JP2010249598A - Three-dimensional shape measuring system and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a three-dimensional shape measuring system which measures a large-sized object under measurement collectively and method. <P>SOLUTION: The three-dimensional shape measuring system 10 applies a grid pattern onto the surface of work W and photographs a resultant deformed grid pattern by a CCD camera 30, thereby measuring the surface shape of the work W. The system includes: a gird pattern position control unit 52 for controlling the position of the grid pattern so that the grid pattern may be applied to a plurality of positions dividing the pitch of the grid pattern; a plurality of illuminators 40 which are arranged at different positions to illuminate the work; an illumination selection control unit 53 for selectively turning on the plurality of illuminators; and an image processor 60 which combines the images of the deformed grid pattern photographed by the camera for each position of the grid pattern and each time the illuminators are selectively turned on. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a three-dimensional shape measurement system and a three-dimensional shape measurement method.

  Conventionally, for example, when a mold used for injection molding is manufactured, it is necessary to accurately measure the shape of the mold. A method for measuring a three-dimensional shape by irradiating a measurement object with a lattice pattern such as moire fringes and photographing a deformed lattice pattern that is deformed due to unevenness of the measurement object for the purpose of such shape measurement. Is known (see, for example, Patent Document 1).

  In this method, the photographing range by the photographing device is normally used at about 50 cm square.

JP-A 63-29208

  However, there is a demand for measuring a large measuring object of about 2 m square, for example, using this technique. In this case, conventionally, it is necessary to divide the surface of the measurement object into a plurality of areas and repeat the measurement many times for each area. Therefore, it takes time for measurement work.

  In addition, since the photographing range of the photographing apparatus is the entire large measurement object, illumination light for illuminating the entire object is required. When the entire object is illuminated with illumination light, it is reflected by a part of the object, and the deformed lattice pattern of that part disappears. As a result, when trying to measure a large measurement object at a time, there is a problem that a part that cannot be measured partially occurs.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a three-dimensional shape measurement system and method capable of collectively measuring a large measurement object.

  The three-dimensional shape measurement system of the present invention (for example, a later-described three-dimensional shape measurement system 10) irradiates the surface of a measurement object (for example, a later-described workpiece W) with a lattice pattern, and displays the obtained deformed lattice pattern with a camera ( For example, it is a three-dimensional shape measurement system that measures the surface shape of a measurement object by photographing with a CCD camera 30, which will be described later, and the lattice pattern is irradiated to a plurality of positions that divide the pitch of the lattice pattern. A lattice pattern position control device (for example, a lattice pattern position control unit 52 described later) that controls the position of the lattice pattern, and a plurality of illumination devices (for example, described later) disposed at different positions to illuminate the measurement object. An illumination device 40), an illumination selection control device (for example, an illumination selection control unit 53 described later) for selectively lighting the plurality of illumination devices, and the case An image processing device (for example, an image processing device 60 described later) that synthesizes an image of a deformed grid pattern photographed by the camera at each position of the pattern and each time the lighting device is selectively turned on; It is characterized by providing.

  According to the present invention, it is possible to display a deformed grid pattern that disappears due to reflection at a part of the object by combining the images of the measurement object that are photographed by selectively turning on the plurality of illumination devices. it can. Therefore, a large measurement object can be measured in a lump.

  In this case, a synchronization device (for example, a synchronization control unit 55 described later) that synchronizes the timing of selective lighting of the illumination device and the shooting timing of the camera is further provided, and for each position of the lattice pattern, It is preferable to perform lighting with the illumination device and photographing with the camera.

  According to the present invention, a required number of images are continuously taken for each position of the lattice pattern. Therefore, there is no possibility that a position error will occur in the required number of images.

  The three-dimensional shape measurement method of the present invention is a three-dimensional shape measurement method for measuring the surface shape of a measurement object by irradiating the surface of the measurement object with a lattice pattern and photographing the resulting deformed lattice pattern with a camera. Then, in a state where one of a plurality of lights arranged at different positions is turned on, a first image of a deformed lattice pattern is photographed at each position while moving the lattice pattern to a plurality of positions that divide the pitch of the lattice pattern. (For example, a loop including step S26 to be described later) and the above-mentioned illuminated lighting is turned off and another one is turned on, and the lattice pattern is divided into a plurality of positions for dividing the pitch of the lattice pattern. A second step (for example, a loop including step S28 to be described later) for photographing the deformed lattice pattern at each position while moving the second step, and the second step for the number of all the illuminations A third step of repeating only, the fourth step (e.g., step S29 described later) for combining an image of the deformation grid pattern taken at each step and preferably contains.

  According to the present invention, there are effects similar to those described above. Further, it is not necessary to synchronize the timing for lighting only one of the plurality of lights with the timing for shooting. Therefore, the configuration is simple and easy to handle.

  The three-dimensional shape measurement method of the present invention is a three-dimensional shape measurement method for measuring the surface shape of a measurement object by irradiating the surface of the measurement object with a lattice pattern and photographing the resulting deformed lattice pattern with a camera. In a state where the lattice pattern is irradiated to one of a plurality of positions dividing the pitch of the lattice pattern, a plurality of lights arranged at different positions are alternately turned on one by one, and in synchronization with the lighting In a state in which the first pattern (for example, a loop including step S6 to be described later) for photographing the deformed grid pattern with each illumination and the grid pattern is irradiated to one different from the position, the plurality of illuminations are alternately performed. A second step (for example, a loop including step S8 to be described later) that illuminates one by one and captures a deformed grid pattern with each illumination in synchronization with the lighting, and the second step is performed at all the positions. A third step of repeating the number, the fourth step (e.g., step S9 described later) for combining an image of the deformation grid pattern taken at each step and preferably contains.

  According to the present invention, a required number of images are taken for each position of the lattice pattern, and this image data is synthesized to generate one piece of image data. Therefore, the influence of reflection included in the synthesized image data is surely removed. Therefore, a large measurement object can be measured in a lump.

  According to the present invention, it is possible to display a deformed grid pattern that disappears due to reflection on a part of an object by combining images of the object to be measured, which are photographed by selectively turning on a plurality of illumination devices. it can. Therefore, a large measurement object can be measured in a lump.

1 is a schematic layout diagram showing an embodiment of a three-dimensional shape measurement system according to the present invention. It is a block diagram of the three-dimensional shape measurement system shown in FIG. It is explanatory drawing which shows a mode that a grid is set to each position which divides | segments the pitch of a lattice pattern equally. It is the schematic which shows generation | occurrence | production of the halation in the state which lighted only one illuminating device. It is the schematic which shows generation | occurrence | production of the halation in the state which lighted only the other illuminating device. FIG. 4B is a schematic diagram illustrating an image in which a halation portion is canceled by combining the image captured in FIG. 4A and the image captured in FIG. 4B. It is a flowchart which shows 1st Embodiment of the three-dimensional shape measuring method which concerns on this invention. It is a flowchart which shows 2nd Embodiment of the three-dimensional shape measuring method which concerns on this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic layout diagram of a three-dimensional shape measurement system 10 according to the present embodiment, and FIG. 2 is a block diagram.

  As shown in FIG. 1, the three-dimensional shape measurement system 10 includes a projector 20, two CCD cameras 30 as cameras, and a plurality of units at a position away from a workpiece W as a measurement object by an appropriate distance. A lighting device 40 is installed. The CCD camera 30 is integrally disposed on both sides of the projector 20 with the projector 20 interposed therebetween. In FIG. 1, only two lighting devices 40 are shown.

  As shown in FIG. 2, the three-dimensional shape measurement system 10 includes a projector 20, a CCD camera 30, an illumination device 40, a control device 50, and an image processing device 60.

  The projector 20 includes a light source 21, a grid 22 positioned in front of the light source 21, and a grid moving unit 23. The grid 22 is composed of a large number of straight lines arranged at a predetermined pitch. When the light source 21 is turned on, the output light from the grid 22 becomes a lattice pattern composed of many parallel lights arranged at a predetermined pitch. This lattice pattern is irradiated onto the surface of the workpiece W. The irradiated lattice pattern is deformed along the surface shape of the workpiece W to generate a deformed lattice pattern. The deformed lattice pattern changes in pitch according to the surface shape of the workpiece W and becomes a curved line. The grid moving unit 23 sequentially moves the grid 22 to a plurality of positions that equally divide the pitch of the lattice pattern.

  The CCD camera 30 captures a deformed grid pattern generated along the surface shape of the workpiece W. Since the deformed grid pattern has a pitch, a measurement accuracy finer than this pitch cannot be obtained only by photographing once. The grid moving unit 23 sequentially moves the grid 22 to a plurality of positions for equally dividing the pitch of the lattice pattern that is the basis of the modified lattice pattern, and the CCD camera 30 captures the generated modified lattice pattern each time. Thereby, the measurement accuracy is improved by the number of divisions of the pitch of the lattice pattern.

  Specifically, the grid 22 is sequentially moved to a position that divides the pitch of the lattice pattern into 14 equal parts, for example, and the deformed lattice pattern generated each time is photographed by the CCD camera 30. Description will be made with reference to the example shown in FIG. 3 in which the pitch of the lattice pattern is divided into eight.

  Initially, as shown in FIG. 3A, the grid 22 is set at a first position where the pitch of the lattice pattern is divided into eight. The CCD camera 30 captures an image of the deformed lattice pattern generated based on the lattice pattern at this position. Subsequently, the second position shown in FIG. 3 (b), the third position shown in FIG. 3 (c), the fourth position shown in FIG. 3 (d), and the fifth position shown in FIG. 3 (e). The grid 22 is set at the sixth position shown in FIG. 3 (f), the seventh position shown in FIG. 3 (g), and the eighth position shown in FIG. 3 (h). The deformed lattice pattern is photographed by the CCD camera 30. That is, a total of eight times are taken.

  Thus, the measurement accuracy of the surface shape of the workpiece W can be increased to the required accuracy by appropriately setting the number of divisions for dividing the pitch of the lattice pattern. The captured image of the deformed lattice pattern is photoelectrically converted and read as a digital image into the image processing device 60 via the control device 50.

  Specifically, the CCD camera 30 has, for example, the number of pixels: 4 million pixels, the shutter speed: 100 to 200 ms, the measurement object: 2 m × 2 m, the distance between the measurement object and the camera: 2 to 4 m, and the measurement accuracy: 200 μm. .

  The illumination device 40 illuminates the workpiece W and the environment in which it is placed. In this three-dimensional shape measurement system 10, the size of the workpiece W to be handled is orders of magnitude larger than that in the conventional case. Therefore, when the illumination device 40 is not used, the amount of light taken by the CCD camera 30 is insufficient. As a result, at least the shutter speed of the CCD camera 30 is slow, and appropriate photographing cannot be performed.

  On the other hand, when there is one lighting device 40, for example, a part of the workpiece W may become a shadow of the illumination light. In the shadowed portion, the amount of light taken by the CCD camera 30 is insufficient, and appropriate photographing cannot be performed. In addition, a part of the workpiece W may cause halation due to reflection of illumination light. In the portion where halation has occurred, the deformed grid pattern disappears from the image. Although it is possible to avoid a part of the work W from being shaded by illumination light by simultaneously lighting a plurality of (n groups) illumination devices 40, a part of the work W causes halation due to reflection of the illumination light. Cannot be avoided.

  The plurality of lighting devices 40 are turned on alternately. An image of a deformed grid pattern photographed by the CCD camera 30 in an environment in which any one lighting device 40 is lit, and a deformed grid pattern photographed by the CCD camera 30 in an environment in which another illuminating device 40 is lit. The effect of illumination light is different from the image of. That is, a portion that is shaded by illumination light in one image is not shaded in the other image. A portion where halation is caused by reflection of illumination light in one image does not cause halation in the other image. This is the same regardless of how many lighting devices 40 are provided.

  Specifically, as shown in FIG. 4A, in a state where only the illumination device 40a is turned on, the Ha portion of the workpiece W causes halation due to reflection of illumination light. In the halation portion Ha, the deformed lattice pattern disappears from the captured image. As shown in FIG. 4B, in a state where only the illumination device 40b is lit, the Hb portion of the workpiece W causes halation due to reflection of illumination light. In the halation portion Hb, the deformed grid pattern disappears from the captured image. As shown in FIG. 4C, by synthesizing the photographed image in which the Ha portion of the workpiece W causes halation and the photographed image in which the Hb portion of the workpiece W causes halation, in the synthesized image, the halation portions Ha and Hb The deformed grid pattern is clearly displayed.

  The illumination device 40 is preferably an LED type surgical light, for example. An LED type surgical light can be switched at high speed.

  The control device 50 includes a lattice pattern on / off unit 51, a lattice pattern position control unit 52, an illumination selection control unit 53, a camera control unit 54, a synchronization control unit 55, an image data storage unit 56, and a three-dimensional coordinate calculation. Unit 57.

  The lattice pattern on / off unit 51 transmits a turn-on command and a turn-off command to the light source 21 of the projector 20. The lattice pattern position control unit 52 transmits a grid movement command to the grid movement unit 23 of the projector 20. The illumination selection control unit 53 selects one illumination device 40 to be lit from the plurality of illumination devices 40 and transmits a lighting command to the illumination device 40. All other illumination devices 40 are turned off. The camera control unit 54 transmits a shooting command to the CCD camera 30. The synchronization control unit 55 synchronizes the lighting command from the illumination selection control unit 53 and the shooting command from the camera control unit 54. That is, the lighting timing of the illumination device 40 and the photographing timing of the CCD camera 30 are synchronized. This will be described later. The image data storage unit 56 stores image data photographed by the CCD camera 30 and supplies the image data to the image processing device 60. The three-dimensional coordinate calculation unit 57 calculates the three-dimensional coordinates of the modified lattice pattern based on the image processing data supplied from the image processing device 60.

  The image processing device 60 synthesizes the image of the deformed lattice pattern photographed by the CCD camera 30 for each position of the lattice pattern and every time the illumination device 40 is selectively turned on. That is, the image processing device 60 synthesizes the image data of the deformed grid pattern photographed by the CCD camera 30 for each position where the grid 22 is set. When m images are taken at one position, m image data are combined to generate one image data. By this combining process, halation included in the image data before combining is removed. When there are n positions where the grid 22 is set, the image processing device 60 performs the same composition process on all the image data captured at the n positions to generate n pieces of image data.

  Specifically, for each position where the pitch of the lattice pattern is divided into 14, the image data captured for the radix of the lighting device 40 is synthesized to generate one piece of image data. As a result, 14 pieces of image data are generated.

  In the three-dimensional shape measurement system 10, the control device 50 operates according to the flowchart shown in FIG. Further, the control device 50 operates according to the flowchart shown in FIG.

FIG. 5 is a flowchart showing the first embodiment of the three-dimensional shape measuring method according to the present invention.
First, in step S1, the light source 21 of the projector 20 is turned on by the control device 50.

  In step S2, the grid 22 of the projector 20 is set to the nth position by the control device 50. That is, the first position is set to the first position.

  In step S <b> 3, only the m-th lighting device 40 is turned on by the control device 50. That is, at first, only the first lighting device 40 is turned on.

  In step S <b> 4, the control device 50 captures the deformed grid pattern by the CCD camera 30. In this case, the lighting of only the mth illumination device 40 in step S3 and the photographing by the CCD camera 30 in step S4 are performed in synchronization.

In step S <b> 5, the control device 50 determines whether shooting has been completed for all the lighting devices 40. That is, when there are, for example, m illumination devices 40 in total, it is determined whether or not shooting has been completed for all m illumination devices 40.
If this determination is NO, the process proceeds to step S6, and if YES, the process proceeds to step S7.

  In step S <b> 6, the control device 50 increments the order m of the lighting devices 40. Therefore, in the second step S <b> 3, only the second lighting device 40 is turned on by the control device 50. Similarly, in the m-th step S3, the control device 50 turns on only the m-th lighting device 40.

On the other hand, when the determination in step S5 is YES and the process proceeds to step S7, in step S7, the control device 50 determines whether or not shooting has been completed at all positions. That is, when there are, for example, n positions at which the grid 22 is set in total, it is determined whether or not shooting has been completed at all the n positions.
If this determination is NO, the process proceeds to step S8, and if YES, the process proceeds to step S9.

  In step S8, the control apparatus 50 increments the order n of the positions where the grid 22 is set. Therefore, in the second step S2, the control device 50 sets the grid 22 to the second position. That is, the grid 22 is moved from the first position to the second position. Similarly, in the n-th step S2, the control device 50 sets the grid 22 to the n-th position.

  On the other hand, if the determination in step S7 is YES and the process proceeds to step S9, the image processing device 60 performs image processing by the control device 50 in step S9. That is, the image data of the deformed grid pattern photographed by the CCD camera 30 is synthesized for each position where the grid 22 is set. Since m pieces of image data are captured at one position, the m pieces of image data are combined to generate one piece of image data. By this synthesis process, the halation included in the image data of the deformed grid pattern is removed. The image processing device 60 performs the same composition processing on all the image data photographed at n locations, and generates n pieces of image data in which the surface shape of the entire workpiece W is captured in detail.

  In step S10, the control device 50 calculates the three-dimensional coordinates of the deformed grid pattern. That is, the three-dimensional coordinates of the workpiece W are calculated based on the image processing data processed by the image processing device 60. Thereby, a three-dimensional measurement result of the surface shape of the workpiece W is obtained.

According to this embodiment, there are the following effects.
(1) Take m images at the position where the grid 22 is set, and synthesize the image data to generate one image data. Therefore, the halation contained in the synthesized image data is surely removed.

  (2) m images are taken continuously. Therefore, there is no possibility that a position error will occur in m images.

  (3) The image data obtained by combining the m pieces of image data is the same as the image data before combining except that the halation is removed. Therefore, the conventionally used three-dimensional coordinate calculation program can be applied as it is.

  (4) After all m images have been captured at the position where the grid 22 is set, the grid 22 is moved to the next position, and all m images have been captured again at that position. This is sequentially performed for all the n positions. Therefore, when the number of shots m at each position is not so large, all shots can be performed within the required time, which is not much different from the case of shooting images one by one at all n positions. .

FIG. 6 is a flowchart showing a second embodiment of the three-dimensional shape measuring method according to the present invention.
Steps S21 and S22 are the same as steps S1 and S2 in the flowchart shown in FIG.

  In step S23, only the mth illumination device 40 is turned on by the control device 50. That is, at first, only the first lighting device 40 is turned on, and all other lighting devices 40 are turned off.

  In step S <b> 24, the control device 50 captures the deformed grid pattern by the CCD camera 30. In this case, only the mth illumination device 40 is turned on in step S23 and only the mth illumination device 40 is turned on in step S23, so that only the mth illumination device 40 is turned on in step S23 and the CCD camera in step S24. It is not necessary to synchronize with the shooting by 30.

In step S25, the control device 50 determines whether or not shooting has been completed at all positions. That is, when there are, for example, n positions at which the grid 22 is set in total, it is determined whether or not shooting has been completed at all the n positions.
If this determination is NO, the process proceeds to step S26, and if YES, the process proceeds to step S27.

  In step S26, the control apparatus 50 increments the order n of the positions where the grid 22 is set. Therefore, in step S22 for the second time, the control device 50 sets the grid 22 to the second position. That is, the grid 22 is moved from the first position to the second position. Similarly, in the n-th step S22, the control device 50 sets the grid 22 at the n-th position.

On the other hand, if the determination in step S25 is YES and the process proceeds to step S27, in step S27, the control device 50 determines whether or not shooting has been completed for all the illumination devices 40. That is, when there are, for example, m illumination devices 40 in total, it is determined whether or not shooting has been completed for all m illumination devices 40.
If this determination is NO, the process moves to step S28, and if YES, the process moves to step S29.

  In step S28, the control device 50 increments the order m of the lighting devices 40. Therefore, in step S23 for the second time, only the second lighting device 40 is turned on by the control device 50. Similarly, in the m-th step S23, only the m-th lighting device 40 is turned on by the control device 50.

  Steps S29 and S30 are the same as steps S9 and S10 in the flowchart shown in FIG.

According to this embodiment, in addition to the same effects as the effects (1) and (3), there are the following effects.
(5) It is not necessary to synchronize the lighting of only the mth illumination device 40 and the photographing by the CCD camera 30. Therefore, the control device 50 does not need to include the synchronization control unit 55, and the configuration becomes simple.

DESCRIPTION OF SYMBOLS 10 ... Three-dimensional shape measurement system 20 ... Projector 30 ... CCD camera (camera)
DESCRIPTION OF SYMBOLS 40 ... Illuminating device 50 ... Control apparatus 52 ... Lattice pattern position control part (grating pattern position control apparatus)
53. Illumination selection control unit (illumination selection control device)
55. Synchronization control unit (synchronization device)
60: Image processing device W: Workpiece (object to be measured)

Claims (4)

A three-dimensional shape measurement system that measures the surface shape of a measurement object by irradiating the surface of the measurement object with a lattice pattern and photographing the resulting deformed lattice pattern with a camera,
A grid pattern position control device that controls the position of the grid pattern so that the grid pattern is irradiated to a plurality of positions that divide the pitch of the grid pattern;
A plurality of illumination devices arranged at different positions to illuminate the measurement object;
An illumination selection control device for selectively lighting the plurality of illumination devices;
An image processing device that synthesizes an image of a deformed lattice pattern captured by the camera for each position of the lattice pattern and each time the illumination device is selectively turned on,
A three-dimensional shape measurement system comprising: The three-dimensional shape measurement system according to claim 1,
A synchronization device that synchronizes the timing of selective lighting of the lighting device and the shooting timing of the camera;
A three-dimensional shape measurement system that performs lighting by all the illumination devices and photographing by the camera for each position of the lattice pattern. A three-dimensional shape measurement method for measuring the surface shape of a measurement object by irradiating the surface of the measurement object with a lattice pattern and photographing the resulting deformed lattice pattern with a camera,
A first step of photographing a deformed lattice pattern at each position while moving the lattice pattern to a plurality of positions that divide the pitch of the lattice pattern in a state where one of a plurality of lights arranged at different positions is turned on. When,
Secondly, in the state where the lit illumination is turned off and the other one is turned on, a deformed lattice pattern is photographed at each position while moving the lattice pattern to a plurality of positions that divide the pitch of the lattice pattern. And the process of
A third step in which the second step is repeated for all the illuminations;
A fourth step of synthesizing the image of the deformed grid pattern photographed in each step;
A three-dimensional shape measuring method comprising: A three-dimensional shape measurement method for measuring the surface shape of a measurement object by irradiating the surface of the measurement object with a lattice pattern and photographing the resulting deformed lattice pattern with a camera,
In a state where the lattice pattern is irradiated to one of a plurality of positions dividing the pitch of the lattice pattern, a plurality of illuminations arranged at different positions are alternately turned on one by one, and each illumination is synchronized with the lighting. A first step of photographing a deformed grid pattern with:
A second step of alternately turning on the plurality of illuminations one by one in a state in which a lattice pattern is irradiated on one of the positions different from the position, and capturing a deformed lattice pattern with each illumination in synchronization with the illumination When,
A third step of repeating the second step by the number of all the positions;
A fourth step of synthesizing the image of the deformed grid pattern photographed in each step;
A three-dimensional shape measuring method comprising:

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