JPH0435685B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention automatically detects the positional deviation and attitude angle of objects for assembling parts in automobiles and home appliances, assembling ICs on circuit boards, etc. It is related to the method of measurement.

[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 automobile bodies, the main bodies of home appliances, IC boards, etc., usually have a constant shape, there is no need to re-identify their shapes; It is sufficient to measure the positional deviation of the object with respect to the reference position and the inclination of the attitude angle with respect to the reference posture, which greatly simplifies the device itself.
It becomes possible to provide it at low cost.

[Problems to be Solved by the Invention] The purpose of the present invention is to identify the positional deviation, attitude angle, and dimensions of an object without using general pattern recognition technology in the above-mentioned factory assembly work, etc. Attach the minimum marks necessary for measurement,
The purpose is to make it possible to easily and inexpensively measure them using the marks.

[Means for Solving the Problems] In order to achieve the above object, in the measurement method of the present invention, a reference mark with directionality is attached to the object whose posture is to be measured, and a reference mark with directionality is attached to the object whose posture is to be measured. From the image of the object on the S-T rectangular coordinate system obtained by
Based on As and the width p 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. , a technical means is adopted in which the positional deviation of the object is measured by calculation based on the coordinate values of the center of gravity position of the directional reference mark and the above-mentioned attitude angle.

[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 mark in the drawing line. positional deviation can be measured. Furthermore, the present invention is advantageous in terms of measurement work in that it is sufficient to attach only one directional reference mark to the object during these measurements.

In addition, since the posture of the object can be easily measured in this way, it is not only easy to implement a device for processing the image signal of the image input device in hardware, but also the real time measurement of the image signal. It is therefore extremely suitable for use in factory production lines and the like.

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

As shown in Fig. 1, in the space where the object A to be measured for positional deviation and attitude angle exists, the x _- y
Set the coordinate system. This measurement target A may be, for example, a planar view of the inside of a car's hood, or the body of a car;
There is no problem even if it is an IC board etc. Also, here, to simplify the explanation using the following formula, x−
A case will be described in which the origin of the y-coordinate system is set at the center of the object A at the reference position, but the origin can be set at any appropriate position.

On the object A, one directional reference mark 1 is attached. This directional reference mark 1
is not only an isosceles triangle as shown in the figure, but also
A directional mark of any shape can be used, and it can be provided at an appropriate position on the object A.

Further, this reference mark 1 can be attached by drawing it on the object A with paint or by pasting a label on the object, but it is also possible to attach it by drawing it on the object A with paint, or by attaching a label to the object. Those having a directional shape can also be used as they are.
However, in order to prevent misrecognition, it is desirable that there are no objects with a similar shape in the vicinity.
If such items are unavoidably present, it is effective to use colored marks to facilitate separation.

When the object A is transported by a belt conveyor or the like and reaches the positional deviation and attitude angle measurement range, as shown in Figure 1, an arbitrary amount of positional deviation and an arbitrary amount of attitude angle inclination from the reference position are measured. have. That is, the center of the object A has a positional shift 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 inclined by an angle θ with respect to the reference posture of the object.

Therefore, in order to measure the above-mentioned positional deviation and attitude angle, first, using an image input device such as an ITV camera,
The above-mentioned directional reference mark 1 is captured as an image.
This image input device does not need to fit the entire object within its field of view, and by arranging the image input device close to the reference mark, 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 posture 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 Fig. 3A, the fixed S-T
Assuming that a planar figure P is placed in a 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 point S where the maximum width of the projected figure P in the S axis direction is As, and the maximum height h in the T axis direction is taken. Coordinates and S of the projective figure P′
The width between one end of the shaft (left side in the figure) is Ap
Then, the ratio between As and Ap is the Q value, which 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. It can be seen that the attitude angle θ can be found by 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.

Furthermore, when measuring the positional deviation of the object, first, the center of gravity position _P1 of the directional reference mark 1 is measured by processing the signal of the above-mentioned image with an image processing device. The position of the center of gravity can be easily measured by known means, but to briefly explain one example, if a reference mark is placed on the X-Y rectangular coordinate system, the position of the center of gravity can be easily measured. Since the coordinates (XG, YG) are 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 center of gravity position P ₁ of the directional reference mark 1 measured as described above is expressed as P 1 (x 1 , y 1 ), and its coordinate value is P ₁ (x ₁ , y ₁ ) when viewed from the x-y coordinate system. ₁ (W/2cosθ−H/2sinθ+Δx, W/2sinθ+H
/2cosθ+Δy).

In addition, W and H in the above formula are the center of gravity position of the reference mark 1 on the object A at the reference position, and x and y.
This is a value equivalent to twice the distance between the axis and the
These values can be determined in advance by measurement.

Furthermore, the center of gravity position of the directional reference mark 1 is
It can also be determined as the relative position of the reference mark on the object A at the reference position with respect to the center of gravity, that is, the positional deviations dx and dy in the x-axis and y-axis directions shown in the figure. In this case, dx, dy are given by dx=W/2(cosθ−1)−H/2sinθ+Δx dy=W/2sinθ+H/2(cosθ−1)+Δy, and therefore, based on the above formula, Calculating the positional deviations Δx and Δy of the center position of object A in the x-axis and y-axis directions, Δx=dx+W/2(1-cosθ)+H/2sinθ Δy=dy-W/2sinθ+H/2(1-cosθ) It can be determined by simple calculations.

As is clear from the above, the positional deviation and attitude angle of the object can be easily measured by simple calculations, and such calculations are not necessary for the image processing device that measures the center of gravity position of the reference mark 1. This can be realized by connecting simple arithmetic circuits.

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. Positional deviation and attitude angle can be easily and inexpensively measured using a single directional reference mark attached to the target object without performing complicated processing on the image.
Furthermore, a device for processing image signals can be easily implemented in hardware, and the measurement can be processed in real time.

[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...Reference mark, A...Object.

Claims (1)

[Claims] 1. A directional reference mark is attached to the object whose orientation is to be measured, and the orientation of the directional reference mark is determined from the image of the object on the S-T rectangular coordinate system obtained by an image input device. The corner is defined 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 the directionality is A method for automatically measuring the posture of an object using a directional reference mark, characterized in that the positional deviation of the object is measured by calculation based on the coordinate value of the center of gravity position of the reference mark and the above-mentioned attitude angle.