JP2913757B2 - Edge position detection method using laser slit light - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to edge position detection using laser slit light.

[Conventional technology]

The method of detecting an edge by image processing includes irradiating the edge with halogen light or fluorescent light, and detecting the shadow generated at the edge or the position at which the color changes at the edge, or the laser slit light at the edge. There is a method of detecting the position where the laser slit light bends at the edge by irradiating the laser beam vertically.

The method of irradiating a halogen light or a light of a fluorescent lamp is easily affected by ambient light because the light is a normal visible light. Further, the displacement in the depth direction of the camera cannot be detected unless stereoscopic binocular vision or the like is applied.

In contrast, the method of irradiating laser slit light is
Since the laser light has a fixed wavelength range, it is hardly affected by ambient light.

In the case of laser slit light, the displacement in the depth direction of the camera can be obtained from the principle of triangulation.

[Problems to be solved by the invention]

As described above, using the laser slit light has many advantages, but when the color of the target edge is different, the reflectance of the laser greatly differs depending on the color of the target edge. It varies greatly depending on the color of the edge. For this reason, when performing image processing on the shape of the laser slit light, if the color of the target edge changes, erroneous detection or undetection is likely to occur.

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

[Means for solving the problem]

In order to solve the above problem, in the present invention, the edge is irradiated with laser slit light, which is captured by a CCD camera, and the point at which the laser slit light of this image is bent at the edge is detected by image processing. In the edge position detection method for finding the edge position, the aperture of the lens attached to the CCD camera is controlled based on the color information of the target work, thereby controlling the amount of reflected laser slit light incident on the CCD camera. The shape at the edge of the laser slit light captured by the laser beam is kept constant regardless of the color of the target work.

[Action]

As a result, the amount of laser slit light reflected by the color of the target edge changes, but the amount of reflected laser slit light incident on the CCD camera is always controlled to be constant, so the shape of the laser slit light captured by the CCD camera Is constant. Therefore, even if the color of the target edge changes, no erroneous detection or undetection occurs.

〔Example〕

 The present invention will be specifically described with reference to the drawings.

 FIG. 1 shows the apparatus of the present invention.

The laser slit light 2 emitted from the laser projector 1 bends at the edge 3.

When the color information 4 of the target edge 3 is sent to the aperture controller 5, the aperture controller 6 controls the aperture of the lens 6 with the remote aperture according to the relationship between the work color and the aperture that have been obtained in advance.

The CCD camera 7 captures an image controlled by the lens with the remote aperture, detects the bending position of the laser slit light using the image processing device 8, and obtains the edge position.

Next, an experiment performed by changing the color of the target work will be described.

FIG. 2 is a diagram showing how the laser slit light is projected on the CCD camera when the target work is white. The width of the laser slit light captured by the CCD camera is wide. Since the CCD camera captures an image obliquely from above, the tip of the laser slit light appears to be bent downward like a bird's beak at the edge. This is where the inflection point indicates the position of the edge.

FIG. 3 shows the profile at this time, where the CCD with the highest luminance is saturated and flattened.

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

As can be seen from FIG. 2, the width of the laser slit is much narrower.

FIG. 5 shows the profile of FIG. It can be seen that the profile has a gentle mountain shape.

As described above, the amount of reflected light varies greatly depending on the color, which indicates that the width of the laser slit light and the shape of the profile vary greatly.

However, when the aperture of the lens is changed, for example, when the target work in FIG.
When the aperture is stopped down to a value of 22, the width of the laser slit light is narrowed as shown in FIG. 6, and the target work shown in FIG. 4 is close to the case of black, and the profile shown in FIG. It is close to black.

As described above, by controlling the aperture of the lens, it is possible to obtain the same laser slit light shape even when the color of the target work is different.

As a method of controlling the aperture, the image signal may be used to control the aperture so that the level of the image signal is constant.However, the color of the symmetric work is known in advance, and the work If the relationship between color and aperture is known, controlling the aperture remotely based on the color information allows the aperture to be set before the actual work arrives at the position detection station. In addition, it is possible to reduce the time required for edge position detection after the work comes to the station.

〔The invention's effect〕

As described above, the present invention solves this problem when the color of the target edge changes by controlling the aperture of the lens based on the color information. Edge detection using laser slit light can also be applied to the detection of the position of an edge, for example, the edge of an automobile body.

[Brief description of the drawings]

1 is an embodiment of the present invention, FIG. 2 is an image when the target work is white, FIG. 3 is a profile in FIG. 2, FIG. 4 is an image when the target work is black, and FIG. FIG. 4 shows the profile when the target work is white, and FIG. 7 shows the profile shown in FIG. DESCRIPTION OF SYMBOLS 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

Claims (1)

(57) [Claims] 1. An edge position for locating an edge by irradiating a laser slit light to an edge, capturing the laser slit light with a CCD camera, and detecting a point where the laser slit light of the image is bent at the edge by image processing. In the detection method, the amount of reflected 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 work, and the edge of the laser slit light captured by the CCD camera is used. An edge position detection method using laser slit light, characterized in that the shape of the object is kept constant regardless of the color of the target work.