Vibration visualization system and vibration visualization method

Abstract

To provide a vibration visualization system, even when vibration of a measuring object is small, capable of measuring a whole vibration state.SOLUTION: A vibration visualization system includes: an imaging part for acquiring video data of each of a first area including first and second measurement points and a second area including second and third measurement points; an extraction part for extracting first vibration data at the first measurement point and second vibration data at the second measurement point from the video data of the first area, and extracting third vibration data at the second measurement point and fourth vibration data at the third measurement point from the video data of the second area; a transfer function calculation part for calculating each transfer function on the basis of each of the first to fourth vibration data; and a natural vibration mode calculation part, when a difference between the transfer function corresponding to the second vibration data and the transfer function corresponding to the third vibration data is a prescribed threshold or less, calculating a natural vibration mode from the transfer function corresponding to the first vibration data, the transfer function corresponding to the second vibration data, and the transfer function corresponding to the fourth vibration data.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD Embodiments of the present invention relate to a vibration visualization system and a vibration visualization method. [Background technology]

[0002] To improve the availability of equipment in power plants, vibration sensors are used to monitor the condition of the equipment. However, depending on the equipment, the measurement target location may be located at a high altitude, making it difficult to install additional sensors and limiting measurement locations.

[0003] Therefore, vibration visualization and measurement methods using camera devices that can capture the surface of the phenomenon being measured without the need for sensors have been proposed. This technology allows for non-contact condition monitoring of the object being measured.

[0004] In non-contact condition monitoring using a camera device, the absolute value of the vibration value obtained from the measurement object may be small. In order to capture small vibrations, it is necessary to narrow the angle of view of the camera device. This limits the range that can be captured, making it difficult to grasp the movement of the entire measurement object, which may reduce the accuracy of fault detection and diagnosis. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] U.S. Patent No. 10,459,615 Summary of the Invention [Problem to be solved by the invention]

[0006] As such, conventional vibration visualization systems and vibration visualization methods have the problem that it is difficult to capture small vibrations, making it difficult to improve the accuracy of fault detection and fault diagnosis for the entire measurement object. The present invention has been made to solve this problem, and has as its object to provide a vibration visualization system and vibration visualization method that make it possible to measure the overall vibration state of the measurement object even if the vibration of the measurement object is small. [Means for solving the problem]

[0007] A vibration visualization system according to an embodiment includes an imaging unit that acquires video data of a first region including first and second measurement points provided on a structure, and a second region including the second measurement point and a third measurement point provided on the structure, and an extraction unit that extracts first vibration data at the first measurement point and second vibration data at the second measurement point from the video data of the first region, and extracts third vibration data at the second measurement point and fourth vibration data at the third measurement point from the video data of the second region. The vibration visualization system according to the embodiment further includes a transfer function calculation unit that calculates transfer functions based on the first to fourth vibration data, respectively, and a natural vibration mode calculation unit that calculates a natural vibration mode of the structure using the transfer function corresponding to the first vibration data, the transfer function corresponding to the second vibration data, and the transfer function corresponding to the fourth vibration data when a difference between the transfer function corresponding to the second vibration data and the transfer function corresponding to the third vibration data is equal to or smaller than a predetermined threshold. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing the configuration of a vibration visualization system according to a first embodiment. FIG. [Figure 2] FIG. 4 is a diagram illustrating an example of a transfer function according to the first embodiment. [Figure 3] FIG. 3 is a diagram illustrating the operation of the vibration visualization system according to the first embodiment. [Figure 4] FIG. 10 is a schematic diagram showing the configuration of a vibration visualization system according to a second embodiment. [Figure 5]FIG. 10 is a schematic diagram showing the configuration of a vibration visualization system according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] In the vibration visualization system of the embodiment, in order to capture minute vibrations of the measurement object, the camera device captures images of the measurement object with a limited angle of view. Therefore, video data from multiple regions is required to measure the entire measurement object. In the vibration visualization system of the embodiment, multiple images are taken of each of multiple regions of the measurement object (imaged object). Then, among the vibration data obtained by the multiple images, data that can be synchronized between the multiple regions is searched for, and the video data of the measurement points included in each region is combined, making it possible to capture the vibration state of the measurement object over a wide area.

[0010] (First embodiment) Embodiments of the present invention will now be described with reference to the drawings. In the following description, identical components will be designated by common reference numerals, and duplicate explanations will be omitted. FIG. 1 is a schematic diagram showing the configuration of a vibration visualization system according to a first embodiment. The vibration visualization system 1 shown in FIG. 1 includes a camera 2 that captures images of a measurement target O and its state, a data collection unit 3 that collects video data captured by the camera 2, and a calculation device 4 that processes the video data collected by the data collection unit 3.

[0011] Camera 2 captures the appearance of measurement object O and generates video data. Measurement points 6a to 6c, 7a to 7c, and 8a to 8c are attached to measurement object O in advance. The measurement points are marks on the surface of measurement object O in a form that can be captured by camera 2, and are not limited to the number mentioned above. The number of measurement points is set as needed to capture the overall vibration of measurement object O, and the measurement points are arranged at a predetermined distance from each other. The measurement points are not limited to marks newly added for the vibration visualization system, and characteristic parts or locations on measurement object O may also be used as measurement points.

[0012] The video data captured by camera 2 contains minute vibrations of the measurement points. Because the vibrations of the target O are so small, the angle of view of camera 2 does not necessarily cover the entire target O. In the example shown in FIG. 1, the area captured by the angle of view of camera 2 is only a portion of the target O, such as area A indicated by the dashed-dotted line and area B indicated by the dashed-two-dot line. To capture all measurement points 6a-6c, 7a-7c, and 8a-8c, camera 2 changes the capture area every time it captures for a predetermined period of time, such as area A, area B, etc. In this case, the capture areas are determined so that common measurement points are included among the multiple captured areas. In the example shown in FIG. 1, area A includes measurement points 6a-6c and 7a-7c, and area B includes measurement points 7a-7c and 8a-8c, so measurement points 7a-7c are common measurement points.

[0013] The data collection unit 3 is a storage device that accumulates multiple pieces of video data captured by the camera 2. The data collection unit 3 can be realized by, for example, a computer device that constitutes a file server or a data server. The data collection unit 3 may also function as an area that stores the calculation results of the calculation unit 4.

[0014] The calculation device 4 has the function of frequency-analyzing the video data accumulated by the data accumulation unit 3, calculating a transfer function, and calculating a natural vibration mode. The calculation device 4 can be realized by a computer device such as a workstation. The calculation device 4 includes a video data acquisition unit 41, a Fourier transform unit 42, a transfer function calculation unit 43, an output unit 44, and an imaging control unit 45.

[0015] The video data acquisition unit 41 acquires the video data accumulated in the data accumulation unit 3 and detects vibration data indicating the vibrations at each of the measurement points 6a to 6c, 7a to 7c, and 8a to 8c. In the example shown in Fig. 1, the vibration data at the measurement points 6a to 6c and 7a to 7c is obtained by capturing an image of the area A. Furthermore, the vibration data at the measurement points 7a to 7c and 8a to 8c is obtained by capturing an image of the area B.

[0016] The Fourier transform unit 42 performs a Fourier transform on the vibration data detected by the video data acquisition unit 41, converting the time axis data into frequency axis data.

[0017] The transfer function calculation unit 43 calculates a transfer function using the Fourier transformed vibration data. The transfer function calculation unit 43 also calculates the natural vibration mode of the object to be measured O using the generated transfer function.

[0018] The output unit 44 outputs, as an image, the natural vibration mode calculated by the transfer function calculation unit 43. The output unit 44 can be realized by, for example, a display device or a printer device. The output unit 44 may output the obtained natural vibration mode to the data accumulation unit 3 or the like as a data file.

[0019] The imaging control unit 45 controls the imaging area of ​​the camera 2. The video data acquisition unit 41 acquires video data of a plurality of areas of the measurement object O. The imaging control unit 45 controls the camera 2 to enable acquisition of video data of a plurality of areas.

[0020] (Calculation of transfer function) When the camera 2 captures an image of an area A of the measurement object O, vibration data X is obtained at measurement points 6a, 6b, and 6c within the range of the area A. 6aA ,X 6bA ,X 6cA are observed (measured) together. Here, "X 6aA " means vibration data at measurement point 6a in region A. Similarly, vibration data X 7aA ,X 7bA ,X 7cA are observed (measured) together.

[0021] If the reference point is the measurement point 6a, the transfer function calculation unit 43 calculates the vibration data X measured at the measurement point 6a as 6aAThe transfer function H between the reference point and the vibration data at other measurement points is calculated. The reference point can be set to any measurement point within the measurement range. Since the vibration data X has been converted into frequency domain data by the Fourier transform unit 42, the transfer function H can be expressed by Equation 1, where f is the frequency. H n (f)=X n (f) / X nbase (f) (1) where X n (f), X nbase (f) shows the vibrations at the measurement points n (6a to 6c, 7a to 7c in FIG. 1) and the vibrations at the reference points, which have been frequency converted.

[0022] Figure 2 is an example of a transfer function H. The frequency at which the peak (maximum point) of the amplitude |H| of the transfer function occurs is the natural frequency. Figure 2 shows three natural frequencies: f1, f2, and f3. For example, we will determine the natural vibration mode by focusing on the lowest natural frequency, f1 (fundamental natural frequency).

[0023] The natural vibration mode is expressed as the amplitude ratio of each measurement point of the structure to the reference point at the corresponding natural frequency. That is, the transfer function calculation unit 43 calculates the ratio of the transfer function at the natural frequency f1. The natural vibration mode Mn(f) at the measurement point n and the frequency f is expressed as follows: M n,1 (f)=H n,1 (f) / H 1,1 (f) ={(X n (f) / X nbase (f))} / {(X1(f) / X nbase (f))} =X n (f) / X1(f) (2) In formula (2), if n=1, 2, ..., is calculated sequentially, the natural vibration mode {M 1,1 (f),M 2,1 (f),…,M n,1 (f)} is required.

[0024] (Combination of imaging areas) To capture the overall vibration of the measurement object O, it is simple to have the camera 2 capture the entire measurement object O. However, because the vibration at the measurement point is minute, it is necessary to narrow the angle of view of the camera 2 so that it can capture even minute vibrations. In the vibration visualization system 1 of this embodiment, the capture area of ​​the camera 2 is a part of the measurement object O (area A and area B in FIG. 1), and the multiple capture areas obtained are combined.

[0025] 1, an example will be explained in which area A and area B are combined. When combining the natural vibration mode calculated in area A and the natural vibration mode calculated in area B, the transfer functions of measurement points 7a, 7b, and 7c where the areas overlap are used.

[0026] Here, measurements are taken multiple times (k times) in an adjacent area B having measurement points 7a, 7b, and 7c overlapping with area A, and the transfer function H n,1 , H n,2 ,····H n,k For example, if the measurement point 7a is used as the reference point, and the transfer function H 7bA and H 7cA Similarly, in the region B, the transfer function H is calculated using the measurement point 7a as the reference point. 7bB1 , H 7cB1、 H 7bB2 , H 7cB2··· H 7bBk , H 7cBk Here, "H 7bBk " "7b" represents the measurement point, "B" represents the area photographed, and "k" represents the number of times photographed.

[0027] The transfer function calculation unit 43 calculates the error between the transfer function at the natural frequency f1 of interest in the region A and the transfer function at the natural frequency f1 of interest in the adjacent region B at each measurement point using the formula (3). Then, the transfer function H of the second term in the numerator of the formula (3) is calculated so that the error of the transfer function at all measurement points is, for example, 1% or less. 7bBk, H 7cBk Explore. (H 7bA -H 7bB1 ) / H 7bA (H7cA -H 7cB1 ) / H 7cA (3)

[0028] If the error between the transfer function calculated in the area A and the transfer function calculated in the area B at the common measurement point is, for example, 1% or less, the transfer function calculation unit 43 calculates the transfer function H 7bBk and H 7cBk and the transfer function H of area A 7bA and H 7cA are considered to be measurement data under the same vibration condition, and the natural vibration mode is calculated using the transfer functions of areas A and B in the data of the number of times of photography. The calculated natural vibration mode can be output as a graphic by the output unit 44. The threshold value for determining the error is not limited to 1%. It can be determined depending on the accuracy required for the transfer function.

[0029] (Operation of the first embodiment) Next, the operation of the vibration visualization system 1 according to the embodiment will be described with reference to FIGS.

[0030] The imaging control unit 45 sets the imaging area of ​​the camera 2 to area A, and the camera 2 images area A (S100). Area A includes measurement points 6a, 6b, 6c, 7a, 7b, and 7c. The camera 2 accumulates the captured video data in the data accumulation unit 3.

[0031] The image data acquisition unit 41 acquires image data of the area A from the data collection unit 3, and calculates vibration data X at the measurement points 6a, 6b, 6c, 7a, 7b, and 7c from the acquired image data. 6aA ,X 6bA ,X 6cA ,X 7aA ,X 7bA ,X 7cA The extracted vibration data is stored in the data accumulation unit 3 (S105).

[0032] The Fourier transform unit 42 converts the vibration data X stored in the data accumulation unit 3 into 6aA ,X 6bA ,X 6cA,X 7aA ,X 7bA ,X 7cA A Fourier transform is performed on (S110).

[0033] The transfer function calculation unit 43 calculates the Fourier transformed vibration data X 6aA ,X 6bA ,X 6cA ,X 7aA ,X 7bA ,X 7cA Using the transfer function H 6aA ,H 6bA ,H 6cA ,H 7aA ,H 7bA ,H 7cA At this time, the calculation is performed using one of the measurement points (measurement points 7a, 7b, 7c in the example shown in FIG. 1) present in the overlapping region of region A and region B as a reference.

[0034] In this embodiment, extraction of vibration data is performed multiple times. If photographing of area A continues (Yes in S120), the process from photographing area A to calculating the transfer function is repeated (S100 to S115).

[0035] When the shooting of area A is to be ended (No in S120), the shooting control unit 45 changes the shooting area of ​​camera 2 from area A to area B, and camera 2 shoots area B (S125). Area B includes measurement points 7a, 7b, 7c, 8a, 8b, and 8c. Camera 2 accumulates the captured video data in the data accumulation unit 3.

[0036] The image data acquisition unit 41 acquires image data of the area B from the data collection unit 3, and calculates vibration data X at the measurement points 7a, 7b, 7c, 8a, 8b, and 8c from the acquired image data. 7aB ,X 7bB ,X 7cB ,X 8aB ,X 8bB ,X 8cB The extracted vibration data is stored in the data accumulation unit 3 (S130).

[0037] The Fourier transform unit 42 converts the vibration data X stored in the data accumulation unit 3 into7aB ,X 7bB ,X 7cB ,X 8aB ,X 8bB ,X 8cB A Fourier transform is performed on (S135).

[0038] The transfer function calculation unit 43 calculates the Fourier transformed vibration data X 7aB ,X 7bB ,X 7cB ,X 8aB ,X 8bB ,X 8cB Using the transfer function H 7aB ,H 7bB ,H 7cB ,H 8aB ,H 8bB ,H 8cB (S140). At this time, the calculation is performed using the reference point used when calculating the transfer function in area A as a reference point among the measurement points (measurement points 7a, 7b, and 7c in the example shown in FIG. 1) present in the overlapping area between area A and area B.

[0039] In this embodiment, vibration data is extracted multiple times. If the image capturing of area B is to continue (Yes in S145), the process from capturing the image of area B to calculating the transfer function is repeated (S125 to S140). By the operations up to this point, multiple images of the image data for each of areas A and B and the transfer functions calculated therefrom are accumulated in the data accumulation unit 3. In the following explanation, it is assumed that the image capturing of area A is performed M times and the image capturing of area B is performed N times, and the transfer function calculated from the image data of area A captured the mth time is defined as H 7aAm (Calculated from the image data of the mth shooting for the measurement point 7a in area A), the transfer function calculated from the image data of area B in the nth shooting is H 7aBn (calculated from the video data of the nth shooting for measurement point 7a in area B).

[0040] When the imaging of area B is to be completed (No in S145), the transfer function calculation unit 43 selects a transfer function of an arbitrary frequency (e.g., fundamental natural frequency f1) at an arbitrary number of times (e.g., the mth time) of imaging of area A. In addition, the transfer function calculation unit 43 selects a transfer function of an arbitrary number of times (e.g., the nth time) of imaging of area B that is common to area A. Then, the transfer function calculation unit 43 calculates the errors of the transfer functions of areas A and B (S150). In the example shown in FIG. 1, the errors α1, α2, and α3 are calculated from the difference between the transfer functions at measurement points 7a, 7b, and 7c that are common to areas A and B, as shown in Equation 4. α1=(H 7aAm -H 7aBn ) / H 7aAm α2=(H 7bAm -H 7bBn ) / H 7bAm α3=(H 7cAm -H 7cBn ) / H 7cAm (4)

[0041] If all of α1 to α3 are not 0.01 (1%) or less (No in S155), a transfer function for another imaging time is selected in area B, and the error calculation is repeated (S150). If the error is not 0.01 or less for all transfer functions of imaging time n in area B, the imaging time m in area A is changed, and the error calculation is repeated again.

[0042] If all of α1 to α3 are 0.01 or less (No in S155), the transfer function calculation unit 43 determines that the transfer functions calculated based on the mth shooting data of the corresponding area A and the nth shooting data of the corresponding area B are the same (S160).

[0043] The transfer function calculation unit 43 combines the area A based on the m-th imaging data and the area B based on the n-th imaging data, and calculates the corresponding transfer function set {H 6aAm ,H 6bAm ,H 6cAm ,H 7aAm ,H 7bAm ,H 7cAm ,H 8aBn ,H 8bBn ,H 8cBn} is determined as the set of transfer functions for the entire object to be measured O.

[0044] The transfer function calculation unit 43 calculates the transfer function set {H 6aAm ,H 6bAm ,H 6cAm ,H 7aAm ,H 7bAm ,H 7cAm ,H 8aBn ,H 8bBn ,H 8cBn} to generate a natural vibration mode, and the output unit 44 outputs the generated natural vibration mode in a graphical form (S165).

[0045] In this embodiment, the transfer function (H 7aAm ,H 7bAm ,H 7cAm ,H 7aBn ,H 7bBn ,H 7cBn ) is calculated, and the error (α1, α2, α3) of the transfer function captured at the natural frequency f of interest is calculated. Data with small errors at all measurement points (7a, 7b, 7c) is considered to be measurement data of the same vibration state, and the natural vibration mode is calculated using the data from both corresponding areas A and B. In this way, with the vibration visualization system of this embodiment, it is possible to generate the natural vibration mode of the entire measurement target without fitting the entire measurement target within the angle of view.

[0046] (Second embodiment) Next, a vibration visualization system according to a second embodiment will be described with reference to Fig. 4. In the vibration visualization system of this embodiment, vibration data extracted by the video data acquisition unit 41 includes two-dimensional parameters. In the following description, identical components are denoted by common reference numerals, and duplicated descriptions will be omitted.

[0047] Fig. 4 is a schematic diagram showing the configuration of a vibration visualization system according to the second embodiment. The vibration visualization system 20 shown in Fig. 4 includes a camera 2 that captures images of the measurement object O and its state, a data collection unit 3 that collects the image data captured by the camera 2, and a calculation device 4 that processes the image data collected by the data collection unit 3.

[0048] The image data acquisition unit 41 acquires the image data accumulated in the data accumulation unit 3 and detects vibration data indicating vibration at each of the measurement points 6a to 6c, 7a to 7c, and 8a to 8c. At this time, the vibration data has parameters of two-dimensional data based on the x and y axes. FIG. 4 shows vibration data X at the measurement points 7a, 7b, and 7c. 7ax,7ay , X 7bx,7by ,X 7cx,7cy are extracted, each containing parameters along the x-axis and y-axis.

[0049] The vibration data having two-dimensional parameters of the x and y axes is Fourier transformed by the Fourier transform unit 42 to generate a transfer function. Here, when combining areas A and B, the errors in the x-axis parameters and the y-axis parameters are calculated. That is, the vibration visualization system of the second embodiment has more comparison items for transfer function errors than the vibration visualization system of the first embodiment, and therefore can improve the accuracy when combining areas A and B.

[0050] (Third embodiment) Next, a vibration visualization system according to a third embodiment will be described with reference to Fig. 5. A vibration visualization system 30 according to this embodiment includes two or more cameras 2, 2a, and vibration data extracted by a video data acquisition unit 41 includes three-dimensional parameters. In the following description, identical components are denoted by common reference numerals, and duplicated explanations will be omitted.

[0051] Fig. 5 is a schematic diagram showing the configuration of a vibration visualization system according to the third embodiment. The vibration visualization system 30 shown in Fig. 5 includes cameras 2 and 2a that capture images of the measurement target O and its state, a data collection unit 3 that collects the video data captured by the cameras 2 and 2a, and a calculation device 4 that processes the video data collected by the data collection unit 3.

[0052] The image data acquisition unit 41 acquires the image data accumulated in the data accumulation unit 3 and detects vibration data indicating vibration at each measurement point. At this time, the vibration data has parameters of three-dimensional data based on the x, y, and z axes. Figure 5 shows vibration data X at measurement points 9a, 9b, and 9c. 9ax,9ay,9az ,X 9bx,9by、9bz ,X 9cx,9cy,9cz are extracted, and each contains parameters in the x-axis direction, y-axis direction, and z-axis direction. 9ax,9ay,9az ,X 9bx,9by、9bz ,X 9cx,9cy,9cz are vibration data at measurement points 9a, 9b, and 9c common to areas A1 and B1 photographed by cameras 2 and 2a, respectively.

[0053] The vibration data having three-dimensional parameters of the x, y, and z axes is Fourier transformed by the Fourier transform unit 42 to generate a transfer function. When combining area A1 and area B1, the errors of the x-axis parameter, y-axis parameter, and z-axis parameter are calculated. That is, the vibration visualization system of the third embodiment has more comparison items for transfer function errors than the vibration visualization system of the first embodiment, and therefore can improve the accuracy when combining areas A1 and B1.

[0054] Furthermore, in the vibration visualization system of this embodiment, since the vibration data has three-dimensional parameters, the transfer functions and natural vibration modes calculated from the vibration data also contain three-dimensional parameters, which means that the natural vibration modes related to the three-dimensional behavior of the measurement object O can be obtained.

[0055] While several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments may be embodied in various other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as set forth in the claims. [Explanation of symbols]

[0056] 1, 20, 30... vibration visualization system, 2... camera (imaging unit), 3... data collection unit (extraction unit), 4... calculation device (natural vibration mode calculation unit), 41... video data acquisition unit, 42... Fourier transform unit, 43... transfer function calculation unit, 44... output unit, 45... shooting control unit, 6a to 6c, 7a to 7c, 8a to 8c... measurement points, A, B... area, O... measurement object.

Claims

1. an imaging unit that acquires image data of a first region including a first measurement point and a second measurement point provided on the structure, and a second region including the second measurement point and a third measurement point provided on the structure; an extracting unit that extracts first vibration data at the first measurement point and second vibration data at the second measurement point from the video data of the first region, and extracts third vibration data at the second measurement point and fourth vibration data at the third measurement point from the video data of the second region; a transfer function calculation unit that calculates a transfer function based on each of the first to fourth vibration data; a natural vibration mode calculation unit that calculates a natural vibration mode of the structure using the transfer function corresponding to the first vibration data, the transfer function corresponding to the second vibration data, and the transfer function corresponding to the fourth vibration data when a difference between the transfer function corresponding to the second vibration data and the transfer function corresponding to the third vibration data is equal to or smaller than a predetermined threshold value; Vibration visualization system with

2. the extraction unit extracts the first to fourth vibration data as two-dimensional data; the transfer function calculation unit calculates a transfer function made up of two-dimensional data based on each of the first to fourth vibration data, The natural vibration mode calculation unit compares the difference between the transfer functions formed from two-dimensional data with a threshold value.

2. The vibration visualization system according to claim 1,

3. the imaging unit includes a first camera that acquires video data of the first area, and a second camera that acquires video data of the second area from a direction different from an imaging direction of the first camera; the natural vibration mode calculation unit calculates a difference between a transfer function corresponding to the second vibration data and a transfer function corresponding to the third vibration data using three-dimensional parameters.

2. The vibration visualization system according to claim 1,

4. a transform unit that performs a Fourier transform on each of the first to fourth vibration data extracted by the extractor, The transfer function calculation unit calculates a transfer function at a fundamental natural frequency.

2. The vibration visualization system according to claim 1,

5. the imaging unit acquires video data of the first and second areas a plurality of times, the extraction unit extracts the first to fourth vibration data for a plurality of times based on the plurality of video data; the transfer function calculation unit calculates transfer functions for a plurality of times based on the first to fourth vibration data for the plurality of times, The natural vibration mode calculation unit selects a combination from the group of transfer functions for the plurality of times, in which a difference between a transfer function corresponding to the second vibration data and a transfer function corresponding to the third vibration data is equal to or less than a predetermined threshold value.

2. The vibration visualization system according to claim 1,

6. acquiring image data of a first region including a first measurement point and a second measurement point provided on the structure, and a second region including the second measurement point and a third measurement point provided on the structure; extracting first vibration data at the first measurement point and second vibration data at the second measurement point from the video data of the first region, and extracting third vibration data at the second measurement point and fourth vibration data at the third measurement point from the video data of the second region; calculating a transfer function based on each of the first to fourth vibration data; When a difference between a transfer function corresponding to the second vibration data and a transfer function corresponding to the third vibration data is equal to or less than a predetermined threshold value, a natural vibration mode of the structure is calculated using a transfer function corresponding to the first vibration data, a transfer function corresponding to the second vibration data, and a transfer function corresponding to the fourth vibration data. A vibration visualization method characterized by:

Images