JP4430680B2 - 3D dimension measuring apparatus and 3D dimension measuring program - Google Patents

Description

  The present invention relates to a three-dimensional dimension measuring apparatus and a three-dimensional dimension measuring program for measuring a three-dimensional dimension of a measurement target based on a slit light image and a luminance image of the measurement target.

  Conventionally, in three-dimensional dimension measurement in which feature points to be measured are extracted by a light cutting method, feature points are extracted using a slit light image obtained by projecting slit light.

  As such a technique, for example, a welding state inspection method and an inspection apparatus (see Patent Document 1) are known in which a three-dimensional shape of a weld bead portion of a butt weld portion is measured to inspect a welding state. This welding state inspection method and inspection apparatus measures a three-dimensional shape of a weld bead to be inspected by a light cutting method in which slit light is projected from a slit light source onto a weld bead and a reflected light image is captured by a TV camera. .

Therefore, the welding state inspection method and inspection apparatus of Patent Document 1 need to extract the weld bead portion to be inspected from the slit light image. The slit light image is an image obtained by viewing the slit light projected on the surface of the welding surface from an oblique direction, and the image is a line image having no shading information. That is, the bending of the line indicates the unevenness of the weld surface.
JP 2005-279653 A

  However, it is difficult to accurately find the boundary of the bead portion only from this line image. In particular, there is a problem that it is difficult to accurately detect the boundary between the plate portion and the bead portion when the butt plate portion is gently welded.

  The present invention has been made to solve the above problems, and provides a three-dimensional dimension measuring apparatus and a three-dimensional dimension measuring program for measuring a three-dimensional dimension of a measurement target with high accuracy and low cost. For the purpose.

  In order to achieve the above object, the three-dimensional dimension measuring apparatus according to claim 1 projects an imaging unit that images a measurement target and generates an image signal, and projects at least one slit-like light on the measurement target. Based on an image signal generated by the slit light projection means, the image pickup means, and an edge extraction means for extracting an edge of the measurement object, and generated by the image pickup means when the slit light projection means is projecting. A slit center line extracting means for extracting a slit center line representing the center position of the slit based on the image signal, the edge extracted by the edge extracting means and the slit center extracted by the slit center line extracting means Slit feature point extracting means for extracting the feature points of the slit based on the line, and before the slit feature point extracting means Based on the coordinates of the feature points, a three-dimensional coordinate calculation means for calculating the three-dimensional coordinates of the feature points, and the feature quantity of the measurement target is calculated based on the three-dimensional coordinates calculated by the three-dimensional coordinate calculation means. Characteristic amount calculation means.

  3. The three-dimensional dimension measuring apparatus according to claim 2, further comprising illumination means for illuminating the measurement object, wherein the edge extraction means is illuminated by the illumination means. Sometimes, the edge to be measured is extracted based on the image signal generated by the imaging means.

  According to the first or second aspect of the invention, since the feature points are extracted based on the line image and the two-dimensional image by the slit light, the three-dimensional dimension of the measurement object can be accurately measured.

  The three-dimensional dimension measuring apparatus according to claim 3 is the three-dimensional dimension measuring apparatus according to claim 1 or 2, wherein the slit extracting means includes a plurality of pixels adjacent in a direction intersecting with a longitudinal direction of the slit reflection image. The slit center line is extracted using the position information of

  According to the invention of claim 3, the center line of the slit representing the center position of the slit can be extracted more accurately.

  The three-dimensional dimension measuring apparatus according to claim 4 is the three-dimensional dimension measuring apparatus according to claim 1 or 3, wherein illumination of the measurement object by the illumination unit and light to the measurement object by the slit light projection unit are provided. Measurement control means for controlling the projections to be performed sequentially or simultaneously.

  According to the invention of claim 4, it is possible to control whether the illumination and the slit light projection are performed sequentially or simultaneously.

  The three-dimensional dimension measuring apparatus according to claim 5 is the three-dimensional dimension measuring apparatus according to any one of claims 1 to 4, wherein the three-dimensional coordinate calculation means includes an imaging system coordinate and a three-dimensional coordinate. Based on the coordinate conversion table indicating the correspondence, the three-dimensional coordinates of the feature points are calculated.

  According to the fifth aspect of the present invention, the conversion of the feature point from the imaging system coordinates to the three-dimensional coordinates can be calculated based on the coordinate conversion table.

  The three-dimensional dimension measuring apparatus according to claim 6 is the three-dimensional dimension measuring apparatus according to any one of claims 1 to 4, wherein the three-dimensional coordinate calculation means converts imaging system coordinates into three-dimensional coordinates. The three-dimensional coordinates of the feature points are calculated based on the coordinate conversion calculation formula.

  According to the sixth aspect of the present invention, the conversion of the feature points from the imaging system coordinates to the three-dimensional coordinates can be calculated based on the coordinate conversion arithmetic expression.

  The three-dimensional dimension measurement program according to claim 7, when the computer projects the edge extraction means for extracting the measurement target edge and the slit light projection means based on the image signal generated by the imaging means. Based on the image signal generated by the imaging means, a slit center line extracting means for extracting a slit center line representing the center position of the slit, the edge extracted by the edge extracting means and the slit center line extracting means Slit feature point extracting means for extracting a feature point of the slit based on the slit center line, and the three-dimensional coordinates of the feature point based on the coordinates of the feature point extracted by the slit feature point extracting means. Based on the calculated three-dimensional coordinate calculation means and the three-dimensional coordinates calculated by the three-dimensional coordinate calculation means Feature amount calculation means for calculating a feature quantity of serial measurement object, to function as a.

  According to the seventh aspect of the present invention, it is possible to cause the computer to function so as to extract feature points based on the line image and the two-dimensional image by the slit light and accurately measure the three-dimensional dimension of the measurement target.

  As described above, according to the present invention, it is possible to accurately detect a feature point of a measurement target, and to obtain an effect of measuring a three-dimensional dimension of the measurement target with high accuracy and low cost.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a functional block diagram of a three-dimensional dimension measuring apparatus 1 according to an embodiment of the present invention.

  As shown in FIG. 1, the three-dimensional dimension measuring apparatus 1 includes a light source 11 that illuminates a measurement target, a slit light source 12 that projects at least one slit light onto the measurement target, illumination by the light source 11, and a slit light source 12. The measurement control unit 13 that controls the projection of the slit light, the reflected light from the light measurement target by the light source 11 is imaged to generate a reflection image, and the slit reflected light from the slit light measurement target by the slit light source 12 is imaged and slit. A TV camera 14 that generates a reflected image and a computer 10 are provided.

  The computer 10 includes a CPU, a ROM, and a RAM. The computer 10 also stores an A / D converter 15 that performs A / D conversion on the image signals of the reflected image and the slit reflected image generated by the TV camera 14, and an image signal obtained by the A / D converter. The image memory 16, the edge extraction unit 17 that extracts the measurement target edge from the image signal stored in the image memory 16, and the slit center position that is the center of the slit reflection image is extracted from the image signal stored in the image memory 16. A slit extracting unit 18, a slit feature point extracting unit 19 for extracting a feature point of the slit from the edge and the center position of the slit, a three-dimensional coordinate calculating unit 20 for calculating a three-dimensional coordinate from the coordinates of the feature point, And a feature amount calculation unit 21 that calculates a feature amount to be measured from three-dimensional coordinates.

  Here, the feature quantity of the measurement target is a representative numerical value representing the characteristic of the measurement target. For example, when the measurement target is a round hole shape, the coordinates are the center coordinates, the radius, the normal vector, and the like, and when the measurement target is a butt weld bead portion, the bead width and the bead height.

(First embodiment)
FIG. 2 shows the measurement by the three-dimensional dimension measuring apparatus 1 for the round hole according to the present embodiment. In the present embodiment, a triangulation method using the TV camera 14 and slit light is employed for measuring the feature points of the round holes. The slit light source 12 projects slit-like light onto a member 30 including a round hole to be measured (hereinafter referred to as “round hole member”), and the slit reflected light is imaged by the TV camera 14.

  Conventionally, a portion corresponding to the circumference of a round hole has been extracted as a feature point from the obtained slit light image 31. However, in this method, feature points are extracted only from the line image, and features such as the surface shape of the measurement object are replaced with slit light images, that is, changes in line inclination of the line image. For this reason, the amount of information is reduced, and the position of the feature point to be extracted varies, which causes an error when specifying the feature point. Therefore, the same TV camera 14 that images the slit light images the measurement object, generates a two-dimensional image 32, and extracts a circumferential portion from the two-dimensional image.

  Next, the effect | action of the three-dimensional dimension measuring apparatus 1 in this Embodiment is demonstrated along the example of an image regarding the round hole measurement shown in FIG. 3, and the flowchart shown in FIG.

  First, in step 100, based on a signal from the measurement control unit 13, the slit light source 12 projects slit light onto the round hole member 30 that is a measurement target, and the light source 11 illuminates the round hole member 30. FIG. 3A is an image in which slit light projection and illumination are performed on the round hole member 30.

  In the present embodiment, the measurement control unit 13 controls the slit light projection by the slit light source 12 and the illumination by the light source at the same time. If it is performed simultaneously, the measurement time is shortened, but the S / N ratio between the slit light and the background is deteriorated, and if it is sequentially performed, the S / N ratio is improved but the measurement time is increased. The light source is not shown in FIG. 2, but this is because a special light source is not used to illuminate the measurement object, but a normal room lighting fixture is used.

  In the case of this embodiment, it is necessary to project a plurality of slit lights in order to extract three or more feature points. In FIG. 2, two slit light sources 12 project two slit lights, but it is also possible to change the position of one slit light source 12 and project the slit light a plurality of times.

  In step 110, the TV camera 14 images the round hole member 30, and slit scattered light obtained by reflecting from the round hole member 30 by slit light projection, and scattered light obtained by reflecting from the round hole member 30 by illumination. An image based on and is generated. FIG. 3B is an image obtained by imaging a state in which the round hole member is subjected to slit light projection and illumination.

  In step 120, the A / D conversion unit 15 performs A / D conversion on the image generated by the TV camera 14. The A / D converted image is stored in the image memory 16.

  In step 130, the slit extraction unit 18 extracts a slit center line representing the center position of the slit. Specifically, the slit extraction unit 18 extracts, from the image stored in the image memory 16, slit center coordinates that are representative positions in the slit width direction in the coordinate system of the TV camera 14. As a method for extracting the slit center coordinates, there are a method for obtaining the position of the luminance center of gravity for a pixel having a luminance value equal to or greater than a value in a direction perpendicular to the slit longitudinal direction, and a method for simply obtaining the center position.

  In step 140, the edge extraction unit 17 extracts an edge corresponding to the circumferential part of the round hole. Specifically, the edge extraction unit 17 extracts an edge after erasing slit light from the image signal stored in the image memory 16 by using an image processing technique. Although the edge can be extracted even if the slit light is included, the slit light is erased in advance in order to extract the edge more accurately. FIG. 3C is an image obtained by erasing slit light from the image of FIG. Further, a grayscale image captured with the slit light turned off in the imaging step may be used.

  As a method of expressing the extracted edge, a method of expressing it as a discrete two-dimensional coordinate sequence on the TV camera 14, and using the center point and radius of the edge corresponding to the circumference using the coordinate system of the TV camera 14. There are a method of expressing with a circle approximation formula or a method of expressing with an ellipse approximation instead of a circle.

  In step 150, the slit feature point extraction unit 19 extracts a point where the edge obtained in the above step and the slit center line intersect as the slit feature point 33. FIG. 3D is an image in which feature points are extracted as intersections between the slit center line and the circumference of a round hole that is an edge.

  In step 160, the three-dimensional coordinate calculation unit 20 converts the coordinates of the feature point 33 in the coordinate system of the TV camera 14 into three-dimensional coordinates. As the coordinate conversion method, there are a method of conversion by referring to a coordinate conversion table created by calibration performed in advance, and a method of calculating by substituting coordinates into a coordinate conversion formula created by calibration.

  The coordinate conversion by the conversion table is performed based on the conversion table illustrated in FIG. This conversion table corresponds to the three-dimensional coordinates (X, Z) for the TV camera pixel (i, j). Here, the Y coordinate is determined by the installation position of the sensor.

  The three-dimensional coordinate calculation unit 20 calculates the three-dimensional coordinates of the feature points using the table shown in FIG. For example, when the feature point in the TV camera coordinates is (i, j) = (123.4,234.5), the three-dimensional coordinate calculation unit 20 performs (i, j) = (123,234), (124,234), (123,235), The coordinates (X, Z) corresponding to (124, 235) are read, and the center of gravity is calculated to calculate (X, Z) coordinates corresponding to (123.4, 234.5).

  In addition, coordinate conversion by the conversion formula is performed as follows. X and Z conversion formulas corresponding to the i and j rows and columns of the above table are obtained by calibration performed in advance. For example, when the feature point in the TV camera coordinates is (i, j) = (123.4, 234.5), the three-dimensional coordinate calculation unit 20 substitutes i = 123, 124 into the conversion formula to obtain the respective X, Z, Substituting j = 234,235, the respective X and Z are obtained. Thereafter, the three-dimensional coordinate calculation unit 20 calculates (X, Z) coordinates corresponding to (123.4, 234.5) by the center of gravity calculation, as in the case of the conversion table described above.

  In step 170, it is determined whether the slit feature point extraction unit 19 has calculated the coordinates of the required number of feature points according to the shape of the measurement target. Depending on the shape, it is necessary to further calculate the coordinates of the feature points. In the round hole measurement according to the present embodiment, in order to obtain three or more three-dimensional coordinates at different edge portions of the round hole, the process returns to step 100 and the above process is repeated at least twice.

  Finally, in step 180, the feature quantity computing unit 21 calculates the three-dimensional coordinates, radius, and normal vector of the center of the round hole as the feature quantity of the round hole from the three-dimensional coordinates of the feature point.

  As described above, according to the three-dimensional dimension measuring apparatus 1 according to the present embodiment, the edge of the circumference of the round hole is obtained by using the grayscale information of the two-dimensional image 32 having a lot of information instead of the slit light image 31. The part can be extracted easily. Then, the three-dimensional dimension measuring apparatus 1 extracts the intersection of the extracted edge portion and the slit center line as the feature point 33, and calculates the three-dimensional coordinates. In this way, the three-dimensional dimension measuring apparatus 1 can accurately extract at least three feature points 33 in the edge portion of the circumference, and can calculate an accurate feature amount of the round hole.

  In addition, according to the three-dimensional dimension measuring apparatus 1, since the slit light image and the two-dimensional image are captured by one TV camera, the feature quantity of the measurement target is calculated only by image processing. There are advantages such as low cost compared to commercially available sensors.

(Second Embodiment)
FIG. 6 shows a weld bead shape according to the second embodiment. In the present embodiment, the feature amount of the bead shape is calculated in order to determine the quality of the weld from the shape of the weld bead 50 shown in the perspective view of FIG. Typical feature values of the bead shape include a bead width 51 and a bead height 52 as shown in the cross-sectional view of FIG. Since these are three-dimensional shapes, the light cutting method is an effective method for measurement.

  The three-dimensional dimension measuring apparatus according to the present embodiment shown in FIG. 7 is configured in the same manner as the functional block diagram shown in FIG. 1, and executes the processing of the flowchart shown in FIG. 3 to set the bead width 51 and the bead height 52. measure. Note that steps different from those of the first embodiment will be described.

  From step 100 through step 120, at step 130, the slit extraction unit 18 extracts a slit center line from the slit light image 61. In the light cutting method, bead feature points are extracted from the slit center line, and their dimensions are measured to calculate a bead feature amount. At this time, it is relatively easy to obtain the bead height 52 from the slit light image, but in order to obtain the bead width 51, it is necessary to determine from where to where corresponds to the bead portion. It is difficult to obtain accurately from the slit light image that is an image.

  In step 140, the edge extraction unit 17 extracts bead end portions from the two-dimensional image 62 of the bead butt portion. Since the two-dimensional image 62 has abundant amount of information such as grayscale information, the flat plate portion and the bead portion by welding can be easily separated.

  In step 150, the slit feature point extraction unit 19 extracts the intersection point between the line image, which is the slit light image 61 by the slit light source 12, and the both ends of the bead as the slit feature point 63, and in step 160, the three-dimensional coordinate calculation unit 20 Obtains the three-dimensional coordinates of the slit feature point 63.

  In step 180, the feature amount calculation unit 21 calculates a bead width 51 and a bead height 52 that are feature amounts of the weld bead 50.

  As described above, according to the three-dimensional dimension measuring apparatus 1 according to the present embodiment, by using not the slit light image 61 of the weld bead 50 but the shading information of the two-dimensional image 62 with a large amount of information, The part can be extracted easily. And the three-dimensional dimension measuring apparatus 1 extracts the intersection of the extracted bead both ends and the slit center line as the feature point 63, and calculates the three-dimensional coordinate. In this way, the three-dimensional dimension measuring apparatus 1 can accurately extract the feature points 63 at both ends of the bead, and can calculate an accurate feature amount of the weld bead 50. In particular, there is a merit that the bead width 51, which has been difficult to measure accurately with the prior art, can be easily and accurately measured.

It is a functional block diagram of the three-dimensional dimension measuring apparatus according to the present invention. It is a figure which shows the measurement of the round hole by the three-dimensional dimension measuring apparatus which concerns on 1st Embodiment. It is an example of an image regarding round hole measurement concerning a 1st embodiment. It is a flowchart which shows the effect | action of the three-dimensional dimension measuring apparatus which concerns on this invention. It is a figure which shows the example of a coordinate conversion table which concerns on this invention. It is a figure which shows the weld bead shape which concerns on 2nd Embodiment. It is a figure which shows the measurement of the weld bead by the three-dimensional dimension measuring apparatus which concerns on 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 3D dimension measuring apparatus 10 Computer 11 Light source 12 Slit light source 13 Measurement control part 14 TV camera 15 A / D conversion part 16 Image memory 17 Edge extraction part 18 Slit extraction part 19 Slit feature point extraction part 20 Three-dimensional coordinate calculation part 21 Feature amount calculator

Claims (7)

Imaging means for imaging a measurement object and generating an image signal;
Slit light projection means for projecting at least one slit-shaped light onto the measurement object;
Edge extraction means for extracting an edge of the measurement object based on an image signal generated by the imaging means;
A slit center line extracting means for extracting a slit center line representing the center position of the slit based on the image signal generated by the imaging means when the slit light projecting means is projecting;
Slit feature point extraction means for extracting feature points of the slit based on the edge extracted by the edge extraction means and the slit centerline extracted by the slit centerline extraction means;
Three-dimensional coordinate calculation means for calculating the three-dimensional coordinates of the feature points based on the coordinates of the feature points extracted by the slit feature point extraction means;
Feature quantity calculation means for calculating the feature quantity of the measurement object based on the three-dimensional coordinates calculated by the three-dimensional coordinate calculation means;
A three-dimensional dimension measuring apparatus. Further comprising illumination means for illuminating the measurement object,
The three-dimensional dimension measuring apparatus according to claim 1, wherein the edge extraction unit extracts the measurement target edge based on an image signal generated by the imaging unit when the illumination unit is illuminating.   3. The three-dimensional dimension measuring apparatus according to claim 1, wherein the slit extracting unit extracts the slit center line using position information of a plurality of pixels adjacent to each other in a direction intersecting a longitudinal direction of the slit reflection image. .   4. The measurement control unit according to claim 1, further comprising: a measurement control unit configured to control the illumination of the measurement target by the illumination unit and the projection of light onto the measurement target by the slit light projection unit sequentially or simultaneously. The three-dimensional dimension measuring apparatus according to claim 1.   The said three-dimensional coordinate calculating means calculates the three-dimensional coordinate of the said feature point based on the coordinate conversion table which shows a response | compatibility with an imaging system coordinate and a three-dimensional coordinate. 3D dimension measuring device.   5. The 3D coordinate according to claim 1, wherein the three-dimensional coordinate calculation means calculates the three-dimensional coordinates of the feature points based on a coordinate conversion calculation formula for converting imaging system coordinates into three-dimensional coordinates. Dimensional dimension measuring device. Computer
Edge extraction means for extracting an edge of the measurement object based on an image signal generated by the imaging means;
A slit center line extracting means for extracting a slit center line representing the center position of the slit based on the image signal generated by the imaging means when the slit light projecting means is projecting;
Slit feature point extracting means for extracting feature points of the slit based on the edge extracted by the edge extracting means and the slit center line extracted by the slit center line extracting means;
3D coordinate calculation means for calculating the 3D coordinates of the feature points based on the coordinates of the feature points extracted by the slit feature point extraction means;
Feature quantity calculation means for calculating the feature quantity of the measurement object based on the three-dimensional coordinates calculated by the three-dimensional coordinate calculation means;
3D dimension measurement program to function as