DE2542904A1 - PROCEDURE FOR INSPECTING AN ITEM - Google Patents

Description

Company door automation systems

Dipl.-Ing. Klaus P. Vetter & Co. KG

5358 Bad Münstereifel

Ohlerath VM 1

Sept. 18, 1975

Method of testing an item

The subject of the present invention is a method which allows the delimitation lines and the texture to check the surfaces of a flat object.

For testing flat objects on the Veäafef its boundary lines and to compare this test with a mister, it has been known so far as far as the material is concerned of the test allows the distortion of electrical and / or magnetic fields through the test objects. This procedure depends on the material of the test object and thus Can only be used to a limited extent. It has also been proposed for the examination of given outlines Bodies that can occupy a specified, limited number of positions when they strike a contact edge, To use television cameras that scan certain critical lines of the field of observation. That was a control These objects are possible to certain qualities locally distributed on the objects, but this method allows not checking the boundary lines and the surface of the test object in its entirety. In addition, the changeover is necessary on differently shaped test objects a considerable amount of preparatory work.

The present invention is based on the object of specifying a testing method with which it can be used in a two-dimensional Object is possible, its boundary lines and also its surface texture with a To compare patterns without determining the position of the object in the

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to change the observation field of a permanently mounted television camera.

The invention relates to a method for checking the boundary lines of a flat object with the aid a television camera recording in polar coordinates and differs from the known in that the camera In a first step, by comparing the partial areas of the object on both sides of the O ° -18O ° line and the 90 ° -27O ° line the camera determines the center of gravity of the object surface and

in a second step, starting from this center of gravity, the boundary lines are recorded in polar coordinates and these saves

and that the storage is compared in a correlating manner with that of a target pattern.

In a further development of the invention, the method can be used for quantitative Detection of the object surface can be used in that in the second step at predetermined intervals of Δγ quantitative differences, for example differences in brightness or color, along the specified intervals each set ^ -axis can be detected and saved.

The storage of the measured values is particularly advantageous of the test specimen and the target pattern in a shift register that is closed in a circle and can be shifted against each other and a comparison of these values in the shift registers brought into congruence via a digital-to-analog converter.

The! Shift registers are also converted by means of a digital-to-analog converter brought to congruence, either by comparing a large number of closely spaced measuring points of the boundary lines

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or by comparing a minority of measuring points distributed approximately evenly on the boundary lines.

The function and particular advantages of the method according to the invention are explained in an example with the aid of the figures.

In Fig. 1, a two-dimensional object 1 lies in the observation field 2 of the television camera, the optical axis of which initially covers the observation field 2 at 3 »the point of intersection of their 0 ° -180 ° line and its 90 ° -27O ° line. In the first At first step, the camera now compares, for example, color contrasts between object 1 and observation field 2 the quantity of the object part surfaces along their 0 ° -18o ° line and shifts this until the object part surfaces are the same and the 0-180 line comes to lie approximately at the dashed line 4 - 4. Corresponding becomes the 90 ° -270 ° line up to the position of the dashed line 5-5 and thus the surface center of gravity at 6 is determined. Starting from this center of gravity 6, the camera records now in polar coordinates the boundary lines of the object 1 and brings them to storage. This gives then a curve, as shown for example in the upper part of the figure. It is noted that the curve in Fig. is quantitatively not identical to the measurement result on an object as shown in FIG. 1, as is the case with an actual borrowed measurement would be the case. Rather, acts it's just an example.

The lower part of FIG. 2 gives the curve as it has been tapped on the target pattern using the same method. A superficial examination already shows that, for example, the maxima 7 and 7 'and 8 and 8 ¹ are shifted relative to one another by an angle in both memories.

The recording of both curves in a shift register,

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which is closed in a circle, now allows these two curves to be brought into congruence by shifting the two registers against each other. For this purpose, either a large number of closely adjacent measuring points of the boundary lines can be compared with one another and brought into congruence, or individual measuring points distributed approximately evenly on the boundary lines can be selected and compared with one another. This is done using a comparator "10 and a digital-to-analog converter 9 · Are brought the registers in Dekkung, the comparison of the respective r values above the co-registered {Λ values also takes place by means of a digital-analog log converter.

This method has the advantage that neither the camera nor the test object have to be moved mechanically in order to obtain the measurement result to be compared with that of the target pattern. Since the entire measuring, registering and comparison process takes place electronically, the check takes place in a particularly short time, which, depending on the required resolution, may only be milliseconds amounts to.

If the object surface is to be recorded quantitatively in a further development of the invention, the scanning beam of the camera moves, starting from the center of gravity 6, either on a spiral or in concentric circles over the surface and registers, ^{for example, differences in brightness at intervals of Δ r} , which are then stored in the memory a multitude of lines between the \ 0 -axis and the curve of the boundary lines. This measurement result can then be compared with the measurement result of the target pattern after the two registers are covered.

Regardless of whether only the delimitation β line or the surface of the object is checked, the method can for the selection of individual objects within given

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Tolerances are used.

The method according to the invention is particularly suitable for the control of products manufactured in large quantities, such as technical end or semi-finished products or to determine the position of an object in relation to a fixed point, for example when using the method in Handling systems.

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Claims (3)

Society for automation systems L bH L Ό U4 Dipl.-Ing. Klaus P. Vetter & Co. KG Bad Münstereifel Ohlerath VM 1 l8. Sept 1975 Patent claims Method for checking the boundary lines of a two-dimensional object with the aid of a television camera recording in polar coordinates, characterized in that the camera in a first step by quantitative comparison of the partial areas of the object on both sides of the 0 ° - 180 ° line and the 90-270 line of the camera determines the center of gravity of the surface of the object and In a second step, starting from this center of gravity, the boundary lines are recorded in polar coordinates and saves this and that the storage is compared in a correlating manner with that of a target pattern. 2. The method according to claim 1 for the quantitative detection of the object surface, characterized in that in the second step quantitative differences, for example brightness or color differences, are detected and stored at predetermined intervals along the J0 axis set at predetermined intervals. 3. The method according to claim 1 or 2, characterized in that the storage of the measured values of the examinee and the target pattern takes place in a closed circuit, mutually displaceable shift registers and the values in the shift registers brought into congruence with each other via a digital-to-analog converter be compared. 709813/0520 INSPECTED Method according to Claim 3 » characterized in that the shift registers are matched by means of the digital-to-analog converter either by comparing a large number of closely spaced measuring points on the boundary lines or by comparing a minority of measuring points distributed approximately evenly on the boundary lines. 709813/0520