JPH049603A - Edge position detection method using laser slit light - Google Patents

Abstract

PURPOSE:To hold the shape of an edge at a constant state independently of the color of an objective work by controlling the stop of a CCD camera in accordance with the color information of an objective edge. CONSTITUTION:The objective edge is irradiated with laser slit light, the state is taken by the CCD camera 7 provided with a lens with remote stop-down mechanism 6 and a point vending the laser slit of the image taken by the camera 7 is detected by an image processor 8 to detect the edge position. The stop of the lens is controlled in accordance with color information impressed by a stop-down controller 5, so that the edge shape through the CCD camera 7 is held at the constant state independently of the color of the objective work.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to edge position detection using laser slit light.

[Conventional technology]

Edges can be detected using image processing, such as by irradiating the edges with halogen light or fluorescent light and detecting the shadows created by the edges or the positions where the color changes at the edges.
There is a method of irradiating a laser slit light perpendicular to the edge and detecting the position where the laser slit light bends at the edge5.A method of irradiating halogen light or fluorescent light is Because it is visible light, it is easily affected by ambient light. Moreover, the deviation of the camera in the depth direction cannot be detected unless stereoscopic binocular viewing or the like is applied.

On the other hand, the method of irradiating laser slit light is
Since laser light has a fixed wavelength range, it is less affected by ambient light.

Furthermore, in the case of laser slit light, the deviation of the camera in the depth direction can be determined based on the principle of triangulation.

[Problem to be solved by the invention]

As described above, there are many advantages to using laser slit light, but when the target edges have different colors, the reflectance of the laser varies greatly depending on the color of the target edges, and this effect causes the shape of the laser slit light to change in the image. varies greatly depending on the color of the target edge. When performing image processing on the shape of the laser slit light, if the color of the target edge changes, false detection or non-detection is likely to occur.

A fourth object of the present invention is to provide a detection method that can prevent erroneous detection or non-detection due to a change in the color of a target edge in edge position detection using laser slit light.

[Failure to solve the problem]

In order to solve the above problem, the present invention irradiates the edge with laser slit light, captures it with a CCD camera, and uses image processing to detect the point where the laser slit light bends at the edge. In the edge position detection method for determining the edge position, the amount of reflected light of the laser slit light incident on the CCD camera is controlled by controlling the aperture of the lens attached to the CCD camera based on the color information of the target workpiece, and CCl' ) The shape at the edge of the laser slit light captured by the camera,
It is characterized by keeping the color constant regardless of the color of the target work.

[Function] As a result, although the amount of reflected laser slit light changes depending on the color of the target edge, the amount of reflected laser slit light that enters the CCD camera is always controlled to be constant. The shape of the captured laser slit light remains constant. Therefore, even if the color of the target edge changes, false detection or non-detection will not occur.

〔Example] The present invention will be explained in detail using figures and beats.

FIG. 1 shows the apparatus of the invention.

A laser slit beam 2 emitted from a laser projector is bent at an edge 3.

When the color information 4 of the target edge 3 is sent to the aperture controller 5, the aperture controller 6 adjusts the remote aperture-equipped lens 6 based on the relationship between the workpiece color and aperture that has been determined in advance.
to control the aperture.

CCU) Camera 7 captures an image controlled by a lens with a remote aperture, detects the bending position of the laser slit light using image processing device 8, and determines the edge position.

Next, I will explain an experiment conducted by changing the color of the target work.

FIG. 2 is a diagram showing how the laser slit light is reflected on the CCD camera when the target work is white. C.C.
The width of the laser slit light captured by the D camera is wide.

Note that since the CCD camera takes the image from diagonally above, the tip of the laser slit light appears to be bent in the shape of a bird's beak at the edge. This is the bending point and you can see where the edge is.

FIG. 3 shows the profile at this time, where the CCD is saturated at the highest brightness and becomes flat.

Next, FIG. 4 shows a case where the target workpiece is made black under exactly the same conditions as in FIG. 2.

As compared to Figure 2, it can be seen that the width of the laser slit is much narrower.

Moreover, the profile of FIG. 4 is shown in FIG.

It can be seen that the shape of the profile shows a gentle mountain shape.

As shown above, it can be seen that the amount of reflected light varies greatly depending on the color, and as a result, the width and profile shape of the laser slit light vary greatly.

However, if you change the aperture of the lens, for example, the second
When the target workpiece in the figure is white, when the aperture is narrowed down from F' value 1.8 to F22, the width of the laser slit light becomes narrower as shown in Figure 6, and the target workpiece in Figure 4 becomes white. In addition, the profile (not shown in FIG. 7) is also similar to that in the case of black in FIG. 4.

By controlling the aperture of the lens in this manner, it is possible to obtain the same shape of the laser slit light even when the target workpieces have different colors.

As a method of controlling the aperture, it is possible to use an image signal to control the aperture so that the level of image correction remains constant, but if the outline and the color of the workpiece to be symmetrical are known, In addition, if the relationship between the workpiece color and the aperture is known, it is better to use the color information to remotely control the aperture and set the aperture before the actual workpiece comes to the position detection station. y), it is possible to shorten the time involved in detecting the edge position after the workpiece arrives at the station.

[Effects of the Invention] As explained above, the present invention solves the problem that occurs when the color of the edge of an object changes by controlling the aperture of the lens using color information. Edge detection using laser slit light can now be applied to detecting the position of edges that change depending on the type of workpiece, such as the edge of an automobile body.

[Brief explanation of the drawing]

Figure 1 is an example of the present invention, Figure 2 is an image when the target work is white, Figure 3 is the profile of Figure 2, Figure 4 is an image when the target work is black, and Figure 5 is an image when the target work is black. FIG. 4 shows the profile, FIG. 6 shows the image when the target work is white, and FIG. 7 shows the file shown in FIG. 6. 1... Laser projector 2... Laser slit light 3... Edge 4... Color information of target edge 5... Aperture controller 6... Lens with remote aperture 7... CCD camera 8...・Image processing device Figure 1 Engraving of drawings Figure 2 Figure 3 Figure 7 CCD camera 4th side Figure 5 Figure 6 Figure '1 1. Table of Cases Small Heisei 2'4 Special Edition No. 11 1; 3 ] 薯3 2. Name of the Invention ``Tsuji Device Detection Method Using Laser Slit Light'' 3゜ Person Who Makes Corrections Case What Relationship Patent Applicant Resident IvT To Kitakyushu City, Fukuryo Prefecture 〇1 Nishi-ku Hijita Fujita 234
No. 6 Mr., Name (662) All Village Stocks Safety Electrical Manufacturing Section Figures 2-7 (Clearly drawn)

Claims (1)

[Claims] An edge method in which the position of the edge is determined by irradiating the edge with laser slit light, capturing it with a CCD camera, and detecting the point at which the laser slit light in this image bends at the edge using image processing. In the position detection method, by controlling the aperture of the lens attached to the CCD camera based on the color information of the target workpiece, the amount of reflected light of the laser slit light incident on the CCD camera is controlled, and the edge of the laser slit light captured by the CCD camera is An edge position detection method using laser slit light that is characterized by keeping the shape of the target workpiece constant regardless of the color of the target workpiece.