JPH0435686B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is useful for assembling parts in automobiles and home appliances, assembling ICs on circuit boards, etc. This paper relates to a method for automatically measuring .

[Prior Art] Various types of pattern recognition technology have been developed to automate work in production factories. Such pattern recognition technology attempts to determine the shape of the object itself by some means, and the equipment used for pattern recognition is usually relatively complex and expensive. .

However, assembly work in various factories, such as engine, battery,
The pattern recognition technology described above is not necessarily required when automating the assembly of fuel tanks, etc., the assembly of various parts to the main body of home appliances, the assembly of ICs to circuit boards, etc. In other words, since the objects of recognition, such as the body of a car, the main body of a home appliance, an IC board, etc., usually have a constant shape, there is no need to distinguish their shapes again; Misalignment of an object relative to its reference position;
It suffices to measure the inclination of the object in relation to the reference posture.Furthermore, there are many cases where products of various sizes and sizes are mixed together, but in this case, it is sufficient to add the dimensions of the product to the measurement target, and this allows the device to It becomes possible to significantly simplify the process itself and provide it at low cost.

[Problems to be Solved by the Invention] The purpose of the present invention is to identify the positional deviation, posture angle, and size of an object without using general pattern recognition technology in the above-mentioned factory assembly work, etc. The object of the present invention is to attach a plurality of marks including a directional reference mark necessary for measurement of the objects, and to make it possible to easily and inexpensively measure them by using the different marks.

[Means for Solving the Problems] In order to achieve the above object, in the measurement method of the present invention, directional reference marks having directionality and appropriate From the image of the object on the S-T rectangular coordinate system obtained by an image input device, the attitude angle of the directional reference mark is determined as S in the projection figure of the mark figure onto the S axis. Maximum axial width
Based on As and the width Ap between the S coordinate of the point that takes the maximum height in the T-axis direction and one end on the S-axis of the projected figure, the Q value given by the ratio of these is measured as a parameter. , by calculation based on the coordinate values of the center of gravity position of each reference mark and the above-mentioned attitude angle,
A technical means is employed to measure the positional deviation of the object and the axial distance between the reference marks.

[Effects of the Invention] According to the measurement method of the present invention, for the image of the object obtained by the image input device,
There is no need to perform complicated processing, and the attitude angle of the object can be measured by simple processing of the directional reference marks in the image. It is possible to measure the positional deviation of objects and the axial distance between reference marks. Furthermore, it is advantageous in terms of measurement work because it is sufficient to simply attach one directional reference mark and one appropriate reference mark to the object during these measurements.

In addition, since the posture and dimensions of an object can be easily measured in this way, it is not only easy to implement a device for processing image signals from an image input device in hardware, but also the above-mentioned image signals This enables real-time processing, and is therefore extremely suitable for use in factory production lines, etc.

[Example] The method of the present invention will be explained in more detail below with reference to the drawings.

As shown in Fig. 1, an x-y coordinate system is set in the space where the object A to be measured for positional deviation, attitude angle, and dimensions exists, with the origin O at the center of the object A ₀ at the reference position. . This measurement object A is
For example, whether it is a two-dimensional view of the inside of a car's hood or the car body,
Furthermore, there is no problem even if it is an IC board or the like. Also,
Here, in order to simplify the explanation using the following formula, we will explain the case where the origin of the x-y coordinate system is set at the center of object A at the reference position, but the origin can be set at any position as appropriate. .

On the object A, one each of a directional reference mark 1 and an appropriately shaped reference mark 2 are attached. The directional reference mark 1 is not limited to an isosceles triangle as shown in the figure, but any directional mark can be used, and it can be provided at an appropriate position on the object A. Further, the reference mark 2 is attached at a point symmetrical position with respect to the directional reference mark 1 and the center of the object A.
They can be provided at appropriate positions, and in this case, from the viewpoint of measurement accuracy, it is desirable to provide them as far apart as possible within a range that does not interfere with the relationship with the image input device described later, such as the diagonal position of the object A. Its shape and size can be selected as appropriate.

These reference marks 1 and 2 can be attached by drawing them on the object A with paint or by pasting a label on the object. You can also use it as is. However, in order to prevent misrecognition, it is desirable that there are no objects with similar shapes in the vicinity, and if such objects exist unavoidably, color marks should be used to facilitate separation. is effective.

When the object A is transported by a belt conveyor or the like and reaches the measurement range for positional deviation, attitude angle, and dimensions, as shown in Figure 1, an arbitrary amount of positional deviation and an arbitrary amount of attitude angle from the reference position are detected. It has a slope. That is, the center of the object A has a positional deviation of Δx and Δy in the x-axis and y-axis directions, respectively, with respect to the origin O of the coordinate system, and is also tilted by an angle θ with respect to the reference posture of the object. .

Therefore, in order to measure the positional deviation, posture angle, and dimension, first, the reference marks 1 and 2 are captured as images using an image input device such as an ITV camera. This image input device can be common to each of the fiducial marks 1 and 2, but it can also be used individually for each mark. In that case, the fiducial mark image input device is placed close to each other to capture images. By doing so, resolution can be increased and measurement accuracy can be improved.

The image signal regarding the directional reference mark 1 inputted by the image input device in this way is subjected to the following processing in the image processing device to measure the direction of the mark, that is, the direction of the object. .

FIG. 2 shows an example of an image within the field of view of the image input device. To measure the attitude angle θ of mark 1 from this image, a Q value, which will be explained below, is used as a parameter.

Now, as shown in Figure 3A, the fixed S-
Assume that a planar figure P is placed in the T rectangular coordinate system at an arbitrary attitude angle θ. Here, θ is positive in the counterclockwise direction and negative in the opposite direction. As shown in Figure 3B, the projection of the plane figure P onto the S axis is taken, and the S coordinate of the point where the maximum width in the S axis direction of the projected figure P is As, and the maximum height h in the T axis direction. and S of the projective figure P′
The width between the end of the shaft on one side (the left side in the figure)
When Ap is the ratio between As and Ap, the Q value is used as a parameter for attitude angle measurement.

Q=Ap/As Here, taking an isosceles triangle as an example, FIG. 4 shows the results of calculating the Q value according to the above formula.

As is clear from Fig. 4, the Q value obtained in this way corresponds uniquely to the attitude angle θ within a certain range centered on θ = 0, and therefore the Q value obtained above corresponds to the attitude angle θ. Therefore, it can be seen that the attitude angle θ can be determined. In addition, when the attitude angle exceeds a certain range (4th
In the figure, when α/2>θ>-α/2), the attitude angle θ cannot be immediately determined from the Q value, but in reality, the attitude angle θ does not become extremely large. Therefore, there is no problem with measurement.

In addition, when measuring the positional deviation of the object, first, by processing the above-mentioned image signal with an image processing device, the centroid positions P 1 and ₂ of the reference marks 1 and 2 are determined.
_P2 is measured. This measurement of the center of gravity can be easily carried out by known means, but to briefly explain one example, if a reference mark is placed on an X-Y orthogonal coordinate system, the coordinates of the center of gravity are Since (XG, YG) is given by XG=∫Xds/∫ds, YG=∫Yds/∫ds, a calculation device that performs this calculation can be connected to the image input device. However, ds is the minute area of the figure.

The centroid positions P ₁ and P _{2 of the reference marks 1 and 2} measured as described above have their coordinates when viewed from the x-y coordinate system as P ₁ (x ₁ , y ₁ ) and P ₂ ( x ₂ , y ₂ ), then their coordinate values are P ₁ (W/2cosθ−H/2sinθ+Δx, W/2sinθ +H/2cosθ+Δy) P ₂ (−W/2cosθ+H/2sinθ+Δx, −W/2sin
θ−H/2cosθ+Δy).

In the above equation, W is the separation distance in the x-axis direction between the two reference marks 1 and 2 on the object A at the reference position, and H is the separation distance in the y-axis direction between the two reference marks 1 and 3. This is the separation distance.

The positional deviations Δx and Δy of the center position of the object A in the x-axis and y-axis directions are the above coordinate values P ₁ (x ₁ , y ₁ ), P _{2 of the center of gravity position measured for the reference marks 1 and 2} .
From (x ₂ , y ₂ ), it can be determined by the simple calculations Δx=x ₁ +x ₂ /2 and Δy=y ₁ +y ₂ /2.

The center of gravity of the reference marks 1 and 2 is x
- Not as the coordinates (x ₁ , y ₁ ), (x ₂ , y ₂ ) in the y coordinate, but the relative position of the reference mark on the object A at the reference position with respect to the center of gravity, i.e., the x axis shown in the figure. and positional deviation in the y-axis direction (dx ₁ , dy ₁ ),
(dx ₂ , dy ₂ ), and the above Δx and Δy can be similarly easily determined using these values.

Furthermore, the dimensions used as standards for distinguishing objects of various sizes, that is, the values of W and H mentioned above, are Δx,
Since the values of Δy and θ are known as described above, for example, based on the coordinate values of the center of gravity position of the reference mark 2, x ₂ = -W/2 cos θ + H/2 sin θ + Δx y ₂ = -W/2 sin θ - H/2 cos θ + Δy, W =2{−(X ₂ cosθ+Y ₂ sinθ) + (Δxcosθ+Δysinθ)} H=2{(X ₂ sinθ−Y ₂ cosθ) −(Δxsinθ−Δycosθ)}

As is clear from the above, the positional deviation, attitude angle, and dimensions of the object can be easily measured by simple calculations.
This can be realized by connecting a simple arithmetic circuit to an image processing device that measures the center of gravity positions P ₁ and P ₂ of the reference marks 1 and 2.

As described in detail above, according to the automatic measurement method of the present invention, in assembly work where the shape of the object is predetermined, the object can be measured without using complicated and expensive pattern recognition technology. It is possible to easily and inexpensively measure positional deviations, attitude angles, and dimensions by using reference marks attached to objects without performing complicated processing on images of objects, and also to process image signals. It is possible to easily convert the device into hardware and perform real-time processing of the measurement.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the measurement method according to the present invention, FIG. 2 is a front view of the field of view of the image input device, and FIG.
Figures A and B are explanatory diagrams regarding the measurement of the Q value, and FIG. 4 is a diagram showing changes in the Q value of an isosceles triangle. 1, 2...Reference mark, A...Object.

Claims (1)

[Claims] 1. Directional reference marks and appropriate reference marks are attached to separate positions on the object whose posture and dimensions are to be measured, and the object on the S-T rectangular coordinate system obtained by an image input device is From the image of the object, the attitude angle of the directional reference mark is determined as the maximum width As in the S-axis direction of the projection figure of the mark figure onto the S-axis,
Based on the width Ap between the S coordinate of the point with the maximum height in the T-axis direction and one end of the projected figure on the S-axis, the Q value given by the ratio is measured as a parameter, and each criterion is A method for determining the posture of an object using directional reference marks, etc., characterized in that the positional deviation of the object and the axial distance between the reference marks are measured by calculations based on the coordinate values of the center of gravity position of the mark and the above-mentioned attitude angle. How to automatically measure dimensions.