JP2006010392A - Through hole measurement system and method, and through hole measurement program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect the position and direction of a through hole formed in a target member.
An image acquisition device 1A that captures a stereo image in which a through hole formed in a workpiece having a predetermined thickness is photographed to show an inner wall surface of the through hole, and an image processing device 2 that processes the acquired image. The image processing apparatus 2 detects the feature points of the inner wall surface portion from the acquired stereo image, and detects the three-dimensional position information of the feature points, and the detected features. The shape of the through hole is predicted based on the three-dimensional position information of the point, the shape predicting means 14 for calculating the substantially cylindrical three-dimensional shape, and the shape based on the distribution of the feature points detected by the position information detecting means And an end specifying means 15 for specifying an end in the substantially cylindrical three-dimensional shape calculated by the predicting means.
[Selection] Figure 1

Description

  The present invention relates to a through-hole measurement system, and more particularly to a system that measures the position and the penetration direction by calculating the shape of a through-hole formed in a thick workpiece. The present invention also relates to a through hole measurement method and a through hole measurement program.

  Many parts mounting holes are formed in a member to which various parts such as a two-wheeled aluminum frame are attached. For example, a plurality of through holes H are formed in the two-wheeled aluminum frame 100 as shown in FIG. However, if the frame is distorted, the position of the mounting hole and the through direction of the hole change, which causes a problem that the mounting part cannot be mounted. Therefore, by inspecting these mounting holes in advance, it is possible to use only the frame within the allowable allowable range, and to speed up the subsequent assembling work.

  And the technique which test | inspects the position of the hole formed in the object member (workpiece | work) is disclosed by patent document 1 and patent document 2. FIG. The measuring method described in Patent Document 1 measures several points on the circumference, which is the outer shape of a circular hole, by scanning with a laser (optical) rangefinder, and calculates the center position of the hole. . Specifically, as shown in FIG. 12A, first, a laser beam is scanned as indicated by straight lines L1 and L2 with respect to the through hole H (FIGS. 12A and 12A) formed in the plate material. To measure the distance (FIGS. 12A and 12). Of the straight lines L1 and L2 that are scanning lines of the laser light, the part represented by a solid line indicates a place where the processed surface of the hole is measured, and the part represented by a dotted line measures the inside of the hole, or This indicates the location where measurement was not possible. By performing laser distance measurement in this way, a point D at which the measurement distance changes rapidly is detected. In the example of FIGS. 12A and 12B, it is assumed that four points are measured. Then, the shape of the through hole H is calculated from this point, and the center position C is calculated (FIGS. 12A and 3).

  In addition, the measurement method disclosed in Patent Document 2 is to measure several points on the circumference, which is the outer shape of a circular hole, and calculate the center position of the hole by slit light irradiation and image processing as described above. . Specifically, as shown in FIG. 12 (b), first, slit light is irradiated to the through holes H (FIG. 12 (b) (1)) formed in the plate material as indicated by reference numerals L3 and L4. (FIGS. 12B and 2), an image in this state is acquired and processed to measure a point D on the circumference, which is the outer shape of the through hole H (FIGS. 12B and 3). Then, the shape of the through hole H is calculated from this point, and the center position C is calculated (FIGS. 12B and 12).

Japanese Patent Application Laid-Open No. 11-23217 Japanese Patent Laid-Open No. 6-258022

  However, since the through hole formed in the plate having a thickness of 1 cm or more is usually chamfered, the technique described in the above-mentioned patent document has a problem that the detection accuracy is lowered. This will be specifically described with reference to FIGS.

First, with reference to FIG. 13, a problem in the case of using the laser rangefinder shown in Patent Document 1 will be described. In the case of scanning with the laser rangefinder 101, the angle characteristic of the laser rangefinder 101 becomes a problem. The angle characteristics are inclination angles θ ₁ and θ ₂ of the surface of the workpiece W that can be measured by the laser range finder 101 as shown in FIG. 13A, and are usually within about ± 30 degrees. On the other hand, since the chamfered surface is ± 45 degrees, when scanning in the direction of arrow Y101 in FIG. 13B, the end portion Hi of the through hole H itself (boundary between the chamfered surface and the through hole) Instead, it becomes impossible to measure the distance at the end Ho of the chamfered surface (the boundary between the chamfered surface and the surface of the workpiece W), and it is determined that the measurement distance has suddenly changed. As a result, as shown in FIG. 13C, the point D may be measured near the end portion Ho of the chamfered surface. Therefore, the end portion Hi of the through hole H cannot be accurately measured, and the measurement accuracy of the center position of the hole is thereby lowered.

  Next, with reference to FIG. 14, a problem when the slit light shown in Patent Document 2 is used will be described. In the case of irradiation with slit light from a slit light source, when the slit light L3 is irradiated to the through hole H as shown in FIGS. 14A and 14B, as shown by an arrow Y102 in FIG. The slit light is also applied to the inner wall of the through hole. Then, when this irradiation state is recognized by image processing, the spot irradiated to the inner wall of the hole is not a point on the outer periphery of the hole, as shown in FIG. Since it is detected as D, the outer periphery of the through hole H cannot be accurately measured as described above, and the measurement accuracy of the center position of the hole is also lowered.

  Due to such problems of the prior art, the above inspection may still be performed manually. Specifically, an operator inspects through a pin in a through hole to be inspected. However, in such manual inspections, the number of products to be inspected is large, and the number of holes to be inspected is large. When inspection objects such as frames are heavy, the operation is difficult for the operator. It will be something.

  For this reason, in the present invention, the position and the axial direction of the through hole formed in the target member can be automatically detected with high accuracy, and the through hole can be easily and inexpensively inspected. The object is to provide a hole measurement system, method and program.

Therefore, in the through hole measurement system of the present invention,
An image acquisition device that captures a stereo image in which a through-hole formed in a workpiece having a predetermined thickness is photographed and an inner wall surface of the through-hole is reflected, and an image processing device that processes the acquired image,
This image processing device
Position information detection means for detecting feature points of the inner wall surface portion from the acquired stereo image and detecting three-dimensional position information of the feature points;
Shape prediction means for predicting the shape of the through hole based on the detected three-dimensional position information of the feature point, and calculating a substantially cylindrical three-dimensional shape;
Based on the distribution of the feature points detected by the position information detection means, an end specifying means for specifying the end of the substantially cylindrical three-dimensional shape calculated by the shape prediction means;
It has the structure of having.

  With such a configuration, first, an image is acquired from the oblique direction of the axis of the through hole by the image acquisition device, and thereby a stereo image in which the inner wall surface is projected is acquired. Then, by stereoscopically viewing the inner wall surface, a plurality of three-dimensional coordinates of feature points on the inner wall surface are detected, and based on these, the three-dimensional shape of the inner wall surface of the substantially cylindrical through hole is predicted and calculated. To do. Thereafter, the distribution of the feature points of the inner wall surface on the cylindrical three-dimensional shape is examined, and is specified as the end portion of the cylindrical through hole based on the distribution. Thereby, the shape of the through hole, the center position, and the like can be accurately detected only by the image acquisition device and the image processing device. In particular, even in the case of a chamfered through hole, it is possible to specify the position of either the end of the chamfered surface or the end of the through hole itself located as the end of the through hole. Measurement accuracy can be improved.

Further, the through hole measurement system of the present invention more specifically,
An image acquisition device configured to photograph a through hole having a concave and convex shape on an inner wall surface formed on a workpiece having a predetermined thickness to acquire a stereo image in which the inner wall surface of the through hole is reflected, and an image for processing the acquired image A processing device,
This image processing device
Position information detecting means for detecting a feature point using the gray value represented on the image based on the uneven shape of the inner wall surface from the acquired stereo image, and detecting the three-dimensional position information of the feature point;
A shape predicting means for predicting the shape of the through hole based on the three-dimensional position information of the detected feature point, and calculating a cylindrical shape corresponding to the through hole;
In the calculated axial direction of the cylinder shape, a position where the number of feature point distributions detected by the position information detection means is specified is specified, and the specified axial position is calculated by the shape prediction means. End specifying means for specifying as an end of the shape;
It has the structure of having.

  By adopting such a configuration, as described above, first, an image is acquired from the oblique direction of the axis of the through hole by the image acquisition device, and thereby a stereo image in which the inner wall surface is projected is acquired. Then, by stereo-viewing the inner wall surface having the concavo-convex shape, the concavo-convex shape is represented by a shading pattern, and the three-dimensional coordinates of the feature points of a large number of inner wall surfaces can be accurately detected. The cylinder shape corresponding to the through hole is predicted and calculated. Thereafter, the distribution of the feature points on the inner wall surface in the axial direction of the cylindrical shape is examined, and the position having the most characteristic points in the axial direction is specified as the end portion of the cylindrical shape. At this time, even if the through hole is chamfered due to the unevenness of the inner wall surface, it is possible to differentiate the chamfered surface from the inner wall surface, so that the end position of the through hole can be reliably detected. Thus, the center position of the through hole can be measured with higher accuracy.

And in this invention, in addition to the said structure,
The end shape specifying unit of the image processing apparatus excludes the feature points detected by the position information detecting unit from the cylindrical shape calculated by the shape predicting unit and excluding those separated by a predetermined distance. Act to identify the end of the
The structure is adopted.

  By adopting such a configuration, it is possible to eliminate the influence of erroneously detected feature points, and to calculate the shape of the through hole with higher accuracy and to detect an accurate center position and the like.

In the present invention, in addition to the above-described configuration,
Based on the three-dimensional position information of the excluded feature points, the edge specifying unit of the image processing apparatus has the number of the excluded feature points most in the axial direction of the cylindrical shape corresponding to the inner wall surface by the shape prediction unit. A configuration is adopted in which a large number of positions are specified and this position is specified as an end portion of the chamfered surface.

  By adopting such a configuration, even if the feature point deviates from the cylindrical shape that is the inner wall surface shape of the through hole, it is not a false detection, but the end of the chamfered surface (the boundary between the chamfered surface and the workpiece surface). ) Since these feature points are often detected at the same position in the axial direction among misdetected points, the end of the chamfered surface of the through hole can be detected by detecting this. The position can be reliably detected. Thereby, the shape and position of the through-hole that has been chamfered can be measured with higher accuracy.

Furthermore, in the present invention,
The image processing apparatus includes an edge contour shape calculating unit that performs edge detection from the acquired stereo image and calculates an edge contour shape of the through hole based on the edge information.
The shape predicting means of the image processing device predicts and calculates the cylindrical shape with the end contour shape calculated by the end contour shape calculating means as the initial end position.
The structure is adopted.

  With this configuration, edge detection is performed from the stereo image, and the three-dimensional position of the end contour shape of the through hole is calculated from the edge information. And this edge part outline shape is temporarily defined as an edge part of the through-hole which is a cylinder shape, and the cylinder shape corresponding to a through-hole is estimated and calculated based on this. After that, as described above, the end position is specified more accurately from the distribution of the feature points. As described above, since the end portion of the cylindrical shape is determined at the time of the shape prediction calculation processing, the cylindrical shape prediction calculation processing is facilitated, and the measurement accuracy of the through-hole shape is improved and measurement is performed as described above. The processing can be speeded up.

  In addition, it is desirable that the position information detection means of the image processing device is configured to detect a feature point of the inner wall surface portion from the stereo image using a phase-only correlation method and detect three-dimensional position information of the feature point. .

  By adopting such a configuration, the phase-only correlation method has a feature that the magnitude of the correlation coefficient becomes significant as compared with the normal correlation. For this reason, even if the distance between the cameras is set to be as short as 10 to 15 mm, the three-dimensional data of the inner wall can be detected with high accuracy. Furthermore, by shortening the distance between the cameras, the imaging area of the cylindrical inner wall can be increased, and a large amount of three-dimensional data on the inner wall can be acquired. Thereby, the shape of a through-hole can be calculated based on these many and highly accurate data, and the measurement accuracy can be further improved.

In addition to the above configuration,
An image acquisition device is arranged so as to acquire a stereo image from one end side of the through hole formed in the work, and illumination means for irradiating the work from the other end side of the through hole is arranged. The structure is set up.

  Thereby, while acquiring the image of a workpiece | work from the one edge part side of a through-hole, it will be illuminated by the illumination means from the back surface side. Then, the image of the workpiece is projected darkly because the light irradiated from the back side is projected in the through portion of the through hole, and the periphery of the end portion of the through hole is backlit. Therefore, it becomes difficult to detect feature points at locations around the through holes, and the number of feature points detected on the chamfered surface is also reduced. On the other hand, since the illumination is irradiated on the inner wall surface of the through hole, many feature points of the inner wall surface can be detected. Therefore, even if a chamfered surface is formed in the through hole, it is not possible to extract a feature point, so that the position of the outer periphery of the chamfered surface can be suppressed from being recognized as an end, and the position of the inner periphery can be determined. It can be recognized as the end of the through hole, and the measurement accuracy of the through hole can be improved.

In addition, the image acquisition device is configured with two sets of image acquisition devices that respectively acquire stereo images,
It is desirable that the two sets of stereo image devices are arranged at positions where images of different portions of the inner wall surface of the through hole can be acquired.

  As a result, the amount of image information of the inner wall surface of the through hole acquired in a stereo image can be increased, and many feature points can be detected, thereby improving the accuracy of the calculated three-dimensional shape of the through hole. In addition, the end position can be reliably detected. Therefore, it is possible to improve the measurement accuracy as a whole.

Here, the present invention is also an image processing apparatus constituting the through hole measurement system,
Position information detection means for detecting feature points of the inner wall surface portion from the acquired stereo image and detecting three-dimensional position information of the feature points;
A shape prediction means for predicting the shape of the through hole based on the detected three-dimensional position information of the feature point, and calculating a substantially cylindrical three-dimensional shape;
Based on the distribution of the feature points detected by the position information detection means, an end specifying means for specifying the end of the substantially cylindrical three-dimensional shape calculated by the shape prediction means;
It has the structure of having.

In addition, the image processing apparatus of the present invention more specifically,
Position information detecting means for detecting a feature point using the gray value represented on the image based on the uneven shape of the inner wall surface from the acquired stereo image, and detecting the three-dimensional position information of the feature point;
A shape prediction means for predicting the shape of the through hole based on the three-dimensional position information of the detected feature point, and calculating a cylindrical shape corresponding to the through hole;
In the calculated axial direction of the cylindrical shape, the position having the largest number of distributions of the feature points detected by the position information detecting means is specified, and the specified axial position is calculated by the shape predicting means. End specifying means for specifying as a cylindrical end,
It has the structure of having.

  In the present invention, there is also provided a program for realizing the above means on a computer.

Furthermore, the present invention also provides an invention of a method realized by the operation of the above system.
A through-hole that measures a through-hole by acquiring a stereo image in which an inner wall surface of a through-hole formed in a workpiece having a predetermined thickness is reflected by an image acquisition device and processing the stereo image using the image processing device A hole measurement method,
Detecting a feature point of the inner wall surface portion from the acquired stereo image, and detecting a three-dimensional position information of the feature point;
Predicting the shape of the through hole based on the detected three-dimensional position information of the feature point, a shape prediction step of calculating a substantially cylindrical three-dimensional shape,
Based on the distribution of the feature points detected in the position information detection step, an end specifying step for specifying an end in the substantially cylindrical three-dimensional shape calculated in the shape prediction step;
It has the structure of having.

In addition, the through hole measuring method is specifically as follows:
By obtaining a stereo image in which the inner wall surface of the through hole having a concavo-convex shape is reflected on the inner wall surface formed on the workpiece having a predetermined thickness by the image acquisition device, and processing the stereo image using the image processing device A through hole measurement method for measuring a through hole,
A position information detection step of detecting a feature point using a gray value represented on the image based on the uneven shape of the inner wall surface from the acquired stereo image, and detecting three-dimensional position information of the feature point;
A shape prediction step of predicting the shape of the through hole based on the three-dimensional position information of the detected feature point, and calculating a cylindrical shape corresponding to the through hole;
In the calculated axial direction of the cylinder shape, the position where the number of feature point distributions detected in the position information detection process is the largest is specified, and the specified axial position is calculated in the shape prediction process. An end specifying step for specifying the end of the shape;
It has the structure of having.

In addition to the above configuration,
The end specifying step excludes the feature points detected in the position information detection step from the cylindrical shape calculated in the shape prediction step by a predetermined distance, and removes the end of the cylindrical shape. You may make it operate | move to identify.

  Further, the edge specifying step is based on the three-dimensional position information of the excluded feature points, and the number of the excluded feature points is the largest in the axial direction of the cylindrical shape corresponding to the inner wall surface in the shape prediction step. And this position may be specified as the outer periphery of the chamfered surface.

In addition to the above configuration,
Before the shape prediction step, an edge detection is performed from the acquired stereo image, and an end contour shape calculation step for calculating an end contour shape of the through hole based on the edge information is provided.
The shape predicting step may be configured to predict and calculate the cylindrical shape using the end contour shape calculated in the end contour shape calculating step as the initial end position.

  Thus, even the image processing apparatus, program, and method having the above-described configuration operate in the same manner as the above-described through-hole measurement system and can achieve the above-described object.

  Since the present invention is configured and functions as described above, according to this, it is possible to accurately detect the shape, the center position, and the like of the through hole formed in the plate material only by the image acquisition device and the image processing device. In particular, even for a chamfered through hole, the position of the chamfered outer periphery or inner periphery can be specified as the end of the through hole, and the measurement accuracy can be improved. It has an unprecedented superior effect.

  The basic configuration of the present invention will be described below. First, the through hole measurement system according to the present invention includes an image acquisition device that acquires a stereo image in which the inner wall surface of the through hole is reflected, and an image processing device that processes the acquired image. Then, the image processing device detects the feature point of the inner wall surface portion from the acquired stereo image and detects the three-dimensional position information of the feature point, and the detected three-dimensional position information of the feature point. Based on the shape prediction means for predicting the shape of the through hole and calculating a substantially cylindrical three-dimensional shape, and the substantially cylinder calculated by the shape prediction means based on the distribution of the feature points detected by the position information detection means And an end portion specifying means for specifying an end portion in the three-dimensional shape.

  Of the above-described configurations, the end portion specifying means is particularly characterized. By the action of this means, the end position of the through hole can be specified with high accuracy, and accordingly, the center position of the through hole can be measured with high accuracy. Hereinafter, a specific configuration of the present invention will be described with reference to each embodiment.

  A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing an outline of the configuration of the present invention. FIG. 2 is a functional block diagram illustrating the configuration of the image processing apparatus. 3 to 5 are explanatory diagrams illustrating processing in the image processing apparatus. FIG. 6 is an explanatory diagram showing the operation.

<Overall configuration>
As shown in FIG. 1, the through-hole measurement system in the present embodiment acquires stereo cameras 1 </ b> A and 1 </ b> B (image acquisition devices) that capture a stereo image by capturing the workpiece W in which the through-hole H is formed, and this acquisition. And a computer 2 (image processing apparatus) for processing an image. In addition, an illuminating device 3 (illuminating means) that irradiates predetermined light from the back side opposite to the image acquisition surface of the workpiece W and transmits the light to the through hole H is provided. Although not shown, the stereo cameras 1A and 1B and the transmitted illumination 3 are attached to a robot arm or the like so that movement can be controlled according to the position of the through hole H on the workpiece W. Hereinafter, each configuration will be described in detail.

<Workpiece, through hole>
In the present embodiment, the through-hole H to be measured is a through-hole H having a circular cross section formed in the workpiece W that is a thick plate material, in other words, the through-hole H having a substantially cylindrical shape (columnar shape). . A plurality of through holes H are formed in the workpiece W, and as will be described later, all these through holes are to be measured. For example, as shown in FIG. 11 described in the conventional example, a frame 100 of a two-wheeled vehicle is a workpiece W, and a through hole H formed in the frame 100 is a measurement target. The through hole H is not limited to a circular cross section.

  The workpiece W is fixedly arranged by a fixing device (not shown), and in this state, the workpiece W is photographed by the stereo cameras 1A and 1B provided in the robot arm or the like. Design information indicating the shape and arrangement position of the workpiece W, the position of the design through hole H formed in the workpiece W, and the like are prepared in advance and stored in the computer 2 as described later.

  Further, the end portion of the through hole H formed in the workpiece W is chamfered. The chamfered surface is formed at an angle of about 45 degrees from the through hole H as shown in FIG. For convenience of explanation, the end portion of the chamfered surface that is located on the surface of the workpiece W is indicated by the symbol Ho (see FIG. 1 and FIG. 5C), and the chamfered surface that is located inside this chamfered surface. And the through hole H is indicated by the symbol Hi as the end of the through hole H.

  Further, a processing mark by drilling or the like is formed on the inner wall surface of the through hole H, and the surface has an uneven shape. As will be described later, when such an inner wall surface is photographed with a camera, a shading pattern appears on the image based on the uneven shape such as a processing mark. This will be described later with reference to FIG.

<Stereo camera>
Stereo cameras 1A and 1B are CCD cameras fixedly arranged on a robot arm or the like with a predetermined interval. Then, a set of stereo images is acquired by two CCD cameras. At this time, the stereo cameras 1 </ b> A and 1 </ b> B are arranged so that images can be acquired from a direction (for example, 30 degrees) inclined with respect to the axial direction of the through hole H. Thereby, as shown to Fig.3 (a), the image in which the inner wall part of the through-hole H was projected can be acquired.

  Here, in this embodiment, as shown in FIG. 1, two sets of stereo cameras 1A and 1B are arranged. The two sets of stereo cameras 1A and 1B each acquire a stereo image. At this time, the stereo cameras 1A and 1B are arranged at positions where images of different portions of the inner wall surface of the through hole H can be acquired. ing. Although the position of the through hole H varies depending on the machining state of the workpiece W and the deformation state of the workpiece W, it is formed so as to be within a certain range according to the design information. Therefore, the through hole H is attached to the robot arm based on the design information. Control the position of the camera. As a specific arrangement, as shown in FIG. 1, one stereo camera 1A and the other stereo camera 1B are arranged at substantially target positions across the axis C1 of the through hole H predicted from the design information. To do. Thereby, one stereo camera 1A can photograph the inner wall surface located below the through hole H in FIG. 1, and the other stereo camera 1B can photograph the inner wall surface located above the through hole H in FIG. It is possible to obtain a wide range of inner wall surface images by combining two pairs of stereo images. Then, as will be described later, the shape and position of the through hole H can be measured with higher accuracy. In the present embodiment, the case where two sets of stereo cameras 1A and 1B are provided is illustrated, but the present invention can be configured with only one set of stereo cameras.

<Lighting device>
Further, as described above, the illumination device 3 is disposed on the opposite side of the stereo cameras 1A and 1B with the workpiece W interposed therebetween, that is, on the back surface side of the workpiece W. This is for transmitting light of a predetermined brightness toward the front side. By doing in this way, in the image acquired from the front side, the penetrating part is projected brightly, and conversely, the surface of the workpiece W on the front side is reflected and darkly projected. At this time, since the inner wall surface of the through hole H is also irradiated with light, the inner wall surface is projected brightly on the acquired stereo image, and the shading pattern based on the uneven shape such as the above-described processing trace is clear. Can be obtained.

<Computer>
The computer 2 includes a general computer including a CPU 10 that is a calculation unit, a memory 20 that is a storage unit, an input unit 30 such as a mouse and a keyboard, and an output unit 40 such as a display and a printer. . This computer may be a personal computer. In this embodiment, the computer is a computer having a relatively high arithmetic processing capability such as a workstation.

  The CPU 10 is mainly configured with a processing unit that executes the following processing. These processing units are realized by reading and incorporating the through hole measurement program into the CPU 10 of the computer 2. The program may be stored in advance in the storage unit of the computer 2 and read out by the CPU, or the program stored in a portable medium such as a CD-ROM may be provided to the image processing apparatus 1. Good. Furthermore, it may be incorporated by downloading from another computer via a network.

  Here, each processing unit constructed in the CPU 10 and data stored in the memory 20 will be described in detail with reference to a functional block diagram showing a configuration of the computer 2 in FIG. 2. In addition, the processing content by each process part is not limited to what is demonstrated below. Of course, each processing unit also realizes the operation described when the operation is described.

  First, the CPU 10 controls the operation of the stereo cameras 1A and 1B to acquire a stereo image, and the gray value expressed on the image based on the uneven shape of the inner wall surface from the acquired stereo image. A feature point detection unit 12 that detects a feature point using the three-dimensional data, and a three-dimensional data calculation unit 13 that detects three-dimensional position information of the feature point are constructed. The feature point detector 12 and the three-dimensional data calculator 13 function as position information detectors.

  Further, the CPU 10 predicts the shape of the through hole based on the detected three-dimensional position information of the feature point and calculates a cylindrical shape corresponding to the through hole, and a shape prediction calculation unit 14 (shape prediction unit). An end specifying unit 15 (end specifying unit) that specifies a position having the largest number of feature point distributions in the calculated axial direction of the cylindrical shape and specifies the specified axial position as an end of the cylindrical shape ) And a through hole information calculation unit 16 that calculates the shape, axial direction, center position, and the like of the through hole from the cylindrical shape whose end is specified.

  Each processing unit will be described in detail. First, the image acquisition processing unit 11 also has a function of controlling a robot arm provided with the stereo cameras 1A and 1B so as to control the positions of the stereo cameras 1A and 1B. At this time, design information representing a design position and a hole direction of the through hole H with respect to the workpiece W is previously input and stored in the computer 2 from the input unit 30 (not shown). An image around a position where the hole H is expected to be formed is acquired.

  Then, from the two sets of stereo cameras 1A and 1B, stereo images obtained by photographing the through holes H from an angle inclined with respect to the axial direction are acquired almost simultaneously, and temporarily stored in a storage device such as the memory 20. Accordingly, a corresponding image temporary storage unit 21 is formed in the memory 20. An example of the stereo image (signs PL and PR) obtained at this time is shown in FIG. Note that this pair of stereo images is acquired by one set of stereo cameras (for example, reference numeral 1A). When two sets of stereo images are provided as in the present embodiment, another pair of stereo images is obtained. can get.

  As shown in FIG. 3A, since the illumination device 3 irradiates light from the side opposite to the photographing side, the surface of the workpiece W appears dark, and appears black in the example of this figure. As a result, the chamfered surface formed at the end of the through hole H also appears black on the image. On the other hand, since the inner wall surface of the through hole H is irradiated with light from the illuminating device 3, uneven shapes such as processing marks formed on the inner wall surface become striped patterns with gray values on the image. Appear in

  Then, the feature point detection unit 12 detects corresponding points of each image (PL, PR) by pattern matching based on the shading pattern appearing on the acquired stereo image. At this time, as shown in FIG. 3B, each image is divided into a plurality of regions, and a region where an inner wall surface on which a shading pattern appears is specified (for example, regions n1 to nn). Then, using one image as a model image, feature points are determined at predetermined intervals or randomly from the region (PL image), and the corresponding points corresponding to the feature points are defined as regions corresponding to the other image (PR image). Search from. For example, when the entire image is 640 × 480 pixels, each of the divided regions is 30 × 30 pixels. Note that when searching for corresponding points in a PR image from a PL image, a range as shown by a white frame and an arrow in FIG. 3A according to the parallax based on the distance from the workpiece, the interval between stereo cameras, and the like. It is better to search for corresponding points by shifting. And while the surface of the workpiece W is black and the penetrating area of the through hole H appears white due to light, the feature appears in the shading pattern only on the inner wall surface, so there are many feature points that can be matched on the inner wall surface. Can be detected.

  Thereafter, the three-dimensional data calculation unit 13 calculates the three-dimensional coordinates of the detected feature points using the principle of stereo vision, and stores the calculated data in the feature point data storage unit 22 formed in the memory 20. Keep it. Then, the feature point detection unit 12 and the three-dimensional data calculation unit 13 perform the same processing as described above on the stereo image obtained from the other stereo camera 1B.

  Next, the shape prediction calculation unit 14 will be described in detail. The shape prediction calculation unit 14 reads all the three-dimensional coordinates of the feature points detected from the inner wall surface from the feature point data storage unit 22 and applies the distribution of these feature points to the cylindrical shape. At this time, the cylindrical fitting process is performed based on a shape prediction rule stored in advance in the shape prediction rule storage unit 23 of the memory 20. For example, the least square method is used to obtain a cylindrical equation having the smallest distance to a point group of three-dimensional data. Since this processing method is already known, its detailed description is omitted.

  Here, the concept of cylindrical fitting will be described with reference to FIG. 4. First, a feature point group D1 from a stereo image by one stereo camera 1A and a feature point group from a stereo image by the other stereo camera 1B. D2 is distributed on three-dimensional coordinates (see FIG. 4A), and a cylindrical shape E representing a cylindrical surface including these is calculated (see FIG. 4B). In addition, in order to perform prediction calculation of a cylindrical shape, you may use only the feature point group D1 detected from the stereo image by a pair of stereo cameras 1A.

  Next, the end part specifying unit 15 will be described in detail. First, as shown by a black circle in FIG. 4C (indicated by reference numeral D3), the end specifying unit 15 is a feature point that is separated from the cylindrical shape by a predetermined distance (threshold value). Is excluded. That is, such a point D3 is determined as a miscorresponding point that has erroneously detected a feature point from the stereo image, and the point is removed. Thereafter, the distribution of normally detected feature points D1 and D2 is further examined in a state where the erroneous correspondence point D3 is removed. Specifically, the distribution number and distribution density of feature points are examined using the position of the cylindrical shape in the axial direction as a parameter. For example, based on the distribution of feature points on the cylindrical shape shown in FIG. 5 (a), as shown in FIG. 5 (b), the position in the axial direction of the cylindrical shape is taken on the horizontal axis, and according to the position. The number of feature point distributions is taken on the vertical axis. And by specifying the position where the most points among these are dense, such a position can be specified as the end Hi of the through hole H as shown in FIG. At this time, even if the specified end portion Hi is a case where the through hole H is chamfered, the end portion Hi becomes the end portion Hi of the through hole itself which is a boundary with the through hole H of the chamfered surface.

  In this way, the through-hole information calculation unit 16 calculates various information about the through-hole H such as the axial direction, the diameter, and the center point C from the obtained shape of the through-hole H which is a cylindrical shape, and the output unit 40 It is displayed to the user via the display, or stored in the through hole information storage unit 24.

  Here, although the case where each processing unit is built in the CPU 10 of one computer 2 is illustrated above, the present invention is not limited to this. Each processing unit may be constructed in a plurality of computers, and may be configured to operate as follows when all the computers cooperate.

<Operation>
Next, the operation of this embodiment will be described with reference to FIG. First, the worker sets a work W on the system (step S1). At this time, the positional relationship between the workpiece W and the cameras 1A and 1B is set so that the inner wall surface of the through hole H can be photographed as described above.

  Subsequently, stereo images of the through holes H are respectively acquired by the two sets of stereo cameras 1A and 1B (step S2). A pair of stereo images acquired by one stereo camera 1A is represented as PLa and PRa, and a pair of stereo images acquired by the other stereo camera 1B is represented by PLb and PRb. Among these, first, the following processing is performed on the stereo images PLa and PRa acquired by one stereo camera 1A.

  Next, the PLa image is divided into arbitrary regions (step S3). At this time, the screen may be divided equally, but each area may include an overlapping portion. Then, using PLa as a model image, numbers n1 to nn are assigned to the divided areas in which the inner wall surface is projected (step S4). In addition, the identification of the divided area in which the inner wall surface is projected is performed based on the gray value of each area, for example. As described above, the surface of the workpiece W is substantially black, and the through portion of the through hole H is substantially white. Therefore, the divided area having a gray value within a predetermined range is an area including the inner wall surface. Is specified. Then, it is searched by template matching whether corresponding points corresponding to the feature points in each divided region of the PLa image exist in the PRa image (step S5). When the corresponding point is found, the three-dimensional data of the feature point is calculated from the parallax information based on the stereo images PLa and PRa (step S6). These calculated three-dimensional data of feature points are stored in the memory 20.

  Then, the same three-dimensional data calculation processing of the feature points on the inner wall surface as described above is performed on the stereo images PLb and PRb acquired by the other stereo camera 1B (steps S7 to S10), and the calculated three-dimensional data is obtained. Data is stored in the memory 20.

  Subsequently, a cylindrical shape applicable to the calculated three-dimensional data of the feature points is calculated (step S11). Then, on the other hand, a point separated from the shape by a predetermined distance is detected from the obtained cylindrical shape, this is determined as an erroneous correspondence point, and removed from the feature point group (step S12). Then, the distribution of the remaining feature points, that is, feature points that are likely to be points on the inner wall surface of the through hole H, with respect to the axial direction of the cylindrical shape is obtained (step S13). Among these, the position in the axial direction where the most feature points are gathered is specified, and this position is determined as a cylindrical end, that is, an end (edge) inside the chamfered surface of the through hole (step S14). .

  Thereafter, the axial direction, center position, and the like of the through hole H are calculated from the cylindrical shape, and such data is output to a monitor or stored in a memory (step S15).

  By doing in this way, the shape of the through hole H can be accurately calculated from the stereo image, and the axial direction and position of the through hole can be accurately measured. Therefore, it can be used when determining whether or not the through hole formed on the workpiece W is accurately formed as designed from the calculated value. In particular, even for a chamfered through hole, the end portion Hi of the through hole H itself located inside the chamfered surface can be specified, and more accurate through hole measurement can be realized. it can.

  Here, the case where illumination is applied from the side opposite to the image acquisition surface of the workpiece W has been described above, but the illumination device 3 is necessary to increase the calculation accuracy of the shape of the through hole, but is not necessarily required. It is not a simple configuration. Also, if the illumination device is not used, or if illumination is applied from the image acquisition surface side and the chamfered surface of the through hole H is clearly shown in the image, Many feature points may be detected. In this case, the end portion obtained as described above is the end portion Ho of the chamfered surface. Even in this case, the center position of the through hole can be accurately calculated by accurately specifying either the end Hi of the through hole H or the end Ho of the chamfered surface. Aim can be achieved.

  Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 7 is an explanatory diagram for explaining the features of this embodiment. FIG. 8 is a flowchart showing the operation in this embodiment.

<Configuration>
The through-hole measurement system in the present embodiment has substantially the same configuration as that in the first embodiment described above, but the predetermined processing unit constructed in the computer 2 is different in the following points. Details will be described below.

  In the computer 2 according to the present embodiment, in addition to the above-described processing units 11 to 16, edge detection is performed from the acquired stereo image, and the edge portion for calculating the edge contour shape of the through hole H is calculated based on the edge information. A contour shape calculation unit (not shown) (end contour shape calculation means) is constructed. Specifically, the end shape contour calculating unit first sets a pair of PLa only for one stereo image acquired by one stereo camera 1A and a pair PLb for only one stereo image acquired by the other stereo camera 1B. Used as a stereo image. Then, an edge line having a predetermined light and shade difference is detected in each of the images PLa and PLb, and three-dimensional data of the edge image is calculated. Thereby, the outline shape of the edge part (opening part) of the through-hole H can be extracted from an image as shown to Fig.3 (a). As described above, by using images of different stereo cameras 1A and 1B, a stereo image having a large parallax can be obtained by each camera having a wide arrangement interval, and the end contour shape F of the through hole H can be obtained more accurately. Can be calculated.

  Further, in the present embodiment, the shape prediction calculation unit 14 uses the calculated three-dimensional data of the end contour shape F, specifically, the cylinder with the position of the end contour shape F as the initial end position. Perform shape fitting processing. In other words, the fitting process is performed by fixing the cylindrical end portion to be fitted in advance to the end contour position.

  Then, as described above, when all the cylindrical shapes E (cylindrical shapes indicated by dotted lines) that may be applied to the distribution of the feature points are fitted, as shown in FIG. Processing must be performed, resulting in a great processing burden. On the other hand, as described above, since the provisional end position F is fixed and determined in advance, the cylindrical shape E to be applied is limited, so that the speed of the fitting process can be increased. However, since the above-described edge contour shape F may be affected by the chamfered surface and may not be an accurate edge shape, it is further processed by the edge identifying unit 15 as described above. It is necessary to perform processing for specifying an accurate end position (end Hi).

<Operation>
Next, the operation of the system in the present embodiment will be described with reference to the flowchart of FIG. First, as shown in steps S21 to S30, stereo images are acquired from the stereo cameras 1A and 1B, feature points on the inner wall surface are detected, and three-dimensional data is calculated. Since the processing up to this point is the same as the operation from step 1 to step S10 shown in FIG. 6 described above, description thereof is omitted.

  Subsequently, edge processing is performed on each of the image PLa from one camera of the one stereo camera 1A and the image PLb from one camera of the other stereo camera 1B. Part) is calculated (steps S31, S32, S33). And this edge part outline shape F is defined as the edge part of the through-hole H, and the cylindrical shape applicable to a feature point group is calculated based on this (step S34).

  Thereafter, the processing is performed in the same manner as described above, and the end portion Hi of the through hole H itself located inside the chamfered surface that is a more accurate end portion position is specified from the distribution of the feature points (steps S35 to S38).

  By adopting such a configuration, in the through hole measurement system in the present embodiment, the approximate end position of the cylindrical shape is determined in advance, and the cylindrical fitting process is performed based on this, so that the cylindrical fitting process is performed. As a result, the measurement accuracy of the through hole shape can be improved and the measurement process can be speeded up.

  Next, a third embodiment of the present invention will be described with reference to FIGS. FIG. 9 is an explanatory diagram for explaining the features of the present embodiment. FIG. 10 is a flowchart showing the operation in this embodiment.

<Configuration>
The through-hole measurement system in the present embodiment has substantially the same configuration as that in the first embodiment described above, but the end specifying unit 15 constructed in the computer 2 is configured to perform the following processing. It is different. Details will be described below.

  In the present embodiment, the end specifying unit 15 basically specifies the end of the cylindrical shape by excluding feature points that are separated from the calculated cylindrical shape by a certain distance, as described above. The processing is performed, and the following processing is performed using the feature points once excluded. That is, based on the three-dimensional data of the excluded feature points, a position where the number of the excluded feature points is the largest in the axial direction of the cylindrical shape is calculated. Specifically, as shown in FIG. 9A, the points indicated by black circles are feature points excluded, but the distribution in the axial direction of the cylindrical shape is examined as shown in FIG. 9B. Then, the most densely located positions are specified on the cylindrical shape as the end where the end Ho of the chamfered surface of the through hole H is located. Moreover, the end part specifying part 15 also specifies the end part Hi of the through-hole H itself located inside the chamfered surface, as described above.

  As described above, the reason for specifying the end portion Ho of the chamfered surface from the distribution of the misdetected feature points is that the chamfering processing is performed on the stereo image due to the influence of the illumination device and the processing trace of the chamfered surface. This is because many points on the surface may be detected as feature points.

<Operation>
Next, the operation of the system in the present embodiment will be described with reference to the flowchart of FIG. First, as shown in steps S41 to S52, stereo images are acquired from the stereo cameras 1A and 1B, feature points on the inner wall surface are detected, and three-dimensional data is calculated. Then, a cylindrical shape that applies to these feature points is calculated, and erroneous corresponding points that deviate from the cylindrical shape by a predetermined distance are removed. Since the processing up to this point is the same as the operation from step 1 to step S12 shown in FIG. 6 described above, description thereof is omitted.

  Subsequently, the position of the end portion Hi of the through hole H, that is, the inner end portion Hi of the chamfered surface is specified from the distribution of the feature points from which the miscorresponding points are removed (steps S53 and S54). At the same time, the distribution of the through holes H in the axial position is also checked for the erroneous correspondence points detected in step S52 (step S55), and the position where the number of the corresponding points is the largest is specified as the position Ho of the chamfered surface. (Step S56).

  Thereafter, the axial direction, center position, and the like of the through hole H are calculated from the calculated cylindrical shape, and such data is output to the monitor or stored in the memory (step S57).

  With such a configuration, the position of the end portion Ho of the chamfered surface can be reliably detected from the distribution of feature points deviating from the cylindrical shape that is the inner wall surface shape of the through hole H. Accordingly, the shape of the through hole that has been chamfered can be measured with higher accuracy, and the axial direction of the through hole H, the diameter and center of the chamfered surface, and the like can be accurately measured.

  Next, a fourth embodiment of the present invention will be described. The through-hole measurement system in the present embodiment has substantially the same configuration as that in the above-described embodiment, but position information configured by a feature point detection unit 12 and a three-dimensional data calculation unit 13 constructed in the computer 2. In the detection process, the feature point pattern matching (corresponding to the stereo image) is performed from the stereo image by using the phase-only correlation method, and thereby the three-dimensional position information of the feature point is detected.

  Here, the phase-only correlation method will be briefly described. The phase-only correlation method is a method in which an image signal is Fourier-transformed to obtain a phase signal in the frequency domain, and a stereo image is correlated by paying attention to this. Thereby, it has the characteristic that the magnitude of a correlation coefficient will appear notably. Since the phase only correlation method is known, its detailed explanation is omitted.

  As described above, by using the phase-only correlation method when calculating the three-dimensional data of feature points, the three-dimensional data on the inner wall surface can be detected with high accuracy even when the distance between the cameras is set as short as 10 to 15 mm. can do. That is, in the through hole measurement system described above, since it is necessary to widely photograph the same part of the inner wall surface with a stereo camera, it is necessary to shorten the interval (baseline) of one stereo camera. Even if it exists, it can measure three-dimensional data with high accuracy. In particular, depth errors can be suppressed. As a result, a more detailed shape of the through hole can be calculated, and the measurement accuracy of the position, the center position, and the like can be further improved.

  The through-hole measurement system, method, and program according to the present invention can accurately calculate the shape, position, axial direction, and the like of a through-hole formed on a thick plate material and chamfered, and therefore, using such a calculation result. Inspection of product accuracy can be performed accurately. Therefore, it can be used as an inspection apparatus for such a product and has industrial applicability.

It is the schematic which shows the structure of the through-hole measurement system which is this invention. 1 is a functional block diagram illustrating a configuration of a computer that is an image processing apparatus according to a first embodiment. FIG. 3 is an explanatory diagram illustrating a process performed by the image processing apparatus according to the first embodiment. FIG. 3A shows an example of the acquired stereo image, and FIG. 3B shows how the stereo image is divided. FIG. 4 is an explanatory diagram illustrating a process performed by the image processing apparatus according to the first embodiment. FIG. 4A shows the distribution of feature points, and FIG. 4B shows a state of cylindrical fitting. FIG. 4C shows the feature point distribution with respect to the cylindrical shape. FIG. 5 is an explanatory diagram illustrating a process performed by the image processing apparatus according to the first embodiment. FIG. 5A shows a feature point distribution with respect to the cylindrical shape, and FIG. 5B shows a feature point distribution in the axial direction of the cylindrical shape. FIG.5 (c) shows a mode when the edge part of a through-hole is specified. 3 is a flowchart illustrating an operation in the first embodiment. FIG. 7 is an explanatory diagram illustrating a process performed by the image processing apparatus according to the second embodiment. FIG. 7A is a diagram showing a state when the cylindrical fitting process is performed without specifying the initial position of the cylindrical end, and FIG. 7B shows the initial position of the cylindrical end. It is a figure which shows a mode when a cylindrical-shaped fitting process is performed. 10 is a flowchart illustrating an operation in the second embodiment. FIG. 9 is an explanatory diagram illustrating a process performed by the image processing apparatus according to the third embodiment. FIG. 9A shows a feature point distribution with respect to the cylindrical shape, and FIG. 9B shows a feature point distribution in the axial direction of the cylindrical shape. FIG.9 (c) shows a mode when the edge part of the chamfering surface outer surface of a through hole is pinpointed. 10 is a flowchart illustrating an operation in the third embodiment. It is a figure which shows an example of the through-hole formed in the workpiece | work. 12 (a) and 12 (b) are explanatory diagrams showing through hole measurement methods in the conventional example. FIGS. 13A to 13C are explanatory diagrams showing problems in the through hole measurement method in the conventional example. FIGS. 14A to 14C are explanatory diagrams illustrating problems in the through hole measurement method in the conventional example.

Explanation of symbols

2 Computer (image processing device)
3 lighting equipment (lighting means)
11 Image Acquisition Processing Unit 12 Feature Point Detection Unit (Position Information Detection Unit)
13 Three-dimensional data calculation unit (position information detection unit)
14 Shape prediction calculation unit (shape prediction means)
15 Edge specifying part (End specifying means)
16 Through-hole shape calculation unit 1A, 1B Stereo camera (image acquisition device)
W Work H Through hole Hi Through hole end Ho Chamfered surface end

Claims (17)

An image acquisition device that captures a stereo image in which a through-hole formed in a workpiece having a predetermined thickness is photographed and an inner wall surface of the through-hole is reflected, and an image processing device that processes the acquired image,
This image processing device
Position information detecting means for detecting feature points of the inner wall surface portion from the acquired stereo image and detecting three-dimensional position information of the feature points;
Shape prediction means for predicting the shape of the through hole based on the detected three-dimensional position information of the feature point, and calculating a substantially cylindrical three-dimensional shape;
Based on the distribution of the feature points detected by the position information detection means, an end specifying means for specifying an end in the substantially cylindrical three-dimensional shape calculated by the shape prediction means;
A through-hole measurement system characterized by comprising: An image acquisition device configured to photograph a through hole having a concave and convex shape on an inner wall surface formed on a workpiece having a predetermined thickness to acquire a stereo image in which the inner wall surface of the through hole is reflected, and an image for processing the acquired image A processing device,
This image processing device
Position information detecting means for detecting a feature point using a gray value represented on the image based on the uneven shape of the inner wall surface from the acquired stereo image, and detecting three-dimensional position information of the feature point;
Shape prediction means for predicting the shape of the through hole based on the detected three-dimensional position information of the feature point, and calculating a cylindrical shape corresponding to the through hole;
In the calculated axial direction of the cylindrical shape, a position having the largest number of distributions of the feature points detected by the position information detecting means is specified, and the specified position in the axial direction is calculated by the shape predicting means. End specifying means for specifying as the cylindrical end,
A through-hole measurement system characterized by comprising:   The edge specifying unit of the image processing apparatus excludes feature points detected by the position information detection unit that are separated from the cylindrical shape calculated by the shape prediction unit by a predetermined distance. The through-hole measuring system according to claim 2, wherein the through-hole measuring system is operated so as to identify the cylindrical end portion.   Based on the three-dimensional position information of the excluded feature points, the end specifying unit of the image processing device has a cylindrical shape in which the number of excluded feature points corresponds to the inner wall surface by the shape prediction unit The through-hole measurement system according to claim 3, wherein the most frequent position in the axial direction is specified, and this position is specified as an end of the chamfered surface. The image processing apparatus includes an edge contour shape calculating unit that performs edge detection from the acquired stereo image and calculates an edge contour shape of the through hole based on the edge information.
The shape predicting means of the image processing device predicts and calculates the cylindrical shape with the end contour shape calculated by the end contour shape calculating means as the initial end position.
The through-hole measuring system according to claim 2, 3 or 4.   The position information detecting means of the image processing device detects a feature point of the inner wall surface portion from the stereo image using a phase only correlation method, and detects three-dimensional position information of the feature point. The through-hole measurement system according to claim 2, 3, 4, or 5.   The image acquisition device is arranged to acquire the stereo image from one end side of the through hole formed in the work, and light is applied to the work from the other end side of the through hole. The through hole measuring system according to claim 2, 3, 4, 5, or 6, further comprising an illuminating means for irradiating. The image acquisition device is composed of two sets of image acquisition devices that respectively acquire stereo images,
The two sets of stereo image devices are arranged at positions where images of different portions of the inner wall surface of the through hole can be acquired, respectively. Through hole measurement system. An image processing device for through-hole measurement that processes the stereo image acquired from an image acquisition device that captures a stereo image in which an inner wall surface of a through-hole formed in a workpiece having a predetermined thickness is reflected, and measures the through-hole. Because
Position information detecting means for detecting feature points of the inner wall surface portion from the acquired stereo image and detecting three-dimensional position information of the feature points;
Shape prediction means for predicting the shape of the through hole based on the detected three-dimensional position information of the feature point, and calculating a substantially cylindrical three-dimensional shape;
Based on the distribution of the feature points detected by the position information detection means, an end specifying means for specifying an end in the substantially cylindrical three-dimensional shape calculated by the shape prediction means;
An image processing apparatus for measuring through-holes. The stereo image acquired from an image acquisition device that has captured a stereo image in which the inner wall surface of the through hole having an uneven shape is formed on the inner wall surface formed on the workpiece having a predetermined thickness is processed to measure the through hole. An image processing apparatus for measuring through-holes,
Position information detecting means for detecting a feature point using a gray value represented on the image based on the uneven shape of the inner wall surface from the acquired stereo image, and detecting three-dimensional position information of the feature point;
Shape prediction means for predicting the shape of the through hole based on the detected three-dimensional position information of the feature point, and calculating a cylindrical shape corresponding to the through hole;
In the calculated axial direction of the cylindrical shape, a position having the largest number of distributions of the feature points detected by the position information detecting means is specified, and the specified position in the axial direction is calculated by the shape predicting means. End specifying means for specifying as the cylindrical end,
An image processing apparatus for measuring through-holes. A through image in which a stereo image in which an inner wall surface of a through hole formed in a workpiece having a predetermined thickness is reflected is acquired by an image acquisition device, and the stereo image is processed using the image processing device to measure the through hole. A hole measurement method,
Detecting a feature point of the inner wall surface portion from the acquired stereo image, and detecting a three-dimensional position information of the feature point;
A shape prediction step of predicting the shape of the through hole based on the detected three-dimensional position information of the feature point, and calculating a substantially cylindrical three-dimensional shape;
Based on the distribution of the feature points detected in the position information detection step, an end specifying step for specifying an end in the substantially cylindrical three-dimensional shape calculated in the shape prediction step;
A through hole measuring method characterized by comprising: By obtaining a stereo image in which the inner wall surface of the through hole having a concavo-convex shape is reflected on the inner wall surface formed on the workpiece having a predetermined thickness by the image acquisition device, and processing the stereo image using the image processing device A through hole measurement method for measuring a through hole,
A position information detection step of detecting a feature point using a gray value represented on the image based on the uneven shape of the inner wall surface from the acquired stereo image, and detecting three-dimensional position information of the feature point;
A shape prediction step of predicting the shape of the through hole based on the detected three-dimensional position information of the feature point, and calculating a cylindrical shape corresponding to the through hole;
In the calculated axial direction of the cylindrical shape, the position having the largest number of distributions of the feature points detected in the position information detection process is specified, and the specified axial position is calculated in the shape prediction process. An end specifying step for specifying as the cylindrical end,
A through hole measuring method characterized by comprising:   The end specifying step excludes the feature points detected in the position information detection step from those that are separated by a predetermined distance from the cylindrical shape calculated in the shape prediction step. The through-hole measuring method according to claim 12, wherein the through-hole measuring method operates to specify an end of the shape.   Based on the three-dimensional position information of the excluded feature points, the end identification step is the most in the axial direction of the cylindrical shape corresponding to the inner wall surface in the shape prediction step. The through hole measuring method according to claim 13, wherein a large number of positions are specified, and this position is specified as an outer periphery of the chamfered surface. Before the shape prediction step, an edge detection is performed from the acquired stereo image, and an end contour shape calculation step for calculating an end portion contour shape of the through hole based on the edge information is provided.
The shape prediction step predicts and calculates the cylindrical shape with the end contour shape calculated in the end contour shape calculation step as an initial end position.
The through-hole measuring method according to claim 12, 13 or 14. A computer that processes the stereo image acquired from an image acquisition device that captures a stereo image in which an inner wall surface of a through hole formed in a work having a predetermined thickness is reflected, and measures the through hole,
Position information detecting means for detecting feature points of the inner wall surface portion from the acquired stereo image and detecting three-dimensional position information of the feature points;
Shape prediction means for predicting the shape of the through hole based on the detected three-dimensional position information of the feature point, and calculating a substantially cylindrical three-dimensional shape;
Based on the distribution of the feature points detected by the position information detection means, an end specifying means for specifying an end in the substantially cylindrical three-dimensional shape calculated by the shape prediction means;
Through hole measurement program to realize The stereo image acquired from an image acquisition device that has captured a stereo image in which the inner wall surface of the through hole having an uneven shape is formed on the inner wall surface formed on the workpiece having a predetermined thickness is processed to measure the through hole. On the computer,
Position information detecting means for detecting a feature point using a gray value represented on the image based on the uneven shape of the inner wall surface from the acquired stereo image, and detecting three-dimensional position information of the feature point;
Shape prediction means for predicting the shape of the through hole based on the detected three-dimensional position information of the feature point, and calculating a cylindrical shape corresponding to the through hole;
In the calculated axial direction of the cylindrical shape, a position having the largest number of distributions of the feature points detected by the position information detecting means is specified, and the specified position in the axial direction is calculated by the shape predicting means. End specifying means for specifying as the cylindrical end,
Through hole measurement program to realize