JP2001012920A - Shape detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extract the edge position and a desired detecting point on a material to be measured accurately by storing the shape of measured projection light in correspondence with the receiving intensity of projection light at each position. SOLUTION: A laser projector 4 projects slit-like light 6 onto a material 1 to be measured and a two-dimensional CCD camera 5 picks up an image 7 where only the part 8 of the slit light is bright. An image processor 9 takes in and processes that image 7. More specifically, a one frame image is stored in an image memory 10, a binarization operating unit 11 extracts only such pixels as exceeding a threshold brightness level and a fine line processor 12 converts an obtained slit light image 13 into fine lines 14 of 1 pixel width. A pixel position extractor 15 extracts the coordinate position of each pixel, a brightness level extractor 16 extracts the brightness level of each pixel from the original image in the image memory 10 and a memory 17 stores the brightness level in correspondence with the coordinate position which are then fetched in an edge position processor 20 in order to extract the edge position of the shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shape detecting device for measuring the shape of a steel plate or the like.

[0002]

2. Description of the Related Art A shape measuring technique for a steel sheet is used in a sheet width measuring device and the like. For those widely used,
There is an edge position detection technology. In this method, a light source is arranged below a steel plate, and a light-receiving element having a large number of elements capable of measuring the received light intensity arranged linearly in the width direction of the plate is arranged above the steel plate to detect the most edge portion where the steel plate blocks light. The technique measures the board width by detecting the most edge portions at both ends of the board width. Japanese Patent Application Laid-Open No. Sho 62-16415 describes a method of irradiating a laser beam and detecting an edge position using the intensity of light reflected from a material to be measured.

[0003] Alternatively, as a technique for measuring the shape of a hot-rolled steel sheet, there is a technique described in JP-A-3-53650. In this method, in order to measure the shape of the hot-rolled steel sheet, the shape defect of the side edge is detected by using the intensity of the reflected light from the material to be measured with respect to the light from the light projector.

[0004]

However, in the case of a thick steel plate bulging in the width direction at the edge portion, in the width measuring device, the most bulging edge portion (hereinafter referred to as the outermost edge position) in the above-mentioned conventional method. ) Is detected, so that there is a disadvantage that the width of the portion where the plate thickness is constant, that is, the width of the surface is measured by an extra amount corresponding to the bulge. The size of the bulge varies greatly depending on the thickness of the plate, and it is difficult to measure the width of the portion where the thickness is constant.

In the technique of detecting a defective shape portion, the reflection intensity distribution at the side edge portion varies depending on the roughness of the surface of the hot-rolled steel sheet, the variation in the reflection intensity due to the adhered substance, and the inclination of the steel sheet. Then, there was a problem that it was difficult to use.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a shape detecting apparatus capable of accurately extracting an edge position on a material to be measured and a desired detection point. That is, the present invention provides the following means.

The first shape detecting device is a shape detecting device for detecting the shape of the material to be measured, and includes means for projecting light onto the surface of the material to be measured, means for measuring the shape of the projected light, The apparatus includes means for measuring the intensity of the received light at each position of the measured projection light, and means for storing the measured shape of the projection light and the intensity of the projection light at each position in association with each other. It is characterized by the following.

The second shape detecting device is a shape detecting device for detecting the shape of the material to be measured, and includes means for projecting light onto the surface of the material to be measured, means for measuring the shape of the projected light, Means for measuring the received light intensity of light at each position of the measured projection light, means for calculating the surface shape of the material to be measured from the shape of the measured projection light, and the calculated surface shape and each Means for storing the received light intensity of the projection light at the position in association with the received light intensity.

[0009] A third shape detecting device is characterized in that, in the first or second shape detecting device, the projected light is slit-shaped light.

The fourth shape detecting device is characterized in that, in the second or third shape detecting device, a method of calculating the surface shape of the material to be measured from the measured shape of the projection light is a light cutting method. It is assumed that.

The fifth shape detecting device includes first, second, third
Alternatively, in the fourth shape detection device, the position or shape of the edge portion is determined based on the shape of the projection light or the calculated surface shape of the material to be measured and the information on the intensity of the received light of the projection light at each position of the shape. It is characterized by comprising a signal processing device for extracting.

A sixth shape detecting device is characterized in that the signal processing device of the fifth shape detecting device includes a plurality of shape change point candidates based on the shape of the projection light or the calculated shape of the surface of the material to be measured. It is characterized by comprising a means for extracting points and a means for detecting an edge position based on information on the intensity of received light from among the candidates for the shape change point.

A seventh shape detection device is a signal processing device of the fifth shape detection device, wherein the signal processing device extracts a plurality of shape change point candidates based on the received light intensity information, and the shape change point candidate And means for detecting an edge position based on the information on the shape of the projection light or the calculated shape of the surface of the material to be measured.

The eighth shape detecting device is a means for extracting a plurality of candidate points that can be shape changing points on the material to be measured based on the information on the shape of the measured projection light in the first shape detecting device. And means for extracting the shape change point from the plurality of candidate points based on the information on the received light intensity.

The ninth shape detecting device is a means for extracting a plurality of candidate points which can be light receiving intensity change points on the material to be measured based on the received light intensity information in the first shape detecting device, Means for extracting the light receiving intensity change point based on the information on the shape of the measured projection light from the candidate points.

A tenth shape detecting device according to the second shape detecting device, extracts a plurality of candidate points that can be shape change points on the measured material based on the calculated information on the surface shape of the measured material. And a means for extracting the shape change point from the plurality of candidate points based on the information on the received light intensity.

An eleventh shape detecting device according to the second shape detecting device, means for extracting a plurality of candidate points which can be light receiving intensity change points on the material to be measured, based on the received light intensity information, Means for extracting the light receiving intensity change point based on the calculated information on the surface shape of the material to be measured from among the candidate points described above.

In the present invention, the shape change point on the material to be measured refers to a boundary point of a portion where the shape of the projection light changes, and includes a concept including an edge position of a portion having a constant plate thickness and an edge position of the extreme end. It is.

In the present invention, the point of change in the received light intensity on the material to be measured is a portion where the intensity of the reflected light from the material to be measured changes,
For example, it refers to a boundary point between a shape change portion, a color change portion, and the like, and is a concept including an edge position of a portion having a constant thickness and an edge position of an endmost portion.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating an overall configuration of a shape detection device according to the present embodiment. In FIG. 1, reference numeral 1 denotes a material to be measured, and the width direction of the material to be measured is a y coordinate, and the thickness direction is a z coordinate. The shape detection device 2 of the present embodiment detects the position and shape of an edge portion of a material to be measured. The shape detecting device 2 is provided with a laser projector 4 as means for projecting light, and a two-dimensional CCD camera 5 as means for measuring the shape of the projected light. A cylindrical lens is provided at the tip of the laser projector 4, and projects the slit-shaped light 6 on the material to be measured. The projection angle is θ. In the two-dimensional CCD camera 5, fine pixels are arranged in a grid pattern, and the intensity of light can be detected for each pixel, and the light receiving intensity of the measured projection light at each position can be measured. Yes, measured material 1
Is disposed directly opposite to the surface of the. As shown in FIG. 7, the image obtained by the two-dimensional CCD camera 5 has a bright portion 8 of the slit light, and the other portions are dark images. The image processing device 9 captures this image and performs an operation. In the image processing device 9, first, an image of one frame is recorded in the image memory 10, and thereafter, a binary arithmetic operation for extracting only pixels having a certain threshold or more with respect to the luminance level of each pixel is performed. The processing unit 11 performs the processing. Subsequently, the thinning processing operation unit 12 obtains the center pixel in the vertical direction of the screen for the image 13 obtained as a result of the binarization operation unit 11, and converts the slit light image into a thin line 14 having a width of 1 pixel. Next, the pixel position extraction calculator 15 extracts the coordinate position on the camera plane of each pixel obtained as a result of the thinning processing calculator 12.

On the other hand, the luminance level extraction calculator 16 extracts the luminance level of each pixel obtained from the original image recorded in the image memory 10. Alternatively, in order to further secure the reliability, among the pixels extracted by the binarization arithmetic unit 11, the average luminance of several points near the pixel obtained as a result of the pixel position extraction arithmetic unit may be obtained. The memory device 17 includes a pixel position extraction operation unit 15 and a luminance level extraction operation unit 16
The coordinate position and the brightness level on the camera plane obtained by the above are stored in association with those obtained from the same pixel.
That is, the measured shape of the projection light and the intensity distribution of the projection light at each position thereof are stored in association with each other.

Further, the coordinate calculator 18 is a device for calculating the surface shape of the material to be measured from the shape of the projection light, and each pixel stored in the memory device 17 is obtained by using a light cutting method (light projection method). Are converted into coordinates in the yz coordinate system of the material to be measured according to the principle formula of triangulation, and the memory device 19 stores the result in association with the original corresponding luminance level.

From the above processing, the coordinates (y, z) of the slit light projection portion and the reflected light intensity p at this point are obtained, and the position information (y, z) and the intensity information (p) are obtained at the edge portion. Is taken into an edge position calculation processing device 20 which is a signal processing device for extracting the position or the shape of. Alternatively, when accurate (y, z) is not required, the coordinates on the camera plane directly stored in the memory device 17 may be used instead of (y, z). In the drawing, the connection status of the devices in this case is indicated by a dotted line connecting the memory device 17 to the edge position calculation processing device. When the measurement points P ₁ (y ₁ , z ₁ , p ₁ ) to P _N (y _N , z _N , p _N ) are plotted on a graph, the shape of the edge of the material to be measured and the reflection intensity at that position Are the curves 21 and 2 shown in FIG.
It is measured as 2. Here, the curve 21 shows the position of the material to be measured in the y direction on the horizontal axis, the position in the z direction on the vertical axis, and the curve 22 shows the received light intensity on the vertical axis, and P (y, z, p).
Is divided into PZ (y, z) and PP (y, p) for display.

When the reflected light of the slit light on the smooth metal surface is represented by a vector whose intensity is a length, an elliptical intensity distribution having the maximum regular reflection direction is obtained. That is, in FIG. 3, at the position A of the plane portion, the shape becomes like an ellipse A, and at the position B of the edge portion, the shape becomes like an ellipse B. Accordingly, a relatively large amount of light reaches the CCD light receiving element 24 through the camera lens 23 at the central portion of the steel plate (position A).
At the edge portion, most of the reflected light is diffused in a direction in which the sensor cannot receive light, so that the amount of light reaching the camera lens 23 is small, and the light receiving intensity observed by the CCD light receiving element 24 is smaller than the position A. Become. Further, even when the laser beam is separated from directly below the camera lens 23 on the side opposite to the edge portion (left side in the figure), the amount of light reaching the camera lens 23 is similarly reduced. In other words, the intensity of the reflected light observed on the entire surface of the steel plate is as indicated by the curve 22 for each position in the y direction of the material to be measured. The edge position calculation processing device 20 stores the waveforms of the curves 21 and 22 and performs an arithmetic process on the waveform to detect the edge position 3.

Next, an example of signal processing for edge position detection executed by the edge position arithmetic processing unit 20 will be described with reference to FIG. This signal processing is realized as software executed in the edge position calculation processing device 20. First, a case where the edge position 3 of a portion where the thickness of the surface of the workpiece 1 is constant is detected will be described. In FIG. 4, the ● marks and + marks indicate the y of the material to be measured, respectively, as in the curves 21 and 22 in FIG.
The coordinates of the direction and the vertical axis are z and the received light intensity p, respectively, and the shape stored in the memory device 19 and the measured value of the received light intensity (point N) are plotted. PZ ₁ (y ₁ , z ₁ ), PZ ₂ (y ₂ , z ₂ ), ...
PZ _n (y _n , z _n ),... PZ _N (y _N , z _N ) and PP ₁ (y ₁ , p ₁ ), P
P ₂ (y ₂ , p ₂ ),... PP _n (y _n , p _n ),... PP _N (y _N , p _N ).

First, a difference value d _n = z _n −z _{n + 1} in the z direction between two points is calculated for PZ _{1 to} PZ _N , and PD _m (m = 1 to
N-1) (y _n, the d _n) in FIG. 4, plotted vertical axis d, a horizontal axis y. Next, five points are taken as candidate points in order from the one having the largest value of d _{1 to} d _N−1 , and these are taken as d _m1 , d _m2 ,
d _m3, and d _m4, d _m5. In the case of FIG. 4, m1 = N-1, m
2 = N-2, m3 = N-3, m4 = N-20, m5 = N
-29.

Then, PP _m1 , PP _m2 , PP _m3 , P
P _m1 , p _m2 , p _m3 , p which are p elements of P _m4 and PP _m5
Selecting the largest of _m4, p _m5, p than plot the results of the PP _m3 = p _N-3 is the maximum value. The position of the _N-3rd point PZ _N-3 (y _N-3 , z
_N-3 ) is the edge position of the part where the thickness of the material to be measured is constant.

Next, a description will be given of a method for detecting the edge position of the end of the material to be measured. For example, assuming that there is a gantry behind the material to be measured and that the reflected light is received by the CCD camera, the reflection from these gantry is generally lower than the reflection intensity from the material to be measured, and PP ′ in FIG. , PZ '. Therefore, if the luminance threshold value TH is set to an appropriate value as shown in FIG. 4 for PP _n (y _n , p _n ), measurement points PP ′ and PZ ′ that are not on the material to be measured can be removed. By taking the maximum position in the y direction from the remaining points P _{1 to} P _N, it is possible to detect the end edge position of the material to be measured. That is, first, a plurality of shape change point candidates to be obtained are extracted by processing the received light intensity information using a threshold value, and then, from these candidate points, the end edge based on the shape information is extracted. The position (point PZ _N ) can be detected.

According to the above embodiment, the slit-shaped light is projected onto the material to be measured, and the shape of the projected light is measured.
Further, the received light intensity at each position of the projected light is measured and stored. Based on the coordinate system of the image obtained by thinning the measured projected light or the calculated coordinate system of the surface shape of the material to be measured, two adjacent points are measured. By using the difference value in the thickness direction of the measurement target material and the received light intensity, the edge position of the portion where the thickness of the measurement target material is constant can be reliably detected. Thereby, even in the case of a thick steel plate whose edge portion is bulged in the width direction, it is possible to reliably measure the width of the portion where the thickness is constant. Further, by using the information of the received light intensity processed using the threshold value and the coordinate system of the thinned image or the coordinate system of the surface shape of the material to be measured, the end position of the edge can be detected.

Further, according to the above-described embodiment, the shape of the material to be measured can be accurately detected. Therefore, when a defective shape of a product such as a steel material is detected, it is incorporated into a production line to inspect the product. Can be performed.

The present invention is not limited to the above embodiment, and various modifications are possible within the scope of the invention. For example, in the above embodiment, the case where the edge position (one point) of the measured material end is detected has been described, but the present invention is not limited to this, and the edge part is detected based on the detected edge position. Another point may be detected, or the shape of the edge portion may be detected. Furthermore, in the above embodiment, the case where the edge position of the end of the measured material is detected has been described. However, the present invention is not limited to this, and the step, the protrusion, the concave portion, and the leading A welded portion of the material and the following material, or a portion having a different color may be detected. When detecting a portion having a different color, first, a plurality of candidate points are detected based on the received light intensity, and then a change point of the portion having a different color is specified based on information on the shape of the projection light. Further, the memory device 19 and the edge position processing device 20 may be configured using a personal computer.

In the above embodiment, the case where a simple difference value between two points is used has been described. However, the present invention is not limited to this, and a difference value of a differentiated value may be used. Alternatively, a difference value of the higher-order differentiated value may be used.

[0033]

According to the present invention, by using the information of the received light intensity together with the information of the shape of the projection light, the shape change point such as the edge of the material to be measured and the light received intensity change point can be more accurately than before. Can be detected.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a shape detection device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a measurement result obtained by a measuring instrument.

FIG. 3 is a view showing a state of reflection of slit light at the time of steel plate measurement.

FIG. 4 is a diagram for explaining a steel plate edge position detection signal processing method.

[Explanation of symbols]

1: Material to be measured 2: Sensor part 3: Edge position of material to be measured 4: Laser projector 5: Two-dimensional CCD camera 6: Slit-like light 7: Image obtained by two-dimensional CCD camera 8: Slit light image 9: Image processing device 10: Image memory 11: Binarization operation unit 12: Thinning processing operation unit 13: Image obtained by binarization operation unit 14: Extract central pixel of slit light image obtained by binarization operation unit 1 pixel width thin line 15: Pixel position extraction calculator 16: Luminance level extraction calculator 17: Memory device 18: Coordinate calculator 19: Memory device 20: Edge position calculation processing device 21: Measurement target material shape curve 22: Measurement target Measurement material surface reflected light received light intensity curve 23: Camera lens 24: CCD light receiving element

Claims (11)

[Claims] 1. A shape detecting device for detecting a shape of a material to be measured, means for projecting light onto a surface of the material to be measured, means for measuring the shape of the projected light, A shape comprising: means for measuring the light reception intensity of light at each position; and means for storing the measured shape of the projection light and the light reception intensity of the projection light at each position in association with each other. Detection device. 2. A shape detecting device for detecting a shape of a material to be measured, a means for projecting light onto a surface of the material to be measured, a means for measuring a shape of the projected light, Means for measuring the light reception intensity of light at each position, means for calculating the surface shape of the material to be measured from the shape of the measured projection light,
Means for storing the calculated surface shape and the received light intensity of the projection light at each position thereof in correspondence with each other. 3. The shape detecting device according to claim 1, wherein the projected light is slit-shaped light. 4. The shape detecting apparatus according to claim 2, wherein the method of calculating the surface shape of the material to be measured from the shape of the measured projection light is a light cutting method. 5. A signal processing for extracting the position or shape of an edge portion based on the shape of the projection light or the calculated surface shape of the material to be measured and information on the intensity of light reception of the projection light at each position of the shape. 5. The shape detecting device according to claim 1, further comprising a device. 6. A means for extracting a plurality of shape change point candidates based on information on the shape of the projection light or the calculated shape of the surface of the material to be measured, the signal processing device comprising: 6. The shape detecting apparatus according to claim 5, further comprising: means for detecting an edge position based on information on light receiving intensity from among the information. 7. The means for extracting a plurality of shape change point candidates based on the received light intensity information, and the signal processing device calculates the shape of the projection light or calculates the shape of the projection light from the shape change point candidates. Means for detecting an edge position based on information on the shape of the surface of the material to be measured.
The shape detection device according to the above. 8. A means for extracting a plurality of candidate points which can be shape change points on a material to be measured based on information on the shape of the measured projection light, and a means for extracting the received light intensity from the plurality of candidate points. 2. A shape detecting apparatus according to claim 1, further comprising means for extracting the shape change point based on information. 9. A means for extracting a plurality of candidate points that can be light-receiving intensity change points on a material to be measured based on the information on the received light intensity, and a shape of the measured projection light from among the plurality of candidate points. 2. A shape detecting apparatus according to claim 1, further comprising: means for extracting the light receiving intensity change point based on the information of (1). 10. A means for extracting a plurality of candidate points that can be shape change points on the measured material based on the calculated information on the surface shape of the measured material, and receiving the light from the plurality of candidate points. 3. The shape detecting apparatus according to claim 2, further comprising: means for extracting the shape change point based on intensity information. 11. A means for extracting a plurality of candidate points that can be light receiving intensity change points on a material to be measured based on the information on the light receiving intensity, and a method of extracting the calculated material to be measured from the plurality of candidate points. 3. A means for extracting the light receiving intensity change point based on surface shape information.
The shape detection device according to the above.