JPH055608A - Method and apparatus for measuring position of circular cross-section object - Google Patents

Abstract

PURPOSE:To enable highly accurate measuement with a single operation by projecting slit light wide in the direction orthogonal to a strip coil axis line and narrow in the direction of the axis line on the outer circumferential surface of the coil to determined the center position of the coil from an oval circular arc image. CONSTITUTION:Slit light 5 which is emitted from a light source 2 and wide in the direction orthogonal to an axis line Sc of a strip coil 1 and narrow in the direction of the axis line Sc is projected onto the outer circumferential surface of the coil 1 so that the optical axis thereof is skewed upward from below to the axis line Sc. Then, an image 4 of the slit light 5 appearing in a semi-elliptic arc projecting downward is taken with an automatically focusing CCD camera 3 and an image processing is performed with a microcomputer 10 or the like. A deviation value from a specified position of the center position of the coil 1 is calculated from the semi-elliptic image. This enables highly accurate measurement with a single operation thereby achieving a simple construction and a low cost free from environment and conditions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for measuring the position of a circular cross-section object and a measuring apparatus therefor. For example, a strip coil formed by winding a strip steel plate such as a rolled steel plate in a spiral shape is gripped and transported or transferred. It is used when doing.

[0002]

2. Description of the Related Art In order to automatically grip a strip coil as described above, information on the outer diameter of the coil and its position is required. Of these, the outer diameter of the coil has a process to be accurately measured before the carrying and transferring process in a normal production line, so the information may be diverted, but the position must be measured each time. I won't. Further, since it is difficult to directly contact the tracing stylus with a coil of hot-rolled steel sheet, it is desirable to use a coil that can be measured as non-contact as possible.

As a main one of the non-contact measuring method and measuring apparatus, one using a photoelectric tube is widely used.
As examples thereof, Japanese Patent Laid-Open Nos. 52-73274 and 5
And those disclosed in JP-A No.
For example, there are those described in Japanese Patent Publication No. 9-103655.
In the former, the light emitting body and the light receiving body are opposed to each other on both sides in the longitudinal direction of the strip coil, and the position is detected when the light from the light emitting body is blocked by the outer circumference of the coil. In the latter, a light emitter and a light receiver are provided on one side of the strip coil in the longitudinal direction, and a reflector is provided on the other side of the coil in the longitudinal direction so that the light reflected from the light emitter to the reflector is blocked by the outer circumference of the strip coil. The position is detected accordingly.

Further, Japanese Patent Application Laid-Open No. 59-230994 discloses that a longitudinal end face of a strip coil is imaged by a TV camera and the imaged information is image-processed to measure the position and outer diameter of the coil. There is.

[0005]

However, in any of the conventional strip coil position measuring methods and measuring devices thereof using a photoelectric tube, it is necessary to install the members and equipment of the device so as to be sandwiched in the longitudinal direction of the coil. Therefore, the device becomes large in size. There is also a problem in that the measurement accuracy is reduced unless the device is installed close to the strip coil. Further, since these measuring methods and measuring devices are intended to detect the position of one part of the outer peripheral surface by one measurement in principle, for example, the substantially circular longitudinal end face of the coil is measured in two axial directions. In order to measure the center position by using at least two measuring devices, it is necessary to install at least two measuring devices or perform the measurement twice or more.

Further, in the latter measuring method and measuring apparatus, it is difficult in practice to make an image with contrast between the longitudinal end face of the coil and its background, and the application conditions are severe. The present invention has been developed in view of these problems, the structure of the device itself is simple, the position of the coil can be measured with high accuracy in a single measurement, and the position measuring method for a circular cross-section object with a wide range of application. And a measuring device therefor.

[0007]

A position measuring method for a circular cross-section object according to the present invention is a method for measuring a position of a circular cross-section object from a predetermined position for measuring the position of a circular cross-section object whose cross-section contour is circular with respect to an axis. In the method, a slit light that is wide in the direction orthogonal to the axis of the circular cross-section object and narrow in the axis direction is projected from the light source onto the outer peripheral surface of the object, and an image of the slit light that appears on the outer peripheral surface of the object is obtained. It is characterized in that an elliptic arc is imaged and the center position of the object is determined from the imaged elliptic arc.

The position measuring device for a circular cross-section object of the present invention comprises:
In a position measuring device of a circular cross-section object for measuring a displacement amount from a predetermined position of a circular cross-section object having a circular cross-section outer shape with respect to an axis, in a direction orthogonal to the axis of the circular cross-section object, the width is wide in the axial direction. A light source for projecting narrow slit light onto the outer peripheral surface of the object, and an image of the slit light appearing on the outer peripheral surface of the object, in a plane including the optical axis of the slit light and the point at the predetermined position, and the slit. It is characterized by comprising an image pickup means for picking up an elliptical arc at a position different from the light source of light and an image processing means for picked up image.

[0009]

In the method and apparatus for measuring the position of a circular cross-section object according to the present invention, for example, slit light having a wide width in the direction orthogonal to the axis of the strip coil and a narrow width in the axial direction is emitted from the light source to the outer peripheral surface of the strip coil. When observed on a plane including the optical axis of the slit light and the point at the predetermined position and at a position different from the light source of the slit light, the slit light appears as a semi-elliptic arc on the outer peripheral surface. The image of this semi-elliptic arc slit light is taken by an image pickup device at a position different from that of the light source, and the pole in the short axis or long axis direction of the elliptic arc is obtained to find the point closest to the image pickup side on the outer peripheral surface of the coil. Is calculated. Since the shortest distance between the light source and the outer peripheral surface of the coil is calculated from the point closest to the imaging side on the outer peripheral surface of the strip coil, this shortest distance and the outside of the strip coil obtained in the preceding strokes are calculated. The amount of deviation of the center position of the coil from the predetermined position is calculated based on the diameter.

[0010]

FIG. 1 shows an embodiment of a method for measuring the position of a circular cross-section object and a measuring apparatus therefor according to the present invention, in which the axis of a strip coil 1 installed in the vertical direction (up end) is predetermined. This is for measuring how much the position P deviates.

In FIG. 1, the slit light 5 emitted from the light source 2 and having a wide width in the direction orthogonal to the axis Sc of the strip coil 2 and a narrow width in the direction of the axis Sc has its optical axis as the axis Sc of the coil 1. It is projected on the outer peripheral surface of the strip coil 1 so as to be oblique from the lower side toward the upper side. And an autofocus CCD camera 3 which is an image pickup means
Is provided on a plane including the optical axis and a point P at a predetermined position and at a position where an imaging axis F orthogonal to the axis Sc of the strip coil 1 is formed.
An image (hereinafter referred to as a semi-elliptic image) 4 of the slit light 5 projected on the outer peripheral surface of the and appearing in the shape of a semi-elliptical arc protruding downward is captured. Then, the image pickup information of the autofocus CCD camera 3 is transmitted to the image processing means constituted by the microcomputer 10 or the like.

Next, various specifications of the apparatus in this embodiment and a calculation and determination method thereof will be described with reference to FIG. The specifications of the strip coil 1 applied to this embodiment are the outer diameter d.
Is 1500 to 3000 mm, and the height (width) h ₁ is 600 to
It is 1800 mm. First, the distance L between the light source 2 of the slit light 5 and the strip coil 1 is 150 even if the maximum outer diameter of the coil 1 is 3000 mm in consideration of a space for manual work.
It should be 0 mm or more. Thereby, the distance L between the light source 2 and the coil 1 was set to 1500 mm to 3000 mm.

Next, it is desirable that the horizontal level (height) H ₂ of the light source 2 of the slit light 5 is at the same level as the height at which the strip coil 1 is installed, that is, 0 mm, considering image processing described later. The positive direction may be set or the negative direction may be set as necessary. In this embodiment, it is set to 0 mm. Next, in setting the angle θ ₁ formed by the optical axis and the axis of the strip coil, when the distance between the light source 2 and the coil 1 becomes the maximum, that is, when the outer diameter d of the strip coil 1 is 1500 mm, Two
Even if the distance L between the coil 1 and the coil 1 is 3000 mm, the lowest point of the semi-ellipse image 4 is the minimum height h ₁ 600 m of the coil 1.
It must be lower than m. Therefore, the angle θ ₁ formed by the optical axis and the axis of the strip coil is set to 79 ° by the following formula 1 using the angle θ formed by the optical axis and the horizontal axis.

3000 × tan (90−θ ₁ ) = 3000 × tan θ <600 (1) ∴θ <11.3 ° ∴θ ₁ = 79 ° When setting the position of this light source, the optical axis is set. It should be noted that the degree of freedom is relatively small due to the restriction of the angle θ ₁ formed by the axis of the strip coil with the axis of the strip coil, and that the slit light diffuses and the accuracy decreases when the light source is moved too far away.

Next, a method of determining the image pickup range and the image pickup angle of the autofocus CCD camera will be described. Auto focus CCD
The installation height H ₁ of the camera 3 with respect to the light source 2 is preferably as close to the front of the lowest point of the semi-ellipse image 4 as possible. The height h of the lowest point of this semi-ellipse image 4 is calculated by the following two equations.

H = L × tan θ + H ₂ (2) From the above equation 2, the height h of the lowest point of the semi-ellipse image 4 is about 300-.
Since the height is 600 mm, the installation height H ₁ of the autofocus CCD camera 3 is set to 450 mm which is the approximate center value of the height h. Incidentally, the ground height H ₀ of the CCD camera 3 in this embodiment is equal to the installation height H ₁ because the installation height H ₂ of the light source 2 is ₀ mm.

The vertical image pickup range of the autofocus CCD camera 3 is required to be at least 300 mm or more according to the above two formulas. On the other hand, when the strip coil 1 is lowered by a crane or the like, it is possible to suppress the error in the horizontal direction to about ± 100 mm. Therefore, the imaging range of the autofocus CCD camera 3 is 300 mm × 300 when the distance between the strip coil 1 and the CCD camera 3 becomes the shortest (1500 mm).
It may be about mm. Therefore, the imaging angle ψ of the autofocus camera 3 is set to about 12 ° from the following three equations.

Ψ = tan ⁻¹ (300/1500) = 11.3 ° ≈12 ° (3) Next, the detection accuracy of this autofocus CCD camera will be examined. Generally, many CCD cameras have 512 × 512 elements. For example, assuming that the positional deviation in the horizontal direction is 50 mm, this 50 mm corresponds to the number of elements in the horizontal direction of the image of 80.3 bits based on the following four equations. Therefore, the detection accuracy in the horizontal direction is 50/80 = 0.625 mm per bit in the horizontal direction.

50 / (1500 × tan 12 °) × 512 = 80.3 (4) On the other hand, assuming that the displacement in the perspective direction is 50 mm, the position of the lowest point of the semi-ellipse image is as follows: It changes by about 9.7 mm depending on the formula. 50 × tan 11 ° ≈9.7 (5) The number of elements in the vertical direction at this time is 9.7 × 0.625 = 6.
Since it is 06 bits, the detection accuracy in the perspective direction is 50 / 6.06 = 8.3 mm per 1-bit element in the vertical direction.

When the position of the CCD camera is set, the angle of view becomes smaller as the camera is farther away, and the slit light image is imaged closer to an ellipse, but the depth of focus becomes correspondingly shallower, and It should be noted that the mechanical error of the installation unit for installing the camera has a great influence. Next, the operation of the measuring apparatus of this embodiment will be described. The dimensions of the measurement are as shown in Figure 1.
The imaging axis direction is the z-axis, the horizontal axis orthogonal to the imaging axis is the x-axis,
The vertical axis is defined as the y-axis.

First, the semi-ellipse image 4 imaged on the screen as shown in FIG. 3a is detected from the difference in luminance, and the image is analyzed into continuous points as shown in FIG. 3b, and each point is coordinate (x, y). Instruct. At this time, an appropriate reduction ratio is added to the coordinates (x, y) so that the coordinates (x, y) can be grasped in advance as the actual size coordinates in which the length or the size of the image is corrected in accordance with the distance. Also, FIG.
In FIG. 3b, for the sake of convenience, the entire view of the strip coil and the semi-elliptic arc-shaped image is captured in the image of the CCD camera.
It only takes an image of the 0 mm x 300 mm imaging range,
The coordinates of each point of the elliptic image imaged in this range are substituted into the elliptic equation to be approximately extended.

This coordinate system is transmitted to the microcomputer 10 having both the image processing means and the arithmetic means of the present invention. A program as shown in FIG. 4 is stored in advance in the microcomputer 10, and various numerical values are calculated according to the program as follows. First, in step S1, the coordinates (x ₁ , y ₁ ) (x ₂ ,
y ₂ ) (however, in principle y ₁ = y ₂ ) is read, then the process proceeds to step S2, in which the median value x _c of both end points is calculated from both x coordinates based on the following equation 6, and Read the y-coordinate y _c corresponding to the median x _c .

X _c = (x ₁ + x ₂ ) ... (6) This median (x _c , y _c ) represents the lowest pole of the short axis of the semi-ellipse image, that is, its position is the strip coil. Of the outer peripheral surface of the coil is closest to the image pickup side, and at the same time, it also serves as the central axis coordinate of the coil in the x-axis direction. Next, in step S3, the distance L from the light source to the point closest to the imaging side on the outer peripheral surface of the strip coil is calculated based on the following equation (7).
To calculate.

L = (y _c + H ₁ ) / tan θ (7) Next, in step S4, the outer diameter d of the strip coil measured before this step is input and the radius r thereof is input.
To calculate. Next, the process proceeds to step S5, and the positional deviation amount dx of the strip coil in the x-axis direction is calculated from the x-coordinate x _{c of the} median value. In this embodiment, the x = 0 axis,
That is, since the y-axis is a vertical axis that passes through a predetermined position where the strip coil is to be installed, the x-coordinate x _c indicates the direction and amount of the axis deviation of the coil as it is.

Next, in step S6, the positional displacement amount dz of the coil in the z-axis direction is calculated from the distance L to the strip coil and the radius r of the coil. In this embodiment, the direction and amount of deviation can be obtained by subtracting the distance 3000 mm between the light source and the predetermined position from the sum of the distance L and the radius r. In this program, steps S1 to S3 correspond to the image processing means of the present invention, and steps S4 to S6 correspond to the computing means.

When an actual strip coil having an actually measured outer diameter of 1658 mm was measured using this position measuring device, d was measured with respect to an actually measured position displacement amount of 14 mm in the x-axis direction.
x = 15.1 mm, measured position shift amount 39 m in z-axis direction
A numerical value of dz = 42.5 mm with respect to m was obtained. It can be understood that the error of these numerical values is sufficiently within the allowable range, considering that the allowable error of the grip portion of the transfer device such as a crane is 25 mm.

In this embodiment, the median value of both end points in the long axis direction of the semi-ellipse image is the pole coordinates in the short axis direction. However, the method of calculating the pole coordinates is not limited to this, and for example, The point at which the half-ellipse image and the horizontal line intersect at one point may be the pole point, and its coordinates may be the pole point coordinates. Further, although the optical axis is set to be inclined from the lower side to the upper side with respect to the axis of the coil, the optical axis may be inclined from the upper side to the lower side with respect to the coil axis. Further, although the imaging axis is set to be orthogonal to the axis of the coil, the imaging axis does not coincide with the optical axis, and the ellipse image can be captured within a range where the optical axis and a point at a predetermined position are located. Any shape may be used as long as it is within the plane including the above. That is, if the slit light is projected on the outer peripheral surface of the strip coil and the image is picked up from a position different from the light source, the image should always appear in an elliptic arc shape. If this elliptic image can be picked up, For example, the same effect as described above can be obtained by projecting slit light on the outer peripheral surface of the coil so as to be orthogonal to the axis of the coil and capturing the image obliquely from below (the position where the light source is in FIG. 1). .. However, it is necessary to sufficiently consider the effects of the depth of focus and mechanical error described above.

Furthermore, although only the measurement of the displacement of the strip coil is described in detail in this embodiment, the present invention can be similarly used for any other circular cross-section objects which do not completely absorb light.

[0029]

As described above, according to the method for measuring the position of a circular cross-section object and the measuring apparatus for the same according to the present invention, for example, a slit having a wide width in the direction orthogonal to the axis of the strip coil and a narrow width in the axial direction. The light is projected from the light source onto the outer peripheral surface of the strip coil, the image thereof is imaged in a semi-elliptic arc shape at a position different from the light source, and the deviation amount of the center position of the coil from the predetermined position is obtained from the semi-elliptic image. Since it is calculated, it is not necessary to measure two points or two times on the outer peripheral surface of the coil as in the conventional method, and it can be used anywhere regardless of the environment and conditions. Furthermore, the structure is simple and the cost is low. It will be cheap.

[Brief description of drawings]

FIG. 1 is a perspective view showing a schematic configuration of a measuring method and a measuring apparatus of the present invention.

2A and 2B are explanatory views of the principle of the measuring method and the measuring apparatus of the present invention, in which FIG. 2A is a front view and FIG. 2B is a side view.

FIG. 3 is an explanatory diagram of image analysis in the measuring method and the measuring apparatus of the present invention.

FIG. 4 is a flowchart showing an example of a program used in the measuring method and the measuring apparatus of the present invention.

[Explanation of symbols]

 1 is a strip coil 2 is a light source 3 is a CCD camera (imaging means) 10 is a microcomputer (image processing means)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yutaka Naruse 1-chome, Mizushima Kawasaki-dori, Kurashiki-shi, Okayama Prefecture (no address) Inside the Mizushima Steel Works, Kawasaki Steel Co., Ltd. Chome (No street number) Inside Kawashima Steel Co., Ltd. Mizushima Steel Works (72) Inventor Toshio Onishi 1st street, Mizushima Kawasaki Road, Kurashiki City, Okayama Prefecture (No street) Inside Kawashima Steel Co., Ltd. Mizushima Steel Works

Claims (1)

Claim: What is claimed is: 1. A method of measuring a position of a circular cross-section object, wherein a displacement amount from a predetermined position of a circular cross-section object having a circular cross-section outline with respect to the axis is measured. On the other hand, a slit light having a wide width in the orthogonal direction and a narrow width in the axial direction is projected from the light source onto the outer peripheral surface of the object, and an image of the slit light appearing on the outer peripheral surface of the object is imaged in an elliptic arc shape. A method for measuring the position and outer diameter of an object having a circular cross section, wherein the center position of the object is obtained from an elliptic arc image. 2. A position measuring device for a circular cross-section object for measuring the amount of displacement of a circular cross-section object from a predetermined position, the cross-section of which is circular in cross-section with respect to the axis, and which is wide in a direction orthogonal to the axis of the circular cross-section object. A light source that projects narrow slit light in the axial direction onto the outer peripheral surface of the object, and an image of the slit light that appears on the outer peripheral surface of the object, including the optical axis of the slit light and the point at the predetermined position. A position measuring device for a circular cross-section object, comprising: an image pickup means for picking up an elliptical arc at a position different from the light source of the slit light in a plane and an image processing means for picking up the image.