JPH0536724B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a shape detection device that can accurately detect the edge of a steel plate by applying image processing technology.

BACKGROUND TECHNOLOGY Steel plate shape detection devices that apply image processing technology have become popular in recent years, but when detecting the shape of a steel plate, it is basic to first detect the edges of the steel plate. Edge detection methods include a binarization method in which a video signal is binarized using a threshold and edges are detected by turning it on and off, and a differential method in which edges are detected by differentiating the video signal. Binarization methods include a fixed threshold method that uses a constant fixed threshold, and a p-tile method and a mode method that change the threshold depending on the object.

FIG. 4 is a diagram showing an example of a conventional method for detecting edges of a steel plate using a binarization method. This method is disclosed in Japanese Patent Application Laid-open No. 77406/1983, and is a method for accurately determining the shear position at the end of a board using a transmission type board width gauge.

In this example, a rod-shaped light source 23 is provided below the steel plate 1 being conveyed and irradiates backlight along the width direction of the steel plate 1, and a one-dimensional light source 23 is provided above the steel plate conveyance path. The image sensor 24 periodically detects an image of the steel sheet 1 in the sheet width direction. The output of this one-dimensional image sensor 24 is input to a signal processing device 25, and edge data corresponding to the position of the steel sheet 1 in the sheet width direction is obtained.

On the other hand, a pulse generator 27 is provided which detects the amount of rotation of the measuring roll 26 and outputs a pulse signal according to the amount of movement of the steel plate 1.
5 and the output of the pulse generator 27, the computer 28 determines the irregular shape of the edge of the steel plate according to the edge data output from the signal processing device 25 and the movement information of the steel plate 1 output from the pulse generator 27. ,
The shearing position at the end of the steel plate is determined, and a shearing command is output to the shearing device 29 at a predetermined timing.

The shearing devices 29 each include shearing blades 30A.
It consists of a pair of drums 30, a shear motor 31, and a shear motor control device 32.

In this example, the calculator 28 calculates the shape of the edge of the steel plate obtained by a set of edge data spanning both sides of the solid-state image sensor at the center position in the one-dimensional image sensor 24 corresponding to the center position of the steel plate 1 in the width direction. The sheet width is determined from the information, and the shearing position at the end of the steel sheet is determined.

In this way, when the plate width is determined from the edge of the steel plate obtained by the set of edge data spanning both sides of the solid-state image sensor at the center position in the one-dimensional image sensor 24, noise caused by scale deposits etc. around the steel plate can be determined. The board width can be measured without being affected.

Problems to be Solved by the Invention However, the method for detecting edges of a steel plate whose edges are based on the assumption that there are edges on the left and right sides of the center of the steel plate, which roughly corresponds to the edge data, is Under adverse environmental conditions, edges can be detected without error if there is rough noise, but if there is complex noise near the edge or the surface of the steel plate is uneven, the edge may be detected incorrectly. It was hot.

Furthermore, as shown in FIG. 5, if the tip of the steel plate 1 has a so-called fish tail shape, and one fin part 1A straddles the center line 1B of the steel plate,
There was a problem in determining the width of the fin portion 1A as the plate width.

In addition, in the case of a transmission type detection method as shown in Fig. 4, since a part of the device, that is, a light source, is provided below the conveyance roller, there are maintenance problems due to dirt or damage to the light source, etc. The point was hot.

SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to solve the above-mentioned conventional problems and provide a steel plate shape detection device that can accurately detect both edges of a steel plate without being affected by noise on or around the steel plate.

Means for Solving the Problems The inventor of the present invention focused on the fact that the distance between both edges detected by a shape detection device should approximately correspond to the width of the steel plate, As a detection method, using a one-dimensional or two-dimensional imaging device,
When detecting the shape of a part including the leading or trailing edge of a steel plate, the approximate center of the obtained two-dimensional target image is selected from among the binarized steel plate edge detection points in the width direction of the plate that contain noise. We have reached the knowledge that the original edge of a steel plate can be detected by selecting an edge detection point that approximately matches the known plate width value.

The present invention was completed as a result of research based on such knowledge, that is, according to the present invention,
an imaging device that scans above a steel plate moving along a conveyance path in the width direction of the steel plate to image the steel plate and outputs an analog video signal; and an imaging device that receives the analog video signal from the imaging device and binarizes the steel plate a binarization device that outputs a binarized signal representing an edge of A sheet width matching circuit that compares a detected sheet width value with a reference sheet width value, selects and outputs the edge position of the steel sheet that provides the detected sheet width value with the smallest deviation, and outputs the detected sheet width value. Equipment is provided.

Function In the steel plate shape detection device as described above, edge detection is performed by the binarization device in the same manner as in the past, and each detected plate width value based on the combination of edges detected in this way and the known The plate width standard value of the steel plate is compared, and the plate width detected by the combination of detection edges with the smallest deviation is determined to be the true measured value, and the edge detection point that provides the combination of detection edges with the smallest deviation is the true edge. is determined and output. Therefore, it is possible to accurately detect the shape of scale, steam, and non-uniformity on the surface of a steel plate, which have been detected incorrectly in the past. The one-dimensional or two-dimensional imaging device of the present invention is installed above a steel plate, and receives the self-luminous light emitted from the steel plate, or irradiates it with another light source and receives the reflected light, thereby removing dirt and dirt from the equipment. Corruption issues can be resolved.

Embodiments Hereinafter, embodiments of the steel plate shape detection apparatus according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a block diagram showing an embodiment of the steel plate shape detection apparatus of the present invention. This embodiment includes an imaging device 2, which is composed of, for example, a solid-state imaging device, which scans the steel plate 1 moving along the steel plate conveyance path in the width direction of the steel plate to take an image of the steel plate 1. The video signal from this imaging device 2 is input to a quantizer 3 and quantized. The signal quantized in this way is
The quantized video signal for at least one image is input to the temporary storage memory 4 and stored therein.

The quantized video signal stored in the memory 4 is first read out for one reference scan and input to the binarization device 5, where it is binarized.

Furthermore, a board width meter such as a photovoltaic width meter or a board width indicator 6 for providing known board width reference value information is provided upstream of the imaging device 2 .

The strip width standard value and the binarized signal at the reference position from the binarization device 5 and strip width indicator 6 described above are input to the strip width matching circuit 7, and the rising edge of the binarized signal (indicating the left edge) is input to the strip width matching circuit 7. ) and falling (indicates right edge)
The board widths obtained from all combinations are compared with the board width reference value, and the combination of edge detection points with the minimum deviation value is output.

The output of the sheet width matching circuit 7 is output to the shape calculator 8, and the shape calculator 8 converts the detected left and right edges of the steel sheet into binary signals on the adjacent scanning lines on the image. The edge signal at approximately the same position as the true edge is taken as the true edge, and by sequentially repeating this scanning to other scanning lines, the steel plate edge position of the entire image is processed and the camber, crop shape, flatness, etc. of the steel plate are calculated. to decide.

Next, with reference to FIG. 2, the operation of the above-described steel plate shape detection apparatus according to the present invention will be explained.

FIG. 2a shows the steel plate 1 detected by the imaging device 2.
This is an image of the end of the steel plate 1, showing that steel plate scale 9, steam 10, or scale deposits 11 are present on and around the steel plate 1. In addition, straight line 12
indicates the current scanning line of the imaging device 2 in the board width direction.

When the imaging device 2 captures the above image,
The reference video signal for one scan outputted by the imaging device 2 is, for example, as shown in FIG. 2b.
In FIG. 2b, the vertical axis indicates the intensity distribution v with respect to the length l in the board width direction of the image being scanned.
The scale 12 shows the same strength as the original steel plate 1, and the steel plate scale 9 reduces the strength from the steel plate 1, both of which cause edge detection errors.

The quantizer 3 converts the above video signal into, for example, a 6-bit or 8-bit digital signal and outputs it to the memory 4. Then, the binarization device 4 performs first differentiation on the quantized signal representing the values shown in FIG. 2b to obtain a differentiated waveform as shown in FIG. Slice it at appropriate slicing levels L ₁ and L ₃ ,
A binary signal as shown in FIG. 2e is output.

This binarization device obtains an intensity histogram of a quantized signal, determines a threshold value TH from the intensity distribution, and slices the quantized signal using the threshold value to produce a binarized signal as shown in Figure 2e. It may also be converted.

FIG. 2d shows the intensity histogram of the video signal of FIG. 2b, which is the basis of such histogram binarization method, that is, the appearance frequency N of each feature value of intensity v.
and a threshold value. As a general way to choose a threshold, if the intensity histogram shows diabeticity,
The valley is detected and the value of this valley is set as the threshold value TH.

The binary signal obtained in the above manner is input to the board width matching circuit, and the deviation of all combinations of the address on the scanning line of each left edge and the address on the scanning line of each right edge is calculated. A deviation as shown in FIG. 2g is determined and compared with a board width reference value as shown in FIG. 2f from the board width indicator 6 to determine the deviation. Then, the combination of the address on the left edge scanning line and the address on the right edge scanning line with the smallest deviation as shown by the circle in Figure 2g is selected, and the combination shown in Figure 2h is selected. A left edge address and a right edge address indicating the plate width are output to the shape calculator 8.

From FIG. 2e, it can be seen that the width of the steel plate is divided due to the steel plate scale 9, and the width of the steel plate is expanded due to the scale deposits 11, which may cause erroneous edge detection. Therefore, in addition to the original board width detection value, there is a possibility that five incorrect board width values may be detected as shown by the x marks in FIG. 2g. However, in the above-mentioned steel sheet shape detection device, the five incorrect sheet width values as shown by the cross marks are determined to be the correct sheet width by comparison with the standard sheet width value from the sheet width indicator 6. There's nothing to do.

FIG. 3 is a block diagram showing an example of the configuration of the plate width matching circuit 7 of the above-described steel plate shape detection apparatus.

The plate width matching circuit 7 shown in the figure is a binarization device 5.
It has an ON gate counter 13 that receives a binary signal from the digitized signal and counts up at the rising edge of the binary waveform indicating the left edge of the binary signal, and each stage of the ON gate counter 13 One input of AND gates 14A to 14N is connected to the output of . Those AND gates 14A~1
The other input of 4N is applied with scan clocks, each clock corresponding to a pixel on one scan line.

The output of each AND gate 14A to 14N is ON
It is connected to the count inputs of counters 15A to 15N, respectively. Therefore, ON count 15A
starts counting when the AND gate 14A opens, that is, from the rising edge of the binarized waveform indicating the first left edge of the binarized signal. and,
The ON count 15B starts counting when the AND gate 14B opens, that is, from the rising edge of the binarized waveform indicating the second left edge of the binarized signal.

Each of the ON counters 15A to 15N is provided with an ON address memory 16A to 16N that receives a scanning address signal indicating a scanning position in the width direction of the steel plate. Those ON address memories 16A to 16
N stores the scanning address when the attached ON counter starts counting, that is, becomes ready for counting.

The count output of each ON counter 15A-15N is connected to one input of a comparator 17A-17N provided for each ON counter.
The board width reference value that is constantly given from the board width indicator 6 is input to the other inputs of these comparators 17A to 17N.

The output of each comparator 17A-17N is connected to minimum deviation memory 18A-18N provided for each comparator.

Further, an OFF gate 19 is provided which receives the binarized signal from the binarizer 5 and outputs a gate pulse corresponding to the falling edge of the binarized waveform indicating the right edge of the binarized signal. , the minimum deviation value memories 18A to 18N take in the outputs of the comparators 17A to 17N only when receiving the gate pulse from the OFF gate 19. Then, when the minimum deviation value memories 18A to 18N are in a cleared state, the minimum deviation value memories 18A to 18N are directly connected to the comparator 17A.
The output is stored from ~17N, and if it is already stored, the memory is updated when the newly acquired deviation is smaller than the already stored deviation,
On the contrary, it is designed to maintain memory when it is large.

Each minimum deviation memory 18A to 18N includes an OFF address memory 20 that receives a scanning address signal.
A to 20N are provided. The OFF address memories 20A to 20N store the scan addresses when the attached minimum deviation value memory is stored from the clear state and when the memory is newly updated.Furthermore, the output of the minimum deviation value memory 18A to 18N and the ON The outputs of the address memories 16A to 16N and the outputs of the OFF address memories 20A to 20N are connected to the minimum value selection storage circuit 21, and when a scanning end signal indicating the end of one scanning line is input,
It is taken into the minimum value selection storage circuit 21. Then, the minimum value selection storage circuit 21 selects the minimum value among the values stored in the total deviation minimum value memories 18A to 18N, and selects the minimum value from the ON address memory of the series of deviation minimum value memories storing the minimum value. Stores the output of OFF address memory.

The minimum value selection storage circuit 21 is connected to an output circuit 22 that outputs an ON address and an OFF address that provide the minimum deviation value.

The plate width matching circuit configured as described above operates as follows.

For example, if the binary signal shown in Figure 2e is
Assuming that it is input to the ON gate counter 13 and the OFF gate 19, the binarized waveform A shown in FIG.
ON gate counter 13 becomes "1" at the rising edge of
As a result, the AND gate 14A whose "1" output is connected to the input opens,
ON counter 15A starts counting the scan clock. At the same time, ON address memory 1
6A stores the scanning address at that time, for example, "0009". However, ON counter 15B to 15N
The counting operation has not yet started.

Thus, when the falling edge of the binary waveform A shown in FIG. 2e is applied to the OFF gate 19, the output of the comparator 17A at that time is taken into the minimum deviation value memory 18A. Now, assuming that the plate width standard value is "0900" and the count value of the ON counter 15A at that time is "0300", the comparator 17A and "0600" are output, and the minimum deviation value memory 18A is stored in the comparator 17A. Capture and store the output "0600". Then, the OFF address memory 20A stores the scanning address at that time, for example, "0309". but,
Other minimum deviation values memories 18B to 18N are
I don't remember anything new.

Next, at the rising edge of the binarized waveform B shown in FIG. 2e, the ON gate counter 13 counts to "2", and as a result, the AND gate 14B whose "2" output is connected to the input opens. , ON counter 15B starts counting the scanning clock. At the same time, the ON address memory 16B stores the scan address at that time, for example, "0659". On the other hand, ON counters 15C to 15N have not started counting operations yet.

Then, when the falling edge of the binarized waveform B shown in FIG.
The output of B is taken into the minimum deviation value memory 18B.

If the count value of the ON counter 15A at that time is "0910", then the comparator 17A outputs "0010" and the minimum deviation value memory 1
8A is the output of comparator 17A "0010"
Compare this with the already memorized "0600" and update your memory to the smaller one, "0010." Then, the OFF address memory 20A updates the memory to the scanning address at that time, for example, "0919".

On the other hand, if the count value of ON counter 15B at that time is "0310", then comparator 17B
outputs "0590" and stores the minimum deviation value memory 18B.
takes in the output "0590" of the comparator 17B and stores it. Then, the OFF address memory 20B stores the scan address at that time, for example, "0919".

However, other minimum deviation memory 18C~
18N does not store anything new.

Further, at the rising edge of the binary waveform C shown in FIG. ) opens,
ON counter 15C (not shown) starts counting the scan clock. At the same time, the ON address memory 16C (not shown) stores the scan address at that time, for example, "0989". However, the counting operation of ON counters 15D to 15N has not yet started.

After that, when the falling edge of the binarized waveform C shown in FIG. 2e is applied to the OFF gate 19, the outputs of the comparators 17A, 17B and 17C at that time
are incorporated into each.

If the count value of the ON counter 15A at that time is "1000", then the comparator 17
A outputs "0100" and the minimum deviation value memory 18A
compares the output "0100" of the comparator 17A with the already stored "0010", and since the current deviation is larger, the previous memory "0010" is maintained and the memory is not updated. In this way, since the memory in the minimum deviation value memory 18A is not updated, the OFF address memory 20A maintains the previous scanning address "0919".

If the count value of the ON counter 15B at that time is "0350", then the comparator 17B
outputs "0550" and stores the minimum deviation value memory 18B.
compares the output "0550" of the comparator 17B with the already stored "0590" and updates the memory to the smaller one, the current "0550". and,
The OFF address memory 20B stores the scan address at that time, for example, "1009".

Furthermore, if the count value of ON counter 15C at that time is "0020", comparator 17C
outputs "0880" and stores the minimum deviation value memory 18C.
takes in and stores the output "0880" of the comparator 17C. Then, the OFF address memory 20C stores the scan address at that time, for example, "1009".

However, other minimum deviation memory 18D~
18N does not store anything new.

After that, when the binarization pulse does not appear and the scanning end signal is input to the minimum value selection storage circuit 21,
The minimum value selection storage circuit 21 includes the minimum deviation value memory 1
8A to 18N output and ON address memory 16
A to 16N outputs and OFF address memory 20
Receives output from A to 20N. Minimum deviation memory 1
Among the deviations stored in 8A to 18N, the smallest one is "0010" stored in the minimum deviation value memory 18A;
The ON address memory 16A of series A stores "0009", and the OFF address memory stores "0919".

Thus, the output circuits are "0009" and "0919"
In response to this, the edge position on the reference scanning line is output.

The embodiments of the steel plate shape detection device according to the present invention have been described above, but as long as the processing speed is compatible with the speed required by the shearing device, the plate width matching circuit can be implemented by a computer running a program capable of performing the above operations. It may be configured.

Effects of the Invention As is clear from the above explanation, the steel plate shape detection device according to the present invention can accurately detect true edge detection points from a plurality of binary edge detection points obtained by a normal edge detection method. can be selected, and the detection accuracy can be greatly improved.

Therefore, the steel plate shape detection device according to the present invention has the following features:
It is possible to detect shapes accurately and with high detection accuracy, it is possible to cut the steel plate at the optimal position, which improves yield, and it is possible to speed up the cutting operation.

In addition, unlike the conventional transmission-type detection method shown in Figure 4, there is no need to provide a part of the device, that is, a light source, below the conveyance roller, so there are no maintenance problems caused by dirt or damage to the device. Nor.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the steel plate shape detection apparatus of the present invention. FIG. 2 is a diagram illustrating the edge detection principle in the present invention. Third
The figure is a block diagram showing a configuration example of a board width matching circuit according to the present invention. FIG. 4 is a diagram illustrating a conventional method for detecting edges of a steel plate. FIG. 5 is a schematic diagram showing an example of a fishtail-type tip shape of a steel plate. (main reference number), 1... steel plate, 2... imaging device,
3... Quantizer, 4... Primary storage memory, 5... Binarization device, 6... Board width indicator, 7... Board width matching circuit, 8... Shape calculator, 13... ON gate counter, 14A to 14N... AND Gate, 15A~1
5N...ON count, 16A~16N...ON address memory, 17A~17N...comparator, 1
8A~18N...Minimum deviation memory, 19...OFF
Gate, 20A~20N...OFF address memory,
21... Minimum value selection storage circuit, 22... Output circuit, 2
3... Rod-shaped light source, 24... One-dimensional image sensor, 2
5... Signal processing device, 26... Measuring roll,
27... Pulse generator, 28... Computer, 29... Shearing device.

Claims (1)

[Claims] 1. An imaging device that scans from above a steel plate moving along a conveyance path along the width direction of the steel plate to image the steel plate and outputs an analog video signal, and an analog video signal from the imaging device. a binarization device that receives and binarizes the signal and outputs a binarized signal representing edges of the steel plate; and a binarization device that receives the binarized signal from the binarization device and detects a plurality of edges obtained from the binarized signals. A plate width matching circuit that compares a plurality of detected plate width values indicated by the combination of points with a reference plate width value, selects and outputs the edge position of the steel plate that provides the detected plate width value with the minimum deviation. Characteristic steel plate shape detection device. 2 The board width matching circuit calculates the difference between each address on the scanning line of the binary signal indicating the left edge and each address on the scanning line indicating the right edge among the binary signals from the binarizing device. 2. The steel plate shape detection device according to claim 1, wherein the steel plate shape detection device calculates the width of the steel plate and outputs the combination of the left edge address and the right edge address that have the smallest difference from the reference plate width. 3. The board width matching circuit includes an ON gate counter that counts a binarized signal indicating a left edge of the binarized signal from the binarizer, and
A plurality of ON counters that are placed in a countable state by the output of one stage of the gate counter and count the scanning clock, and a plurality of ON counters that are attached to each ON counter and receive a scanning address signal, and the ON counter is placed in a countable state. An ON address memory that stores the scanning address at the time of turning, a comparator that is attached to each ON counter and that compares the output of that ON counter with the board width reference value and outputs the deviation, and an attached to each comparator. The deviation output from the comparator is taken in when a binarized signal indicating the right edge of the binarized signal from the binarizing device is received, and when it is smaller than the previous stored value, the deviation is taken in. and an OFF address memory that is attached to each minimum deviation memory and receives a scanning address signal and stores the scanning address when the minimum deviation memory updates its stored value. , receives the output of each minimum deviation memory, each ON address memory, and each OFF address memory, selects the minimum value among the values stored in the total deviation minimum value memory, and selects the minimum value of the deviation that stores the minimum value. A minimum value selection storage circuit that selects and stores the outputs of the ON address memory and OFF address memory of the value memory series, and an output that is connected to the minimum value selection storage circuit and outputs the ON address and OFF address that give the minimum deviation value. 3. The steel plate shape detection device according to claim 2, further comprising a circuit.