step 513).

On the other hand, as shown in FIG. 4, the arithmetic device 35 takes in the feature amount data in the storage device 34 (step 521), and calculates the total area of the mountain mass within the field of view (step 52).
2) Further, calculate the ratio of the area of the mountain mass to the area of the entire viewing area as data quantitatively indicating the status of the piping in the viewing area.Step 523) Depending on whether the ratio exceeds a predetermined value or not, The status of the piping is determined (step 524).

In this embodiment, the brightness of the image is monitored during the inspection so that the image of the inner peripheral surface of the pipe is always properly processed under constant conditions and the situation can be accurately grasped. Then, the amount of light received by the TV camera 13 is adjusted as necessary.

Next, the operation will be explained based on an actual inspection procedure.

In FIG. 5, as a preprocessing step, several points are photographed at a predetermined position on the inner circumferential surface of the pipe where the area ratio of the scale exfoliation portion in the entire field of view is known (step 53).
1), by monitor TV5.

It is determined whether the image at that time is an appropriate one that faithfully represents the situation inside the pipe. If it is not appropriate, the aperture of the TV camera 13 is changed using the aperture adjustment motor 16 (step 533). Once the image is obtained, the TV camera 13 is aimed at the target 17 to take a picture (step 534), and the brightness distribution as shown in FIG. 6(B) obtained corresponding to the input image as shown in FIG. 6(A) is obtained. Therefore, a certain range δ (di~
d2) (for example, dl and δ) are determined as reference values (step 535), and are stored in the storage device 3 along with data such as the amount of light emitted by the lighting device (power supply voltage) and the aperture opening at that time.
4 (step 836).

During actual inspection, the robot 10 is run and stopped at each predetermined inspection area to take pictures. robot 1
While 0 is running, the TV camera 13 is in a direct viewing state, and the light intensity of the illumination device 14 is set to the maximum, and the focal position and aperture are set by remote control so that they are suitable for the direct viewing state.

When the test site is reached, the TV camera 13 is switched to the side view state, the light intensity and aperture are adjusted to the values previously set for the test, and the target 17 is first photographed (step 537).
). At this time, if the peak value of the image brightness distribution is within the previously stored reference range (step 838), the inner peripheral surface of the pipe is photographed (step 539); if it is not within the reference range, the mirror 14b is TV camera 13 due to dirt etc.
The amount of light received by target 1 may change.
The aperture is changed by the aperture adjustment motor 16 so that the brightness of the image No. 7 falls within the reference range (step 540), the target is photographed again in step S41, and step S
Execute 38.

The above operations are repeated for each inspected site until the end of the inspection (step 542). As a result, the processing conditions for the image of the inner circumferential surface of the pipe can be kept substantially constant, improving inspection accuracy.

In the example described above, both the adjustment of the amount of received light when determining the reference range in the preprocessing stage and the adjustment of the amount of received light to match the brightness to the reference range in the inspection stage were performed by changing the aperture (step S33.40). ), when adjusting one or both of them, the power supply voltage of the lighting device 14 may be changed to change the amount of light emitted, thereby adjusting the brightness.

In addition, if the power supply voltage is expected to fluctuate for some reason, it is desirable to check the amount of light received for each inspection site as in the example above, but if there is no voltage fluctuation or if the mirror is dirty, etc. In less extreme cases, the amount of received light may be checked every few inspections or at any time.

Furthermore, if there is almost no change during the inspection, at the beginning, photograph the target under predefined conditions based on the previous inspection of the piping, and if necessary, after adjusting the amount of light received, The inspection may be continued to the end in this state.

G0 Effect of the Invention According to the present invention, in an optical inspection device for piping that is equipped with an image processing function and is capable of quantitatively evaluating the condition of piping, the brightness of the captured image can be set correctly. When using image processing to determine the state of peeling inside, the processing conditions can always be kept in an appropriate state.
Inspection accuracy improves.

[Brief explanation of the drawing]

1 to 6 show an embodiment of the present invention, FIG. 1 is a block diagram of an optical inspection device for piping, FIG. 2 is a flowchart showing feature extraction processing operation, and FIG. 3 is a feature amount A diagram showing an example of an extracted image, FIG. 4 is a flowchart showing the piping situation evaluation processing operation, FIG. 5 is a flowchart showing the received light amount adjustment processing operation, and FIG. 6 shows the target image and its brightness distribution. It is a diagram. FIG. 7 is a diagram showing a conventional example. 2: Piping 10: Robot 11: Wheels 12: Traveling motor 13: T
V-camera 14: Illumination device 15: Illumination device motor 16 Two-aperture adjustment motor 17: Target 20: Robot control device 30: Analysis device 41: Printer agent Fuyuki Nagai, patent attorney Figure 2, Figure 4, Figure 5 Figure 6 Input image horizontal pixels

Claims (1)

[Scope of Claims] A traveling body that travels within a pipe; a lighting device mounted on the traveling body that illuminates the inner peripheral surface of the pipe; and a viewing area that is mounted on the traveling body and illuminated by the lighting device. In an optical inspection device for piping, which is equipped with a two-dimensional camera that takes pictures and a feature extraction means that performs feature extraction processing on image data of a visual field taken by the two-dimensional camera, a reference reflector; a reference value setting means for setting a reference value of appropriate brightness based on an image obtained by a two-dimensional camera when the reflector is illuminated with an arbitrary amount of light; An optical inspection for piping characterized by comprising: an adjusting means for adjusting the amount of light received by the two-dimensional camera to obtain the appropriate brightness based on the result of comparison with the brightness of the image of the illuminated reflector taken by the two-dimensional camera. Device.