JP2016176806A - State determination device, state determination system and state determination method for structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize precise detection in a remote and non-contact manner while discriminating a defect such as a crack, detachment, an internal cavity in a structure from one another.SOLUTION: A state determination device according to the invention includes: a displacement calculation part that uses time-series imagery of a structure surface before and after load application to calculate a two-dimentional space distribution of displacement in the time-series imagery; a correction quantity calculation part that calculates a correction quantity on the basis of displacement in a normal direction of the structure surface due to the load application, which is measured from an imaging direction of the time-series imagery; a displacement correction part that subtracts the correction quantity from the two-dimentional space distribution of displacement in the time-series imagery to extract the two-dimensional space distribution of displacement of the structure surface; and an abnormality determination part that specifies a defect in the structure on the basis of comparison between the two-dimensional space distribution of displacement of the structure surface and a preset space distribution of displacement.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a technique for remotely determining a state such as a defect occurring in a structure.

  In concrete structures such as tunnels and bridges, it is known that defects such as cracks, delamination and internal cavities generated on the surface of the structure affect the soundness of the structure. Therefore, in order to accurately determine the soundness of the structure, it is necessary to accurately detect these defects.

  Detection of defects such as cracks, delamination, and internal cavities of structures has been performed by visual inspection or hammering inspection by an inspector, and the inspector needs to approach the structure for inspection. For this reason, there are problems such as an increase in work cost by preparing an environment where work can be performed in the air and loss of economic opportunities by regulating traffic for setting the work environment. A remote inspection method is desired.

  There is a method based on image measurement as a method for determining the state of a structure from a remote location. For example, a technique has been proposed in which an image obtained by imaging a structure with an imaging device is binarized with a predetermined threshold, and an image portion corresponding to a crack is detected from the binarized image (patent) Reference 1). Moreover, the technique which detects the crack which has arisen in the structure from the stress state of a structure is proposed (patent document 2, patent document 3). Also, a system (Patent Document 4) that uses both an infrared imaging device or a visible light imaging device and a laser imaging device to automatically analyze a captured image to determine a defect of a measurement object, and has excellent portability There has been proposed a method (Patent Document 5) for creating a defect map from an image captured by an image capturing means. Furthermore, Non-Patent Document 1 discloses a method for improving the detection accuracy of cracks by detecting the movement of a crack region from a moving image on the surface of a structure.

JP 2003-035528 A JP 2008-232998 A JP 2006-343160 A JP 2004-347585 A JP 2002-236100 A JP 2012-132786 A

Z. Wang, et al. , “Crac-opening displacement estimation method based on sequence of motion vector field images for civic instructoration inspiration inspection”, 14 Media I / Symposium.

  However, in the above technique, for example, when imaging the lower surface of a structure such as a bridge, the structure is deflected by a load, so that the displacement of the surface to be imaged moves in the normal direction of the surface (out-of-plane Displacement) is added to the displacement in the in-plane direction of the surface having information on the defect of the structure (referred to as in-plane displacement). For this reason, there existed a problem that the precision at the time of detecting the defect of a structure fell.

  Patent Document 6 proposes a method of correcting an out-of-plane displacement amount from a displacement of a captured image in a method of measuring distortion generated on the surface of a measurement object. In Patent Document 6, the amount of out-of-plane displacement is read from side images before and after deformation of the structure. For this purpose, two video devices are provided, a first video device that images the surface of the structure and a second video device that images the side surface.

  However, in this method, in order to photograph the side surface, another image device is required in addition to the image device photographing the surface, and there is a problem of an increase in cost. Furthermore, in the case of a bridge, for example, for measuring the side of the bridge, it is necessary to fix the imaging device or to secure a scaffold for the worker, so the workability is poor and the measurement accuracy decreases. There is.

  The present invention has been made in view of the above problems, and its purpose is to separate out-of-plane displacement due to movement in the normal direction of the structure surface from displacement due to load on the image of the structure surface with good workability. Thus, the in-plane displacement of the structure surface can be extracted. Accordingly, it is possible to accurately detect a defect such as a crack or peeling of a structure or a defect such as an internal cavity from a remote location without contact.

  The state determination apparatus according to the present invention measures from a time-series image before and after applying a load on the surface of a structure, a displacement calculation unit that calculates a two-dimensional spatial distribution of the displacement of the time-series image, and measurement from the imaging direction of the time-series image. A correction amount calculation unit that calculates a correction amount based on the amount of movement of the surface of the structure in the normal direction due to the load application, and subtracts the correction amount from a two-dimensional spatial distribution of displacement of the time-series image, Based on a comparison between the displacement correction unit that extracts the two-dimensional spatial distribution of the displacement of the structure surface, the two-dimensional spatial distribution of the displacement of the structure surface, and the spatial distribution of the displacement provided in advance, An abnormality determination unit that identifies a defect.

  The state determination system according to the present invention includes a displacement calculation unit that calculates a two-dimensional spatial distribution of displacement of the time-series image from time-series images before and after applying a load on the surface of the structure, and a normal of the structure surface by applying the load. A correction amount calculation unit that calculates a correction amount based on a moving amount of a direction, and subtracts the correction amount from a two-dimensional spatial distribution of the displacement of the time-series image to extract a two-dimensional spatial distribution of the displacement of the structure surface. A state determination apparatus comprising: a displacement correction unit; and an abnormality determination unit that identifies a defect of the structure based on a comparison between a two-dimensional spatial distribution of displacement of the surface of the structure and a spatial distribution of displacement provided in advance. An imaging unit that captures the time-series image and provides it to the state determination device; and a distance measurement unit that measures the amount of movement from the imaging direction of the time-series image and provides the state determination device.

  The state determination method according to the present invention calculates the two-dimensional spatial distribution of the displacement of the time series image from the time series images before and after applying the load on the surface of the structure, and measures the load application measured from the imaging direction of the time series image. A correction amount based on the amount of movement of the structure surface in the normal direction is calculated, and the correction amount is subtracted from the two-dimensional space distribution of the displacement of the time-series image to obtain a two-dimensional space of the displacement of the structure surface The distribution is extracted, and the defect of the structure is specified based on the comparison between the two-dimensional spatial distribution of the displacement of the structure surface and the spatial distribution of the displacement provided in advance.

  According to the present invention, the in-plane displacement of the structure surface can be extracted by separating out-of-plane displacement due to movement of the structure surface in the normal direction from the displacement due to the load on the image of the structure surface with good workability. become. As a result, it is possible to accurately perform remote and non-contact detection that distinguishes defects such as cracks and peeling of structures and internal cavities.

It is a block diagram which shows the structure of the state determination apparatus of embodiment of this invention. It is a block diagram which shows the specific structure of the state determination apparatus of embodiment of this invention. It is a block diagram which shows the structure of the state determination system of embodiment of this invention. It is a figure for demonstrating the relationship between the state (when healthy) of a structure, and the displacement of a surface. It is a figure for demonstrating the relationship between the state (in the case of a crack) of a structure, and the displacement of a surface. It is a figure for demonstrating the relationship between the state (in the case of peeling) of a structure, and the displacement of a surface. It is a figure for demonstrating the relationship between the state of a structure (in the case of an internal cavity), and the displacement of a surface. It is a figure which shows the result of having calculated the displacement of the surface of the X direction of the structure (in the case of a crack) before and behind a load in the displacement calculation part. It is a figure which shows the result of having calculated the displacement of the surface of the Y direction of the structure (in the case of a crack) before and behind a load by the displacement calculation part. It is a block diagram which shows the structure of the distance measurement part of embodiment of this invention. It is a figure which shows the mode of the movement of the position of the structure part surface of the measuring object of the distance measurement part of embodiment of this invention. It is a figure for demonstrating the calculation method of the correction amount in the correction amount calculation part of embodiment of this invention. It is a figure which shows the result of having calculated the in-plane displacement of the surface of the surface of the X direction of the structure (in the case of a crack) before and behind a load in the displacement correction | amendment part. It is a figure which shows the result of having calculated the in-plane displacement of the surface of the Y direction surface of the structure (in the case of a crack) before and behind a load by the displacement correction | amendment part. It is a figure for demonstrating the calculation method of the correction amount when there exists inclination in the correction amount calculation part of embodiment of this invention. It is the figure which showed distribution of the stress field around a crack. It is the figure which showed distribution of the stress field around a crack. It is a figure which shows the example of the two-dimensional distribution (X direction) of the displacement amount around a crack (when a crack is shallow). It is a figure which shows the example of the two-dimensional distribution (Y direction) of the displacement amount around a crack (when a crack is shallow). It is a figure which shows the example of the two-dimensional distribution (X direction) of the displacement amount around a crack (when a crack is deep). It is a figure which shows the example of the two-dimensional distribution (Y direction) of the displacement amount around a crack (when a crack is deep). It is a figure explaining the pattern matching with the displacement distribution (pattern of the X direction of a displacement) by the abnormality determination part. It is a figure explaining the pattern matching with the displacement distribution (the pattern of the Y direction of a displacement) by the abnormality determination part. It is a figure explaining pattern matching with the displacement distribution (pattern of the differential vector field of a displacement) by an abnormality determination part. It is a perspective view which shows the two-dimensional distribution of the stress of the surface seen from the imaging direction in case an internal cavity exists. It is a top view which shows the two-dimensional distribution of the stress of the surface seen from the imaging direction in case an internal cavity exists. It is a figure which shows the contour line (X component) of the displacement of the surface seen from the imaging direction in case an internal cavity exists. It is a figure which shows the contour line (Y component) of the displacement of the surface seen from the imaging direction in case an internal cavity exists. It is a figure which shows the stress field of the surface seen from the imaging direction in case an internal cavity exists. It is a figure explaining the response at the time of giving an impulse stimulus to a structure in case an internal cavity exists (position ABC which obtains a response is shown). It is a figure explaining the response at the time of giving an impulse stimulus to a structure in case an internal cavity exists (the response in position ABC is shown). It is a figure which shows the contour line (X component) of the displacement of the surface seen from the imaging direction in case peeling exists. It is a figure which shows the contour line (Y component) of the displacement of the surface seen from the imaging direction in case peeling exists. It is a figure which shows the stress field of the surface seen from the imaging direction in case peeling exists. It is a figure explaining the time response of a displacement at the time of giving impulse stimulus to a structure in case exfoliation exists. It is a flowchart which shows the state determination method in the state determination apparatus of embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the preferred embodiments described below are technically preferable for carrying out the present invention, but the scope of the invention is not limited to the following.

  FIG. 1 is a block diagram illustrating a configuration of a state determination device according to an embodiment of the present invention. The state determination apparatus 100 according to the present embodiment includes a displacement calculation unit 101 that calculates a two-dimensional spatial distribution of displacement of the time-series image from time-series images before and after applying a load on the surface of the structure, and an imaging direction of the time-series image. The correction amount is calculated from a correction amount calculation unit 102 that calculates a correction amount based on the amount of movement of the surface of the structure in the normal direction measured by applying the load, and the correction amount is calculated from a two-dimensional spatial distribution of the displacement of the time-series image. Based on the comparison between the displacement correction unit 103 that subtracts and extracts the two-dimensional spatial distribution of the displacement of the structure surface, the two-dimensional spatial distribution of the displacement of the structure surface, and the spatial distribution of the displacement provided in advance. And an abnormality determination unit 104 that identifies a defect of the structure.

  FIG. 2 is a block diagram showing a specific configuration of the state determination apparatus according to the embodiment of the present invention. The state determination device 1 includes a displacement calculation unit 2, a correction amount calculation unit 3, a displacement correction unit 4, a differential displacement calculation unit 5, an abnormality determination unit 6, and an abnormality map creation unit 9. The abnormality determination unit 6 includes a two-dimensional spatial distribution information analysis unit 7 and a time change information analysis unit 8.

  FIG. 3 is a block diagram illustrating a configuration of the state determination system according to the embodiment of this invention. The state determination system 10 includes a state determination device 1, an imaging unit 11, a distance measurement unit 12, and a tilt measurement unit 13. The state determination apparatus 1 is an apparatus shown in FIG. The imaging unit 11 is an imaging camera. In FIG. 3, the structure 15 which is the object to be measured has a beam-like structure supported at two points. Various defects 14 may exist in the structure 15.

  The imaging unit 11 captures the surface of the structure 15 before and after applying a load to the structure 15 as a time-series image on the XY plane. Further, the imaging unit 11 inputs the captured time-series image to the displacement calculation unit 2 of the state determination device 1.

  The distance measuring unit 12 detects a distance (referred to as an imaging distance) between the imaging unit 11 and the surface of the structure 15 captured by the imaging unit 11. Furthermore, the distance measuring unit 12 detects a change in which the imaging distance changes when the surface of the structure 15 moves in the normal direction of the surface, for example, when the structure 15 is bent by applying a load. That is, the distance measuring unit 12 can measure the imaging distance and the amount of change from the same direction as the imaging direction of the video unit 11. The distance measuring unit 12 inputs the imaging distance and the change amount to the correction amount calculating unit 3 as distance information.

  In addition, although the normal line is referred to when the surface is a curved surface, when the surface has a plurality of small curved surfaces and forms a large curved surface as a whole, the normal line for the large curved surface is used here. . Moreover, although it is called a perpendicular for the case where the surface is a plane, in the following description, it will be expressed as a normal line for simplicity.

  The inclination measurement unit 13 detects the inclination angle of the normal of the surface of the structure 15 with respect to the optical axis at the center of the imaging direction of the imaging unit 11, that is, the inclination angle of the structure 15, and sends the inclination information to the correction amount calculation unit 3. Enter as. The tilt measurement unit 13 can acquire tilt information from the same direction as the imaging direction of the video unit 11.

  The displacement calculation unit 2 calculates the displacement for each (X, Y) coordinate on the XY plane of the time series image. That is, the displacement in the frame image at the first time after the load application is calculated using the frame image before the load application imaged by the imaging unit 11 as a reference. Next, the displacement with respect to the image before the load is calculated for each time-series image, such as the displacement of the frame image at the next time after the load is applied and the displacement of the frame image at the next time. The displacement calculation unit 2 can calculate the displacement using image correlation calculation. Further, the displacement calculation unit 2 can also represent the calculated displacement as a displacement distribution diagram having a two-dimensional spatial distribution on the XY plane.

  The correction amount calculation unit 3 uses the distance information from the distance measurement unit 12 and the inclination information from the inclination measurement unit 13 to cause the structure 15 to be included in the displacement calculated by the displacement calculation unit 2 due to the load. The displacement (referred to as out-of-plane displacement) due to the surface of the structure 15 moving in the normal direction of the surface by bending is calculated.

  The displacement correcting unit 4 subtracts the out-of-plane displacement calculated by the correction amount calculating unit 3 from the displacement calculated by the displacement calculating unit 2 or the displacement distribution diagram, thereby generating a displacement (in the surface of the structure 15 ( (Referred to as in-plane displacement). The displacement correction unit 4 inputs the extracted in-plane displacement to the differential displacement calculation unit 5 and the abnormality determination unit 6.

  The differential displacement calculation unit 5 performs spatial differentiation on the displacement or displacement distribution diagram, and calculates a differential displacement distribution diagram in which the differential displacement or the calculated differential displacement is a two-dimensional differential space distribution on the XY plane. The calculation results of the displacement correction unit 4 and the differential displacement calculation unit 5 are input to the abnormality determination unit 6.

  The abnormality determination unit 6 determines the state of the structure 15 based on the input calculation result. That is, the abnormality determination unit 6 determines the location and type of the abnormality (defect 14) of the structure 15 from the analysis results of the two-dimensional spatial distribution information analysis unit 7 and the time change information analysis unit 8. Furthermore, the abnormality determination unit 6 inputs the determined location and type of the abnormality of the structure 15 to the abnormality map creation unit 9. The abnormality map creation unit 9 maps the spatial distribution of the abnormal state of the structure 15 on the XY plane, records it as an abnormality map, and outputs it.

  The state determination device 1 can be an information device such as a PC (Personal Computer) or a server. By using a CPU (Central Processing Unit), which is a computing resource of an information device, and a memory or HDD (Hard Disk Drive), which is a storage resource, the CPU is used to operate a program so that each unit constituting the state determination device 1 is Can be realized.

  4A to 4D are diagrams for explaining the relationship between various abnormal states of the structure 15 and in-plane displacement of the surface. FIG. 4A is a side view of the beam-like structure 15 supported at two points. As shown in FIG. 4A, the imaging unit 11 in FIG. 3 is arranged under the condition of imaging the lower surface of the structure 15 from the imaging direction (Z direction). At this time, if the structure 15 is healthy, as shown in FIG. 4A, compressive stress acts on the upper surface of the structure 15 and tensile stress acts on the lower surface with respect to the vertical load from the upper surface of the structure 15. . Note that the structure 15 does not have to be a beam-like structure that is supported at two points as long as the same stress is applied.

  Here, when the structure 15 is an elastic body, the stress is proportional to the strain. The Young's modulus, which is a proportional constant, depends on the material of the structure. Since the strain proportional to the stress is a displacement per unit length, the strain can be calculated by spatially differentiating the result calculated by the displacement correcting unit 4 with the differential displacement calculating unit 5. That is, the stress field can be obtained from the result of the differential displacement calculation unit 5.

  As shown in FIG. 4B, when a crack exists, the cracked portion is largely displaced by a load. On the other hand, the stress around the cracked portion is not transmitted by the cracked portion, so the tensile stress on the lower surface of the structure 15 is smaller than the healthy state shown in FIG. 4A.

  In addition, as shown in FIG. 4C, when peeling is present, the appearance seen from the lower surface of the structure 15 is observed as the case of cracking. However, in the case of peeling, there is no stress transmission between the peeling part and the upper part thereof. Therefore, the displacement due to the load only translates a certain amount in a certain direction in the peeled portion, and no distortion which is a spatial differential value is generated. Therefore, it is possible to distinguish between cracking and peeling by using strain information obtained by spatially differentiating displacement due to load.

  In addition, as shown in FIG. 4D, when an internal cavity is present, stress transmission is prevented in the internal cavity, so that the stress on the lower surface of the structure 15 is reduced. Therefore, since the distortion calculated from the image is also reduced, it is possible to find an internal cavity that cannot be directly seen from the outside of the structure 15.

  Hereinafter, with reference to FIG. 5A and FIG. 5B, a method for removing the out-of-plane displacement and extracting the in-plane displacement will be described by taking as an example a case where a crack along the Y direction as shown in FIG. 4B exists. FIG. 5A is a diagram illustrating a result of the displacement calculation unit 2 calculating the displacement of the surface in the X direction due to a load when there is a crack in the Y direction of the structure 15 in FIG. 3. FIG. 5B is a diagram illustrating a result of calculating the displacement of the surface in the Y direction by the displacement calculation unit 2 in the same case as FIG. 5A. Here, the imaging distance is 5 m, the structure 15 is concrete having a length of 20 m, a thickness of 0.5 m and a width of 10 m (Young's modulus is 40 GPa), and a doubly supported beam is used under conditions equivalent to those when a load of 10 t is applied. ing.

  In FIG. 5A showing the displacement in the X direction, a displacement of ± 170 μm occurs in the imaging range of ± 200 mm. In FIG. 5B showing the displacement in the Y direction, a displacement of ± 160 μm is linearly generated in the imaging range of ± 200 mm. The displacement in the X direction is a displacement in which an out-of-plane displacement is superimposed on an in-plane displacement. On the other hand, the displacement in the Y direction is a displacement of only out-of-plane displacement.

  FIG. 6A shows the configuration of the distance measuring unit 12. The distance measuring unit 12 measures the distance between the imaging unit 11 and the surface of the structure 15. The distance measuring unit 12 includes a signal generator 121, a transmitter 122, a receiver 123, a time comparator 124, and a distance calculator 125.

  The signal generator 121 generates a pulse signal. The transmitter 122 transmits an ultrasonic wave corresponding to the pulse signal generated by the signal generator 121. The ultrasonic wave transmitted from the transmitter 122 is reflected by the surface of the structure 15 and received by the receiver 123. The time comparator 124 calculates the time from transmission to reception from the time when the transmitter 122 transmits the ultrasonic wave and the time when the receiver 123 receives the ultrasonic wave. This is the time for the ultrasonic wave to reciprocate the distance z between the distance measurement unit 12 and the surface of the structure 15 (corresponding to the distance between the imaging unit 11 and the surface of the structure 15).

  Further, the time comparator 124 calculates the time before and after applying a load to the structure 15, so that the structure 15 is deflected by the load and the surface of the structure 15 moves in the normal direction of the surface. A time difference Δt corresponding to the distance change Δz caused by this is obtained. The distance calculator 125 calculates the distance z from the time from transmission to reception of the ultrasonic wave, and the change Δz of the distance z from the time difference Δt, and inputs it to the correction amount calculation unit 3 of the state determination device 1 as distance information. .

  FIG. 6B is a diagram showing how the surface positions of the distance measurement unit 12 and the structure unit 15 that is a measurement target are moved. The distance between the distance measuring unit 12 and the surface of the structure 15 is output for each time. For example, at time t1, the time from transmission to reception is 29.412 msec. The sound speed was 340 m / sec. And the distance between the imaging unit 11 and the surface of the structure 15 is 5 m. At time t2, the time from transmission to reception is 29.388 msec. The sound speed was 340 m / sec. And the distance is found to be 4.996 m. Here, if the time t1 is the time before the load is applied and the time t2 is the time after the load is applied, the change Δz due to the deflection of the structure 15 or the like is calculated as 4 mm. Note that the time t1 and the time t2 are preferably matched with the timing at which the imaging unit 11 captures time-series images before and after the load. As a result, the accuracy of correction can be increased.

  For example, the signal generator 121 sets the pulse width of the pulse signal to 12.5 μsec. (The band is 4 kHz with the pulse ON / OFF), and the time comparator 124 is 25 nsec., Which is 1/500 of the pulse width of the pulse signal. A distance resolution of 8.5 μm can be obtained by enabling time comparison up to (with a pulse ON / OFF of 2 MHz). The distance measurement unit 12 may use a laser beam or a microwave as well as an ultrasonic wave as long as the same resolution can be obtained. The method of triangulation may be used as a method other than using a time difference. The method used may be used.

  The correction amount calculation unit 3 calculates the out-of-plane displacement δi based on the distance change Δz before and after the load obtained from the distance measurement unit 12. FIG. 7 is a diagram for explaining a correction amount calculation method in the correction amount calculation unit 3. In FIG. 7, the change Δz of the distance corresponds to the deflection of the structure before and after the load, and the change Δz is expressed as the deflection δ. The change Δz is not limited to the amount of deflection, and includes, for example, the case where the position of the surface to be imaged moves in the normal direction of the surface due to the entire structure 15 sinking due to the load. May be.

As shown in FIG. 7, when a deflection (deflection amount δ) occurs in the structure 15 due to a load, the imaging surface of the imaging unit 11 has an in-plane displacement Δx that is a two-dimensional spatial distribution of the displacement of the structure surface. Apart from the corresponding Δxi, an out-of-plane displacement δi due to the deflection amount δ occurs. The out-of-plane displacement δi and the in-plane displacement Δxi are expressed by Equation 1 and Equation 2, respectively, where L is the imaging distance, f is the focal length of the lens, and x is the distance from the imaging center of the structure surface. .
δi = x · f · {1 / (L−δ) −1 / L} (Formula 1)
Δxi = Δx · f / (L−δ) (Formula 2)
Here, when the deflection amount δ before and after the load of the structure 15 is 4 mm, the imaging distance L is 5 m, and the lens focal length f is 50 mm, the imaging is performed when the distance x from the imaging center on the surface of the structure 15 is 200 mm. The out-of-plane displacement δi of the surface is 1.6 μm from Equation 1. On the other hand, when an in-plane displacement Δx of 160 μm is present on the surface of the structure 15, the in-plane displacement Δxi of the imaging surface is 1.6 μm from Equation 2.

  In this manner, the displacement of the time-series image calculated by the displacement calculator 2 and the displacement distribution diagram representing the two-dimensional spatial distribution on the XY plane are superimposed with the out-of-plane displacement δi equivalent to the in-plane displacement Δxi. There may be. The displacement correction unit 4 extracts the in-plane displacement Δxi by subtracting the out-of-plane displacement δi obtained by the correction amount calculation unit 3 from the displacement obtained by the displacement calculation unit 2 as a correction amount.

  The in-plane displacements extracted by subtracting the out-of-plane displacement obtained by the correction amount calculation unit 3 from the displacements calculated by the displacement calculation unit 2 in FIGS. 5A and 5B are shown in FIGS. 8A and 8B, respectively. FIG. 8A is a diagram illustrating a result of the displacement correction unit 4 calculating the in-plane displacement of the surface in the X direction due to a load of a structure having a crack in the Y direction. FIG. 8B is a diagram illustrating a result of calculating in-plane displacement of the surface in the Y direction by a load of a similar structure by the displacement correction unit 4. It can be seen that in the cracked portion, a sudden in-plane displacement of 20 μm that is discontinuous in the X direction occurs. On the other hand, it can be seen that no in-plane displacement occurs in the Y direction.

  As can be seen from FIGS. 5A and 5B and FIGS. 8A and 8B, when it is previously known that in-plane displacement has occurred only in the X direction and not in the Y direction, FIG. 5B is subtracted from FIG. 5A. Thus, the in-plane displacement of FIG. 8A can be obtained.

  FIG. 9 is a diagram for explaining out-of-plane displacement when the structure 15 is inclined in the correction amount calculation method in the correction amount calculation unit 3 according to the embodiment of the present invention. In the correction amount calculation unit 3, an inclination angle θ of the surface normal of the structure 15 with respect to the optical axis at the center of the imaging direction of the imaging unit 11 (that is, the inclination angle of the structure 15) is inclined from the inclination measurement unit 13. Input as information.

As shown in FIG. 9, when the normal of the surface of the structure 15 is rotated by θ about the Y axis, the coordinate with the optical axis of the imaging unit 11 as the z axis and the normal of the surface of the structure are z. The relationship with the coordinate “′” is expressed by Equation 3, Equation 4, and Equation 5.
x ′ = x · cos θ + z · sin θ (Formula 3)
y ′ = y (Formula 4)
z ′ = − x · sin θ + z · cos θ (Formula 5)
Further, the XY coordinates of the imaging surface rotated by θ are mapped by Expressions 6 and 7.
X = x ′ · f / (L−z ′) (Formula 6)
Y = y ′ · f / (L−z ′) (Formula 7)
Therefore, the out-of-plane displacement δxi in the X direction and the surface in the Y direction due to the displacement from the coordinates P1 (x1, y1, z1) to the coordinates P2 (x2, y2, z2) due to the deflection of the structure 15 due to the application of a load. The external displacement δyi is expressed by Expression 8 and Expression 9, respectively (Y component is not shown in FIG. 9).
δxi = x2i−x1i = x2 · f / (Lz2) −x1 · f / (Lz1) (Formula 8)
δyi = y2i−y1i = y2 · f / (Lz2) −y1 · f / (Lz1) (Equation 9)
In FIG. 9, the case where the normal of the surface of the structure 15 is rotated by θ with respect to the optical axis at the center of the imaging direction of the imaging unit 11 with the Y axis as an axis is handled. The correction can be performed in the same way when the axis is used.

  The inclination measuring unit 13 can measure the inclination by detecting the direction of gravity using a capacitance type acceleration sensor based on MEMS (Micro Electro Mechanical Systems) technology. Further, as long as the inclination can be measured, various types of acceleration sensors and various gyro sensors may be used.

  The in-plane displacement of the structure surface that is the output of the displacement correction unit 4 is replaced with the distortion of the structure surface by the differential displacement calculation unit 5. Multiplying the strain on the surface of the structure by the Young's modulus results in stress, and from this, the stress field on the surface of the structure is obtained. The displacement information obtained by the displacement correction unit 4 and the strain information obtained by the differential displacement calculation unit 5 are input to the abnormality determination unit 6.

  The abnormality determination unit 6 is a two-dimensional spatial distribution information analysis unit for specifying the type and location of the defect with respect to the displacement information obtained by the displacement correction unit 4 and the strain information obtained by the differential displacement calculation unit 5. 7 and the time change information analysis unit 8 are previously provided with a threshold value for determining a defect and a characteristic displacement and distortion pattern corresponding to the type of defect. Then, the two-dimensional spatial distribution information analysis unit 7 and the time change information analysis unit 8 are as shown in FIGS. 4A to 4D by comparing displacement information and strain information with the threshold value or by pattern matching with the pattern. Determine the healthy state or defects such as cracks, delamination and internal cavities.

  FIG. 8A shows an example of in-plane displacement of the surface in the X direction of the structure due to a load when a crack along the Y direction exists. It can be seen that a 20 μm discontinuous in-plane displacement occurs in the cracked portion. Such a sudden displacement does not occur in a healthy state with no defects. Therefore, it is possible to detect a crack by confirming a displacement exceeding this by providing a threshold value for the magnitude of discontinuous displacement in advance.

  10A and 10B are diagrams showing the distribution of the stress field around the crack portion calculated by the differential displacement calculation unit 5 when there is a crack along the Y direction. As shown in FIG. 10A, since the stress direction is bent by cracking, even when tensile stress is applied to both ends of the structure in the X direction in FIG. 10A, the stress direction near the crack is Y direction as shown in FIG. 10B. The components are generated. Therefore, cracks can also be detected by detecting the presence or absence of the component in the Y direction. In addition, since the distribution of the stress field around the crack is known as a stress intensity factor in an elastic body showing a linear response, the information can also be used.

  11A to 11D show examples of the two-dimensional displacement distribution of the displacement amount around the crack. 11A and 11B are displacement contour lines in the horizontal direction (X direction) in FIG. 4B and in the direction perpendicular to the paper surface in FIG. 4B (Y direction), respectively. As shown in FIG. 11A, with respect to the X direction, the density of the displacement contour lines is sparser around the crack than in the area where there is no crack. This corresponds to the portion of the gentle displacement on the outside of the sudden displacement at the crack portion shown in FIG. 8A. The displacement at this portion is gentler than the displacement when there is no crack.

  In addition, as shown in FIG. 11B, a component in the Y direction of displacement is generated around the cracked portion with respect to the Y direction. This corresponds to the Y-direction component of the stress field (strain) shown in FIG. 10B.

  11C and 11D show cases where the cracks are deeper than those in FIGS. 11A and 11B, respectively. In this case, the density of the displacement contour lines becomes sparser around the crack in each of the X direction and the Y direction. It is also possible to know the depth of cracks from this density information.

  The above crack determination is performed by the two-dimensional spatial distribution information analysis unit 7 in the abnormality determination unit 6 in FIG.

  In the case where there is a crack, as shown in FIG. 8A, in the cracked portion, the amount of displacement increases rapidly in response to an increase in the opening of the crack. Therefore, it is possible to estimate that there is a crack at a location where a displacement amount exceeding the threshold value is detected by providing a threshold value for the displacement amount per unit length in the X direction or the Y direction in advance.

  Further, the strain in the X direction increases rapidly at the cracked portion. From this, it is possible to estimate that there is a crack at a location where a strain exceeding the threshold is detected by providing a threshold in advance in the value of strain in the X direction.

  Further, as shown in FIGS. 10A and 10B, when there is a crack, distortion in the Y direction occurs. Therefore, by providing a threshold value in advance in the strain value in the Y direction, it can be estimated that there is a crack at a location where a strain exceeding the threshold value is detected.

  Each of the above threshold values can be set by a simulation using the same dimensions and materials as the structure or an experiment using a reduced model. Furthermore, an actual structure can be set from data accumulated by measuring over a long period of time.

  The above determination can also be made by a pattern matching process as described below, without using the above numerical comparison.

  12A to 12C are diagrams for explaining the pattern matching processing of the displacement distribution by the two-dimensional spatial distribution information analysis unit 7. According to the displacement correction part 4 and the differential displacement calculation part 5, as shown to FIG. 11A-11D, a displacement amount can be represented on a XY plane as a displacement distribution map. As shown in FIG. 12A, the two-dimensional spatial distribution information analysis unit 7 rotates and enlarges / reduces the X-direction pattern of the displacement around the crack stored in advance, and the displacement distribution diagram obtained by the displacement correction unit 4 By the pattern matching, it is possible to determine the direction and depth of the crack. Here, the X-direction pattern of the displacement around the crack stored in advance can be created in advance by simulation or the like for each depth and width of the crack.

  Further, as shown in FIG. 12B, the two-dimensional spatial distribution information analysis unit 7 rotates and enlarges / reduces the Y-direction pattern of the displacement around the crack stored in advance, and the displacement distribution obtained by the displacement correction unit 4 The direction and depth of the crack are determined by pattern matching with the figure. Here, the Y-direction pattern of the displacement around the crack stored in advance can be created in advance by simulation or the like for each depth and width of the crack.

  Further, as shown in FIG. 12C, the two-dimensional spatial distribution information analysis unit 5 rotates and enlarges / reduces the previously stored pattern of the differential vector field around the crack, and is obtained by the differential displacement calculation unit 5. The direction and depth of the crack are determined by pattern matching with a differential vector field (corresponding to a stress field). Here, the differential vector field pattern of the displacement around the crack stored in advance can be created in advance by simulation or the like for each depth and width of the crack.

  Correlation calculation is used for the pattern matching. Various other statistical calculation methods may be used for pattern matching.

  Although the case where the structure 15 has cracks has been described above, the case where the structure 15 has an internal cavity and the case where peeling occurs will be described below.

  13A and 13B show a two-dimensional distribution of stress on the surface viewed from the imaging direction when an internal cavity as shown in FIG. 4D exists. FIG. 13A is a perspective view, and FIG. 13B is a plan view. As shown in FIG. 13B, stress acts in the X direction in the figure due to the load, but the stress field bends in the hollow portion, and therefore a component in the Y direction in the figure exists in the stress.

  FIGS. 14A to 14C are diagrams showing the contour lines of the displacement of the surface and the stress field viewed from the imaging direction when the internal cavity exists. FIG. 14A shows the contour lines of the X component of the displacement, and FIG. 14A shows the contour lines of the Y component of the displacement. 14B and the stress field are shown in FIG. 14C, respectively.

  In the hollow portion, as described in the explanation of FIG. 4D, the amount of strain is reduced, and therefore the density of the contour line of the X component of the displacement shown in FIG. 14A is reduced. Moreover, the contour line of the Y component of the displacement shown in FIG. 14B is a closed curve. Furthermore, the stress field that is the differential of the displacement shown in FIG. 14C is bent at the hollow portion. Since the influence of the surface stress field becomes more prominent as the cavity portion is closer to the surface, the depth from the surface of the cavity portion can also be estimated from the bending method of the stress field.

  Here, the displacement pattern in the X direction of the displacement around the cavity, the displacement pattern in the Y direction of the displacement around the cavity, and the differential vector field (corresponding to the stress field) stored in advance in the two-dimensional spatial distribution information analysis unit 7 As in the case of determining a crack, applying FIG. 14A to FIG. 12A, FIG. 14B to FIG. 12B, and FIG. 14C to FIG. 12C makes it possible to determine the state of the position and depth of the internal cavity. For the pattern matching, correlation calculation is used, but other statistical calculation methods may be used.

  In addition, even if there are internal cavities, it is possible to presume that there are internal cavities when the threshold values are set in advance for these displacement amounts and strains based on the characteristics of the displacement amounts and strains in the Y direction. it can.

  FIG. 15A and FIG. 15B are diagrams illustrating a response when a load is applied to a structure having an internal cavity for a short time (referred to as impulse stimulation). Impulse stimulation can be applied, for example, to a position where a load is applied. FIG. 15B shows the time response of the displacement at each point on the surface of A, B, and C shown in FIG. 15A in response to this impulse stimulus. At point A where there is no internal cavity, stress transmission is fast and the amplitude of displacement is large. On the other hand, at point C, since stress is not transmitted in the internal cavity, stress is transmitted from the periphery of the cavity, so that stress transmission is slow and the displacement amplitude is small. Further, the stress transmission time and amplitude at the point B which is an intermediate point between the points A and C are intermediate values between the points A and C. Therefore, when the frequency distribution of the displacement distribution in the plane of the structure viewed from the imaging direction is analyzed by the time change information analysis unit 8 in the abnormality determination unit 6, the region of the internal cavity is determined from the amplitude and phase near the resonance frequency. Can be identified. Further, the internal cavity may be determined from the shift of the resonance frequency.

  Even when the load is applied for a long time, a change in displacement corresponding to FIG. 15B is confirmed at the initial stage of applying the load. However, in this case, the convergence value of the displacement is not zero but a value that balances the load. Therefore, even when a load is applied for a long time, the internal cavity region can be specified by the time change information analysis unit 8.

  The time response processing of the above displacement is performed by frequency analysis using fast Fourier transform in the time change information analysis unit 8. For frequency analysis, various frequency analysis methods such as wavelet transform may be used.

  FIGS. 16A to 16C are diagrams showing the contour lines of the displacement of the surface and the stress field as seen from the imaging direction when there is peeling, and FIG. 16A shows the contour lines of the X component of the displacement and FIG. 16A shows the contour lines of the Y component of the displacement. FIG. 16B shows the stress field in FIG. 16C.

  As shown in FIG. 4C, when there is peeling, an appearance similar to a crack is observed when viewed from the lower surface of the beam-like structure. However, since there is no stress transmission between the peeled portion and its upper part, the displacement before and after the load only translates by a certain amount in the fixed direction at the peeled portion, and no distortion which is a spatial differential value is generated.

  FIG. 16A shows contour lines of the X component of displacement. Since the peeled portion is not distorted and moves in a certain direction, there is no contour line. Using this feature, the abnormality determination unit 6 determines that there is peeling. In addition, since the point A in the figure is difficult to transmit stress due to tearing due to peeling, the contour lines are sparse compared to the point B which is a healthy part. The abnormality determination unit 6 may determine the peeled portion and the healthy portion using this property.

  FIG. 16B shows contour lines of the Y component of the displacement. A displacement in the Y direction occurs outside the outer periphery of the peeled portion. Using this feature, the abnormality determination unit 6 can determine that there is peeling. In addition, the stress field that is the differential of the displacement shown in FIG. 16C is 0 or a value in the vicinity thereof at the peeled portion. Using this feature, the abnormality determination unit 6 can determine that there is peeling.

  Here, the displacement pattern in the X direction of the displacement around the separation, the displacement pattern in the Y direction of the displacement around the cavity, and the differential vector field (corresponding to the stress field) stored in advance in the two-dimensional spatial distribution information analysis unit 7 As in the case of determining the crack depth, the position of the peeling can be determined by applying FIG. 16A to FIG. 12A, FIG. 16B to FIG. 12C, and FIG. For the pattern matching, correlation calculation is used, but other statistical calculation methods may be used.

  FIG. 17 is a diagram illustrating a time response when a structure having delamination receives an impulse stimulus. In the time response, the peeled portion and the healthy portion have waveforms in which the displacement directions are opposite, that is, the phases are 180 ° different. Moreover, since the peeled portion is light, the amplitude is large. By performing frequency analysis on the displacement distribution in the plane of the structure viewed from the imaging direction by the time change information analysis unit 8, the separation portion can be identified from the amplitude and phase. In addition, since the peeled portion floats from the entire structure, the peeled portion may include a frequency component different from that of the entire structure. Therefore, the peeled portion may be determined from a shift in resonance frequency.

  In the above processing, the frequency analysis in the time change information analysis unit 8 uses fast Fourier transform. For frequency analysis, various frequency analysis methods such as wavelet transform may be used.

  FIG. 18 is a flowchart showing a state determination method of the state determination apparatus 1 of FIG.

  In step S <b> 1, the displacement calculation unit 2 of the state determination device 1 calculates the displacement amount before and after applying the load in the time series image of the surface of the structure 15 before and after applying the load imaged by the imaging unit 11. A frame image before applying a load, which is a reference for calculation, is captured, and further, a frame image after applying the load is captured in time series.

  Furthermore, the displacement calculation unit 2 calculates the amount of displacement in the X and Y directions of the image after applying the load with respect to the image before applying the load as a reference. Furthermore, a displacement distribution diagram (contour lines of the displacement amount) displayed on the XY plane may be used as the two-dimensional distribution of the calculated displacement amount. Further, the displacement calculation unit 2 inputs the calculated displacement amount or displacement distribution diagram to the displacement correction unit 4.

  In step S <b> 2, the correction amount calculation unit 3 receives the distance information between the imaging unit 11 and the surface of the structure 15, the optical axis of the imaging unit 11, and the structure from the distance measurement unit 12 and the inclination measurement unit 13, respectively. The angle information of the angle formed by the normal of the 15 surfaces is acquired.

  In step S3, the correction amount calculation unit 3 calculates an out-of-plane displacement from the distance information and the angle information.

  In step S <b> 4, the displacement correction unit 4 extracts the in-plane displacement by subtracting the out-of-plane displacement obtained by the correction amount calculation unit 3 from the displacement amount obtained by the displacement calculation unit 2. That is, the displacement correction unit 4 calculates the in-plane displacement in the XY direction of the surface of the structure 15 after applying the load with respect to the reference before applying the load. Further, the calculated two-dimensional distribution of in-plane displacement may be a displacement distribution diagram (contour line of displacement amount) displayed on the XY plane. The displacement correction unit 4 inputs the calculated result to the differential displacement calculation unit 5 and the abnormality determination unit 6.

  In step S5, the differential displacement calculation unit 5 spatially differentiates the in-plane displacement or displacement distribution diagram input from the displacement correction unit 4 to calculate a differential displacement amount (stress value) or a differential displacement distribution diagram (stress field). To do. The differential displacement calculation unit 5 inputs the calculated result to the abnormality determination unit 6.

  The following steps S6, S7, and S8 are steps in which the two-dimensional spatial distribution information analysis unit 7 of the abnormality determination unit 6 determines cracks, separation, and internal cavities that are defects in the structure. The determination method will be described with reference to the above-described pattern matching method and threshold value method.

  In step S6, the two-dimensional spatial distribution information analysis unit 7 of the abnormality determination unit 6 determines the state of cracks, separation, and internal cavities from the input displacement amount or displacement distribution diagram in the X direction.

  First, a determination method by pattern matching will be described. The two-dimensional spatial distribution information analysis unit 7 includes, as a database, displacement distribution patterns created in advance corresponding to cracks, internal cavities, widths and depths of separation, as shown in FIGS. 12A, 14A, and 16A. ing. The two-dimensional spatial distribution information analysis unit 7 performs pattern matching by rotating and enlarging / reducing these displacement distribution patterns with respect to the X-direction displacement distribution diagram input from the displacement correction unit 4 to detect defects in the XY plane. Determine the position and type.

  Next, a determination method based on a displacement amount threshold will be described. The two-dimensional spatial distribution information analysis unit 7 determines, for example, the continuity of the displacement amount based on the input displacement amount in the X direction. That is, as shown in FIG. 8A, the presence / absence of continuity is determined based on the presence / absence of a steep change equal to or greater than the displacement amount threshold. The two-dimensional spatial distribution information analysis unit 7 determines that there is a possibility that a crack or separation may exist in any part of the XY plane when there is a steep change without continuity. While the continuous flag DisC (x, y, t) is set to 1, the displacement amount data at a location where there is a steep change is recorded as numerical information. Here, t is the time on the time-series image of the frame image captured in step S1.

  The abnormality determination unit 6 inputs the defect information determined by pattern matching, or the discontinuity flag DisC (x, y, t) or numerical information determined by the displacement amount threshold value, to the abnormality map creation unit 9.

  In step S7, the two-dimensional spatial distribution information analysis unit 7 of the abnormality determination unit 6 determines the state of cracks, separation, and internal cavities from the input displacement amount or displacement distribution diagram in the Y direction.

  First, a determination method by pattern matching will be described. The two-dimensional spatial distribution information analysis unit 7 includes, as a database, displacement distribution patterns created in advance corresponding to cracks, internal cavities, widths and depths of separation as shown in FIGS. 12B, 14B, and 16B. ing. The two-dimensional spatial distribution information analysis unit 7 performs pattern matching on the displacement distribution diagram in the Y direction input from the displacement correction unit 4 by rotating and enlarging and reducing these displacement distribution patterns, and in the XY plane. Determine the position and type of the defect.

  Next, a determination method based on a displacement amount threshold will be described. When there are cracks, delamination, and internal cavity defects, displacement is also generated in the Y direction. Therefore, when the two-dimensional spatial distribution information analysis unit 7 detects a displacement larger than a predetermined threshold value, the two-dimensional spatial distribution information analysis unit 7 determines that there is a defect in the part and sets the orthogonal flag ortho (x, y, t) to 1. At the same time, the displacement amount data of the location where the displacement amount greater than the threshold is detected is recorded as numerical information.

  The abnormality determination unit 6 inputs the defect information determined by pattern matching, or the orthogonal flag ortho (x, y, t) or numerical information determined by the displacement amount to the abnormality map creation unit 9.

  In step S8, the two-dimensional spatial distribution information analysis unit 7 of the abnormality determination unit 6 determines the state of cracks, separation, and internal cavities from the input differential displacement amount (stress value) or differential displacement distribution diagram (stress field). To do.

  First, a determination method by pattern matching will be described. The two-dimensional spatial distribution information analysis unit 7 includes, as a database, displacement distribution patterns created in advance corresponding to cracks, internal cavities, widths and depths of separation as shown in FIGS. 12C, 14C, and 16C. ing. The two-dimensional spatial distribution information analysis unit 7 performs pattern matching on the differential displacement distribution diagram input from the differential displacement calculation unit 5 by rotating and enlarging / reducing these displacement distribution patterns, so that defects in the XY plane are detected. Determine the position and type.

  Next, a determination method based on the threshold of the differential displacement amount will be described. For example, the strain in the X direction increases rapidly because the differential value of the displacement diverges at the cracked portion. From this, it is possible to determine that there is a crack at a location where a strain exceeding the threshold is detected by providing a threshold value in advance for the strain value. The two-dimensional spatial distribution information analysis unit 7 determines that a crack is present at the location based on the input differential displacement, sets 1 in the differential value flag Diff (x, y, t), Is recorded as numerical information.

  The abnormality determination unit 6 inputs the defect information determined by pattern matching, or the differential value flag Diff (x, y, t) and numerical information determined by the differential displacement amount to the abnormality map creation unit 9.

  In step S9, the displacement calculation unit 2 determines whether the processing of each frame image of the time series image has been completed. That is, when the number of frames of the time-series image is n, it is determined whether or not the n-th process is finished. If the number of processes is less than n (NO), the processes from step S1 are repeated. This is repeated until n sheets are completed. Note that n is not limited to the total number of frames, and can be set to an arbitrary number. When the process has finished n sheets (YES), the process proceeds to step S10.

  In step S10, the time change information analysis unit 8 of the abnormality determination unit 6 determines the time response of the displacement as shown in FIG. 15B or FIG. 17 from the time-series displacement amount or the displacement distribution diagram corresponding to the n frame images. Is analyzed. That is, from n displacement distribution diagrams I (x, y, n), a time frequency distribution (time frequency is assumed to be f) is an amplitude A (x, y, f) and a phase P (x, y, f). Calculated. The time change information analysis unit 8 determines that there is an internal cavity at a position where a phase shift occurs when the time frequency distribution has a characteristic in which the phase differs depending on the location as shown in FIG. 15B. Moreover, when the polarity of the displacement is reversed as shown in FIG. The time change information analysis unit 8 inputs the above time frequency distribution calculation result and defect determination result to the abnormality map creation unit 9.

  In step 11, the abnormality map creation unit 9 creates an abnormality map (x, y) based on the information input in the above steps. The results sent from the two-dimensional spatial distribution information analysis unit 7 and the time change information analysis unit 8 are data groups related to the point (x, y) on the XY coordinates. The state of the structure of these data is determined by the two-dimensional spatial distribution information analysis unit 7 and the time change information analysis unit 8 in the abnormality determination unit 6.

  These determinations are made with respect to the displacement amount or displacement distribution diagram in the X direction, the displacement amount or displacement distribution diagram in the Y direction, the differential displacement amount or the differential displacement distribution diagram, and the time response of the displacement or the differential displacement. For this reason, the abnormality map creation unit 9 has the determination based on the displacement amount in the X direction and the differential displacement amount even if data loss occurs, for example, the determination based on the displacement amount in the Y direction cannot be performed. Thus, the state of the relevant part in the XY coordinates can be determined. Based on this determination, an abnormality map (x, y) can be created.

  In addition, when determining the defect state, if the determination of the displacement in the X direction, the displacement in the Y direction, and the differential displacement is different, the determination may be made by majority vote. Alternatively, the item having the largest difference from the threshold value that is the criterion may be determined.

  Also, the abnormality map creation unit 9 can express the degree of defects based on the various numerical information described above. For example, the width and depth of a crack, the dimension of peeling, the dimension of an internal cavity, the depth from the surface, and the like can be expressed.

  In addition, the abnormality map creation unit 9 creates the abnormality map (x, y) for the determination of the defect state of the structure performed by the two-dimensional spatial distribution information analysis unit 7 and the time change information analysis unit 8 in the abnormality determination unit 6. It can also be done on the occasion. That is, analysis data may be obtained from the two-dimensional spatial distribution information analysis unit 7 and the time change information analysis unit 8, and the defect map creation unit 9 may determine the defect state based on the analysis data.

  The result output of the abnormality map creation unit 9 may be information in a form that can be directly visualized by a person using a display device, or information in a form that is read by a machine.

  In the present embodiment, for example, the lens focal length of the imaging unit 11 is 50 mm, the pixel pitch is 5 μm, and a pixel resolution of 500 μm can be obtained at an imaging distance of 5 m. The image pickup element of the image pickup unit 11 is monochrome and has a pixel count of 2000 horizontal pixels and 2000 vertical pixels, and can capture a 1 m × 1 m range at an imaging distance of 5 m. The frame rate of the image sensor can be 60 Hz.

  Further, in the image correlation in the displacement calculation unit 2, sub-pixel displacement estimation by quadratic curve interpolation can be used so that displacement can be estimated up to 1/100 pixels and a displacement resolution of 5 μm can be obtained. The following various methods can be used for subpixel displacement estimation in image correlation. In addition, a smoothing filter can be used to reduce noise during differentiation in displacement differentiation.

  For subpixel displacement estimation, interpolation using a quadric surface, an equiangular straight line, or the like may be used. In addition, for image correlation calculation, SAD (Sum of Absolute Difference) method, SSD (Sum of Squared Difference) method, NCC (Normalized Cross Correlation) method, ZNCC (Zero-means Normalized Cross method), etc. May be. Any combination of these methods and the above-described subpixel displacement estimation method may be used.

  The lens focal length of the imaging unit 11, the pixel pitch of the imaging element, the number of pixels, and the frame rate may be appropriately changed according to the measurement target.

  In the present embodiment, for example, the beam-like structure can correspond to a bridge, and the load can correspond to a traveling vehicle. In the above description, the load is applied to the beam-like structure. However, even when the load moves on the bridge like a traveling vehicle, it is possible to detect cracks, internal cavities, and separation. In addition, if the material exhibits the same behavior as described above in terms of material mechanics, a structure having other materials, sizes and shapes, or a load method different from loading the structure, for example, a load is suspended. It can also be applied to a load method such as lowering.

  Moreover, as long as it can measure a time-series signal of a spatial two-dimensional distribution of the surface displacement of a structure, it is not limited to a time-series image, but an array-shaped laser Doppler sensor, an array-shaped strain gauge, an array-shaped vibration sensor. An array-type acceleration sensor or the like may be used. Spatial two-dimensional time-series signals obtained from these array sensors may be handled as image information.

  In the present embodiment, distance information and inclination information for calculating out-of-plane displacement due to movement of the structure surface in the normal direction are set to the imaging timing from the same direction as the imaging direction for imaging the image of the structure surface. It can be acquired together. In principle, the amount of movement of the structure surface in the normal direction can be obtained by measuring the amount of deflection due to the load from the side surface direction of the structure. However, for example, when the structure is a bridge or the like, measurement from the side surface of the bridge is extremely difficult in work, and therefore the measurement accuracy is also lowered. Since this embodiment can also solve this problem in work, the displacement of the image on the structure surface can be corrected with high accuracy.

  As described above, according to the present embodiment, the surface of the structure surface is separated from the displacement due to the load of the image of the structure surface with good workability from the out-of-plane displacement due to the movement of the structure surface in the normal direction. The internal displacement can be extracted. As a result, it is possible to accurately perform remote and non-contact detection that distinguishes defects such as cracks and peeling of structures and internal cavities.

  The present invention is not limited to the above embodiment, and various modifications are possible within the scope of the invention described in the claims, and these are also included in the scope of the present invention.

  Moreover, although a part or all of said embodiment may be described also as the following additional remarks, it is not restricted to the following.

Appendix (Appendix 1)
A displacement calculating unit that calculates a two-dimensional spatial distribution of displacement of the time-series image from a time-series image before and after applying a load on the surface of the structure;
A correction amount calculation unit that calculates a correction amount based on the amount of movement in the normal direction of the surface of the structure due to the load application, measured from the imaging direction of the time-series image;
A displacement correction unit that subtracts the correction amount from the two-dimensional spatial distribution of the displacement of the time-series image to extract the two-dimensional spatial distribution of the displacement of the structure surface;
A state determination apparatus comprising: an abnormality determination unit that identifies a defect of the structure based on a comparison between a two-dimensional spatial distribution of displacement of the structure surface and a spatial distribution of displacement provided in advance.
(Appendix 2)
The state determination system according to appendix 1, wherein the correction amount calculation unit calculates the correction amount based on the movement amount obtained by correcting an inclination angle of the structure.
(Appendix 3)
The state determination apparatus according to appendix 2, wherein the movement amount in the normal direction of the surface of the structure or the inclination angle of the structure is measured at the same timing as the time-series image capturing.
(Appendix 4)
A differential displacement calculator that calculates a two-dimensional differential spatial distribution from the two-dimensional spatial distribution of the displacement of the structure surface;
The abnormality determination unit specifies one of the defects of the structure, based on a comparison between the two-dimensional differential space distribution and a differential space distribution of differential displacement provided in advance. State determination device.
(Appendix 5)
5. The state determination device according to claim 1, wherein the abnormality determination unit specifies a defect of the structure based on a temporal change of a two-dimensional spatial distribution of displacement of the structure surface.
(Appendix 6)
The state determination apparatus according to appendix 4 or 5, wherein the abnormality determination unit specifies a defect of the structure based on a temporal change of the two-dimensional differential space distribution.
(Appendix 7)
The state according to any one of appendices 1 to 6, wherein the abnormality determination unit identifies a defect of the structure based on a comparison between a displacement amount of the surface of the structure and a threshold value provided in advance. Judgment device.
(Appendix 8)
8. The abnormality determination unit according to any one of appendices 4 to 7, wherein the abnormality determination unit identifies a defect of the structure based on a comparison between a differential displacement amount of a displacement of the structure surface and a threshold provided in advance. State determination device.
(Appendix 9)
9. The state determination device according to claim 1, further comprising an abnormality map creation unit that creates an abnormality map indicating the location and type of the defect based on a determination result of the abnormality determination unit.
(Appendix 10)
The state determination apparatus according to any one of appendices 1 to 9, wherein the type of the defect includes cracks, peeling, and internal cavities.
(Appendix 11)
The state determination apparatus according to appendix 10, wherein the spatial distribution of the displacement provided in advance and the differential spatial distribution of the differential displacement provided in advance are based on information on the crack, the separation, and the internal cavity.
(Appendix 12)
12. The two-dimensional spatial distribution according to any one of appendices 1 to 11, wherein the two-dimensional spatial distribution includes a distribution of displacement in the X direction on the XY plane of the displacement and a distribution of displacement in the Y direction on the XY plane of the displacement. State determination device.
(Appendix 13)
A displacement calculation unit that calculates a two-dimensional spatial distribution of the displacement of the time-series image from time-series images before and after applying a load on the surface of the structure, and a correction amount based on a movement amount of the structure surface in the normal direction due to the load application A correction amount calculation unit for calculating the displacement, a displacement correction unit for subtracting the correction amount from a two-dimensional spatial distribution of the displacement of the time-series image to extract a two-dimensional spatial distribution of the displacement of the structure surface, and the structure A state determination device including an abnormality determination unit that identifies a defect of the structure based on a comparison between a two-dimensional spatial distribution of surface displacement and a spatial distribution of displacement provided in advance;
An imaging unit that captures the time-series images and provides the state determination device;
A distance measurement unit that measures the amount of movement from the imaging direction of the time-series image and provides the distance determination unit with the distance determination unit.
(Appendix 14)
An inclination measuring unit that measures an inclination angle of the structure and provides the state determination device;
The state determination system according to appendix 13, wherein the correction amount calculation unit calculates the correction amount based on the movement amount obtained by correcting the tilt angle.
(Appendix 15)
The distance measuring unit or the tilt measuring unit measures the movement amount in the normal direction of the surface of the structure or the tilt angle of the structure at the same timing as the time-series image capturing. The state determination system described.
(Appendix 16)
A differential displacement calculator that calculates a two-dimensional differential spatial distribution from the two-dimensional spatial distribution of the displacement of the structure surface;
The abnormality determination unit identifies a defect of the structure based on a comparison between the two-dimensional differential space distribution and a differential space distribution of differential displacement provided in advance.
The state determination system according to any one of appendices 13 to 15.
(Appendix 17)
The state determination system according to any one of appendices 13 to 16, wherein the abnormality determination unit identifies a defect of the structure based on a temporal change in a two-dimensional spatial distribution of displacement of the structure surface.
(Appendix 18)
The state determination system according to appendix 16 or 17, wherein the abnormality determination unit identifies a defect of the structure based on a temporal change of the two-dimensional differential space distribution.
(Appendix 19)
The state according to any one of appendices 13 to 18, wherein the abnormality determination unit identifies a defect of the structure based on a comparison between a displacement amount of the surface of the structure and a threshold value provided in advance. Judgment system.
(Appendix 20)
20. The abnormality determination unit according to any one of appendices 16 to 19, wherein the abnormality determination unit identifies a defect of the structure based on a comparison between a differential displacement amount of the displacement of the structure surface and a threshold value provided in advance. State determination system.
(Appendix 21)
21. The state determination system according to any one of appendices 13 to 20, further including an abnormality map creation unit that creates an abnormality map indicating the location and type of the defect based on a determination result of the abnormality determination unit.
(Appendix 22)
The state determination system according to any one of appendices 13 to 21, wherein the type of the defect includes cracks, peeling, and internal cavities.
(Appendix 23)
The state determination system according to appendix 22, wherein the spatial distribution of the displacement provided in advance and the differential spatial distribution of the differential displacement provided in advance are based on information on the crack, the separation, and the internal cavity.
(Appendix 24)
The two-dimensional spatial distribution includes the distribution of the displacement in the X direction on the XY plane of the displacement and the distribution of the displacement in the Y direction on the XY plane of the displacement. State determination system.
(Appendix 25)
From the time-series images before and after applying the load on the structure surface, calculate the two-dimensional spatial distribution of the displacement of the time-series image,
The amount of correction based on the amount of movement in the normal direction of the surface of the structure due to the load application, measured from the imaging direction of the time-series images,
Subtracting the correction amount from the two-dimensional spatial distribution of the displacement of the time series image to extract the two-dimensional spatial distribution of the displacement of the structure surface;
A state determination method for identifying a defect in the structure based on a comparison between a two-dimensional spatial distribution of displacement of the structure surface and a spatial distribution of displacement provided in advance.
(Appendix 26)
The state determination method according to appendix 25, wherein the correction amount is calculated based on the movement amount obtained by correcting the inclination angle of the structure.
(Appendix 27)
27. The state determination method according to appendix 26, wherein the amount of movement in the normal direction of the surface of the structure or the inclination angle of the structure is measured at the same timing as the time-series image is captured.
(Appendix 28)
Calculating a two-dimensional differential spatial distribution of the two-dimensional spatial distribution from the two-dimensional spatial distribution;
28. The state determination method according to one of appendices 25 to 27, wherein a defect of the structure is specified based on a comparison between the two-dimensional differential space distribution and a differential space distribution of differential displacement provided in advance.
(Appendix 29)
29. The state determination method according to one of appendices 25 to 28, wherein a defect of the structure is specified based on a time change of the two-dimensional spatial distribution.
(Appendix 30)
30. The state determination method according to appendix 28 or 29, wherein a defect of the structure is specified based on a time change of the two-dimensional differential space distribution.
(Appendix 31)
31. The state determination method according to any one of appendices 25 to 30, wherein a defect of the structure is specified based on a comparison between a displacement amount of the surface of the structure and a threshold value provided in advance.
(Appendix 32)
31. The state determination method according to one of appendices 28 to 30, wherein a defect of the structure is specified based on a comparison between a differential displacement amount of the displacement of the structure surface and a threshold value provided in advance.
(Appendix 33)
The state determination method according to appendixes 25 to 32, wherein an abnormality map indicating the location and type of the defect is created based on the determination result.
(Appendix 34)
34. The state determination method according to one of appendices 25 to 33, wherein the type of the defect includes cracks, peeling, and internal cavities.
(Appendix 35)
35. The state determination method according to appendix 34, wherein the spatial distribution of the displacement provided in advance and the differential spatial distribution of the differential displacement provided in advance are based on information on the crack, the separation, and the internal cavity.
(Appendix 36)
36. The one-sided item according to any one of appendices 25 to 35, wherein the two-dimensional spatial distribution includes a distribution of displacement in the X direction on the XY plane of the displacement and a distribution of displacement in the Y direction on the XY plane of the displacement. State determination method.

DESCRIPTION OF SYMBOLS 1,100 State determination apparatus 2 Displacement calculation part 3 Correction amount calculation part 4 Displacement correction part 5 Differential displacement calculation part 6 Abnormality determination part 7 Two-dimensional spatial distribution information analysis part 8 Time change information analysis part 9 Abnormality map preparation part 10 State determination System 11 Imaging unit 12 Distance measuring unit 13 Inclination measuring unit 14 Defect 15 Structure 121 Signal generator 122 Transmitter 123 Receiver 124 Time comparator 125 Distance calculator

Claims (10)

A displacement calculating unit that calculates a two-dimensional spatial distribution of displacement of the time-series image from a time-series image before and after applying a load on the surface of the structure;
A correction amount calculation unit that calculates a correction amount based on the amount of movement in the normal direction of the surface of the structure due to the load application, measured from the imaging direction of the time-series image;
A displacement correction unit that subtracts the correction amount from the two-dimensional spatial distribution of the displacement of the time-series image to extract the two-dimensional spatial distribution of the displacement of the structure surface;
A state determination apparatus comprising: an abnormality determination unit that identifies a defect of the structure based on a comparison between a two-dimensional spatial distribution of displacement of the structure surface and a spatial distribution of displacement provided in advance. The state determination system according to claim 1, wherein the correction amount calculation unit calculates the correction amount based on the movement amount obtained by correcting an inclination angle of the structure. The state determination apparatus according to claim 2, wherein the amount of movement of the surface of the structure in the normal direction or the inclination angle of the structure is measured at the same timing as the imaging of the time series image. A differential displacement calculator that calculates a two-dimensional differential spatial distribution from the two-dimensional spatial distribution of the displacement of the structure surface;
The abnormality determination unit identifies a defect of the structure based on a comparison between the two-dimensional differential space distribution and a differential space distribution of differential displacement provided in advance. The state determination device described. 5. The state determination device according to claim 1, wherein the abnormality determination unit specifies a defect of the structure based on a temporal change of a two-dimensional spatial distribution of a displacement of the structure surface. The state determination device according to claim 4, wherein the abnormality determination unit specifies a defect of the structure based on a temporal change of the two-dimensional differential space distribution. A displacement calculation unit that calculates a two-dimensional spatial distribution of the displacement of the time-series image from time-series images before and after applying a load on the surface of the structure, and a correction amount based on a movement amount of the structure surface in the normal direction due to the load application A correction amount calculation unit for calculating the displacement, a displacement correction unit for subtracting the correction amount from a two-dimensional spatial distribution of the displacement of the time-series image to extract a two-dimensional spatial distribution of the displacement of the structure surface, and the structure A state determination device including an abnormality determination unit that identifies a defect of the structure based on a comparison between a two-dimensional spatial distribution of surface displacement and a spatial distribution of displacement provided in advance;
An imaging unit that captures the time-series images and provides the state determination device;
A distance measurement unit that measures the amount of movement from the imaging direction of the time-series image and provides the distance determination unit with the distance determination unit. An inclination measuring unit that measures an inclination angle of the structure and provides the state determination device;
The state determination system according to claim 7, wherein the correction amount calculation unit calculates the correction amount based on the movement amount obtained by correcting the tilt angle. The distance measuring unit or the tilt measuring unit measures a movement amount in a normal direction of the surface of the structure or a tilt angle of the structure at the same timing as capturing the time-series image. 8. The state determination system according to 8. From the time-series images before and after applying the load on the structure surface, calculate the two-dimensional spatial distribution of the displacement of the time-series image,
The amount of correction based on the amount of movement in the normal direction of the surface of the structure due to the load application, measured from the imaging direction of the time-series images,
Subtracting the correction amount from the two-dimensional spatial distribution of the displacement of the time series image to extract the two-dimensional spatial distribution of the displacement of the structure surface;
A state determination method for identifying a defect in the structure based on a comparison between a two-dimensional spatial distribution of displacement of the structure surface and a spatial distribution of displacement provided in advance.

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