JP2531488B2 - In-pipe measurement method - Google Patents

In-pipe measurement method

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Publication number
JP2531488B2
JP2531488B2 JP5198493A JP19849393A JP2531488B2 JP 2531488 B2 JP2531488 B2 JP 2531488B2 JP 5198493 A JP5198493 A JP 5198493A JP 19849393 A JP19849393 A JP 19849393A JP 2531488 B2 JP2531488 B2 JP 2531488B2
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image
point
pipe
tube
position
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JPH0755426A (en
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宏一 木村
健悦 柴野
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株式会社機動技研
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Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe measuring method. More specifically, the inside of a water supply and sewer pipe is photographed with a TV camera or the like, and the photographed image is observed to check for damages, cracks, and foreign substances in the pipe. The present invention relates to a method for acquiring position information of measurement points in a pipe, distance information between measurement points, and the like from a photographed image in a technology for investigating the existence and the like.

[0002]

2. Description of the Related Art A small T pipe is installed in a narrow pipe where an operator cannot enter.
A technique for running a self-propelled vehicle or robot equipped with a V camera and displaying the condition inside the pipe on a TV monitor installed outside to perform a pipe inspection is already known. A graphic scale or graphic cursor is displayed on the TV monitor so as to be superposed on the photographed image, and the graphic image and the photographed image are compared with each other to try to accurately know the position and distance information of the measuring point in the pipe. Technology is also being developed.

However, the photographed image displayed on the TV monitor is the actual position or distance of the measuring point in the pipe enlarged or reduced at a constant rate. Therefore, in order to accurately know the actual position of the measurement point and the distance between the measurement points from the photographed image, it is necessary to know the scaling ratio of the photographed image. However, the scaling ratio of the captured image is T
It depends on the distance from the V camera to the measurement point. Therefore, conventionally, when the measurement point comes to a certain distance from the TV camera, the position of the measurement point is measured on the captured image at that time, or the two measurement points have the same distance to the TV camera. It was necessary to measure the distance between the measurement points in a line.

However, the TV on the self-propelled vehicle that runs in the piping
It is difficult to accurately know the distance between the camera and a measurement point existing at an arbitrary position in the tube, and it is also difficult to always arrange the arbitrary measurement point at a constant distance from the TV camera. As a method for solving such a problem, there is a technique disclosed in Japanese Patent Laid-Open No. 3-212610. In this method, a stereoscopic TV camera is used, and a length measurement image for stereoscopic vision is displayed so as to be superposed on a photographed image displayed on a stereoscopic TV monitor. By adjusting the length measurement images so that they are visible at the same distance, the accurate position and distance of the measurement point can be measured.

However, in this improved technique, the three-dimensional T
Since a V camera and a stereoscopic image processing device are required,
There is a problem that the device becomes complicated and the processing cost is high, and further improvement is desired. Therefore,
The subject of this invention is to use a stereoscopic TV camera without using
An object of the present invention is to provide an in-pipe measuring method capable of easily and accurately obtaining position and distance information of a measuring point inside the tubular body.

[0006]

According to the in-tube measuring method of the present invention for solving the above-mentioned problems, the inside of the measuring tube body is photographed in the tube axis direction by the image photographing means, and on the obtained photographed image,
Information on the measurement point position and the section of the tube including the measurement point is obtained, and the position information on the measurement point is acquired based on this image information and the previously derived correlation between the image position and the actual position.

In the present invention, on the premise that the inner diameter of the measuring pipe is known, the position information of the measuring point is obtained with the inner diameter of the measuring pipe as a reference. Therefore, the material and dimensions of the measuring tube can be freely set, but the inner diameter thereof must be measured in advance or applied to a tube having a known inner diameter. The image capturing means for capturing the inside of the tubular body may be a device such as a normal TV camera, a CCD camera, or a photographic camera capable of capturing an image inside the tubular body.
Arbitrary photographing means can be used. These cameras may capture normal visible light or may capture invisible light such as infrared rays or radiation. The image capturing means is provided with an optical system in which a single lens or a plurality of lenses are combined, and the image obtained by this optical system is fixed on a film or converted into electrical image information to obtain a captured image. obtain. The optical system may have a constant magnification ratio or focal length of an image, may have a focal length that can be changed in a plurality of steps, or may have a zoom mechanism that can continuously change the focal length. If the focal length of the optical system changes,
It suffices to correct the value of the focal length in the relational expression described later. The image capturing means may be provided with an illuminating device for illuminating the inside of the tubular body, a moving mechanism for changing the position and direction of the camera, a swinging mechanism, and the like.

If the electric image information obtained by the image capturing means is displayed on the image display means installed outside the measuring tube body, the operator can observe the inside of the tube body while performing the measuring work. It can be performed. As the image display means, a so-called TV monitor, a liquid crystal display panel, or the like including a cathode ray tube can be used. The image display means includes enlarging and printing the image pickup film and projecting the image without converting the image photographing means into electrical image information.

In the photographed image displayed on the image display means, the actual position and distance information of the measuring pipe body is enlarged or reduced. The position and distance information of the measuring tube is optically scaled on the stage taken by the image taking means, that is, on the imaging surface, and then the image information obtained on the imaging surface is electronically converted, Even at the stage of enlarging and printing the imaging film, the photographed image is enlarged or reduced. The actual position or distance of the measuring tube and the scaling ratio of the image on the imaging surface are determined by the optical characteristics of the optical system described above. Further, the scaling ratio of the image on the imaging surface and the image finally obtained on the display screen or the like is determined by the mechanical or electrical structure of the image capturing means or the image display means. Some image display means are provided with a function capable of changing the enlargement / reduction ratio of the screen, and the enlargement / reduction ratio of the image also changes when printing or enlarged projection from an imaging film. Therefore, in such a case, it is necessary to correct the image scaling ratio described later.

It is preferable that the image display means is provided with a so-called superimpose function, that is, a function of displaying a tube cross-section pointing image, a measurement point pointing image, a scale image, and the like, which will be described later, on the photographed image. These tube cross-section instruction images and the like are created and display-controlled by a computer or an image processing device connected to the image display means. The computer and the image processing device have a display position and size of the tube cross-section instruction image,
An input device for instructing the shape etc. is provided. It is also possible to connect to the image display means an image analysis device that analyzes the photographed image and obtains necessary information. Furthermore, an external device such as a storage device that stores the captured image and the acquisition information, a printing device that prints the measurement result, an information transmission device that transmits the measurement information to an external device, and the like can be provided.

The image capturing means is preferably mounted on a self-propelled vehicle which can travel inside the tube. The structure of the self-propelled vehicle is
A structure similar to that used for normal tube inspection can be adopted. The self-propelled vehicle may be configured to be able to travel in any direction by wheels or the like, or may be configured to travel along a track or a guide rail laid inside the pipe. The self-propelled vehicle may be equipped with only the image capturing means, or may be equipped with some of the devices connected to the image capturing means. Information shall be provided between the equipment mounted on the self-propelled vehicle and the equipment installed outside the measuring tube by a communication cable or wireless. For self-propelled vehicles,
It is also possible to install a working device for performing repair work on the pipe body.

The in-pipe measuring method of the present invention is carried out as follows using the above-mentioned apparatus. First, the inside of the measuring tube is photographed in the tube axis direction by the image photographing means. Specifically, the image capturing means may be arranged so that the center axis of the optical system of the image capturing means and the center axis of the tubular body are aligned or at least parallel to each other. In the captured image, the inner wall surface of the measurement tube body is concentric or eccentric with overlapping centers and gradually decreases in the depth direction. .

On this photographed image, information such as the center point and radius of the tube cross section including the measurement point and the position of the measurement point are obtained as image information. The measurement point is one point of a measurement target such as a scratch or a foreign substance existing in the tubular body. The pipe cross section including the measurement point is a cross section obtained by cutting the measurement pipe body along a plane orthogonal to the pipe axis direction and on which the measurement point exists. If the measurement point is on the inner surface of the pipe,
Assuming a circular cross section that cuts the pipe at the circumference including the measurement point,
The center point of this circular cross section and the distance from the center point to the inner surface may be obtained. When the measurement point is closer to the center than the inner surface of the pipe, it is assumed that the line extending from the measurement point to the inner surface of the pipe intersects the inner surface of the pipe, and the pipe is cut along the circumference including this point. If a cross section is assumed, the center point and the like can be obtained as described above.

The pipe cross-section including such measurement points may be obtained by a person who sensuously determines it from an image. Further, in order to assist human judgment, the photographed image displayed on an image display means such as a TV monitor is overlaid, and the superimpose function is used to form a cross line, an annular line, a broken arc line,
While displaying the pipe cross-section indication image consisting of figures such as points, this pipe cross-section indication image can be enlarged / reduced or moved freely in the front / rear and left / right directions. It is preferable that the position of the tube cross section or the position of the center point can be accurately acquired by matching the circumference and the center point. Further, it is also possible to analyze the photographed image with an image analyzer and perform arithmetic processing with a computer or the like to obtain information on the cross section of the tube.

If the central axis of the tube body and the central axis of the optical system of the image photographing means are coincident with each other at the time of photographing the image, the center points of all the cross sections of the pipe are coincident with each other on the photographed image. That is, the tube cross section is displayed in a concentric shape. In this case, it suffices to find the center point of one measurement point, that is, the tube cross section. When the central axis of the tube body and the central axis of the optical system of the image capturing means are parallel and deviated during image capturing, the position of the center point shifts on the captured image according to the depth distance of the tube cross section. In this case, for each pipe cross section, information about the pipe cross section such as the center point may be obtained. Further, if it is possible to calculate the center point of a plurality of pipe cross sections, and calculate the position of the center point in an arbitrary pipe cross section based on the amount of deviation and information of the distance in the depth direction that is obtained in advance, Eliminates the hassle of finding the center point of the pipe cross section for all measurement points.

For obtaining the position of the measuring point, the position of the measuring point can be easily and accurately obtained by using the same measuring point indicating image as the tube cross section indicating image. Information about the position of the measurement point and the center point of the tube cross section on the captured image is input to a computer or the like and used in the arithmetic processing for obtaining the actual position information of the measurement point, which will be described later.

In order to obtain the information on the actual position of the measurement point from the information on the measurement point and the tube cross section on the photographed image obtained above, the correlation between the two is derived in advance and a mathematical expression expressing this correlation is obtained. And so on. In particular,
The following relational expressions (A) to (C) can be applied. In the following relational expressions, D: Radial distance from the measurement point to the center point of the pipe cross section in the pipe cross section including the measurement point DP: Radial distance from the point on the inner surface of the pipe to the center point of the pipe cross section θ: Pipe cross section The angle between the reference line extending in the radial direction from the center point and the line connecting the center point of the pipe cross section from the measurement point.

(A) The axial linear distance L from the measurement point to the optical system of the image capturing means is determined by the following equation (1). L = {R0 / (DP.Ce) +1} .f (1) where Ce: image expansion / contraction coefficient R0: actual inner radius of the tube f: focal length of optical system of image capturing means Ce Method.

A reference point is set on the inner surface of the measuring tube at a distance L0 from the optical system of the image taking means, and the inside of the measuring tube is photographed in the tube axis direction. The tube cross section including the reference point is obtained, the radial distance D0 from the center point to the reference point is measured, and from these values, the value of the actual tube inner surface radius R0 and the focal length f of the optical system, the following formula is obtained.
(1) The image enlargement / reduction coefficient Ce is calculated by ′.

Ce = (R0 / D0) .f / (L0-f) (1) 'In addition, the structure of the image capturing means and the image display means may be changed, or the screen size of the image display means may be adjusted. In such a case, the image scaling coefficient Ce may change. When such a factor that changes the image scaling coefficient Ce occurs,
The image scaling factor Ce described above may be remeasured. Further, it is convenient to automatically adjust the image enlargement / reduction coefficient Ce by interlocking with a screen control mechanism such as an image display means. This is the same when the focal length f of the optical system changes.

The above-described method of calculating Ce is the case where the focal length f of the optical system is known in advance. Even when the focal length f is not known, the focal length f is obtained by the following method, and then Ce is calculated. Can be asked. Preliminary distance L 1
And two reference points P 1 and P 2 for which L 2 is known, on the same photographed image as described above, the radial distance D of the tube cross section
Find the ratio B of 1 and D 2 . If the equations (1) for the points P 1 and P 2 are made simultaneous, the following equation can be obtained.

F = (L 2 −B · L 1 ) / (1−B) (1) ″ Here, B = D 1 / D 2 The obtained value of f and the above equation (1) ′ The absolute position of the measurement point can be found by adding the absolute position of the image shooting means to the distance L from the optical system of the image shooting means to the measurement point obtained above. Is
It is position information that represents the position of a self-propelled vehicle or the like on which the image capturing means is mounted, by a distance or direction from a reference position set on the ground surface or the like outside the tubular body. If you know the absolute position of the measurement point,
It is possible to know the exact position when repairing or replacing the pipe at the position of the measurement point. In order to know the image capturing means or the absolute position of the self-propelled vehicle, various surveying methods using electromagnetic waves, lasers, or the like, or a device for obtaining position information of a moving object may be used.

(B) The radial distance R from the measurement point to the center point of the pipe cross section is calculated by the following equation (2). R = D.R0 / DP (2) where, R0: actual pipe inner surface radius (C) The angle X between the measuring point and the reference line is calculated by the following formula (3). X = θ (3) By combining the relational expressions (1) to (3) in the above items (A) to (C), it is possible to obtain a three-dimensional positional relationship between arbitrary measurement points. . Also, if you know the positional relationship between any two points,
It is also possible to obtain the area and volume of an arbitrary solid figure. That is, it is possible to obtain information on the position, distance, area, volume, etc. of an arbitrary measurement target.

For example, the axial linear distance LAB between two points AB on the inner surface of the pipe is calculated based on the equation (1) as follows: LAB = (R0 / Ce) .f. (1 / DA-1 / DB) ... (11) DA, DB: Radial distance from points A and B to the center point C on the photographed image Linear distance MAB between two points AB on the inner surface of the tube with the same tube cross section
From the above formula (3), MAB = 2R0 sin (θAB / 2) (31) θAB: The narrow angle of the line connecting the AB point and the center point C. The arc distance M′AB between the two points AB is , M'AB = θAB · R0 (32) The linear distance XAB between any two points AB on the inner surface of the pipe is (1
By combining equations (1) and (31), XAB = {(LAB) 2 + (MAB) 2 } 0.5 ...... (12) Straight line distance N between two points AB radially separated in the same pipe cross section
AB is based on the above (1), NAB = (R0 / D). (DA-DB) (13) Correlation equation (1) between the position information on the image and the actual position as described above. If (31) and the calculation process are programmed in the computer in advance, they can be processed quickly and accurately.

Next, in order to directly know the information on the actual position and distance of the measurement point on the display screen of the image display means such as a TV monitor, a scale image may be displayed on the display screen. The graduation image is an image in which graduations and numbers are displayed at regular intervals, and can be created by the same means as the tube cross-section pointing image and the measurement point pointing image. As the scale image, a pipe axis direction scale linearly extending in a direction parallel to the pipe axis direction of the pipe body, a radial scale consisting of a part of a line extending from the center point of the pipe cross section in the radial direction, the center point of the pipe cross section There is a circumferential scale that extends concentrically with the circumferential direction. The scale interval and scale number of the scale image should be created based on the correlation between the position on the image of the measurement point and the actual position as described above, specifically the correlation equations (1) to (31). Good.

By displaying such a scale image on the photographed image on the display screen and comparing the position on the image of the measurement point with the scale image, by counting the scale of the scale image or reading the scale numbers, The position information of the measurement point can be acquired. In addition, it is possible to read the position information of the measurement point intuitively on the scale image,
If the accurate position of the measurement point is acquired from the above-described measurement point instruction image, more accurate position information can be obtained and the position information of the measurement point can be easily used for calculating the distance or area between the measurement points.

[0027]

FIG. 2 schematically shows a state in which the inside of the measuring tube 10 is photographed by the image photographing means, and FIG. 3 shows the display screen 42 of the TV monitor displaying the photographed image. The operation of the present invention will be described with reference to these drawings. In FIG. 2, a point P is set on the inner surface of the tube. The distance R0 from the point P to the central axis C of the pipe body 10 is half the diameter of the pipe body 10, that is, the radius. Distance L from point P
There is a reference position of the optical system 32 of the image capturing means 30 at a position separated by only. The reference position of the optical system 32 is a position serving as an optical reference, and may not coincide with the physical center position. An image pickup surface 34 is located behind the optical system 32.
The central axis of the optical system 32 is aligned with the central axis C of the tubular body 10. The distance f from the reference position of the optical system 32 to the focal point F of the optical system 32 is the focal length. The light emitted from the point P passes through the optical system 32 and is captured as a point P ′ on the imaging surface 34. The distance from the central axis C to the point P'is H.

The point P'captured on the image pickup surface 34 is processed as electronic information and displayed as a point PD on the display screen 42 of the TV monitor. On the display screen 42, the inner surface state of the tubular body 10 is displayed as a group of concentric circles that decrease from the front to the depth direction. The distance from the point PD to the center point C of the pipe cross section including the point PD is DP. In FIG. 2, the following formula is established from the function of the optical system 32.

H / f = R0 / (L-f) (4) Ce = H / DP (5) where Ce is the image captured by the imaging surface 34 and the display screen 42. It represents the enlargement or reduction ratio with the generated image, that is, the image enlargement or reduction coefficient. The image enlargement / reduction coefficient Ce is determined by the characteristics of the electronic information processing circuit from the image capturing means 30 to the image display means, and is a constant that is not affected by the position of the point P.

The following equation is obtained from the above equations (4) and (5). Ce = (R0 / DP) * {f / (Lf)} (6) Therefore, L = {R0 / (DP * Ce) +1} * f (1) In this equation (1), Image scaling factor Ce, radius of tube 10 R0
, The focal length f can all be known in advance, so by measuring the distance DP between the point P on the display screen 42 and the center point C, the distance from the actual point P in the tubular body 10 to the optical system 32 can be measured. The distance L is calculated.

Similarly, the above equations (2) and (3) are also obtained. In any of the equations (1), if the positional relationship between the point P and the center point C on the display screen 42 is known, the actual positional information of the point P can be obtained. In this way, the position information of the point P can be obtained from the image of the inside of the tube body 10 taken in the tube axis direction, because the inner circumference of the tube body 10 is deep from the front to the depth in this taken image. The image is displayed in a reduced size at a constant rate depending on the distance from the image capturing means, and the distance from the center of the tube 10 to the inner surface of the tube, that is, the radius R0 of the tube 10 is always constant. This is because it is used. Based on the scaling ratio between the radius R0 of the tubular body 10 and the radius DP appearing on the photographed image, the scaling ratio of the positional relationship between the arbitrary point P and the center point C of the cross section of the pipe including the point P is determined. I understand.

That is, according to the present invention, the radius R of the tubular body 10 is
As a result of focusing on the fact that 0 is constant and the radius DP of the tubular body 10 at each cross-sectional position is enlarged and reduced at a constant ratio in the image taken in the axial direction of the tubular body 10, The actual position information of the point P can be simply and accurately obtained only by obtaining the information of the pipe cross section including the above point P and the position information of the point P in the pipe cross section.

[0033]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the overall configuration of an in-pipe measuring device according to the present invention and a state of implementation of measurement work. A shaft 92 is excavated in the ground 90, and the buried pipe 10 is buried horizontally from the side surface of the shaft 92. This buried pipe 10 serves as a measuring pipe body. Inside the measuring tube 10,
Self-propelled vehicle 6 equipped with a TV camera 30 as image capturing means
0 is sent. The structure of the self-propelled vehicle 60 is the same as that used for normal in-pipe measurement or in-pipe work. The cable 62 connected to the self-propelled vehicle 60 is the buried pipe 1
From the rear end of 0, through the vertical shaft 92, to the cable reel 6 on the ground.
It has been pulled out to 4. Cable 62 is a self-propelled vehicle 60
Power to the vehicle, the self-propelled vehicle 60 and the TV camera 30.
Send command information to control the work of the TV camera 30
It converts the images taken in to electrical signals and transmits them to the ground. On the ground, information is transmitted from the cable reel 64 to the image control device 40 and a personal computer (hereinafter abbreviated as personal computer) 50.

The image control device 40 has its display screen 42.
A captured image obtained by the TV camera 30 is displayed on. The personal computer 50 operates a program for calculating the position and distance of the measuring point from the image information. In addition, the personal computer 50 creates a center point designating image, a measurement point designating image, a scale image, etc., and a superimposing circuit incorporated in the personal computer 50 causes the display screen 42 of the image control device 40 to overlay the photographed image. Then, the various images are displayed. Also, using the input device of the personal computer 50, change the position and shape of the center point designating image,
The desired image can be overlaid on the desired position of the captured image, and the information on the moving position and shape of the center point instruction image is
It is sent to the personal computer 50. The image control device 40 and the personal computer 50 may be integrated, or the respective functional structures described above may be partially replaced. For example, it is possible to display a photographed image and a center point instruction image on the display screen of the personal computer 50.

Next, a method of performing in-pipe measurement using the above-mentioned in-pipe measuring device will be described. A method for measuring the image expansion / contraction coefficient Ce before starting the in-tube measurement will be described. However, if the image expansion / contraction coefficient Ce can be calculated in advance from the structure and characteristics of the TV camera 30 and the image control device 40, such measurement is not necessary.

In FIG. 2, a reference point P0 whose distance L0 is known is set in advance. This reference point P0 may be set in the measuring pipe body 10 that actually performs the measurement, or
Prepare a dummy tube having the same diameter as the above, or a dummy tube whose diameter is known in advance regardless of the measuring tube body 10, set a reference point P0 in such a dummy tube, and measure the image enlargement / reduction coefficient Ce. May be performed.

The TV camera 30 photographs the inside of the measuring tube 10 in the tube axis direction. Then, a captured image is obtained on the display screen 42 as shown in FIG. On this captured image,
From the center point C of the pipe cross section including the reference point P0 to the reference point PD0
Measure the radial distance D0 to. The determination of the center point C is based on the procedure described later. The actual tube inner surface radius R0 and the focal length f of the optical system are measured in advance.

From the above measurement result, the image expansion / contraction coefficient Ce is calculated by the above equation (1) '. When the focal length f of the optical system is unknown, the same measurement as the previous term is performed for the two reference points P 1 and P 2 whose distances L 1 and L 2 are known in advance, and the respective measurement results are given in (1) above. ), The focal length f and the image expansion / contraction coefficient Ce can be obtained by solving the obtained simultaneous equations.

Specifically, the focal length f of the optical system is obtained by the following equation, for example. f = (L 2 −B · L 1 ) / (1−B) (14) Here, B is from the center point C of the tube cross section at each of the points P 1 and P 2 on the captured image. Is the ratio of the radial distances DP1 and DP2 of B, and is expressed by B = DP1 / DP2. Next, the self-propelled vehicle 60 equipped with the TV camera 30 is fed into the measurement tube body 10 for actual measurement, and an image is taken in the tube axis direction of the measurement tube body 10.

At this time, the photographed image as shown in FIG.
It is assumed that it is displayed on the display screen 42. On the display screen 42, a center point designating image 110 composed of a crosshair that crosses the entire screen vertically and horizontally and a measurement point designating image 112 composed of a small crosshair cursor are displayed so as to be superimposed on the intraluminal surface image 10 '. Center point instruction image 1 by key input on PC 50
Move 10 cross intersections vertically and horizontally. Center point instruction image 1
The cross intersection of 10 is made to coincide with the center point C of the tube inner surface image 10 '. The center point C of the tube inner surface image 10 'can be known based on the curved surface shape of the tube inner surface. Specifically, since a clear circular contour shape appears at the joint between the pipes,
It can be seen that there is a center point C exactly in the center of this circular contour. It is also possible to find the center point C from the processing marks in the circumferential direction formed when processing the inner surface of the tubular body. In the figure,
Since the position of the center point C is always at the same position in the depth direction of the tube inner surface image 10 ′, if the center point C is determined at any tube cross-section position, then the center point C is the same center for any measurement point. The position information of the point C can be used. Inner surface image 1
If the center point C is deviated in each of the tube sections 0'in the depth direction, the center point C may be obtained in the tube section to be measured.

Next, the measurement point instruction image 112 is moved so as to match the position of the target measurement point PD. In the figure, the measurement point PD is the point on the inner surface of the pipe, but the same operation is performed even if the measurement point PD is present at a position closer to the center side from the inner surface of the pipe. With this, the positions of the measurement point PD and the center point C are input to the personal computer 50.
The central point C is calculated by the arithmetic processing program in the personal computer 50.
To the measurement point PD from the center point C and the measurement point PD
An angle θ and other necessary data indicating how many times the line connecting the lines deviates from a reference line, for example, a vertical line, are calculated.

The distance L from the TV camera 30 to the measuring point PD on the inner surface of the pipe is obtained by the arithmetic processing program of the personal computer 50 based on the equation (1). This information, TV
The absolute position of the measurement point PD can be specified by adding information indicating the traveling position of the vehicle 60 equipped with the camera 30. In the upper right of FIG. 3, a method for obtaining the straight line distance LAB between two points AB axially separated on the inner surface of the pipe is described. A
For both measurement points B, the position on the image and the position of the center point C are obtained in the same manner as the above-mentioned work. The distance from the image capturing means 30 to each measurement point AB is calculated from the equation (1) as described above, and the distance LAB between both measurement points AB is calculated from the equation (11). This method can be used to measure the length of cracks or scratches on the inner surface of the tubular body 10.

At the lower left of FIG. 3, a scale image 120 is displayed. This scale image 120 is the image 1 of the inside of the tube.
A straight line is formed from the center point C of 0 ′ in the radial direction, and scale lines are provided at predetermined intervals. The intervals between the scale lines are created as follows. First, a virtual measurement point is set on the inner surface of the tube at a constant distance from the image capturing means 30, the position of each measurement point is calculated on the captured image, and the actual interval between the measurement points is calculated. Then, the intervals of the scale lines are gradually changed and displayed in accordance with the scaling ratio with the intervals between the measurement points appearing on the captured image. The relationship between the distance between the measurement points and the distance between the scale lines can be easily obtained from the equation (11). As a result, the distance between the scale lines is wide at the position far from the center point C, and the distance between the scale lines is narrow at the position close to the center point C.

By displaying the scale image 120 as described above near the two points AB, it is possible to know the distance between the two points AB by comparing the positions of both points AB and the scale image 12. Become. It is also possible to match the origin position of the scale image 120 with one of the points A or B and read the distance to the other point B or A with the distance numerical value displayed on the scale image.

Next, FIG. 4 illustrates a method of measuring the distance between two points AB on the inner surface of the tube within the same tube cross section.
The position of the center point C is obtained using the center point instruction image 110, and the position of the measurement point AB is obtained using the measurement point instruction image 112, as in the above case. The measurement points AB are all radial distances D from the center point C. From these data, the personal computer 50 performs an operation to calculate the included angle θAB between the line AC and the line BC. Specifically, for example, an angle θA formed by the line AC and an angle θB formed by the line BC with respect to a reference line such as a vertical line may be obtained, and θAB = θA−θB may be calculated. By substituting this result into the equation (31) or the equation (32), the straight line distance or the arc distance between the AB points can be obtained.
This method can be used to measure flaws and cracks that occur circumferentially on the inner surface of the tube.

In the upper left of FIG. 4, an arc-shaped scale image 12 is shown.
2 is displayed. The scale image 122 has scale lines at predetermined angles. The relationship between the interval between the scale lines and the angle does not change even if the measurement point AB is present at any position in the depth direction of the in-tube surface image 10 '. If this scale image 122 is displayed near the measurement point AB, the included angle θAB between the measurement points AB can be immediately read. The scale lines of the scale image 122 can be displayed in length units instead of in angle units. In this case, if the radial distance D of the measurement point A or B and the relationship between the angle and the arc distance shown in the above equation (32) are displayed, the scale line or scale numerical value of the length unit can be displayed. Good.

Next, FIGS. 5 and 6 explain a method of measuring the position and the radial distance of the measurement point AB existing on the center side of the inner surface of the tubular body 10. In FIG. 5, a point P represents a point on the inner surface of the tubular body 10, and points A and B represent points on a line connecting the point P and the center point C. The distance from points A and B to the center point C is the distance RA
And RB. On the photographed image shown in FIG. 6, points A and B appear in the middle of the line connecting the center point C and the point P on the inner surface of the tube, and the distance from each point to the center point C is the distances DA and D.
Obtained as B. Then, from the equation (13), the point AB
The distance NAB between them can be calculated. Of course, the distance from the point P to the point A or B can be similarly measured. This method can be used to measure the height of foreign matter protruding inward from the inner surface of the tubular body 10.

Both the method of FIG. 3 and the method of FIG. 4 have been described as the measuring method when the measuring point is on the inner surface of the tubular body 10, but the method of FIG. 5 and the method of FIG. 3 or FIG. If you combine the
It becomes possible to measure the axial position and the circumferential position. Further, the method of FIG. 5 can be used to measure a shift at a joint between the pipe bodies 10 in a pipe line in which a plurality of pipe bodies 10 are connected. The method is described in FIGS. 7 and 8.

In FIG. 7, it is assumed that the tube body 11 on the side closer to the image capturing means 30 and the tube body 12 on the far side are displaced from each other. The center line C 2 of the center line C 1 and the tube 12 of the tube 11 step is generated. If the distance from the center line C 1 of the pipe body 11 to the point A on the inner surface of the pipe body 12 is RA, then RA
= R0, and the distance RB from point B on the inner surface of the tube 11 to the center line C 1 of the tubular body 11, which is shorter than the difference RA -RB is a shift amount.

On the photographed image of FIG. 8, the center point designation image 11
The cross point of 0 is the center point C of the inner surface image 11 ′ of the tubular body 11.
Set to 1 . The measurement point instruction image 112 is sequentially aligned with the points A and B to obtain the respective positions on the image. Then, the distance NAB of the point AB can be calculated from the equation (13). In this case, the calculation is further simplified because D and DA match in the equation (13). In this method, the tube 12
It is not necessary to obtain the center point C 2 of the inner surface image 12 ′ of. On the contrary, it is also possible to measure the deviation amount from the distance of the point AB to the center point C 2 of the inner surface image 12 ′ of the tubular body 12. Further, the amount of deviation can be measured from the positions of the center points C 1 and C 2 . To know the direction of deviation, the angle θ of the point AB with respect to the reference line may be calculated, or the direction vector of the center points C 1 and C 2 may be calculated.

Next, FIGS. 9 and 10 explain a method of combining the above-mentioned respective methods to measure a linear distance XAB between two points AB on the inner surface of the pipe and axially separated from each other. In FIG. 9, the inner surface of the tubular body 10 is separated by 2 in the axial direction.
There is a point AB. An image of this is shown in FIG. In the tube inner surface image 10 ', points A and B appear at positions DA and DB from the center point C. DA and DB
Are different. Further, the included angle θAB between the line CA and the line CB is also obtained. Based on these pieces of information obtained from the photographed image, the linear distance between the two points AB is calculated by the following procedure.

In FIG. 9, when a point A'projected from the point A on the cross section including the point B is hypothesized, the distance LAA 'of AA' becomes (11)
It can be calculated by applying the formula. Next, in the cross section including the point B, the included angle θAA 'between CA' and CB is equal to the included angle θAB between CA and CB on the captured image in FIG. 10, so the linear distance MBA 'of BA' is (31) ) Can be applied to calculate.
Then, the AB distance can be calculated by applying the equation (12) from the relationship of the three sides of the triangle ABA '. In addition, in FIG. 9, the distance along the pipe inner surface of the point AB indicated by a chain double-dashed line is also known by the procedure described above, since the straight line distance between the points and the angle formed by each side are known. It can be easily determined by applying the formula for.

By combining the methods for obtaining the distance between two points AB under various conditions as described above, the positions of arbitrary two points AB appearing on the photographed image and the center point of the tube cross section including each point Or, if necessary, by measuring the position of a point on the inner surface of the tube in each cross section of the tube, it is understood that the distance between any two points AB on the photographed image can be calculated based on this information. By knowing the length of the side formed by the arbitrary two points AB and the angle formed by the side, the area of the arbitrary figure can be calculated, and further, the volume of the object surrounded by the arbitrary figure can be calculated. As a specific method of calculating the distance, area, and volume, known geometrical knowledge or a graphic formula may be applied according to each condition.

In the above description, as shown in FIG. 2, the central axis C of the tubular body 10 and the optical system 32 of the image pickup means.
The center point C of the tube inner surface image 10 'is assumed not to change in the depth direction of the tube on the photographed image shown in FIG. However, in the actual measurement, the self-propelled vehicle 60 is connected to the tubular body 1 having various diameters.
The position of the TV camera 30 may be
It may not be at the center of the tubular body 10. In such a case,
If the TV camera 30 is movably provided with respect to the self-propelled vehicle 60 and the TV camera 30 is moved so that the center of the TV camera 30 coincides with the center of the tube body 10, the TV camera 3
In the image photographed at 0, as shown in FIG. 3 and the like, the center point C of the intraluminal surface image 10 'is always at the same position.

Further, the optical system 30 of the image photographing means and the tube body 1
Even if an image is taken with the center axis of 0 being displaced, the target measurement can be performed. That is, the tube inner surface image 10 '
Even if the center point C of is different in the position in the depth direction of the pipe cross section, if the position of the center point C is known for each pipe cross section including the measurement point, the relationship such as the above equation (1) holds as it is. From the above, it is possible to obtain the information on the position and distance of the target measurement point by performing the same calculation.

Furthermore, in the image 10 'of the inside of the tube, two points P
If the shift amounts of the center points C 1 and C 2 of 1 and P 2 are measured, the shift amount per unit distance can be obtained from the axial distance L 12 between the two points and the shift amount of the center point. If this value is known, the shift amount of the center point between arbitrary measurement points can also be calculated. Next, FIGS. 11 and 12 show a case where the tube cross-section pointing image and the scale image are different from those in the above-described embodiment.

As shown in FIG. 11, instead of the center point designating image 110, an annular circumference designating image 114 is superimposed and displayed on the intraluminal surface image 10 'of the display screen 42 as a pipe cross-section designating image. . In the figure, the circumference instruction images 114a and 11
Although two images of 4b are shown at the same time, in actuality, either one may be displayed. This circumference instruction image 114
Allows its size and front, rear, left and right positions to be freely moved. In this example, the measuring tube 1
It shows a case where the tube axis of 0 and the center axis of the optical system of the image capturing means 30 are deviated, and in the tube inner surface image 10 ', the center point of each tube cross section is constant from the front side to the back side. The ratio is off.

If this circumference indication image 114 is adjusted so as to match the intended tube cross section, the position and the position of the center point C in the cross section of the tube can be determined from the size and position of the circumference indication image 114 at that time. The radial distance D from the center point C to the inner surface of the pipe can be known. Since a circumferential line such as a seam between pipes and a processing mark is shown in the inner surface image 10 ′ of the tubular body, it is relatively easy to match the circumferential instruction image 114 with such a circumferential line. It enables efficient measurement work.

In the embodiment shown in FIG. 12, a large number of ring scale images 124 whose radius decreases from the front side to the back side are displayed as the scale images. Between the adjacent ring scale images 124, an arc scale image 126 consisting of only a part of the ring is displayed. The intervals, radii, and deviations of the center points of the respective ring scale images 124 and arc scale images 126 are adjusted so as to match the display of the inner surface of the tube in the inner surface image 10 'of the tube. That is, the annular scale image 124 is displayed for each constant distance in the pipe axis direction, and the adjacent circular scale images 124 are divided by the constant distance in the pipe axis direction to display the arc scale image 126. ing.
Therefore, the intervals between the circular scale image 124 and the circular scale image 126 on the display screen 42 are changed at a constant ratio instead of at equal intervals, and the position and radius of the center point are also changed at a constant ratio. .

If such an annular scale image 124 and an arc scale image 126 are displayed, the axial distance between arbitrary measurement points on the inner surface of the pipe, the distance from the image photographing means 30 to the measurement point, etc. Only by comparing the scale images 124 and 126 with each other, it is possible to read the approximate value by the scale amount without using the measurement point instruction image 112 or the like. Therefore, while observing the inner surface image 10 ′ of the tube, it is possible to roughly know the position and the distance information such as the defect portion, which is effective for improving the efficiency of the in-tube inspection work. However, after obtaining the outline information from the ring scale image 124 or the arc scale image 126, the position of the accurate measurement point is determined using the measurement point instruction image 112, and the accurate position information and the distance information are obtained. Can also be obtained.

The ring scale image 124 as described above is matched with the display state of the inner surface of the tube in the inner surface image 10 'of the tube.
A method of displaying the arc scale image 126 will be described. As shown in FIG. 11, the circumference instruction image 114 is
It is displayed so as to be superimposed on the tube inner surface image 10 ', and is adjusted so that the circumferential direction instruction image 114a coincides with the tube inner surface at an appropriate position on the front side in the tube axis direction. With this, the center point in the cross section of the pipe, the radius to the inner surface of the pipe, and the like are obtained. Next, the circumference instruction image 114b is adjusted so as to match the inner surface of the tube at an appropriate position on the inner side in the tube axis direction, and the center point in this tube cross section, the radius to the inner surface of the tube, and the like are obtained. The deviation of the center points and the rate of change of the radius per unit distance can be found from the ratio of the deviations of the center points and the radii of the two sections of the pipe. From this result, for any position in the tube axis direction,
Since the position and the radius of the center point to be displayed on the display image 42 can be determined, the display image 42 is displayed for each constant distance in the tube axis direction.
It is possible to obtain the position and the radius of the center point to be displayed on each of the circular scale images 124. The arc scale image 126 can be similarly displayed.

[0062]

As described above, the in-pipe measuring device according to the present invention has the following characteristics:
By utilizing the fact that the distance from the center point of the pipe cross section to the inner surface of the pipe, that is, the inner radius, is reduced and displayed at a fixed ratio according to the distance from the image capturing means, the measurement point position and the measurement point on the captured image are used. The position of the measurement point is determined based on the correlation between the position information on this image and the position of the measurement point on the image and the actual position, which is obtained only by obtaining information such as the center point of the pipe cross section containing Real position information can be acquired. Moreover, the work described above does not require special equipment or large-scale equipment, and has been used for conventional in-house inspections such as a normal TV camera and a TV monitor that displays captured images. Since it can be carried out with a simple device, the working cost becomes economical.

As a result, it is possible to obtain the position and distance information of an arbitrary measuring point in the pipe easily and with sufficient accuracy and to accurately grasp the condition inside the pipe only by photographing the above-mentioned image. Therefore, it is possible to easily know the internal conditions of a narrow pipe that cannot be entered by a human or a pipe in a dangerous environment with simple equipment, and it is possible to greatly contribute to the improvement of the capability of this type of in-pipe measurement work.

[Brief description of drawings]

FIG. 1 is an overall structural diagram of an in-pipe measuring device for carrying out the present invention.

[Figure 2] Schematic diagram explaining the measurement principle

FIG. 3 is a front view showing a TV monitor screen.

FIG. 4 is a front view showing a TV monitor screen in another embodiment.

FIG. 5 is a schematic view of the inside of a tube showing another embodiment.

FIG. 6 is a front view showing the TV monitor screen in the same state as above.

FIG. 7 is a schematic view of the inside of a pipe showing another embodiment.

FIG. 8 is a front view showing the TV monitor screen in the same state as above.

FIG. 9 is a schematic view of the inside of a pipe showing another embodiment.

FIG. 10 is a front view showing the TV monitor screen in the same state as above.

FIG. 11 is a front view showing a TV monitor screen of another embodiment.

FIG. 12 is a front view showing a TV monitor screen of another embodiment.

[Explanation of symbols]

 10 Measuring Tube 30 Image Capturing Means 32 Optical System 34 Imaging Surface C Tube Central Axis (Optical System Central Axis) P Measuring Point 42 Display Screen 110 Center Point Pointing Image 112 Measuring Point Pointing Image 114 Circumference Pointing Images 120, 122, 124, 126 scale image

Claims (5)

(57) [Claims]
1. An image capturing means captures an image of the inside of a measuring tube body whose inner diameter is known in advance in the tube axis direction, and in the obtained captured image, information of the measuring point position and the section of the tube including the measuring point is displayed. Obtain the information on this image and the previously derived measurement
An in-pipe measuring method characterized in that position information of a measuring point is acquired based on a correlation between a position on an image based on an inner diameter of a pipe and an actual position.
2. The method according to claim 1, wherein the photographed image is displayed on the image display means as a means for obtaining information on the tube cross-section including the measurement point, and the tube cross-section instruction image is displayed by being superimposed on the displayed photographed image. Then, an in-pipe measuring method in which the pipe cross-section pointing image is adjusted so as to match the pipe cross-section including the measurement point, and information of the pipe cross-section pointing image at this time is acquired.
3. The method according to claim 1, wherein
As a means for obtaining the position of the measurement point, the photographed image is displayed on the image display means, the measurement point instruction image is displayed so as to be superimposed on the displayed photographed image, and the measurement point instruction image is made to match the position of the measurement point. An in-pipe measurement method of adjusting and acquiring the position of the measurement point instruction image at this time.
4. The method according to claim 1, wherein
The captured image is displayed on the image display means, and the scale image in which the image is adjusted based on the correlation between the position on the image and the actual position, which is derived in advance, is displayed by being superimposed on the captured image on the display screen. An in-pipe measuring method for acquiring position information of a measuring point by comparing the position of the measuring point on the image with a scale image.
5. The method according to claim 1, wherein
Radial distance D from the measurement point to the center point of the pipe cross section, radial distance D P from the point on the inner surface of the pipe to the center point of the pipe cross section, and center point of the pipe cross section From at least one of the included angles θ between the reference line extended in the radial direction from the measurement point and the line connecting the center point of the pipe cross section from the measurement point, and measure these values from the following (A) to (C) terms. In-pipe measurement method that obtains the position information of the measurement point through at least one of the procedures. (A) The axial linear distance L from the measurement point to the optical system of the image capturing means is calculated by the following equation (1). L = {R0 / (DP.Ce) +1} .f (1) where Ce: image expansion / contraction coefficient R0: actual inner radius of the tube f: focal length of optical system of image capturing means Ce Method. A reference point is set on the inner surface of the measuring tube at a position at a distance L0 from the optical system of the image capturing means, and the inside of the measuring tube is photographed in the tube axis direction. The included tube cross section is obtained, the radial distance D0 from the center point of this tube cross section to the reference point is measured, and from these values and the actual tube inner surface radius R0 and the value of the focal length f of the optical system, the following formula (1) The image enlargement / reduction coefficient Ce is calculated by ′. Ce = (R0 / D0) .f / (L0-f) ... (1) '(B) Radial distance R from the measuring point to the center point of the pipe cross section
Is calculated by the following equation (2). R = (D / DP) .R0 (2) Here, R0: Actual pipe inner surface radius (C) The angle X between the measuring point and the reference line is calculated by the following formula (3). X = θ (3)
JP5198493A 1993-08-10 1993-08-10 In-pipe measurement method Expired - Fee Related JP2531488B2 (en)

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