JP2941107B2 - Work surface inspection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a work surface inspection method for detecting a surface defect such as a painted surface of a work and its smoothness.

[0002]

2. Description of the Related Art As a conventional technique, there is a method shown in FIG. That is, the light from the light projecting means 2 attached to the arm or the like of the robot (not shown) is irradiated onto the work surface 6 via the convex lens 4, and the light is converged on the detecting means 8 such as a CCD camera. Further, image processing is performed on the captured image 10a (see FIG. 6B) obtained by the detection means 8, and the coating state of the work surface 6 is checked to check for adhesion of dust, the presence or absence of scratches, and the like. In this case, by inspecting the work surface 6 using the convergent light, the range that can be inspected at one time can be expanded.

[0003]

However, in the case of the prior art as described above, if the work surface 6 is flat, the detection light is guided to the light receiving surface of the detection means 8 well.
If the work surface 6 is a curved surface as shown in FIG. 7A, the detection light is diffused on the work surface.
The dark portion 12 is generated at 0b (see FIG. 7B). That is, as shown in FIG. 6, when the work surface 6 is flat, all the captured images 10a can be used as the effective inspection surface 14. However, when the work surface 6 is curved, FIG.
Since the detection light is diffused on the work surface 6 as shown in FIG.
2 occurs, and the effective inspection surface 14 becomes narrow.

In this case, when image processing is performed on the entire surface of the captured image 10b, the dark portion 12 other than the effective inspection surface 14 is processed.
Image processing is performed up to. Therefore, the inspection time is wasted and the inconvenience of prolonging the entire inspection time is revealed.

The present invention has been made in order to solve this kind of problem. By performing image processing only on an effective inspection surface of a captured image, the image processing time can be reduced and the entire inspection can be performed. It is an object of the present invention to provide a work surface inspection method capable of reducing time.

[0006]

In order to achieve the above object, the present invention provides a light projecting means for irradiating detection light toward a surface to be measured, and a reflected light of the detection light from the surface to be measured. A method for inspecting the surface of a workpiece having a curved surface, using a surface inspection apparatus having a detection unit that receives light, and a condensing optical system that converges the reflected light on a light receiving surface of the detection unit, A step of sequentially displacing the surface inspection device along the surface of the work, receiving the detection light by the detection means, binarizing the obtained images, and detecting the plurality of binarized image data. A step of extracting image data relating to an effective inspection surface of a workpiece irradiated with light and holding them in a non-overlapping state, and performing a predetermined image processing on the held image data. It is characterized by.

[0007]

The image taken by the detecting means is binarized, and only image data relating to the effective inspection surface of the image is extracted and held so as not to be duplicated for each image data. The image of the inspection surface can be collectively processed as one image. Therefore, there is no need to process the captured image for an image other than the effective inspection surface, and the overall inspection time is reduced.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A work surface inspection method according to the present invention will be described.
Preferred embodiments will be described in detail below with reference to the accompanying drawings.

In this embodiment, a description will be given based on an inspection method using a work surface inspection apparatus in an automobile production line.

As shown in FIG. 1, the work surface inspection apparatus 20 is mounted on a robot 22, and a light source 24 is fixed to an arm 26 of the robot 22 and connected to the light source 24 by an optical fiber bundle 28. A focusing optical system 30 composed of a Fresnel lens and the like and a CCD camera 32 serving as a detecting means are fixed to the wrist part 34. The CCD camera 32 is connected to an image processing device 36 that performs image processing and the like on the work surface 35, and the image processing device 36 and the robot controller 38 are connected.

As shown in FIG. 2, the image processing device 36 converts the image data input from the CCD camera 32 into an A /
The signal is converted into a digital signal by the D converter 40 and input to the image density memory 42 as gradation image data. The gradation image data in the image density memory 42 is converted into binary image data by the image processor 44 and input to the binary image memory 46. The gradation image data stored in the image density memory 42 and the binarized image data stored in the binarized image memory 46 are displayed on a monitor TV 50 via a D / A converter 48 as appropriate. The image processor 4
4, a microprocessor 52, a memory 54, and an external input / output I / F 56 are connected via a bus 58. The external input / output I / F 56 includes a robot controller 3
8 is connected, and an external computer 59 for managing processing results is connected.

Next, the operation of the work surface inspection device 20 and the image processing device 36 configured as described above will be schematically described with reference to a flowchart shown in FIG.

First, the image processing device 36 and the robot controller 38 are initialized (step S2). Subsequently, a processing pattern of an image described later is input from the robot controller 38 to the image processing device 36 (Step S).
4). After the above setting is completed, the robot 22 is driven, and the operation of the arm 26 causes the inspection light from the light source 24 to pass through the optical fiber bundle 28 and the condensing optical system 30 to a predetermined area of the work surface in a predetermined range. Is irradiated, the reflected light of the inspection light is incident on the CCD camera 32, and the image data is input to the image processing device 36 (step S6).

The image data input to the image processing device 36 is converted into gradation image data as a digital signal by an A / D converter 40 and input to an image density memory 42. The image processor 44 sets a binarization level as a reference for binarizing the image into a bright part and a dark part based on the histogram of the gradation image data (step S8).

Hereinafter, predetermined image processing is performed according to the processing pattern input from the robot controller 38 (step S10).

As a first processing pattern, when the work surface 35 to be inspected is a plane and the gradation image data is binarized, it is converted into binarized image data based on the binarization level, It is stored in the binarized image memory 46 (step S12). Then, in the binarized image data, a dark part isolated in a bright part is extracted as an isolated point (step S14). Based on the size of the isolated point, it is determined whether or not it is dust, and is sorted out (step S1).
6) The number and size of dust in one section in the processing pattern are transferred to the computer 59 via the external input / output I / F 56 and stored (step S18). The above processing is performed on all the sections set on the work surface (step S20). After the image processing for all blocks is completed,
The computer 59 outputs the inspection result (step S22).

As the second and third processing patterns, when the work surface 35 is a curved surface and a window is set for an image captured by the CCD camera 32, a window having a predetermined processing range is selected. Then, the part corresponding to the dark part of the obtained image is deleted from the image processing target (step S24). Alternatively, after binarizing the image, a window is calculated and obtained based on the distribution of the bright parts, and the dark part is deleted from the image processing target as in step S24 (step S26).

As the fourth and fifth processing patterns, when the work surface 35 is a curved surface and an image synthesis is selected, only the bright portion is extracted from the binarized image having a bright portion and a dark portion, and one frame is extracted. Image synthesis is performed n times until image data of the corresponding number is accumulated (step S28, step S3).
0). Alternatively, a window is calculated and obtained in the same manner as in step S26, and an image of only a bright portion obtained using this window is stored in the binarized image memory 46 for one frame so as not to overlap, and image synthesis is performed (step S32). ,
Step S30). Images obtained in this way include:
In order to prevent erroneous detection of dust or the like at the boundary between the bright part and the dark part, expansion or reduction processing such as removal of fine particles is performed (step S34). Subsequently, as in the first processing pattern, dust detection in step S16 and subsequent steps is performed. By performing processing on the image synthesized as described above, after the bright portions of a plurality of images are captured in one image, image processing can be performed collectively, so that the image processing speed is improved.

Next, a detailed description will be given of a case where the work surface is a curved surface and the obtained image is synthesized (when step S28 or step S32 is selected in step S10 in FIG. 3).

First, the image synthesis in step S28 will be described with reference to FIGS.

First, all storage areas of the binary memories No. 0 to No. 2 constituting the binary image memory 46 are initialized to 0 (black).

Subsequently, an image of the first section is input from the CCD camera 32. In this case, when teaching the robot controller 38, the arm 26 of the robot 22 is used.
Operation and the position of the CCD camera 32 are controlled.
The camera 32 is adjusted so that the bright portion comes to the upper part of the frame. The input image is temporarily stored in the image density memory 42 as gradation image data, and then binarized based on the binarization level set in step S7 of the flowchart in FIG. In the binarized image, the bright part is 1
(White) and the dark portion as 0 (black) are stored in the binary memory No. 0 constituting the binary image memory 46.

Further, the images of the binary memories No. 2 and No. 0 in the binary image memory 46 are stored in the image processor 4.
At 4, a logical sum is obtained for each pixel, a new image is synthesized, and this is input to the binary memory No. 1 of the binary image memory 46.

Next, after the CCD camera 32 is moved by the robot controller 38, the image of the second adjacent section is taken into the image processing device 36 from the CCD camera 32. In this case, the bright portion of the image is previously set in the CCD camera 3 by teaching of the robot controller 38.
It is set so as to be located at the center of the second frame, that is, not to overlap with the bright part in the image of the first section. Therefore, the image is binarized to make the bright part 1
(White) and the dark part as 0 (black) and newly input to the binary memory No. 0.

Here, the image-synthesized binary memory No. 1
And the image of the binary memory No. 0, to which the new image has been input, is ORed for each pixel in the image processor 44, and the images are combined. In this case, the bright portions of the images of the first section and the second section do not overlap by the teaching of the robot controller 38 as described above. Therefore, as shown in the illustration of the main part of the image composition in FIG.
2 is newly stored.

Similarly, the robot 22 is driven and the arm 2
6 is displaced, and the image of the adjacent third section is input to the binary memory No. 0 from the CCD camera 32. Then, the composite screen input to the binary memory No. 2 and the screen newly input to the binary memory No. 0 are combined, and the binary memory No.
1 is stored. Also in this case, as shown in FIG. 4, the bright portions of the first, second, and third images are stored without overlapping.

In this manner, the inspection image of the work surface in which the first to third sections are continuously curved surfaces is synthesized,
By performing image processing as one image, the area of a dark portion that does not require image processing is reduced, and the image processing speed is greatly improved, as compared to the case where image processing is performed on three images individually.

Although the three images have been combined here, it is of course possible to change the number of images to be combined according to the width of the bright part.

Next, the image combining in step S32 will be described with reference to the flowcharts of FIGS. 1 to 3 and FIG.

First, the storage areas of the binary memories No. 0 to No. 2 constituting the binary image memory 46 are all initialized to 0 (black) (step S2 in FIG. 3). Subsequently, the image of the first section is input from the CCD camera 32. The input image is temporarily stored in the image density memory 42 as gradation image data, and then a binarization level is set in step S8 of the flowchart in FIG. 3, and the image is binarized based on the binarization level. Value. The binarized image is input to the binary memory No. 1 with the bright part being 1 (white) and the dark part being 0 (black) (step S40).

Subsequently, when the x direction and the y direction are set as shown in FIG. 5 for the binary memory No. 1, the pixels corresponding to the bright portions are added in the x direction and the y direction, respectively. A histogram is created, and based on this histogram, a window is set in a portion corresponding to the bright portion,
Using this window, the image is again divided into a bright portion and a dark portion, and is newly input to the binary memory No. 2 (step S42). Next, a binary memory to which the composite image is input
The remaining area of No. 0 is the width Δy of the window in the y direction.
It is determined whether or not it is larger than the area determined by (Step S44). When the remaining area is larger than the width Δy, the logical sum of the image of the binary memory No. 0 and the binary memory No. 2 is obtained. In this case, the image of binary memory No. 2 is
In the drawing, it is shifted upward and synthesized. The combined image is newly input to the binary memory No. 1 (step S46). Similarly, in the composite image of the binary memory No. 1, the remaining area is confirmed, and whether or not the composition can be performed again is compared with a preset amount (step S48). If synthesis is possible, the image synthesis from step S40 is repeated. In the case of the second or subsequent image synthesis, step S4
The image formed by the window newly formed in step 2 is synthesized in the screen synthesis in step S46 so that the image is not overlapped with the image formed by the previously formed window and is not separated. Therefore, for example, as shown in the lower part of FIG. 5, an image synthesized four times is synthesized without interruption from the first time to the fourth time.

On the other hand, when the width Δy of the window exceeds the width of the remaining area of the binary memory No. 1 in step S44, or in step S48, the width of the remaining area of the newly synthesized image further increases. When the new image composition is disabled, the moving image composition ends. By performing such processing, the same effect as that of the image synthesis in step S28 can be obtained, and the bright portion of a larger number of images can be synthesized into one image by displacing the position of the window at the time of image synthesis. Use it effectively,
Further, the speed of image processing can be further improved.

[0033]

According to the work surface inspection method of the present invention, the following effects can be obtained.

That is, the image fetched by the detecting means is binarized, and only the image relating to the effective inspection surface in the image is extracted and held so as not to be duplicated. By performing image processing
The time required for image processing can be reduced, and the overall inspection time is also reduced.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a work surface inspection apparatus in a work surface inspection method according to one embodiment of the present invention.

FIG. 2 is a schematic explanatory view of an image processing apparatus in a work surface inspection method according to one embodiment of the present invention.

FIG. 3 is an overall flowchart of a work surface inspection method according to an embodiment of the present invention.

FIG. 4 is an explanatory view of a main part of image synthesis of a work surface inspection method according to one embodiment of the present invention.

FIG. 5 is an explanatory view of a main part of image composition of the work surface inspection method according to one embodiment of the present invention.

FIG. 6 is an explanatory diagram of a work surface inspection method in a conventional example.

FIG. 7 is an explanatory diagram of a work surface inspection method in a conventional example.

[Explanation of symbols]

 Reference Signs List 20 work surface inspection device 22 robot 32 CCD camera 35 work surface 36 image processing device 38 robot controller 42 image density memory 44 image processor 46 binary image memory

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-227910 (JP, A) JP-A-64-82180 (JP, A) JP-A-64-66547 (JP, A) 27342 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01N 21/88 G01B 11/30 G06T 7/00

Claims (3)

(57) [Claims] 1. A light projecting means for irradiating detection light toward a surface to be measured, a detection means for receiving reflected light of the detection light from the surface to be measured, and a light receiving surface of the detection means for receiving the reflected light. Using a surface inspection device equipped with a focusing optical system that converges
A method for inspecting a surface of a work having a curved surface, wherein the surface inspection device is sequentially displaced along the surface of the work,
A step of receiving the detection light by the detection means and binarizing each of the obtained images; and an image relating to an effective inspection surface of the workpiece irradiated with the detection light from the plurality of binarized image data. A method for inspecting a workpiece surface, comprising: extracting data and holding the data in a non-overlapping state; and performing predetermined image processing on the held image data. 2. The work surface inspection method according to claim 1, further comprising the step of performing teaching of a surface inspection device in advance so that a plurality of image data do not overlap. 3. The work surface inspection method according to claim 1, wherein the step of holding the image data includes the steps of: setting a window indicating an area of an effective inspection surface based on the binarized image data; And c. Maintaining the extracted image data of the effective inspection surface in a non-overlapping state.