Deformation calculating device, deformation measuring device, and deformation calculating method

Abstract

A deformation calculating device capable of calculating deformation with 1 camera correcting a positional change of a measurement object even in the absence of a reference point which does not move. Provided are: a deformation calculating section (11) which calculates a simple calculation deformation of a measurement region (2) using a digital image correlation method; a viewpoint change removing section (12) which subtracts an apparent strain which is inversely calculated assuming no deformation in the measurement region (2) from the simple calculation deformation to calculate a temporary deformation; and a generalization section (13) which outputs a deformation obtained by averaging the temporary deformation calculated by sequentially modifying a first image selected from a first image group and a second image selected from a second image group and applying the temporary deformation calculated by the deformation calculating section (11) and the viewpoint change removing section (12) as the deformation of the measurement region (2) from a first photographing period to a second photographing period.

Description

Technical Field

[0001] This application relates to a deformation calculation device, a deformation measurement device, and a deformation calculation method. Background Technology

[0002] As a method for measuring the deformation of an object, digital image correlation (DIR) is known. This method compares images obtained by photographing an object during a first and second photographic period at different times, thereby measuring the deformation non-contactly. In DIR, the displacement of the photographed area is detected using the correlation of the brightness value distribution. This is based on the fact that the diffuse image of the object's surface moves with the object's surface, preserving its brightness value distribution during both the first and second photographic periods. The displacement and strain that maximize the correlation of brightness values ​​in the images before and after deformation are searched at each position on the image, thereby determining the deformation of the object. However, in DIR, if the relative position of the camera and the object changes between the first and second photographic periods, the object's movement and magnification / reduction are projected onto the photographed images, resulting in apparent deformation. Therefore, a problem exists: if the relative position of the camera and the object changes between the first and second photographic periods, the deformation of the object cannot be accurately measured.

[0003] To address this problem, one existing method involves photographing the object using multiple cameras positioned at different locations. The relative positions of the cameras and the object are then measured using stereoscopic vision principles, eliminating the influence of changes in their relative positions to measure deformation. However, this method, requiring multiple cameras at distinct locations, tends to complicate and increase the size of the measurement system. Furthermore, accurately determining the relative positions of the cameras increases the labor required compared to using a single camera. Therefore, a method has been proposed that corrects for positional changes relative to the object using only a single camera to achieve a simpler deformation measurement.

[0004] As one method for measuring deformation by correcting and measuring the positional changes of an object using a single camera, the following method is proposed: For the deformation amount detected by digital image correlation, a reference area that does not produce displacement or strain is set within the photographic area, and a coordinate transformation formula representing the relationship between the coordinate position on the photographic image before deformation and the coordinate position on the image after deformation is obtained, and the error caused by the movement of the camera is subtracted from the measured displacement (for example, see Patent Document 1).

[0005] Patent Document 1: Japanese Patent No. 5013047 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] In the technology of Patent Document 1, the photographic area must include an object whose position does not change before and after the deformation of the object being measured, as a reference point for measuring the relative position of the camera and the object being measured. Therefore, the following problem exists: when it is difficult to set a stationary reference point, for example, when the deformation of the object being measured covers the entire photographic area, deformation cannot be measured.

[0008] This application was made to solve the above-mentioned problems, and its purpose is to provide a deformation calculation device that can use a camera to correct and measure the positional changes of an object to calculate deformation even in the absence of a stationary reference point.

[0009] Solution for solving the problem

[0010] The deformation calculation apparatus disclosed in this application comprises: a deformation calculation unit that uses a first image selected from a first image group obtained by photographing the measurement area from different relative positions during a first photography period and a second image selected from a second image group obtained by photographing the measurement area from different relative positions during a second photography period different from the first photography period to calculate the simple calculated deformation of the measurement area using a digital image correlation method; a viewpoint change removal unit that subtracts the apparent strain calculated by assuming no deformation in the measurement area from the simple calculated deformation to calculate the temporary deformation; and a synthesis unit that outputs the deformation obtained by averaging the temporary deformation calculated by the deformation calculation unit and the viewpoint change removal unit from the first photography period to the second photography period as the deformation of the measurement area from the first photography period to the second photography period.

[0011] The effects of the invention

[0012] The deformation calculation apparatus disclosed in this application includes: a deformation calculation unit that uses a first image selected from a first image group obtained by photographing the measurement area from different relative positions during a first photography period and a second image selected from a second image group obtained by photographing the measurement area from different relative positions during a second photography period different from the first photography period to calculate the simple calculated deformation of the measurement area using digital image correlation; a viewpoint change removal unit that subtracts the apparent strain calculated by assuming no deformation in the measurement area from the simple calculated deformation to calculate the temporary deformation; and an integration unit that outputs the deformation obtained by averaging the temporary deformation calculated by the deformation calculation unit and the viewpoint change removal unit by sequentially selecting the first image from the first image group and the second image from the second image group, as the deformation of the measurement area from the first photography period to the second photography period. Therefore, even in the absence of a stationary reference point, deformation can be calculated by correcting the positional change of the measurement object with a single camera. Attached Figure Description

[0013] Figure 1 This is a block diagram showing the structure of the deformation calculation device based on Embodiment 1.

[0014] Figure 2 This is a perspective view of the structure in Embodiment 1 under tensile load.

[0015] Figure 3 This is a perspective view of the structure with defects in Implementation Method 1.

[0016] Figure 4 It is a diagram used to illustrate the deformation, displacement, and strain in this application.

[0017] Figure 5 This is a diagram used to illustrate the apparent deformation caused by the movement of the camera device in Embodiment 1.

[0018] Figure 6 This is a flowchart showing the details of the deformation calculation process based on Implementation Method 1.

[0019] Figure 7 This is a block diagram showing the structure of the deformation calculation device based on Embodiment 2.

[0020] Figure 8 This is a perspective view of the structure in embodiment 2 under the applied bending moment.

[0021] Figure 9 This is a diagram showing the measurement area during the first image capture in Embodiment 2.

[0022] Figure 10This is a diagram showing the measurement area during the second image capture in Embodiment 2.

[0023] Figure 11 This is a block diagram showing the structure of the deformation calculation device based on embodiment 3.

[0024] Figure 12 This is a perspective view of the structure in Embodiment 3, which is subjected to a uniaxial tensile or compressive load.

[0025] Figure 13 This is a schematic diagram illustrating an example of the hardware of a variant computing device based on Embodiment 1, Embodiment 2, and Embodiment 3.

[0026] Figure 14 This is a diagram illustrating the structure of the deformation measuring device in Embodiment 4.

[0027] (Explanation of reference numerals in the attached image)

[0028] 1: Structure; 2: Measurement area; 3: Defected area; 4: Defect; 5: Tensile load; 6: Bending moment; 7c, 7d: Photographic plane; 8: Load; 10, 10a, 10b: Deformation calculation device; 11: Deformation calculation unit; 12: Viewpoint change removal unit; 13, 13a, 13b: Integration unit; 20, 20a, 20b, 20c, 20d: Camera device; 30: Area before deformation; 31: Area after deformation with only displacement; 32: Area after deformation due to displacement and strain; 100, 100a, 100b: Deformation measurement device; 201: Processor; 202: Memory; 300: Moving device; 301: Wheel. Detailed Implementation

[0029] Hereinafter, the deformation calculation apparatus involved in implementing the embodiments of this application will be described in detail with reference to the figures. Furthermore, the same symbols in the figures denote the same or equivalent parts.

[0030] Implementation method 1.

[0031] Figure 1 This is a block diagram illustrating the structure of the deformation calculation device 10 based on Embodiment 1. For example... Figure 1 As shown, the deformation calculation device 10 includes a deformation calculation unit 11, a viewpoint change removal unit 12, and an integration unit 13. The deformation measurement device 100 includes the deformation calculation device 10 and a camera device 20.

[0032] The deformation calculation device 10 based on Embodiment 1 is used for various applications such as deformation measurement of test pieces in the laboratory or inspection of the time-dependent changes in the shape of infrastructure equipment. Hereinafter, assuming the inspection of infrastructure equipment, the operation of the deformation calculation device 10 using digital image correlation will be explained as an example of measuring the strain changes of the structures constituting the infrastructure equipment. Assume the following: a first inspection is performed during a first imaging period, and a second inspection is performed during a second imaging period after the equipment has been used for a fixed period from the first imaging period. The image of the structure captured by the imaging device 20 during the first imaging period is compared with the image of the structure captured by the imaging device 20 during the second imaging period using digital image correlation, thereby inspecting the deterioration of mechanical components caused by the operation of the equipment. Hereinafter, the structure to be photographed will be defined as the subject, and the range of deformation measured on the surface of the structure will be defined as the measurement area.

[0033] When photographing structures constituting infrastructure equipment, it is difficult to set the relative positions of the camera (which serves as the imaging device 20) and the subject to be exactly the same during the first and second photography periods. As a result, when the shape change of the subject is measured using images of the subject obtained during the first and second photography periods and digital image correlation is used, it is difficult to measure the shape change of the subject with high accuracy because the amount of movement caused by the change in the relative position of the camera and the subject is included as an error. In addition, for example, when the subject is positioned in a narrow area, it is sometimes impossible to increase the distance between the subject and the camera so that the subject covers the entire imaging range of the camera. In such cases, it is difficult to include reference points in the subject that do not undergo displacement within the imaging range of the camera, and it is difficult to determine the relative position of the camera and the subject when using techniques that require reference points for measuring the relative position of the camera and the subject. Hereinafter, the operation of the deformation calculation device 10 based on Embodiment 1, which does not require reference points for measuring the relative position of the imaging device 20 and the subject, will be explained.

[0034] Regarding the subject whose shape change is measured by the deformation calculation device 10 based on embodiment 1, assuming as follows: Figure 2 and Figure 3 The diagram shows a rectangular structure 1 with a tensile load 5 applied along its long side. A measurement area 2 is defined on the surface of structure 1. Figure 2 and Figure 3 In this system, the structure 1 is represented by an orthogonal coordinate system, the surface of the measurement area 2 is set as the xy plane, and the axis perpendicular to the xy plane is set as the z axis. Figure 2 This refers to structure 1 during the first photographic period. Figure 3This refers to structure 1 during the second photographic period. Structure 1 is... Figure 2 The first photographic period shown is a uniform cross-section, while... Figure 3 During the second photographic period shown, defect 4 was generated in defect area 3, resulting in... Figure 3 The shape change occurred in the measurement area 2 during the second imaging period shown. Based on Embodiment 1, the deformation calculation device 10 photographs the measurement area 2 of the structure 1 by the imaging device 20 during the first imaging period and again by the imaging device 20 during the second imaging period. Using digital image correlation, the deformation of the measurement area 2 caused by the defect 4 is calculated based on each image. The calculated deformation of the measurement area 2 is used, for example, to estimate the location and size of the defect 4.

[0035] It is desirable to pre-apply a random pattern to the measurement area 2 of structure 1. A random pattern refers to a non-repeating, isotropic pattern with high contrast. For example, a black paint is sprayed onto the measurement area 2 of structure 1 after a white paint is applied, thereby creating the random pattern. Alternatively, if the surface of structure 1, which is the measurement area 2, already possesses a high-contrast random pattern, then no paint application is necessary. Examples of surfaces of structure 1 that already possess a high-contrast random pattern include concrete surfaces.

[0036] The imaging device 20 takes pictures of the measurement area 2 during the first imaging period to output an image, and takes pictures of the measurement area 2 during the second imaging period to output an image. The deformation calculation device 10 compares the image of the measurement area 2 taken by the imaging device 20 during the first imaging period with the image of the measurement area 2 taken by the imaging device 20 during the second imaging period using digital image correlation, thereby calculating the deformation of the measurement area 2.

[0037] Figure 4 This is a diagram illustrating deformation, displacement, and strain in this application. In this application, deformation is explained as a general term for displacement and strain. Region 30 before deformation represents a specific region of measurement region 2 observed during the first photograph. Region 31 after deformation, where only displacement occurred, represents a specific region of measurement region 2 observed during the second photograph when the deformation was only displacement. Here, u is used... x u y Displacement is indicated. Region 32, after deformation based on displacement and strain, represents a specific region of measurement region 2 observed during the second imaging process when the deformation involves both displacement and strain. Here, u is used... x u y Displacement is represented by... Indicates strain.

[0038] The following describes the details of the operation of the imaging device 20 and the deformation calculation device 10. During the first imaging period, the imaging device 20 takes multiple photographs of the measurement area 2, outputting multiple images as a first image group. Furthermore, during the second imaging period, the imaging device 20 takes multiple photographs of the measurement area 2, outputting multiple images as a second image group. In the imaging device 20, the measurement area 2 is photographed more than twice during the first imaging period, preferably more than ten times, outputting more than two, preferably more than ten, image data, which is defined as the first image group. The first image group can be images obtained by continuously capturing still images, or images obtained by capturing moving images and extracting multiple frames from those moving images to obtain still images. Each image included in the first image group is captured under different relative positions of the imaging device 20 to the measurement area 2. Regarding the method of changing the relative position of the measurement area 2 and the imaging device 20, the imaging device 20 can be moved parallel to the measurement area 2, the distance between the measurement area 2 and the imaging device 20 can be changed, or the angle of the imaging device 20 relative to the measurement area 2 can be changed. Alternatively, two or more of the following can be performed simultaneously: parallel movement, distance change, and angle change.

[0039] In the imaging device 20, during the second imaging period, the measurement area 2 is photographed two or more times, preferably ten or more times, and two or more image data images are output, preferably ten or more, and these are set as a second image group. The second image group can be images obtained by continuously capturing still images, or images obtained by capturing moving images and extracting multiple frames from the moving images to obtain still images. Each image included in the second image group is captured under different relative positions of the imaging device 20 to the measurement area 2. Regarding the method of changing the relative position of the measurement area 2 and the imaging device 20, the imaging device 20 can be moved parallel to the measurement area 2, the distance between the measurement area 2 and the imaging device 20 can be changed, or the angle of the imaging device 20 relative to the measurement area 2 can be changed. In addition, two or more of the parallel movement, distance change, and angle change can be performed simultaneously.

[0040] In the deformation calculation unit 11, a first image group and a second image group are acquired as outputs of the imaging device 20. The deformation calculation unit 11 selects one image from the first image group as the first image and one image from the second image group as the second image. Using the shape of the measurement region 2 contained in the first image as a reference, the shape change of the measurement region 2 contained in the second image is calculated using digital image correlation, and the two-dimensional distribution of displacement and strain is calculated. These two-dimensional distributions of displacement and strain are output as simple deformation calculation. In addition, the deformation calculation unit 11 outputs the first image and the second image used in calculating the simple deformation calculation together with the simple deformation calculation. During the first and second imaging periods, the relative position of the measurement region 2 and the imaging device 20 is different. Therefore, the simple deformation calculation output by the deformation calculation unit 11 is the deformation formed by the apparent displacement and strain caused by the change of viewpoint superimposed on the deformation of the measurement region 2.

[0041] In the viewpoint change removal unit 12, a temporary deformation, which is a two-dimensional distribution of displacement and strain in the measurement area 2, is obtained based on the simple calculated deformation, the first image, and the second image output by the deformation calculation unit 11, and the obtained temporary deformation is output. Figure 5 This diagram illustrates the apparent deformation caused by the movement of the camera device 20. Figure 5 In, with Figure 2 and Figure 3 Similarly, the structure 1 is represented by an orthogonal coordinate system, the surface of the measurement area 2 is set as the xy plane, and the axis perpendicular to the xy plane is set as the z axis. Figure 5 This diagram illustrates a portion of the photographic process performed on the measurement region 2 of structure 1 during a first photographic period and a second photographic period. The image obtained during the first photographic period from the position of imaging device 20a is the first image, and the image obtained during the second photographic period from the position of imaging device 20b is the second image. The diagram shows the apparent strain x in the x-direction of the measurement region 2 in the second image obtained from the position of imaging device 20b, relative to the point of interest (x, y) on the measurement region 2 in the first image obtained from the position of imaging device 20a. s It is approximately obtained through the following equation (1).

[0042] [Number 1]

[0043]

[0044] exist Figure 5 In equation (1), (x c y c) is the center coordinate of the rotation of the position of the camera device 20b relative to the position of the camera device 20a; z is the distance from the position of the camera device 20a to the measurement area 2; δz is the distance from the position of the camera device 20b relative to the position of the camera device 20a to the point (x). c y c The change in distance is θ, which is the change in the rotation angle of the position of the camera device 20b relative to the position of the camera device 20a, and φ is the direction of rotation of the position of the camera device 20b relative to the position of the camera device 20a.

[0045] In other words, (x c y c ) is the coordinate of a point on the xy-plane when a perpendicular line is drawn from the camera device 20a that captured the first image to the xy-plane, which serves as the plane of the measurement area 2; z is the coordinate of the point (xy-plane) between the camera device 20a and the point (xy-plane). c y c The distance between the camera device 20b and the point (x) is z+δz. c y c The distance from point (x) to point (x). c y c The direction from the camera device 20a and from point (x) c y c The angle formed by the direction of the camera device 20b. Additionally, as the connecting point (x... c y c The angle between the projection of the line segment of the camera device 20b onto the xy plane and the x-axis is φ.

[0046] If we can find the six coefficients θ, φ, x in equation (1) c y c Given z and δz, the strain caused by the movement of the camera device 20, which is included in the simple calculated deformation output by the deformation calculation unit 11, can be back-calculated. In the viewpoint change removal unit 12, for at least 6 different points of interest (x, y) on the measurement area 2, the strain in the x-direction of the simple calculated deformation output by the deformation calculation unit 11 and the strain in the x-direction of the points of interest (x, y) on the measurement area 2 obtained by formula (1) are compared. s The method that minimizes the difference determines θ, φ, and x. c y c The six coefficients are z, δz, and z. The strain x in the x-direction is represented by equation (1), which has already determined the six coefficients. s Assuming the apparent deformation is caused by the movement of the camera device 20, the apparent deformation is subtracted from the simple calculated deformation output by the deformation calculation unit 11, thereby obtaining the temporary deformation as a two-dimensional distribution of the displacement of the measurement area 2.

[0047] Regarding the apparent y-direction strain y of the measurement area 2 in the second image obtained from the position of the camera device 20b, relative to the point of interest (x, y) on the measurement area 2 in the first image obtained from the position of the camera device 20a of the measurement area 2. s It is approximately obtained through the following equation (2).

[0048] [Number 2]

[0049]

[0050] strain x in the x-direction s Similarly, if the six coefficients θ, φ, x of equation (2) can be obtained... c y c , z, δz, then the strain caused by the movement of the camera device 20 included in the simple calculated deformation output as the deformation calculation unit 11 can be calculated in reverse. In the viewpoint change removal unit 12, for at least 6 different points of interest (x, y) on the measurement area 2, the simple calculated deformation output as the deformation calculation unit 11 is compared with the strain y in the y direction of the points of interest (x, y) on the measurement area 2 obtained by formula (2). s The method that minimizes the difference determines θ, φ, and x. c y c The six coefficients are z, δz, and δz. The strain y in the y-direction is represented by equation (2), which has already determined the six coefficients. s Assuming the apparent deformation is caused by the movement of the camera device 20, the apparent deformation is subtracted from the simple calculated deformation output by the deformation calculation unit 11, thereby obtaining a temporary deformation that is a two-dimensional distribution of the displacement of the measurement area 2. The temporary deformation obtained by the viewpoint change removal unit 12, which is calculated by the above process and obtained by subtracting the strain in the x-direction and the strain in the y-direction from the simple calculated deformation, is output.

[0051] In the above explanation, when the measurement area 2 is planar, the apparent strain caused by the change of viewpoint is shown. Even if the surface of the structure 1 has a complex shape, if there are planar regions on the surface with small curvature that can be regarded as planes, the planar regions can be set as the measurement area 2, and the apparent strain y in the y direction of the point of interest (x, y) on the measurement area 2 can be obtained by equations (1) and (2). s Therefore, it is possible to calculate the local deformation of the walls of structures with multiple local planes, such as buildings or bridges.

[0052] When the measurement area 2 is not planar, for example, spherical, as a correction term calculated geometrically, a total of four parameters—the radius of the sphere and the three values ​​representing the x, y, and z directions of the sphere's center—are added to equations (1) and (2). This allows the apparent strain of the measurement area 2 due to changes in viewpoint to be represented. When the measurement area 2 is cylindrical, as a correction term calculated geometrically, the axis parallel to the central axis of the cylinder is designated as the x-axis. A total of four parameters—the radius of the cylinder, the two values ​​representing the y and z directions of the central axis of the cylinder, and the x-axis representing the direction in which the central axis of the cylinder extends—are added to equations (1) and (2). This allows the apparent strain of the measurement area 2 due to changes in viewpoint to be represented. According to this method, the deformation of structures with circular shapes, such as pipes or tanks, can be calculated.

[0053] Even when the measurement area 2 is not a plane, sphere, or cylinder, the deformation of structures of various shapes can be calculated by adding correction terms corresponding to the shape of the measurement area 2 to equations (1) and (2). When the measurement area 2 is a plane, fewer parameters are required to calculate the apparent strain caused by the change of viewpoint compared to when the measurement area 2 is not a plane, so the calculation in the viewpoint change removal unit 12 can be performed in a shorter time.

[0054] It may also include a distance measuring device that measures the relative position change between the camera device 20 and the measurement area 2 during the first and second photography periods. The apparent strain is further calculated in the viewpoint change removal unit 12 using the information on the relative position change output by the distance measuring device. Examples of distance measuring devices include ultrasonic gap sensors, laser displacement gauges, and contact displacement gauges. The relative position change output by the distance measuring device is, for example, the change in distance from the camera device 20 to the surface of the measurement area 2 when viewing the measurement area 2 from the camera device 20 in a predetermined direction. When the distance measuring device measures the relative position change in one direction from the camera device 20 to the measurement area 2, the coefficients z and δz in equations (1) and (2) can be calculated in the viewpoint change removal unit 12 based on the information on the relative position change output by the distance measuring device. When the distance measuring device measures the relative position change from the camera device 20 to the measurement area 2 in three or more different directions, or when using three or more distance measuring devices set in different positions, the viewpoint change removal unit 12 can calculate all the coefficients in equations (1) and (2) based on the information of the relative position change. According to this method, by measuring the relative position change between the camera device 20 and the measurement area 2 independently of the image with the measured deformation, the coefficients of equations (1) and (2) are not affected by the deformation error obtained by the image correlation method, thus improving the measurement accuracy.

[0055] The device may also include a posture measuring device. When the structure 1 remains stationary, this device measures the posture changes of the camera device 20 during the first and second imaging periods. The apparent strain is then calculated in the viewpoint change removal unit 12 using the posture change information output by the posture measuring device. The posture measuring device may be, for example, a gyroscope sensor or a motion tracking device. The coefficients θ and φ in equations (1) and (2) can be determined based on the posture change information output by the posture measuring device. Alternatively, a motion tracking device may also be included to measure the position and rotation changes of the camera device 20 during the first and second imaging periods. The apparent strain is then calculated in the viewpoint change removal unit 12 using the position and rotation change information output by the motion tracking device. All coefficients in equations (1) and (2) can be determined based on the position and rotation change information output by the motion tracking device. According to this method, since the relative position information between the camera device 20 and the measurement area 2 is not used, the apparent strain caused by the viewpoint change can be calculated even when the measurement area 2 undergoes significant deformation, enabling high-precision measurement of deformation.

[0056] In the deformation calculation unit 11, one image is selected from the first image group and set as the first image, and one image is selected from the second image group and set as the second image. However, by sequentially changing the first image selected from the first image group and the second image selected from the second image group, the deformation calculation unit 11 and the viewpoint change removal unit 12 process all combinations of images contained in the first image group and images contained in the second image group. That is, when there are m images in the first image group and n images in the second image group, m*n choices are made as combinations of the first image and the second image, and the deformation calculation unit 11 and the viewpoint change removal unit 12 process each combination of images to obtain m*n temporary deformations.

[0057] Furthermore, the deformation calculation unit 11 outputs a first image and a second image used in calculating simple deformation, and the viewpoint change removal unit 12 receives the first image and the second image from the deformation calculation unit 11. However, the deformation calculation unit 11 may only output simple deformation calculation, and the viewpoint change removal unit 12 may receive the first image and the second image from the imaging device 20. Alternatively, the data of the first image group and the second image group, which are outputs of the imaging device 20, may be stored in a storage unit inside the deformation calculation device 10, and the deformation calculation unit 11 and the viewpoint change removal unit 12 may read the data of the first image and the second image from this storage unit. The storage unit may be implemented, for example, by a memory. The memory may be, for example, a semiconductor memory, a disk, etc.

[0058] Furthermore, assuming there are m images in the first image group and n images in the second image group, m*n combinations of the first and second images are selected, and the deformation calculation unit 11 and the viewpoint change removal unit 12 process each combination of images. However, it is also possible to: select m*n combinations of the first and second images, process all of them with the deformation calculation unit 11, store the results in the internal storage of the deformation calculation device 10, and then process the viewpoint change removal unit 12 for the m*n combinations of the first and second images.

[0059] The temporary deformation output by the viewpoint change removal unit 12 contains random errors in the deformation of the measurement area 2. The removal of these random errors in the temporary deformation output by the viewpoint change removal unit 12 is performed by averaging multiple temporary deformations. The synthesis unit 13 averages the m*n temporary deformations obtained through the above process to remove random errors and outputs the deformation of the measurement area 2. For example, the averaging process involves fixing a point (x, y) on the measurement area and averaging the values ​​of the m*n temporary deformations. In the individual temporary deformations calculated using the i-th image obtained during the first photography period and the j-th image obtained during the second photography period, the displacement at the point (x, y) on the measurement area is set to (u...). x (i, j, x, y), u y When (i, j, x, y) is used, the displacement (U) at point (x, y) on the averaged measurement area is expressed by the following equation (3). x (x, y), U y (x, y)).

[0060] [Number 3]

[0061]

[0062] Similarly, the strain at point (x, y) in the measurement area is set as (ε). x (i, j, x, y), ε y When (i, j, x, y) is used, the strain (E) at point (x, y) on the averaged measurement area is expressed by the following equation (4). x (x, y), E y (x, y)).

[0063] [Number 4]

[0064]

[0065] The integration unit 13 can also average the selected temporary deformations from the m*n temporary deformations obtained through the above processing and output them as the deformation of the measurement region 2. For example, by selecting a portion of the m*n temporary deformations according to predetermined conditions, the integration unit 13 can improve the accuracy of the output deformation of the measurement region 2. As a predetermined condition, for example, if the random error contained in the temporary deformation is sufficiently greater than the actual deformation of the measurement region 2 of the subject, a temporary deformation with a smaller deformation of the measurement region 2 can be selected. For example, in situations such as... Figure 3 When the defect 4 generated in the structure 1 shown is generated near the surface opposite to the measurement area 2, the deformation generated in the measurement area 2 due to the defect 4 is limited to the part of the measurement area 2 close to the defect 4. In the part of the measurement area 2 far from the defect 4, the displacement is uniformly almost zero. Therefore, it is considered that the proportion of random error in the temporary deformation is large from the perspective of the measurement area 2 as a whole. Therefore, temporary deformations with small variance of strain in the overall measurement area 2 can be judged to have small random error. Therefore, in the integration unit 13, for example, only temporary deformations with variance of strain in the overall measurement area 2 less than a predetermined threshold are averaged and output as the deformation of the measurement area 2. Through the above processing, in the integration unit 13, the deformation obtained by averaging multiple temporary deformations selected according to predetermined conditions is output as the deformation of the measurement area 2 between the first and second imaging periods.

[0066] In addition, the integration unit 13 can also calculate and output the displacement distribution of the measurement region 2 by spatially integrating the deformation of the measurement region 2 between the first and second photography periods in the x and y directions.

[0067] Next, a flowchart will be used to illustrate the details of the processing of the deformation calculation device 10. Figure 6 This is a flowchart illustrating the processes performed by the deformation calculation device 10. Steps S11 and S12 are processes performed during the imaging stage, and steps S13 to S18 are processes performed during the deformation calculation stage. Steps S11 and S12 are performed by the imaging device 20, steps S13, S14, and S16 are performed by the deformation calculation unit 11, step S15 is performed by the viewpoint change removal unit 12, and steps S17 to S19 are performed by the integration unit 13. Steps S11 and S12 are imaging steps, steps S13 and S14 are deformation calculation steps, step S15 is a viewpoint change removal step, and steps S17 to S19 are integration steps.

[0068] In step S11, the camera device 20 changes its relative position to the measurement area 2 during the first imaging period to take multiple photographs, creating a first image group composed of multiple images, and then proceeds to step S12. In step S12, the camera device 20 changes its relative position to the measurement area 2 during the second imaging period to take multiple photographs, creating a second image group composed of multiple images, and then proceeds to step S13.

[0069] In step S13, the deformation calculation unit 11 selects one image from the first image group as the first image and selects one image from the second image group as the second image, and proceeds to step S14. In step S14, the deformation calculation unit 11 uses the first image and the second image and calculates the two-dimensional distribution of displacement and strain in the measurement area 2 using digital image correlation as the simple deformation calculation, and proceeds to step S15. In step S15, the viewpoint change removal unit 12 calculates the temporary deformation as the two-dimensional distribution of displacement and strain in the measurement area 2 based on the simple deformation calculation, the first image, and the second image, and proceeds to step S16. In step S16, it is checked whether the temporary deformation has been calculated for all combinations of the first and second images. If the temporary deformation has not been calculated for all combinations, the process returns to step S13; if the temporary deformation has been calculated for all combinations, the process proceeds to step S17.

[0070] In step S17, the integration unit 13 selects temporary deformations where the variance of the overall strain of the measurement region 2 is less than a predetermined threshold, and proceeds to step S18. In step S18, the integration unit 13 averages the temporary deformations selected in step S17 to calculate the deformation of the measurement region 2, and proceeds to step S19. In step S19, the integration unit 13 outputs the deformation of the measurement region 2 calculated in step S18, and the process ends.

[0071] As described above, the deformation calculation apparatus 10 based on Embodiment 1 includes: a deformation calculation unit 11, which uses a first image selected from a first image group obtained by photographing the measurement area 2 from different relative positions during a first photography period and a second image selected from a second image group obtained by photographing the measurement area 2 from different relative positions during a second photography period different from the first photography period, and calculates the simple calculated deformation of the measurement area 2 using digital image correlation; a viewpoint change removal unit 12, which subtracts the apparent strain calculated by assuming no deformation in the measurement area 2 from the simple calculated deformation to obtain a temporary deformation; and a synthesis unit 13, which outputs the deformation obtained by averaging the temporary deformation calculated by the deformation calculation unit 11 and the viewpoint change removal unit 12 by sequentially reselecting the first image selected from the first image group and the second image selected from the second image group, as the deformation of the measurement area 2 from the first photography period to the second photography period. Therefore, even in the absence of a stationary reference point, deformation can be calculated by correcting the positional change of the measurement object with a single camera.

[0072] Implementation method 2.

[0073] Figure 7 This is a diagram showing the structure of the deformation calculation device 10a based on embodiment 2. Figure 7 The deformation calculation device 10a based on embodiment 2 shown is... Figure 1 Compared to the deformation calculation device 10 based on Embodiment 1, the integration unit 13 is replaced by the integration unit 13a. The deformation measurement device 100a based on Embodiment 2 includes the deformation calculation device 10a and the camera device 20.

[0074] In the deformation calculation device 10a based on Embodiment 2, the out-of-plane displacement in the measurement region 2 of the structure 1 is calculated. Regarding the subject whose shape change is measured by the deformation calculation device 10a based on Embodiment 2, it is assumed that... Figure 8 The structure 1 shown is subjected to a uniform bending moment 6. In the deformation calculation device 10a, the curvature change of the measurement area 2 is calculated when the bending moment 6 applied to the structure 1 varies between the first and second photography periods. Figure 9 This is a diagram showing the situation in measurement area 2 when the first image was captured during the first photography period. Figure 10 This is a diagram showing the situation in measurement area 2 when the second image was taken during the second photography session. (Example) Figure 9 and Figure 10 As shown, the flat measurement area 2 during the first imaging period deforms downward along the y-axis during the second imaging period due to the change in bending moment 6. Under such deformation, the strain of the measurement area 2 during the second imaging period, based on the measurement area 2 during the first imaging period, becomes constant regardless of the location. Furthermore, in Figure 10 In the measurement area 2, the out-of-plane displacement is the largest at the center and the smallest at the periphery. Under such circumstances, the deformation calculation device 10a calculates the out-of-plane displacement with different values ​​at each position of the measurement area 2, thereby enabling the calculation of the deformation caused by the bending moment 6 applied to the structure 1.

[0075] exist Figure 9 In the image, there is a photographic plane 7c parallel to the measurement area 2, which includes the position of the imaging device 20c when the first image is captured, and a point (x) on the measurement area 2. d y d The distance z is d .like Figure 10 As shown, the photographic plane 7d, which is located at the position of the camera device 20d when the second image is captured and is parallel to the measurement area 2, and the point (x) on the measurement area 2. d y d The distance increases to z. d +δz d At time, point (x) d y d The apparent reduction is observed to be negative strain, expressed by the following equation (5), regardless of direction.

[0076] [Number 5]

[0077]

[0078] Here, δz d Because of from Figure 9 The position of the camera device 20c changes as follows Figure 10 The change in distance δz between the measurement area 2 and the camera device 20 caused by the position of the camera device 20d. d1 and the out-of-plane displacement δz within the measurement area d2 It is formed by adding these two components. Among them, δz d1 δz is a fixed value independent of the location within the measurement area. d2 This is a value that varies depending on each location within the measurement area. In Implementation 2, δz is calculated... d2 The curvature change of the measurement area 2 is calculated, and the deformation caused by the bending moment 6 applied to the structure 1 is calculated.

[0079] In the deformation calculation device 10a based on Embodiment 2, the processing in the camera device 20, the deformation calculation unit 11, and the viewpoint change removal unit 12 is the same as that in the deformation calculation device 10 based on Embodiment 1. In the integration unit 13a, the same processing as that in the integration unit 13 of the deformation calculation device 10 based on Embodiment 1 is first performed. The deformation value of the measurement region 2 obtained at this time is the distribution of strain in two orthogonal directions on the surface of the measurement region 2, which is an apparent magnification or reduction caused by the out-of-plane displacement of the measurement region 2. In the integration unit 13a, the average value of the strain in one of the two directions, or the average value of the strain in both directions, is compared with the value of Equation (5), and δz is removed. d The component in the measurement area is a fixed value, and the out-of-plane displacement δz of measurement area 2 is calculated from this component. d2 .

[0080] As described above, the deformation calculation device 10a based on Embodiment 2 is a deformation calculation device 10a that calculates the deformation of the measurement area 2 of the structure 1 to which a uniform bending moment 6 is applied. The integration unit 13a calculates the average value of the strain of deformation in one direction on the surface of the measurement area 2, or the average value of the strain of deformation in two orthogonal directions on the surface of the measurement area 2. The component that is a fixed value in the measurement area 2 is removed from the calculated average value, thereby calculating the local out-of-plane displacement of the measurement area 2. Therefore, even in the absence of a non-moving reference point, the out-of-plane displacement can be calculated by using a camera to correct for the positional change of the measured object.

[0081] Implementation method 3.

[0082] Figure 11 This is a diagram showing the structure of the deformation calculation device 10b based on embodiment 3. Figure 11 The deformation calculation device 10b based on embodiment 3 shown is... Figure 1 Compared to the deformation calculation device 10 based on Embodiment 1, the integration unit 13 is replaced by the integration unit 13b. The deformation measurement device 100b based on Embodiment 3 includes the deformation calculation device 10b and the camera device 20.

[0083] In the deformation calculation device 10b based on embodiment 3, the strain and displacement of the measurement region 2 are calculated when the Poisson's ratio of the structure 1 subjected to uniaxial tensile or compressive load is known. Even when the measurement region 2 deforms uniformly, the displacement δz caused by the change in distance between the measurement region 2 and the imaging device 20 is estimated in the deformation calculation device 10b. s Calculate the uniform strain produced on the surface of the measurement area 2 due to uniaxial tensile or compressive load.

[0084] Regarding the subject whose shape change is measured by the deformation calculation device 10b based on embodiment 3, assuming as follows: Figure 12 The structure 1 shown is subjected to a uniaxial tensile or compressive load 8. The direction of the load 8 is parallel to the y-axis, and the strain distribution in the x and y directions is calculated in the deformation calculation device 10b.

[0085] In the deformation calculation device 10b based on Embodiment 3, the processing in the imaging device 20, the deformation calculation unit 11, and the viewpoint change removal unit 12 is the same as that in the deformation calculation device 10 based on Embodiment 1. In the integration unit 13b, the same processing as that in the integration unit 13 of the deformation calculation device 10 based on Embodiment 1 is first performed. The strain in the y-direction, which is the direction of the load 8, in the deformation value of the measurement area 2 obtained at this time is set as the first strain E. y In measurement region 2, the first strain E will be... y The strain in the x-direction, which is orthogonal to the direction of the second strain, is defined as E. x At that time, the true strain (ε) generated in measurement region 2 was used. x , ε y and out-of-plane displacement δz s E can be expressed by the following equations (6) and (7) (E) x E y In addition, z d It is the distance between a point on the measurement area 2 and the photographic plane that includes the position of the camera device 20 when the first image is captured and is parallel to the measurement area 2.

[0086] [Number 6]

[0087]

[0088] [Number 7]

[0089]

[0090] Here, regarding ε x With ε y The relationship is expressed using Poisson's ratio γ by the following equation (8).

[0091] [Number 8]

[0092]

[0093] Based on the above, the following equations (9) and (10) express the (E) calculated by the deformation calculation device 10b. x E y ) and the true strain (ε) caused by load 8 x , ε y The relationship between ).

[0094] [Number 9]

[0095]

[0096] [Number 10]

[0097]

[0098] In the integrated section 13b, the true strain (ε) generated in the measurement region 2 due to the load 8 is calculated according to equations (9) and (10). x , ε y ), and output it.

[0099] As described above, the deformation calculation device 10b based on Embodiment 3 is a deformation calculation device 10b that calculates the deformation of the measurement region 2 of a structure 1 subjected to a uniaxial tensile or compressive load 8 with a known Poisson's ratio. The integration unit 13b calculates a first strain as the strain in the direction of the load 8 and a second strain as the strain in the measurement region 2 in the direction orthogonal to the first strain, and uses these as the deformation of the measurement region 2. Based on the deformation of the measurement region 2 and the Poisson's ratio, the true strain generated in the measurement region 2 is calculated. Therefore, even in the absence of a stationary reference point, the true strain of the measurement region 2 of the structure 1 with a known Poisson's ratio can be calculated by correcting the positional changes of the measured object with a single camera.

[0100] Figure 13 This is a schematic diagram illustrating an example of the hardware of the warp computing devices 10, 10a, and 10b based on Embodiments 1, 2, and 3. The warp computing unit 11, the viewpoint change removal unit 12, and the integration units 13, 13a, and 13b are implemented by a processor 201, such as a CPU or system LSI, that executes programs stored in the memory 202. Alternatively, multiple processing circuits can jointly execute the above functions. Furthermore, the above functions can also be implemented using dedicated hardware. When implementing the above functions using dedicated hardware, the dedicated hardware may be, for example, a single circuit, a composite circuit, a programmable processor, an ASIC, an FPGA, or hardware combining these. The above functions can also be implemented through a combination of dedicated hardware and software, or a combination of dedicated hardware and firmware. When the warp computing devices 10, 10a, and 10b have an internal storage unit, the storage unit is implemented by the memory 202. The camera device 20, the processor 201, and the memory 202 are interconnected via a bus.

[0101] Implementation method 4.

[0102] Figure 14This is a diagram illustrating the structure of the deformation measuring device based on Embodiment 4. The deformation measuring device based on Embodiment 4 mounts an imaging device 20 to a moving device 300, for example, having wheels 301, and performs imaging of the measurement area 2 while moving the imaging device 20. The moving unit of the moving device 300 is not limited to wheels 301, but may also be, for example, a caterpillar. Using a... Figure 14 The image acquired by the camera device 20 is used to calculate the deformation of the measurement area 2 using the methods shown in Embodiments 1 to 3.

[0103] It can also be set to Figure 13 The illustrated structure includes a memory 202 and a processor 201 mounted on a mobile device 300, and the deformation is calculated by the mobile device 300. Alternatively, hardware with a memory 202 and a processor 201 can be prepared independently of the mobile device 300, and the deformation can be calculated based on an image transmitted from the mobile device 300.

[0104] According to the deformation measuring device based on Embodiment 4, by using a small moving device 300, it is possible to enter narrow areas that are difficult to measure manually to measure the deformation of the measurement area 2. Furthermore, since it is not necessary to accurately position the moving device 300 during measurement, images for deformation measurement can be acquired in a short time.

[0105] Implementation method 5.

[0106] The deformation calculation device based on Embodiment 5 calculates the deformation of the measurement region 2 of the structure 1 undergoing vibration or rotational motion, using data from a first image group and a second image group obtained by photographing the measurement region 2 with a fixed camera device 20. Even when the camera device 20 is fixed, it is possible to obtain the first image group and the second image group obtained by photographing with different relative positions of the camera device 20 to the measurement region 2. Deformation can be calculated without moving the camera device 20 or stopping the movement of the structure 1, thus simplifying the measuring equipment and the measurement process.

[0107] This application describes various exemplary embodiments, but the various features, methods and functions described in one or more embodiments are not limited to the application of a particular embodiment and can be applied to the embodiment alone or in various combinations.

[0108] Therefore, numerous variations not illustrated are conceivable within the scope of the technology disclosed in this application. These include variations of at least one structural element, additions, omissions, and extraction of at least one structural element combined with structural elements from other embodiments.

Claims

1. A deformation calculation device, comprising: The deformation calculation unit uses a first image selected from a first image group and a second image selected from a second image group to calculate the simple deformation of the measurement area using digital image correlation. The first image set was obtained by photographing the measurement area from different relative positions during a first photography period, and the second image set was obtained by photographing the measurement area from different relative positions during a second photography period, different from the first photography period; The viewpoint change removal unit calculates the temporary deformation by subtracting the apparent strain calculated under the assumption that there is no deformation in the measurement area from the simple calculated deformation. as well as The synthesis unit, as the deformation of the measurement area from the first photography period to the second photography period, outputs the deformation obtained by averaging the temporary deformation calculated by the deformation calculation unit and the viewpoint change removal unit, which is obtained by sequentially selecting the first image from the first image group and the second image from the second image group.

2. The deformation calculation device according to claim 1, characterized in that, The output of the synthesis unit is only the deformation obtained by averaging the temporary deformation in which the variance of the overall strain of the measurement area is less than a predetermined threshold, obtained by sequentially reselecting the first image from the first image group and the second image from the second image group, and applying the deformation calculation unit and the viewpoint change removal unit to all combinations of the first image and the second image.

3. The deformation calculation device according to claim 1, characterized in that, The deformation calculation device is a device for calculating the deformation of the measurement area of ​​a structure to which a uniform bending moment has been applied. The integration unit calculates the average value of the strain of the deformation in one direction on the surface of the measurement area, or the average value of the strain of the deformation in two orthogonal directions on the surface of the measurement area, and calculates the local out-of-plane displacement of the measurement area by removing the component that becomes a fixed value in the measurement area from the calculated average value.

4. The deformation calculation device according to any one of claims 1 to 3, characterized in that, The deformation calculation device is a deformation calculation device that calculates the deformation of a structure that has locally flat regions on its surface. The flat area is designated as the measurement area. The viewpoint change removal unit sets the measurement area as a plane to calculate the temporary deformation.

5. The deformation calculation device according to claim 1, characterized in that, The deformation calculation device is a device for calculating the deformation of the measured region of a structure with a known Poisson's ratio and subjected to a uniaxial tensile or compressive load. The synthesis unit calculates a first strain as the strain in the direction of the load and a second strain as the strain in the measurement region in a direction orthogonal to the first strain, and uses this as the deformation of the measurement region. The synthesis unit calculates the true strain generated in the measurement area based on the deformation and Poisson's ratio of the measurement area.

6. The deformation calculation device according to any one of claims 1 to 3, characterized in that, The first image group is defined as a collection of images obtained by extracting multiple still images from the moving images obtained by photographing the measurement area during the first photography period, and the second image group is defined as a collection of images obtained by extracting multiple still images from the moving images obtained by photographing the measurement area during the second photography period.

7. The deformation calculation device according to any one of claims 1 to 3, characterized in that, The deformation calculation device is a device for calculating the deformation of the measurement area of ​​a structure undergoing vibration or rotation. The deformation is calculated using the first image group and the second image group obtained by photographing the measurement area using a fixed camera device.

8. A deformation measuring device, comprising: The deformation calculation device according to any one of claims 1 to 5; and A camera device captures images of the first image group and the second image group.

9. A deformation measuring device, comprising: The deformation calculation device according to any one of claims 1 to 5; The camera device captures images of the first image group and the second image group; and A moving device that moves the camera device.

10. A deformation measuring device, comprising: The camera device takes pictures of the measurement area from different relative positions during a first photography period to output a first image group, and takes pictures of the measurement area from different relative positions during a second photography period different from the first photography period to output a second image group. A distance measuring device for measuring the relative positional change of the camera device with respect to at least one direction of the measurement area during the first and second photography periods; The deformation calculation unit uses a first image selected from the first image group and a second image selected from the second image group to calculate the simple calculated deformation of the measurement area using digital image correlation. The viewpoint change removal unit uses the information about the relative position change to subtract the apparent strain calculated by subtracting the apparent strain calculated by assuming no deformation in the measurement area from the simply calculated deformation to obtain the temporary deformation; as well as The synthesis unit, as the deformation of the measurement area from the first photography period to the second photography period, outputs the deformation obtained by averaging the temporary deformation calculated by the deformation calculation unit and the viewpoint change removal unit, which is obtained by sequentially selecting the first image from the first image group and the second image from the second image group.

11. A deformation measuring device, comprising: The camera device takes pictures of the measurement area from different relative positions during a first photography period to output a first image group, and takes pictures of the measurement area from different relative positions during a second photography period different from the first photography period to output a second image group. A posture measuring device for measuring changes in the posture of the camera device during the first and second photography periods; The deformation calculation unit uses a first image selected from the first image group and a second image selected from the second image group to calculate the simple calculated deformation of the measurement area using digital image correlation. The viewpoint change removal unit uses the information about the posture change to subtract the apparent strain calculated by subtracting the apparent strain calculated by assuming no deformation in the measurement area from the simple calculated deformation to obtain the temporary deformation; as well as The synthesis unit, as the deformation of the measurement area from the first photography period to the second photography period, outputs the deformation obtained by averaging the temporary deformation calculated by the deformation calculation unit and the viewpoint change removal unit, which is obtained by sequentially selecting the first image from the first image group and the second image from the second image group.

12. A deformation calculation method, comprising: The deformation calculation step uses a first image selected from a first image group and a second image selected from a second image group to calculate the simple deformation of the measurement area using digital image correlation. The first image group is obtained by taking pictures of the measurement area from different relative positions during a first photography period, and the second image group is obtained by taking pictures of the measurement area from different relative positions during a second photography period different from the first photography period. The viewpoint change removal step involves subtracting the apparent strain, calculated assuming no deformation in the measurement area, from the simply calculated deformation to obtain the temporary deformation; and The synthesis step, as the deformation of the measurement area from the first photography period to the second photography period, outputs the deformation obtained by averaging the temporary deformation obtained by sequentially selecting a first image from a first image group and a second image from a second image group, and applying the deformation calculation step and the viewpoint change removal step.

Images