JP2013170829A - Strain measuring device and strain measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a strain measuring device and a strain measuring method capable of measuring strain by obtaining an image of strain occurring on the surface of a measurement object with an imaging device without directly measuring the strain, and even when the surface of the measurement object is three-dimensionally deformed, correcting an error of the image to improve accuracy of strain measurement.SOLUTION: A strain measuring device according to the present invention comprises: at least one imaging device that obtains an image by photographing the surface of a measurement object from predetermined two points; and an arithmetic device that performs arithmetic processing on displacement amount of the surface of the measurement object by a triangulation method to calculate strain on the surface of the measurement object.

Description

  The present invention relates to a strain measuring device and a strain measuring method for measuring the strain on the surface of a measurement object.

  2. Description of the Related Art Conventionally, a method for measuring strain generated on the surface of an object to be measured using an imaging device such as a camera or a video camera or a strain gauge is known.

  For example, from the image read with a line scanner that is formed by pasting or painting grid-like markers at equal intervals on the surface of the measurement object, and touching or bringing the marker before and after deformation of the measurement object into contact A method for calculating the strain of a measurement object is disclosed (for example, see Patent Document 1).

  In addition, a strain gauge in which a thin metal wire that becomes a resistor in the gauge body is placed in a folded state is attached to the surface of the measurement object, and the resistance value of the metal wire that is a resistor according to the deformation of the measurement object The method of calculating the strain of the measurement object from the change of the is used.

JP 2007-263611 A

  However, in the strain measuring method described in Patent Document 1, it is necessary to attach or form a grid-like marker at equal intervals on the surface of the measurement object accurately. End up. Further, the line scanner must be brought into contact with or close to the measurement object when reading the marker.

  Further, in a strain measurement method using a strain gauge, a temperature drift may occur due to deterioration of a metal wire, and an accurate resistance value may not be shown. And since a measured value is dependent on the length of a strain gauge main body, it may be smaller than the length of a strain gauge main body, and the distortion which arises locally may not be measured correctly. Furthermore, since the strain gauge is attached with an adhesive, the strain gauge may be separated from the measurement object when the measurement object is repeatedly deformed.

  Therefore, there is a demand for a strain measurement method that can easily and highly accurately measure an image by acquiring an image from a remote position without directly measuring the strain generated on the surface of the measurement object.

  Further, as shown in FIG. 11, when the strain measurement region 14 on the surface of the measurement object 51a is three-dimensionally deformed (for example, deformation in the out-of-plane direction) like the measurement object 51b, as shown in FIG. In the acquired image, an error occurs in the acquired image due to the enlargement / contraction of the image, such as the image 52 to the image 53, and the strain measurement accuracy decreases.

  Therefore, it is desired to improve the accuracy of strain measurement by correcting the error of the acquired image even when the surface of the measurement object is three-dimensionally deformed.

  The present invention has been made in view of the above-described problem, and obtains an image with an imaging device from a remote position without directly measuring the strain generated on the surface of the measurement object, and the surface of the measurement object is An object of the present invention is to provide a strain measuring apparatus and a strain measuring method capable of correcting the error of an image even when three-dimensionally deformed and improving the accuracy of strain measurement.

  According to a first aspect of the present invention for solving the above-described problem, at least one imaging device that captures an image of a surface of a measurement object from two predetermined points and acquires the image, and 2 acquired by the imaging device. And a calculation device that calculates the distortion of the surface of the measurement object by calculating the amount of displacement of the surface of the measurement object by triangulation based on each image at a point. It is a measuring device.

  A second invention is a strain measurement apparatus according to the first invention, wherein the imaging devices are a first imaging device and a second imaging device installed at the two predetermined points.

  A third invention is the strain measuring apparatus according to the first invention, further comprising an imaging device moving means for reciprocatingly moving the imaging device between the two predetermined points.

  According to a fourth invention, in any one of the first to third inventions, the arithmetic device is acquired based on two predetermined imaging positions of the imaging device and a collimation angle of the imaging device. The strain measuring apparatus is characterized in that an image error is corrected by obtaining a deformation amount in an out-of-plane direction of the image.

  According to a fifth aspect of the present invention, the triangulation method is used to obtain an image by imaging the surface of the measurement object from two predetermined points, and based on each image at the two points acquired in the imaging step. A strain calculating step of calculating a strain on the surface of the measurement object by calculating a displacement amount of the surface of the measurement object.

  According to the present invention, even when an image is acquired from a remote position without directly measuring the distortion generated on the surface of the measurement object, and the surface of the measurement object is three-dimensionally deformed, the error in the image is reduced. Correction can improve the accuracy of strain measurement.

FIG. 1 is a diagram schematically illustrating a configuration of a strain measuring apparatus according to the present embodiment. FIG. 2 is a schematic configuration diagram of the arithmetic device according to the present embodiment. FIG. 3 is a diagram illustrating a state in which an image is divided into a plurality of areas. FIG. 4 is a diagram illustrating an example of a method for comparing the target image and the comparison image. FIG. 5 is a schematic diagram for explaining the degree of correlation between the target image and the comparison image. FIG. 6 is a conceptual diagram illustrating a method for calculating strain from the amount of displacement. FIG. 7 is a diagram for explaining an example of a flow for measuring strain with the strain measuring apparatus according to the present embodiment. FIG. 8 is a diagram simply illustrating the configuration of the strain measuring apparatus according to the present embodiment. FIG. 9 is a schematic configuration diagram of an imaging device moving unit of the strain measuring apparatus according to the present embodiment. FIG. 10 is a cross-sectional view taken along the line AA of FIG. FIG. 11 is a diagram illustrating an example when the surface of the measurement object is deformed in the out-of-plane direction. FIG. 12 is a diagram for explaining image errors when the surface of the measurement object is deformed in the out-of-plane direction.

  Hereinafter, embodiments of a strain measuring apparatus and a strain measuring method according to the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by the content described in the following Examples. In addition, constituent elements in the following embodiments described below include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those in a so-called equivalent range. Furthermore, the constituent elements disclosed in the following embodiments described below can be appropriately combined.

  A strain measuring apparatus according to the present embodiment will be described with reference to the drawings. FIG. 1 is a diagram schematically illustrating a configuration of a strain measuring apparatus according to the present embodiment. FIG. 2 is a schematic configuration diagram of the arithmetic device according to the present embodiment.

  As illustrated in FIG. 1, the strain measuring apparatus 10 a according to the present embodiment includes imaging devices 11 a and 11 b that capture an image of the surface of the measurement target 13 and acquire an image, and an operation that calculates strain based on the acquired image. Device 12.

  The imaging devices 11a and 11b include main bodies 21a and 21b having imaging elements such as a CCD and a CMOS, and lenses 22a and 22b that form an image of a subject on the imaging element. The imaging devices 11a and 11b are respectively arranged at two predetermined points on the front side of the measurement object 13 so that the surface of the measurement object 13 can be imaged from a distant position, and image the surface of the measurement object 13. Images 35a and 35b are acquired.

  As shown in FIG. 1, the predetermined two points are the distance between the centers of the main bodies of the imaging devices 11a and 11b by W, and the distance between the imaging devices 11a and 11b and the surface of the measurement object 13 is I. It is only a position away. Further, the angle formed by the center line A1 and the center line A2 of the collimation angles of the imaging devices 11a and 11b is θ. The collimation angles are the angles θ1 and θ2 formed by the collimation lines 23a and 23b and the collimation lines 24a and 24b from the imaging devices 11a and 11b illustrated in FIG. 1 toward the targets 25 and 26.

  In the present embodiment, the imaging devices 11a and 11b are installed at the two predetermined points described above, and the surface of the measurement object 13 is imaged from a position away from each of the imaging devices 11a and 11b to obtain images 35a and 35b. To get. In this way, by measuring an image of the surface of the measuring object 13 using a stereo method that captures images from two predetermined points, measurement of the amount of deformation in the out-of-plane direction using parallax (triangulation) is performed. Can do. Then, the image error is corrected based on the principle of triangulation method to be described later.

  The images 35 a and 35 b acquired by the imaging devices 11 a and 11 b are sent to the arithmetic device 12 and stored in the storage unit 42.

  In the present embodiment, when calculating the distortion of the surface of the measurement object 13 based on images 35a and 35b stored in the storage unit 42 of the arithmetic unit 12 described later, the principle of triangulation method described later is used. An error in the out-of-plane direction of the image can be corrected.

  The imaging devices 11a and 11b may be any devices that can acquire images. For example, a known digital camera or digital video camera can be used.

  Next, the operation of the strain measuring apparatus 10a according to the present embodiment will be described. First, the principle of the triangulation method will be described with reference to FIG. As shown in FIG. 1, a state is shown in which the two imaging devices 11 a and 11 b are photographing the surface of the measurement target 13 and the targets 25 and 26 from two predetermined positions. In the principle of the triangulation method, as shown in FIG. 1, two target coordinates 25 and 26 from the positions of the imaging devices 11a and 11b and the imaging devices 11a and 11b are taken for the images 35a and 35b captured by the imaging devices 11a and 11b. The angles θ1 and θ2 in the shooting direction are obtained, and the imaging positions of the two imaging devices and the collimation angles of the imaging devices are determined.

  Next, collimation lines 23a and 23b and collimation lines 24a and 24b heading from the two positions of the imaging devices 11a and 11b toward the targets 25 and 26 are determined, and these collimation lines 23a and 23b and collimation lines 24a are determined. , 24b is obtained. Here, since the intersection of these collimation lines is actually at the position of the targets 25 and 26, if the coordinates of these intersections are determined, the coordinate value of the target is determined. In this manner, the amount of deformation in the out-of-plane direction of the measurement target 13 can be calculated by calculating the coordinate values of all the targets to be measured.

  In this embodiment, since the imaging devices 11a and 11b acquire images from two predetermined points, the imaging positions of the two imaging devices 11a and 11b and the collimating angles θ1 and θ2 of the imaging devices are obtained in advance. be able to. Therefore, based on the imaging positions of the two imaging devices 11a and 11b and the collimation angles θ1 and θ2 of the imaging devices, the two images 35a acquired by the triangulation method even when the surface of the measurement target 13 is deformed out of plane. , 35b, the amount of deformation in the out-of-plane direction of the image can be obtained, and the error of the image can be corrected.

  Thus, according to the strain measuring apparatus 10a of the present embodiment, since the images are acquired by the imaging apparatuses 11a and 11b from two predetermined points, the triangulation method is used even when the surface of the measuring object 13 is deformed out of plane. The amount of deformation in the out-of-plane direction of the image can be obtained based on the two images 35a and 35b acquired by the above method, and even when the surface of the measurement target 13 is three-dimensionally deformed in the out-of-plane direction, the image error is corrected. The accuracy of strain measurement can be improved.

  Further, according to the strain measuring device 10a of the present embodiment, images are acquired by the imaging devices 11a and 11b from a position apart from the position generated without directly measuring the strain generated on the surface of the measurement target 13, and the strain is obtained by image analysis. Can be calculated with high accuracy.

  Next, the arithmetic device will be described. As illustrated in FIG. 2, the arithmetic device 12 includes an I / F unit 41 that captures images 35 a and 35 b captured by the imaging device 11 a and a hard disk drive that stores the images 35 a and 35 b captured by the I / F unit 41. A storage unit 42 such as a CPU, an arithmetic unit 43 such as a CPU that reads and executes a program or the like held in the storage unit 42, executes an input unit 44 such as a keyboard or a mouse, and an output unit 45 such as a display or a printer. And. As the arithmetic unit 12, for example, a personal computer can be applied.

  The storage unit 42 captures an image of the measurement object 13, stores the captured images 35a, 35b,... In the storage unit 42, and measures from the images 35a, 35b captured by the imaging program 42a. A displacement amount calculation program 42b for calculating the displacement amount of the object 13 and a strain calculation program 42c for calculating strain based on the displacement amount calculated by the displacement amount calculation program 42b are stored.

  Next, processing executed by the imaging program 42a, the displacement calculation program 42b, and the strain calculation program 42c will be described.

<Processing executed by the imaging program 42a>
The calculation unit 43 receives values related to imaging conditions such as the imaging range, imaging distance, and focal length of the imaging device 11a from the user by the input unit 44, and performs processing for changing the setting of the imaging device 11a to each received value. Run.

  Subsequently, the calculation unit 43 transmits an imaging signal for executing imaging to the imaging devices 11a and 11b. Imaging is performed by the imaging devices 11 a and 11 b that have received the imaging signal, and an image obtained by imaging the surface of the measurement object 13 is acquired. All the acquired images are stored in the storage unit 42 via the I / F unit 41.

  The computing unit 43 executes a process for imaging the surface of the measurement target 13. Thereby, the image 35a and the image 35b are acquired.

<Processing executed by displacement amount calculation program 42b>
The calculation unit 43 reads the images 35 a and 35 b from the storage unit 42, compares the images 35 a and 35 b with each other, and executes a process of calculating the displacement amount of the surface of the measurement target 13.

  For the calculation of the displacement amount, a digital image correlation method capable of calculating the displacement amount from the luminance value distribution of the images 35a and 35b can be used.

  FIG. 3 is a diagram illustrating a state in which an image is divided into a plurality of areas. Specifically, as shown in FIG. 3, first, the image 35a and the image 35b are each divided into a plurality of areas Eij (for example, 36 × 36 pixels).

  Next, one area Eij (for example, area E22) is selected from the plurality of areas Eij of the image 35a. Hereinafter, one area Eij selected from the area Eij of the untransformed image 35a is referred to as a target image 35aa.

  Further, a comparative image 35bb is extracted by designating a cutout section (for example, 72 × 72 pixels) slightly larger than the area Eij for the image 35b. Note that the size of the cut-out section can be set regardless of the size of the area Eij, and can be set as appropriate according to the processing capability of the calculation unit 43 and the like.

  FIG. 4 is a diagram illustrating an example of a method for comparing the target image 35aa and the comparison image 35bb. FIG. 5 is a schematic diagram for explaining the degree of correlation between the target image 35aa and the comparison image 35bb. In the following description, as shown in FIG. 4, the left-right direction in the figure is the X-axis direction, and the up-down direction in the figure is the Y-axis direction.

  As illustrated in FIG. 4, the calculation unit 43 superimposes the target image 35aa on the comparison image 35bb and shifts the position of the target image 35aa in the vertical direction, and determines the position that obtains the best correlation with the target image 35aa. It is specified from 35bb. As shown in FIG. 5, the degree of correlation increases as the value of the correlation function S = f (x, y) decreases, and the degree of correlation of the luminance value distribution increases and the accuracy of position detection increases. Since the actual displacement amount may be smaller than the size of one pixel, the luminance value distribution is interpolated using a spline function or the like so that the displacement amount can be detected with a resolution of one pixel or less, and the function S Position coordinates and X axis directions, Y axis directions, and XY directions (directions inclined by 45 ° from the X axis toward the Y axis) are calculated (Δx, Δy, Δxy), respectively.

  The process of superimposing the target image 35aa on the comparison image 35bb described above is repeatedly performed for all the areas Eij, and the X-axis direction, the Y-axis direction, and the XY direction for each area Eij in the entire image 35b after deformation. Displacement amounts (Δx, Δy, Δxy) are respectively calculated.

  Subsequently, the calculation unit 43 stores the calculated displacement amounts (Δx, Δy, Δxy) in the storage unit 42.

  In this embodiment, the case where the digital image correlation method is used as the image analysis method has been described. However, the present invention is not limited to this method, and a general image analysis method may be used.

<Processing executed by strain calculation program 42c>
FIG. 6 is a conceptual diagram illustrating a method for calculating strain from the amount of displacement. As shown in FIG. 6, the calculation unit 43 reads the displacement amounts (Δx, Δy, Δxy) in the X-axis direction, the Y-axis direction, and the XY direction from the storage unit 42 and strains the image 35b after the deformation. A calculation area Eij (for example, E44) to be calculated is selected, and two areas Eij (for example, X44) that are point-symmetrical with a predetermined distance L from the selected calculation target area Eij (for example, E44) as a central point. When calculating the axial direction, processing for calculating the strain of the calculation target area Eij (for example, E44) is executed based on the respective displacement amounts (Δx, Δy, Δxy) in E14, E74). Here, the distance between the two areas Eij existing in a point-symmetrical position with the calculation target area Eij as the center point is defined as a distance GL between the scores. Since the two areas Eij are in point symmetry with respect to the calculation target area Eij, the inter-score distance GL is twice the predetermined distance L.

  The calculation unit 43 receives the value of the inter-score distance GL from the user via the input unit 44 such as a keyboard, and each distortion (Δx, Δy, Δxy) in the X axis direction, the Y axis direction, and the XY direction in the calculation target area Eij. The process of calculating is executed.

(When calculating strain in the X-axis direction)
As shown in FIG. 6, when calculating the strain εx in the X-axis direction of the area Eij (for example, E44), it is ± 0.5 GL away in the X-axis direction based on the inter-score distance GL set by the user. The strain εx is calculated from the displacement amount of the two areas Eij (for example, E14 and E74). The strain εx is calculated by the following formula (1).
εx = (Δx (x + 0.5GL, y) −Δx (x−0.5GL, y)) / GL (1)
Here, εx: strain in the X-axis direction in each area Eij, Δx: displacement amount in the X-axis direction in each area Eij, GL: distance between scores.

(When calculating strain in the Y-axis direction)
Also, as shown in FIG. 6, when calculating the strain εy in the Y-axis direction of the area Eij (for example, E44), both areas Eij separated by ± 0.5 GL in the Y-axis direction based on the inter-score distance GL The strain εy is calculated from the displacement amount (for example, E41, E47). The strain εy is calculated from the following equation (2).
εy = (Δy (x, y + 0.5GL) −Δy (x, y−0.5GL)) / GL (2)
Here, εy is a strain in the Y-axis direction in each area Eij, and Δy is a displacement amount in the Y-axis direction in each area Eij.

(When calculating strain in the XY direction)
Further, when the strain εxy in the XY direction of the area Eij is calculated, the strain εxy is calculated from the displacement amount of both areas Eij that are separated by ± 0.5 GL in the XY direction based on the inter-score distance GL. The strain εxy is calculated from the following equation (3).
εxy = (Δxy (x + 0.5GL, y + 0.5GL) −Δxy (x−0.5GL, y−0.5GL)) / GL (3)
Here, εxy is a strain in the XY direction in each area Eij, and Δxy is a displacement amount in the XY direction in each area Eij.

  Subsequently, the calculation unit 43 stores the strains (εx, εy, εxy) in the X-axis direction, the Y-axis direction, and the XY direction calculated by the above formulas (1), (2), and (3), respectively. To store.

  Subsequently, the calculation unit 43 calculates the X-axis direction and the Y-axis direction calculated as described above based on the deformation amount in the out-of-plane direction of the image obtained based on the two images 35a and 35b acquired by the triangulation method described above. And the error of each strain (εx, εy, εxy) in the XY direction are corrected, and the corrected strain (εx, εy, εxy) in the X-axis direction, the Y-axis direction, and the XY direction are stored in the storage unit 42. .

  Finally, the calculation unit 43 transmits each corrected strain (εx, εy, εxy) to the output unit 45 and displays it on the monitor of the output unit 45.

  Next, the flow of strain measurement for measuring the strain of the measurement object 13 using the strain measurement apparatus 10a according to the present embodiment will be described.

  FIG. 7 is a diagram illustrating an example of a flow for measuring strain. As shown in FIG. 7, a heat resistant paint or the like is sprayed irregularly on the surface of the measurement target region of the measurement target 13 by spraying or the like in advance (step S10). At this time, the marks have different shapes and outer dimensions, and the arrangement is irregular. In this example, a heat-resistant paint or the like is sprayed on the surface of the object to be measured by spraying or the like, but the present invention is not limited to this. You may make it adhere.

  Next, the calculation unit 43 of the calculation device 12 receives values such as an imaging range, an imaging distance, and a focal length as imaging conditions of the imaging devices 11a and 11b from the user through the input unit 44 (step S11). Note that the above imaging conditions may be automatically input from the imaging devices 11a and 11b.

  Next, the surfaces of the measurement object 13 are imaged by the imaging devices 11a and 11b controlled by the arithmetic device 12, and images 35a and 35b are acquired (step S12). The images 35 a and 35 b acquired by the imaging devices 11 a and 11 b are sent to the arithmetic device 12 and stored in the storage unit 42.

  In the displacement amount calculation step (step S13), the calculation unit 43 executes the above-described displacement amount calculation program 42b based on the images 35a and 35b stored in the storage unit 42, so that the X-axis direction, the Y-axis direction, and the XY The amount of displacement (Δx, Δy, Δxy) in the direction is calculated (step S13). The calculated displacement amounts (Δx, Δy, Δxy) are stored in the storage unit 42 by the calculation unit 43. If each displacement amount ((DELTA) x, (DELTA) y, (DELTA) xy) is calculated, it will transfer to a distortion | strain calculation process (step S14).

  In the strain calculation step (step S14), the above-described strain calculation program is based on the displacement amounts (Δx, Δy, Δxy) calculated by the calculation unit 43 in the displacement amount calculation step (step S13) stored in the storage unit 42. 42c is executed to calculate respective strains (εx, εy, εxy) in the X-axis direction, the Y-axis direction, and the XY direction (step S14). The calculated strains (εx, εy, εxy) are stored in the storage unit 42 by the calculation unit 43. Subsequently, the calculation unit 43 calculates the X-axis direction and the Y-axis direction calculated as described above based on the deformation amount in the out-of-plane direction of the image obtained based on the two images 35a and 35b acquired by the triangulation method described above. And the error of each strain (εx, εy, εxy) in the XY direction are corrected, and the corrected strain (εx, εy, εxy) in the X-axis direction, the Y-axis direction, and the XY direction are stored in the storage unit 42. .

  Next, the process proceeds to an output step (step S15) for outputting each corrected strain (εx, εy, εxy). In the output step (step S15), the calculation unit 43 reads out the corrected strains (εx, εy, εxy) from the storage unit 42, transmits them to the output unit 45, and displays them on the monitor of the output unit 45 or the like.

  According to the strain measuring device 10a of the present embodiment, since the images are acquired by the imaging devices 11a and 11b from two predetermined points, even if the surface of the measuring object 13 is deformed out of plane, the 2 obtained by the triangulation method. The amount of deformation in the out-of-plane direction of the image can be obtained based on the two images 35a and 35b, and the image error can be corrected. Therefore, according to the strain measuring apparatus 10a of the present embodiment, even when the surface of the measurement target 13 is three-dimensionally deformed in the out-of-plane direction, the error of the image can be corrected and the accuracy of strain measurement can be improved.

  Further, according to the strain measuring device 10a of the present embodiment, the imaging device 11a, 11b captures the surface of the measurement object 13, and the strain is calculated based on the captured image. Strain can be calculated accurately from the location.

  A strain measuring apparatus 10b according to the present embodiment will be described. The strain measuring apparatus 10b according to the present embodiment has a configuration in which the imaging apparatuses 11a and 11b included in the strain measuring apparatus 10a according to the first embodiment illustrated in FIG. Except for the configuration provided with the means 15, it is the same as the first embodiment. The same components as those in the first embodiment are denoted by the same reference numerals, and a duplicate description is omitted.

  FIG. 8 is a diagram simply illustrating the configuration of the strain measuring apparatus according to the present embodiment.

  As illustrated in FIG. 8, the strain measuring device 10 b according to the present embodiment includes an imaging device 11 c that captures an image of the surface of the measurement target 13 and acquires an image, and an arithmetic device 12 that calculates strain based on the acquired image. And imaging device moving means 15 for reciprocatingly moving the imaging device between two predetermined points.

  The imaging device 11c includes a main body 21c having an imaging element such as a CCD or CMOS, and a lens 22c that forms an image of a subject on the imaging element. The imaging device 11c is arranged on the imaging device moving means 15 on the front side of the measurement object 13 so that the surface of the measurement object 13 can be imaged from a distant position, and images the surface of the measurement object 13 to obtain an image 35a, 35b is acquired.

  As shown in FIG. 8, the predetermined two points are the distance between the center of the main body of the imaging device 11c before and after the movement by W, and the distance between the imaging device 11c before and after the movement and the surface of the measurement object 13 Is a position separated by I. Further, the angle formed by the center line B1 and the center line B2 of the collimation angle of the imaging device 11c before and after the movement is θ. The collimation angles are angles θ1 and θ2 formed by the collimation lines 23a and 23b and the collimation lines 24a and 24b from the imaging devices 11a and 11b illustrated in FIG. 8 toward the targets 25 and 26.

  In the present embodiment, the image pickup device 11c is moved by the image pickup device moving means 15 to the two predetermined points described above, and the image of the surface of the measurement object 13 is picked up from the position separated by the image pickup device 11c before and after the movement. 35a and 35b are acquired. In this way, by measuring an image of the surface of the measurement object 13 using a stereo method in which imaging is performed from two predetermined points by one imaging device 11c, measurement of the amount of deformation in the out-of-plane direction using parallax is performed. (Triangulation) can be performed. Then, the image error is corrected based on the principle of the triangulation method described in the first embodiment.

  The images 35 a and 35 b acquired by the imaging device 11 c before and after the movement are sent to the arithmetic device 12 and stored in the storage unit 42.

  In the present embodiment, the principle of the triangulation method described above when calculating the distortion of the surface of the measurement object 13 based on the images 35a and 35b stored in the storage unit 42 of the arithmetic device 12 described in the first embodiment. Can correct the error in the out-of-plane direction.

  The imaging device 11c may be any device that can acquire an image. For example, a known digital camera, digital video camera, or the like can be used.

  Next, the imaging device moving unit 15 will be described. FIG. 9 is a schematic configuration diagram of the imaging device moving unit 15 of the strain measuring apparatus 10b according to the present embodiment. FIG. 10 is a cross-sectional view taken along the line AA of FIG.

  As illustrated in FIGS. 9 and 10, the imaging device moving unit 15 has a base 31, a moving table 32 that moves the imaging device 11 c, a rotation table 33 that rotates the imaging device 11 c, and a moving table 32. A step motor 34 and a screw rod 35 for moving a predetermined distance between two points, and a step motor 36 and a screw rod 37 for rotating the rotary table 33 by a predetermined angle are provided. An imaging device 11 c is installed on the rotary table 33.

  The base 31 is a base that supports the moving table 32 and the step motor 34. The moving table 32 reciprocates between two predetermined points as indicated by an arrow C by a screw rod 35 driven by a step motor 34. When the moving table 32 moves between two predetermined points as indicated by an arrow D by the step motor 36, the rotary table 33 includes a center line B1 and a center line B2 of collimation angles of the imaging device 11c before and after the movement. Is rotated by an angle θ formed by (see FIG. 8). Note that the position of the moving table 32, the moving distance W, and the angle θ at which the rotating table 33 rotates are set in advance.

  The position of the moving table 32 and the moving distance W and the angle θ at which the rotary table 33 rotates are controlled by step motors 34 and 26, respectively, and the step motors 34 and 26 are controlled by the arithmetic unit 12.

  Thus, the imaging device moving means 15 of the strain measuring device 10b of the present embodiment reciprocally moves the imaging device 11c installed on the rotary table 33 on the moving table 32 between two predetermined points. The angle can be rotated.

  In the present embodiment, by using the imaging device moving means 15, the images 35a and 35b on the surface of the measurement target 13 are acquired by a single imaging device 11c using a stereo method of imaging from two predetermined points. Thus, the measurement of the amount of deformation in the out-of-plane direction using parallax (triangulation) can be performed. The image error can be corrected based on the principle of the triangulation method described above.

  Therefore, according to the present embodiment, since the image is acquired by the imaging device 11c from two predetermined points using the imaging device moving means 15, the triangulation method is used even when the surface of the measuring object 13 is deformed out of plane. The amount of deformation in the out-of-plane direction of the image can be obtained based on the two images 35a and 35b acquired by the above, and the image error can be corrected. Therefore, according to the strain measurement apparatus 10b of the present embodiment, even when the surface of the measurement target 13 is three-dimensionally deformed in the out-of-plane direction, the error of the image can be corrected and the accuracy of strain measurement can be improved.

  As described above in the first and second embodiments, the strain measurement apparatus according to the present invention uses parallax in order to acquire an image of the surface of the measurement object using the stereo method of imaging from two predetermined points. Measurement of the amount of deformation in the out-of-plane direction (triangulation) can be performed, and image errors can be corrected based on the principle of triangulation. Therefore, according to the present invention, even when the surface of the measurement object is three-dimensionally deformed in the out-of-plane direction, the error of the image can be corrected and the accuracy of strain measurement can be improved.

  In addition, according to the strain measuring device of the present invention, the surface of the measurement object is imaged by the imaging device, and the strain is calculated based on the captured image. Therefore, the strain is accurately calculated from a place away from the measurement object. can do.

10a, 10b Strain measuring device 11a, 11b, 11c, 11d Imaging device 12 Arithmetic device 13 Measurement object 14 Strain measuring region 15 Imaging device moving means 21a, 21b, 21c Main body 22a, 22b, 22c Lens 23a, 23b, 24a, 24b Imaging device collimation angle 25, 26 Target 31 Base 32 Moving table 33 Rotating table 34, 36 Step motor 35, 37 Screw rod 35a, 35b, 35aa, 35bb, 52, 53 Image 41 I / F unit 42 Storage unit 43 Calculation unit 44 Input unit 45 Output unit 51a, 51b Measurement object θ Angle formed by center line of collimation angle of imaging device θ1, θ2 Collimation angle of imaging device A1, A2, B1, B2 Collimation angle of imaging device Center line

Claims (5)

At least one imaging device that captures an image of the surface of the measurement object from two predetermined points;
Based on each image at two points acquired by the imaging device, an arithmetic device that calculates the displacement of the surface of the measurement object by triangulation and calculates the distortion of the surface of the measurement object;
A strain measuring apparatus comprising: In claim 1,
The strain measuring device is characterized in that the imaging device is a first imaging device and a second imaging device installed at the two predetermined points. In claim 1,
A strain measuring apparatus comprising: an imaging apparatus moving means for reciprocatingly moving the imaging apparatus between the two predetermined points. In any one of Claims 1-3,
The computing device corrects an image error by obtaining a deformation amount in an out-of-plane direction of the acquired image based on two predetermined imaging positions of the imaging device and a collimation angle of the imaging device. A strain measuring device characterized by that. An imaging step of acquiring an image by imaging the surface of the measurement object from two predetermined points;
Based on the respective images at the two points acquired in the imaging step, a strain calculation step of calculating a displacement of the surface of the measurement object by calculating a displacement amount of the surface of the measurement object by a triangulation method,
A strain measurement method characterized by comprising:

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