JP2013092465A - Three-dimensional surface inspection device and three-dimensional surface inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a three-dimensional surface inspection device which allows a three-dimensional defect such as a recess and a large flaw on the surface to be accurately and rapidly inspected with a simple structure at low cost, even in the case of having acute mirror reflection from a measurement object.SOLUTION: A three-dimensional surface inspection device includes a camera device 3 which takes a picture of a measurement object X, a filter membrane which is arranged in a curve form so as to cover the measurement object, curve pattern light projection means 5 which projects pattern light having a curved intensity distribution with a periodic intensity distribution along the curve form of the filter membrane to the measurement object through the filter membrane, and defect detection means 13 which detects a three-dimensional defect in the surface of the measurement object through a decoding process to convert the curved intensity distribution to a linear intensity distribution for the picture taken by the camera device 3.

Description

  The present invention relates to a three-dimensional surface inspection apparatus and a three-dimensional surface inspection method for inspecting non-contact three-dimensional defects such as dents and large wrinkles on the surface of a measurement object such as an automobile and its parts.

  Inspections such as wrinkles, dents and paint peeling on the surface of automobile bodies are very important in automobile production and recycling. However, at present, these quality inspections rely on the visual inspection of skilled workers, which not only varies depending on the worker, but also places an excessive burden on the worker. Therefore, there is a demand for a surface inspection apparatus capable of performing a surface inspection of a measurement object at high speed and with high accuracy in a non-contact manner using a digital photographing apparatus such as a digital camera or a digital video camera.

  Three-dimensional image measurement for measuring a measurement object having a three-dimensional shape such as an automobile body can be broadly divided into a passive method and an active method. A typical passive measurement method includes a stereo measurement method using two cameras. The stereo measurement method is a technique for clarifying the corresponding point relationship between two images taken by two cameras using the image features of each part of the measurement object, and calculating the three-dimensional coordinates. Although it is suitable for measuring contours and the like, it is not suitable for measuring parts with few features such as gentle surfaces.

  On the other hand, as a typical active measurement method, there is a pattern light projection measurement method. The pattern light projection measurement method actively applies a feature to the measurement object by projecting the pattern light onto the measurement object, so that it can be applied to measurement of a part having a small feature such as a gentle surface.

  A phase shift analysis method is also known in which pattern light such as a sine wave is projected onto a measurement object and a plurality of reflection pattern images are used. For example, methods described in Patent Documents 1 and 2 have been proposed in order to shorten the measurement time of three-dimensional image measurement based on pattern light projection and improve measurement accuracy. In the method of Patent Document 1, the use of the optimum intensity modulation pattern light can realize three-dimensional image measurement by one-time projection of pattern light, and the measurement time can be shortened and the accuracy can be improved. It is not suitable for measuring the surface of the body.

  Further, in the method of Patent Document 2, more accurate three-dimensional image measurement can be realized by using a measurement line pattern having a higher density and a reference line pattern, but to a measurement object with strong surface reflection such as highlight. Is difficult to apply. That is, three-dimensional image measurement based on a general pattern light projection technique is difficult to apply to a glossy object such as an automobile body, that is, an object having a strong specular reflection.

  Therefore, the following techniques have been proposed for objects with strong specular reflection. For example, in the method of Patent Document 3, the surface inspection can be performed even on a measurement object with severe specular reflection by preventing the light source light from directly hitting the measurement object. In the method described in Patent Document 4, a linear light / dark pattern is projected onto a measurement object, and a defect on the surface of the measurement object is detected by analyzing a boundary point of the reflection pattern. It can be used to measure surface dents.

JP 2006-145405 A JP 2011-185872 A JP 2010-185820 A JP 2010-85165 A

  However, since the method of Patent Document 3 uses a two-dimensional image measurement technique, it can perform two-dimensional measurement such as surface flaws of automobiles, but performs three-dimensional inspections such as the depth of a dent. I can't. The method of Patent Document 4 is an analysis method mainly using pattern boundary points, and is an analysis method similar to binarized image analysis. Therefore, it is difficult to accurately measure the depth of unevenness. is there. In addition, it is difficult to measure unevenness where there is no boundary line.

  Therefore, in the present invention, it is possible to inspect three-dimensional defects such as surface dents and large wrinkles with high accuracy and high speed at a low cost with a simple structure even for a measurement object with severe specular reflection. It is an object to provide a three-dimensional surface inspection apparatus and a three-dimensional surface inspection method.

  The three-dimensional surface inspection apparatus of the present invention has an imaging device for photographing a measurement object, a filter film disposed in a curved surface and covering the measurement object, and a periodic intensity distribution along the curved surface of the filter film. Curved pattern light projection means for projecting the pattern light of the curved surface intensity distribution and projecting onto the measurement object through the filter film, and the curved surface intensity distribution to the linear intensity distribution for the image photographed by the photographing apparatus It includes a defect detection means for detecting a three-dimensional defect on the surface of the measurement object by performing a decoding process for conversion.

  Further, the three-dimensional surface inspection method of the present invention is a curved surface intensity distribution pattern having a periodic intensity distribution along the curved surface shape of the filter film with respect to the filter film disposed in a curved surface and covering the measurement object. A process of projecting light and projecting it onto a measurement object through a filter film, photographing the measurement object with a photographing device, and converting a curved intensity distribution into a linear intensity distribution for the photographed image This includes detecting a three-dimensional defect on the surface of the measurement object.

  According to these inventions, the pattern light is not directly projected onto the measurement object, but is projected through the filter film. Therefore, even if the measurement object has severe specular reflection, the light source of the pattern light on the surface Therefore, the surface defect of the measurement object can be easily detected from the photographed image by normally photographing the measurement object. At this time, the projected pattern light has a periodic intensity distribution along the curved surface shape of the filter film. However, if the curved surface intensity distribution is converted into a linear intensity distribution by decoding processing on the photographed image. Since the three-dimensional defect portion on the surface of the measurement object deviates from the linear intensity distribution, this three-dimensional defect portion can be detected.

  According to the present invention, even if the object to be measured has a severe specular reflection, the light source of the pattern light is not directly reflected on the surface thereof. The surface defect of the measurement object can be easily detected, and a three-dimensional defect portion such as a dent or a large wrinkle on the measurement object surface can be detected with high accuracy and high speed at low cost.

1 is an overall configuration diagram of a three-dimensional surface inspection apparatus in an embodiment of the present invention. It is a block diagram which shows the detailed structure of the three-dimensional surface inspection apparatus of FIG. It is a flowchart of the inspection process by the three-dimensional surface inspection apparatus in this embodiment. It is an image figure of curved-surface space intensity distribution pattern light generation of the surface inspection apparatus in the embodiment of the present invention. It is another Example of the projection pattern of the surface inspection apparatus in embodiment of this invention. (A) is a figure which shows intensity distribution of the image when there is no shape change, such as a dent, on the surface of a measurement object, (b) is a figure which shows intensity distribution of the decoding analysis result of (a). (A) is a figure which shows intensity distribution of an image in case there exists shape changes, such as a dent, on the surface of a measurement target object, (b) is a figure which shows intensity distribution of the decoding analysis result of (a).

  Hereinafter, a three-dimensional surface inspection apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall configuration diagram of a three-dimensional surface inspection apparatus according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a detailed configuration of the three-dimensional surface inspection apparatus of FIG.

  As shown in FIG. 1, the three-dimensional surface inspection apparatus in the embodiment of the present invention inspects three-dimensional defects such as wrinkles and dents on the surface of a measurement object X such as an automobile body and its parts in a non-contact manner. The linear light source 1 is disposed between the linear light source 1 and the measurement object X so that the light from the linear light source 1 does not directly hit the measurement object X. It comprises a filter film 2 that uniformly attenuates light, a camera device 3 as a photographing device for photographing the measurement object X, and a computer 4 to which the linear light source 1 and the camera device 3 are connected.

  The linear light source 1 is an ordinary commercially available linear illumination device such as a fluorescent lamp or LED. The filter film 2 is formed in a curved shape such as a dome shape or a tunnel shape using a translucent material, and dimmes and diffuses the light from the linear light source 1. A plurality of linear light sources 1 are arranged along the curved surface of the filter film 2.

  The transmittance of the filter film 2 is appropriately selected according to the light amount of the linear light source 1 and the surface reflectance of the measurement object X, but is generally in the range of 5% to 95%. The camera device 3 is a digital camera. The camera device 3 may be any photographing device capable of acquiring digital image data, such as an 8-bit, 10-bit, 12-bit, or 16-bit device, an image sensor such as a 3CCD, 1CCD, or CMOS, or a still image. Any device such as a camera, a video camera, and a video camera may be used.

  The computer 4 includes an interface (not shown) for connecting the linear light source 1 and the camera device 3, and the storage means 10 and the projection pattern light control means shown in FIG. 2 are executed by executing an inspection program (not shown). 11, functions as a photographing unit 12, a defect detection unit 13, a size estimation unit 14, an inspection result expression unit 15 and an output unit 16.

  The projection pattern light control means 11 controls a plurality of linear light sources 1, for example, on / off control, thereby causing a curved intensity distribution pattern light having a periodic intensity distribution along the curved surface of the filter film 2. Is projected. Control data of the linear light source 1 by the projection pattern light control means 11 is stored in the storage means 10.

  The photographic means 12 controls the camera device 3 with the optimum parameters (hereinafter referred to as “imaging parameters”) necessary for photographing an image applicable to the examination, and photographs the surface of the measurement object X. The image data taken is stored in the storage device 10. Shooting parameters and the like necessary for controlling the camera device 3 are stored in the storage unit 10. Further, the storage means 10 also stores data of results calculated by each means described later.

  The defect detection means 13 detects three-dimensional defects such as dents and large wrinkles on the surface of the measurement object X by analyzing the image data input by the photography means 12. The size estimation means 14 estimates the size (diameter, depth, etc.) of the detected three-dimensional defect by image analysis.

  The inspection result expression means 15 expresses inspection results such as the position, shape and size of the three-dimensional defect on the monitor of the computer 4 in a manner that is easy for the user to understand. Further, the inspection result expression means 15 has a function of enlarging display, reduction display, whole display, partial display, etc. on the monitor as necessary. The output unit 16 stores or outputs a photographed image, an inspection result, and the like in various media using an image, a text file, a table, a graph, a numerical value, and the like.

  As shown in FIG. 2, the curved pattern light projection unit 5 includes a linear light source 1 and a projection pattern light control unit 11. The linear light source 1 adjusts the overall positional relationship, the distance between each other, and the distance between the filter films 2 in advance in order to generate the necessary projection pattern light.

  Next, an inspection process for a three-dimensional defect portion such as a dent on the surface of the measurement object X by the three-dimensional surface inspection apparatus according to the present embodiment will be described. FIG. 3 is a flowchart of inspection processing by the three-dimensional surface inspection apparatus in the present embodiment.

  Before using the surface inspection apparatus, the linear light source 1 is set. In the setting, first, the position of the linear light source 1 and the interval between the linear light sources 1, that is, the distance between the linear light sources 1 is adjusted (S 101). Subsequently, the distance between the linear light source 1 and the filter film 2 is adjusted to provide an environment for generating curved-surface intensity distribution pattern light (S102). The above setting does not need to be performed before each measurement, and may be performed only once when the surface inspection apparatus is constructed.

  Subsequently, on / off of each linear light source 1 is controlled by a command from the projection pattern light control means 11 of the computer 4 to generate curved spatial intensity distribution pattern light for measurement (S103). FIG. 4 is an image diagram of the generation of curved-surface intensity distribution pattern light. FIG. 4A is an image diagram of the arrangement of the linear light sources 1 and the intensity distribution of pattern light generated around the curved surface of the surface of the filter film 2. (B) is an image figure of intensity distribution of pattern light when filter film 2 of (a) is developed on a plane (arc R is straightened). As shown in FIG. 4B, the intensity distribution of the pattern light having the curved surface intensity distribution in FIG. 4A is a pattern light whose intensity distribution becomes a sine wave when developed on a plane.

  Next, the photographic means 12 of the computer 4 adjusts the photographic parameters of the camera device 3, the curved intensity distribution pattern light reflected from the measurement object X is photographed by the camera device 3, and the image is input to the computer 4. (S104). The photography unit 12 analyzes the intensity distribution of the input image and determines whether the image is ideal for defect detection. If the image is an ideal image, the process proceeds to the next process. If the image is not an ideal image, the image capturing parameter of the camera device 3 is adjusted repeatedly until an ideal image is captured, and the image is captured (S105).

  When an ideal image is taken, the defect detection means 13 performs a decoding process for converting a sine wave, which is a pattern light of a curved intensity distribution, into a linear intensity distribution (S106). At this time, if there is no shape change such as a dent on the surface of the measurement object X, the intensity distribution of the photographed image is a clean sine wave distribution as shown in FIG. It becomes a linear intensity distribution as shown in b). On the other hand, if there is a shape change such as a dent on the surface of the measurement object X, the intensity phase distribution of the image of the defective part such as the dent changes as shown in FIG. It can no longer be obtained. Therefore, when the decoding is performed, as shown in FIG. 5B, the defective portion deviates from the straight line, so that it can be determined that there is a defect such as a dent in the portion deviating from the straight line (S107).

  Further, the size and depth of the dent are estimated by the size estimation means 14. The range deviating from the straight line shown in FIG. 7B is proportional to the size of the dent, and the extent deviating from the straight line is proportional to the depth of the dent. Can be estimated (S108). The inspection result can be expressed by computer graphics on the monitor of the computer 4 by the inspection result expression means 15 (S109), and can be stored in various storage media or output by the output means 16 (S110). ).

  In the above embodiment, pattern light having a sinusoidal intensity distribution is used as the pattern light of the curved surface intensity distribution. However, as other pattern light, a periodic light such as a trapezoidal wave or a rectangular wave as shown in FIG. It is also possible to use pattern light having a strong intensity distribution.

  In the three-dimensional surface inspection apparatus according to the present embodiment, the pattern light is not directly projected onto the measurement object X, but is projected through the filter film 2 and is attenuated and diffused by the filter film 2. Even if it is a terrible measurement object X, the light source of the pattern light is not directly reflected on its surface. Therefore, by photographing the measurement object X normally, the measurement object X can be easily obtained from the captured image. Surface defects can be detected, and processing can be performed in a short time of several seconds to several tens of seconds.

  Further, the pattern light projected onto the measurement object X has a periodic intensity distribution along the curved surface shape of the filter film 2, and the curved surface intensity distribution is decoded into a linear intensity distribution for the photographed image. Since the three-dimensional defect portion on the surface of the measurement object X deviates from the linear intensity distribution, it is possible to easily detect this three-dimensional defect portion in a few seconds to a few tens of seconds. It is possible to inspect three-dimensional defects such as dents.

  INDUSTRIAL APPLICABILITY The three-dimensional surface inspection apparatus and the three-dimensional surface inspection method of the present invention are useful as an apparatus and method for inspecting three-dimensional defects such as dents and large wrinkles on the surface of measurement objects such as automobiles and parts thereof in a non-contact manner. In particular, it is suitable for inspection of a measurement object having a severe specular reflection.

X Measurement object 1 Linear light source 2 Filter film 3 Camera device 4 Computer 5 Curved pattern light projection means 10 Storage means 11 Projection pattern light control means 12 Photographing means 13 Defect detection means 14 Dimension estimation means 15 Inspection result expression means 16 Output means

Claims (4)

A photographing device for photographing a measurement object;
A filter film disposed in a curved surface and covering the measurement object;
A curved surface pattern light projection means for projecting a pattern light of a curved surface intensity distribution having a periodic intensity distribution along the curved surface of the filter film, and projecting it onto the measurement object via the filter film;
Defect detection means for detecting a three-dimensional defect on the surface of the measurement object by performing a decoding process for converting the curved surface intensity distribution into a linear intensity distribution on the image photographed by the photographing apparatus. Including 3D surface inspection equipment. The curved surface pattern light projection means includes:
A plurality of linear light sources arranged along the curved surface of the filter film;
2. A projection pattern light control means for controlling the plurality of linear light sources to form a curved light intensity distribution pattern light having a periodic intensity distribution along the surface shape of the filter film. 3D surface inspection equipment.   The three-dimensional surface inspection apparatus according to claim 1, wherein the pattern light of the curved surface intensity distribution is a periodic intensity distribution having a sine wave shape, a rectangular wave shape, or a trapezoidal wave shape. A pattern light of a curved surface intensity distribution having a periodic intensity distribution is projected along the curved surface shape of the filter film on a filter film that is arranged in a curved surface and covers the measurement object, and passes through the filter film. Projecting onto the measurement object;
The measurement object is imaged by an imaging device, and a three-dimensional defect on the surface of the measurement object is detected by performing a decoding process on the captured image to convert the curved surface intensity distribution into a linear intensity distribution. A three-dimensional surface inspection method comprising detecting.

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