JP2545151B2 - Angle measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention is suitable for measuring, for example, the bending angle of a bent work piece or the current bending angle of a work piece under bending work. The present invention relates to an angle measuring device.

(Prior Art) Conventionally, for example, when measuring a bending angle of a bent work, it is common to inspect the work by applying a jig for angle measurement such as a squarer or a tractor having a predetermined angle.

However, these methods have a problem that a personal error of a measurer is generated and measurement takes a lot of time. Moreover, in the automation process of the factory, it was impossible to automate the inspection process. Furthermore, in the folding machine, the bending is done by the relative movement of the upper die and the lower die, but the angle is measured during the bending work, and the automatic bending, that is, the moving position of the die is finally determined. The bending angle could not be automatically determined to be the target bending angle.

Therefore, conventionally, for example, Japanese Patent Publication No. Sho 63-2687 (a plate bending angle detecting device for press brake) detects the minimum bending angle of the work by imaging the end face of the work being bent with a visual sensor, and We are trying to perform automatic bending.

(Problems to be Solved by the Invention) However, in the conventional method of detecting the bending angle of a work with a visual sensor, such as Japanese Patent Publication No. 63-2687, the work end face is imaged and the bending angle at the work end face is detected. However, the bending angle cannot be accurately detected, and even if automatic bending is performed using this detection value, high-precision bending cannot be performed. It was

That is, in the case of a plate-shaped work that is bent,
The end face is usually distorted at the stage of the material, has burrs, or has a tapered cross section, and it is difficult to detect a regular bending angle from the shape of the work end face.

In particular, when imaging the end face of the workpiece by the reflection type imaging method, when the end face of the workpiece is a tapered surface, the reflected light has unevenness, and the image obtained by the reflected light has an actual shape. Will be different. If a transmissive imaging device is to be constructed, a projector for that purpose must be provided, which makes the device large and difficult to generalize.

Further, in the angle detection on the work end face, since the set position of the visual sensor is limited to the work end face direction, there is a problem that the frame structure of the folding machine is limited.

In addition, in the angle detection on the end face of the work, the work is distorted into an arc shape when viewed from the front side of the folding machine due to the so-called drooping phenomenon, so the detected bending angle is not a representative value of the work bending angle. There was a problem.

Further, conventionally, there is a problem that a large amount of calculation is required to form the equation of the approximate straight line when the angle is calculated, and the processing time becomes long.

[Structure of the Invention] (Means for Solving the Problems) In view of the conventional problems as described above, the present invention relates to a light emitter that irradiates two planes intersecting a work with planar light, and the above-mentioned 2
A camera for capturing an image of a light beam pattern of planar light emitted on a plane, and an image capturing signal of the camera for converting into a binary signal 2
The binarization circuit, the image memory that stores the binarized image data by the binarization circuit, and the image data of this image memory are stored in the matrix pattern from the 0,1 data of the adjacent 2 × 2 pixels. Direction code generation logic for classifying horizontal, right tilt, left tilt, and vertical direction codes, and the intersection line of the two planes and the ray pattern based on the direction codes output from the direction code generation logic. And a CPU for calculating the angle formed by.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the accompanying drawings.

1 to 3 are explanatory views showing the angle measuring method of this example.

In FIG. 1, a crossing angle α of a work W (thickness is not considered) having two planes 1 and 2 as a surface to be measured.
In order to measure, the intersection line 3 of these two planes 1 and 2 is made to coincide with the X axis, and a CCD camera 4 as a visual sensor is arranged on the Z axis orthogonal to this X axis. It is assumed that an image is taken in the field of view 5 with the intersection point (origin) 0 of facing. The optical axis of the camera 4 is Lc. The plane coordinates of the CCD area sensor at this time are equivalent to the plane coordinates XY, where Y is an axis orthogonal to both axes XZ.

On the other hand, a plane obtained by inclining the YZ plane by an angle β is used as a plane light irradiation surface, and the plane light 7 passing through the origin 0 is irradiated onto this plane. Such planar light 7 can be emitted from a light emitter 8 such as a laser diode. A slit is provided at a tip portion of the light emitter 8 in a direction parallel to the irradiation surface, and a laser diode provided therein irradiates a laser beam toward the irradiation surface. Therefore, the surface light 7 emitted from the light emitter 8 is the surface to be measured.
A linear ray pattern that passes the origin O on both sides when hitting 1, 2
Form 9,10. The irradiation surface does not necessarily have to pass through the origin O, and may be a plane obtained by moving the plane passing through the origin O in parallel. The optical axis of the light emitter 8 is L ₀ .

Here, as shown in FIG. 2, the intersection angle α of the two planes 1 and 2
Can be expressed as the sum of the inclination angles α ₁ and α ₂ of the planes 1 and 2 with respect to the Z axis.

α = α ₁ + α ₂ (1) Therefore, the crossing angle α between the two planes can be obtained by measuring the inclination angles α ₁ and α ₂ and obtaining the sum thereof.

3 (a) is a plan view of FIG. 2, FIG. 3 (b) is a front view, and FIG. 3 (c) is a right side view.

In the figure, the plan view of FIG. 3 (a) can be imaged on the area sensor of the CCD camera 4.

Therefore, in the plan view of FIG. 3A, the angles formed by the ray patterns 9 and 10 with the X axis are θ ₁ and θ ₂ , and the widths of the planes 1 and 2 are
B ₁ , B ₂ , and in the front view of FIG. 3B, the height of each plan view is H ₁ , H ₂ , the projected length of each ray pattern 9, 10 on the X axis is L ₁ ,
Given L ₂ , the following equation holds for plane 1.

From this, it can be seen that α ₁ becomes tan α ₁ = tan θ ₁ · tan β α ₁ = tan ⁻¹ (tan θ ₁ · tan β) (5).

Similarly, in plane 2, α ₂ = tan ⁻¹ (tan θ ₂ · tan β) (6).

Therefore, the bending angle α of the work can be calculated by the equation (1).

When β = 45 degrees, α = θ ₁ + θ ₂ and therefore it is convenient that there is no need to perform the calculations of equations (5) and (6).

In the above measuring method, the crossing angle α between the two planes 1 and 2 is obtained by one sheet of light 7 and one CCD camera 4, but a pair of the sheet of light 7 and the CCD camera 4 is used, and each unit It is also possible to measure the inclination angle of each surface to be measured using equations (5) and (6), respectively, and obtain the intersection angle α of the two planes from the positional relationship of the optical axes Lc of both units. In this case, it is also possible to use only the planar light 7 in common.

Further, in the above-mentioned embodiment, the planar light 7 is composed of slit light, but the planar light can also be obtained by scanning the irradiation surface with a linear beam.

Further, although the CCD camera 4 is used as the visual sensor in the above embodiment, any other camera may be used as long as it can capture a two-dimensional image. Further, although the slit light from the laser diode is taken as an example of the light emitter 8, any light may be used as long as it can irradiate a planar light.
However, since the linearity of the planar light affects the angle detection accuracy, a light emitter having high linearity such as a laser beam can detect with higher accuracy.

FIG. 4 is a block diagram showing an example of an image processing apparatus connected to the CCD camera 4.

The image processing apparatus 11 of this example includes a CPU 1 on the system bus 12.
3, ROM14, RAM15, an input / output device (I / O) 16, a display interface 17, and an image memory 18, which are connected to the image signal S of the CCD camera 4 into a binary signal. A binarization (A / D) circuit 19 for conversion is provided.

A display 20 is connected to the display interface 17. The input / output device 16 is connected to, for example, a folding machine control device 21.

In the above configuration, the image memory 18 is stored in FIG.
The image shown in FIG. 5 is obtained, the processing shown in FIG. 5 is executed by the CPU 13, the angle α is measured, and the calculation result is output to the display device 20 or the control device 21.

In this example, when the video signal S is A / D converted, the image parts of the light ray patterns 9 and 10 are binarized so as to be “1” and the other image parts are stored in the image memory 18. , Windows W1 and W2 that are provided in advance for this image data
It is assumed that the angles θ ₁ and θ ₂ are obtained from the area “1” in (see FIG. 7). The angles θ ₁ and θ ₂ can be obtained by, for example, formulating an equation of an approximate straight line by the method of least squares and obtaining the slope of this straight line.

6 to 11 are explanatory views of the image processing apparatus by the direction code method. In the image processing shown in FIG. 4, this apparatus requires a large amount of calculation to establish an equation of an approximate straight line by the least squares method, and the processing time becomes long. Therefore, this is improved to speed up the processing. It is a thing.

The direction code method is based on Hidehiko Takano's "Pattern recognition technology" (published October 15, 1984, Information Research Committee, p.31-32).
As shown in FIG. 8, the direction of the outer periphery of the contour portion of the figure is coded, and as shown in FIG.
Considering adjacent 2 × 2 pixels in a matrix pattern, intersections A _{i, j} , A _{i, j + 1} , A of mutually adjacent matrices
_{i + 1, j + 1} , A From the data of 0,1 in _{i + 1, j} , the horizontal (HORI
[-]), Tilt right (SLOR [)]), tilt left (SLO
L [(]), vertical (VERT [I]), body (BODY
[*]), Space (SPAC []), corner (VERX
[+]) Is classified into seven codes and processed by hardware to speed up the processing.

The symbols x and + shown in the equation represent logical product and logical sum, respectively.
Overline Represents exclusive logic.

This coding is shown in the image data window of Fig. 7.
When applied to W1 and W2, code is generated as shown in Fig. 10.

Therefore, in this example, the addition operation of the following equation is performed for this to obtain H and V of the following equation.

H = Σ (HORI [−] + Σ (SLOR [)]) + Σ (SLOL [(] + Σ (VERT [I]) ... (7) V = Σ (SLOR [)] + Σ (SLOL [(]) ... (8) ) As a result, the angle θ _{0 formed} by the ray patterns 9 and 10 with the X axis
To Can be obtained as

FIG. 6 shows the above coding process and (7),
FIG. 9 is a block diagram showing the configuration of an image processing device 22 that performs the processing of equations (8) and (9).

This device 22 outputs the output of the binarization circuit 19 shown in FIG.
Direction code generation logic that generates the above-mentioned direction code by inputting through the line delay circuit 24, 1-dot delay circuit 25, 26
Have 27. In addition, terminal T ₁ for inputting the judgment signal that it is within the window, terminal T ₂ for inputting the adder zero chloria signal, and terminal T for inputting the addition result bus output signals of HORI, SLOR, SLOL, and VERT, respectively. _{It has 3} , T ₄ , T ₅ , and T ₆ . Further, AND gates 28, 29, 30, 31 for outputting the signals HORI, SLOR, SLOL, VERT output by the direction code generation logic 27 according to in-window judgment signals, and adders 32, 33 for adding the outputs of these gates. , 34, 35 and the gates 36, 3 for giving the output of each adder to the bus 12 according to each bus output signal.
It has 7,38,39. The clear terminals of the adders 32, 33, 34 and 35 are connected to the terminal T ₂ .

The CPU 13 calculates the equation (9) from the obtained data to obtain the angle θ _{0 formed} by the ray patterns 9 and 10 and the X axis.

FIG. 11 shows a timing chart for each signal of the image processing device 22. As shown, the video signal S for one frame is binarized data (1,0),
After outputting the judgment signal in the window, HORI, SLOR, SLOL, VER
The T addition result bus output signal is sequentially output, and then the adder zero clear signal is output.

In the image processing device 22 having the above configuration, the CPU 13 has (9)
Since only the calculation of the expression is performed and all other processing is performed by hardware, the processing becomes extremely fast. This is
In particular, when performing automatic bending in a folding machine, it is important that real-time angle measurement is performed and acceleration speed is not reduced.

 Next, a specific configuration example of the angle measuring device will be shown.

The measuring device shown in FIG. 12 is provided with an ultra-compact CCD camera 41, a laser diode 43 for irradiating slit light 42 as planar light, and an image pickup circuit 44 in a small box 40, and a measurement angle on the upper surface thereof. Is provided with a 7-segment display 45.

The camera 41 is arranged so as to capture a vertically downward image at a predetermined focal position distance. The laser diode is arranged so as to irradiate the focal point of the camera 41 with the slit light 42 at an angle of 45 ° with respect to the imaging direction.

The image pickup circuit 44 enters the image pickup preparation after the power is turned on, observes the light ray pattern on the work W obtained by the slit light 42, and measures the image at the time when a part of the light ray pattern passes on the image pickup axis for angle measurement. The image signal is captured as
The image is output to the image processing apparatus as shown in FIG. The box 40 may be provided with a handle so that it can be carried. In this case, it is preferable that an operating switch is provided on the grip portion, and the image pickup circuit is provided with a determination circuit for picking up an image when the light beam pattern reaches the focus position of the camera 41 based on the vertical operation.

In the above configuration, the angle measuring device can measure the angle by the equations (1) to (6).

FIG. 13 is an example in which the angle measuring device shown in FIG. 12 is used to detect a product angle having a V-shaped cross-sectional structure.

That is, in order to measure the angle of the work (semi-finished product) 49 transferred by the belt conveyor 48 between the processing machines 46 and 47, an angle measuring device 50 similar to the device shown in FIG. 12 is fixed to the upper surface of the belt conveyor 8. Arranged, by connecting the processing machine 46, 47 and the angle measuring device 50 with the host computer 51,
The angle of the work 49 is measured so that the angle is appropriate. The host computer 51 can output a processing command to the processing machine 46, and can output a processing command for correcting the angle to the next processing machine 47 based on the measurement result of the angle measuring device 50.

In the embodiment shown in FIG. 12 and FIG. 13, the angle α of the work W is measured by irradiating the upper surface side of the work W with one sheet of light, but a pair of imaging provided with a camera and a light emitting diode is used. The device may be used to obtain the tilt angles of the two planes of the work W with respect to the respective imaging directions, and the intersection angle α of the two planes may be obtained by combining them. In this case, the imaging directions of both imaging devices are generally arranged in parallel, but even if the imaging directions of both imaging devices are tilted relative to each other, if the relationship is clarified, the It is possible to obtain α.

Further, in the above-described embodiment, the angle of the acute angle portion is measured from the upper surface example of the work W, but the angle α can be measured by imaging the work W from the obtuse angle direction.

The present invention is not limited to the above-mentioned embodiments, but can be implemented in appropriate modes by making appropriate design and modification.

[Effects of the Invention] As can be understood from the above description of the embodiments, in short, the present invention is based on two planes (1,
2) a light emitter (8) for irradiating the surface light (7), and the above 2
A camera (4) for imaging the light ray pattern (9, 10) of the planar light (7) irradiated on the plane (1, 2), and the camera (4)
A binarization circuit (19) for converting the image pickup signal (S) of FIG. 2 into a binarization signal, an image memory (18) for storing the image data binarized by the binarization circuit (19), and The image data in the image memory (18) can be set horizontally (HORI) from 0,1 data of 2 × 2 images that are adjacent in a matrix pattern.
Direction code generation logic (27) that classifies each direction code as right tilt (SLOR), left tilt (SLOL), and vertical (VERT),
Based on each direction code output from the direction code generation logic (27), the angle (θ ₀ between the intersecting line (3) of the two planes (1, 2) and the ray pattern (9, 10). ) CPU (13) for computing, and is provided with.

As is apparent from the above configuration, in the present invention, the direction code generation logic 27 causes the image data in the image memory 18 to be horizontal and right based on the 0,1 data of the 2 × 2 images adjacent in the matrix pattern. The inclination code, the left inclination, and the vertical direction code are classified. Based on the classified direction codes, the CPU 13 causes the intersection line 3 of the two planes 1 and 2 and the ray pattern 9,
The angle θ ₀ formed by 10 is calculated.

That is, the direction code generation logic 27 performs direction code classification processing, and the CPU 13 calculates an angle based on the classified direction code. Therefore, the load on the CPU 13 is reduced and the angle calculation processing is performed at high speed. Is what you can do.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing the principle of measuring the intersection angle of two planes, and FIG.
The figure is an explanatory view of the YZ plane, FIG. 3 (a) is a plan view of FIG. 2, FIG. 3 (b) is a front view of FIG. 2, and FIG. 3 (c) is a right side surface of FIG. 4 and 5 are block diagrams showing an example of the configuration of the image processing apparatus, and FIG. 5 is a flowchart showing a measurement method,
FIG. 6 is a block diagram showing another configuration example of the image processing apparatus of FIG.
FIG. 7 is an explanatory view of a window for processing a ray pattern, FIG. 8 is an explanatory view of a matrix of 2 × 2 pixels, FIG. 9 is an explanatory view showing types of direction codes, and FIG. 10 is a direction code. Illustration of the image memory coded in
FIG. 11 is a time chart showing the processing method of the image signal,
FIG. 12 is a perspective view of an image pickup device equipped with a CCD camera and a laser diode, and FIG. 13 is an explanatory diagram showing an application example of the image pickup device to a processing line. 1,2 …… Measured surface, 3 …… Crossing line 4 …… CCD camera, 7 …… Planar light 8 …… Light emitter, 9,10 …… Ray pattern α …… Measurement angle, θ …… Image memory Detection angle on

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-54-36758 (JP, A) JP-A-60-247415 (JP, A) JP-A-63-246603 (JP, A)

Claims (1)

(57) [Claims] 1. A light emitter (8) for irradiating a plane light (7) on two planes (1,2) intersecting with a work (W), and a plane irradiating on the two planes (1,2). Ray pattern of light (7) (9,1
0) and a binarization circuit (19) for converting the imaging signal (S) of the camera (4) into a binarized signal.
And an image memory (18) for storing the image data binarized by the binarization circuit (19), and the image data of the image memory (18) is composed of 2 × 2 pixels adjacent to each other in a matrix pattern. Direction code generation logic (27) that classifies horizontal (HORI), right tilt (SLOR), left tilt (SLOL), and vertical (VERT) direction codes from 0, 1 data, and this direction code generation logic (27 ) Based on each direction code output from the above), the intersecting line (3) of the two planes (1, 2)
An angle measuring device comprising: a CPU (13) for calculating an angle (θ ₀ ) formed by the light beam pattern (9, 10).