Resonance frequency determination device, structure diagnosis device, resonance frequency determination method, structure diagnosis method and program

Abstract

To enable accurate determination of a frequency accompanied by a resonance characteristic of a structure.SOLUTION: An resonance frequency determination device includes: an amplitude characteristic acquisition unit that acquires a first amplitude frequency characteristic from first oscillation data detected by using a first sensor, and acquires a second amplitude frequency characteristic from second oscillation data; a phase characteristic acquisition unit that acquires a phase frequency characteristic on the basis of the first amplitude characteristic and second amplitude frequency characteristic; a resonance candidate frequency acquisition unit that acquires one or more resonance candidate frequencies serving as a candidate of a resonance frequency in a structure; and a resonance frequency determination unit that determines whether the phase frequency characteristic is non-linearly in the resonance candidate frequency, and determines the resonance candidate frequency in which it is determined that the phase frequency characteristic is non-linearly in the resonance candidate frequency as a resonance frequency, of the one or more resonance candidate frequencies.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a resonant frequency determination device, a structure diagnosis device, a resonant frequency determination method, a structure diagnosis method, and a program. [Background technology]

[0002] There is known a technique for diagnosing deterioration, damage, or soundness of a structure using the vibration characteristics of the structure. The vibration characteristics used to diagnose deterioration, damage, or soundness of the structure include the natural frequency of a specific natural vibration mode of the structure. The vibration of the structure is measured by a sensor, such as a displacement sensor, a velocity sensor, or an acceleration sensor, arranged on the structure. The natural vibration mode refers to the manner in which vibration appears in an object vibrating at a natural frequency. The natural vibration mode is represented by the spatial distribution of vibration amplitude in an object vibrating at a natural frequency. Generally, a structure has multiple natural vibration modes. The vibration of the structure is represented by the superposition of multiple natural vibration modes.

[0003] As a related technique, Patent Document 1 discloses a vibration measuring device for measuring vibrations of structures such as bridges and buildings. In Patent Document 1, one or more sensors are installed on the structure. An impact is applied to the structure using a wooden or plastic hammer. The vibration measuring device calculates the first and second vibration modes based on signals detected by the sensors when the structure is impacted. The vibration measuring device calculates the natural frequency based on the first and second vibration modes. The vibration measuring device compares the natural frequencies calculated for the same structure at different times. This allows the diagnostician to understand changes in vibration characteristics over time. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-183362 Summary of the Invention [Problem to be solved by the invention]

[0005] Generally, the natural frequency, which is a resonance characteristic of a structure, is extracted based on the frequency spectrum characteristics of the acceleration time history waveform. Specifically, the frequency of the spectrum peak in the frequency characteristics of the acceleration amplitude is extracted as the natural frequency. However, the spectrum peaks in the frequency characteristics include not only the spectrum peaks associated with the resonance characteristics of the structure, but also spectrum peaks associated with mechanical vibrations caused by disturbances, i.e., the surrounding environment or the vehicle. If a spectrum peak caused by a disturbance is extracted as the natural frequency, there is a risk of erroneous diagnosis of damage to the structure.

[0006] One of the objects of the present disclosure is to provide a resonance frequency determination device, a structure diagnosis device, a resonance frequency determination method, a structure diagnosis method, and a program that can accurately determine the frequency associated with the resonance characteristics of a structure. [Means for solving the problem]

[0007] A resonant frequency determination method according to a first aspect of the present disclosure includes: acquiring a first amplitude-frequency characteristic from first vibration data detected using a first sensor, among a plurality of sensors each for detecting vibrations occurring in a structure, that is located closest to an expansion joint connecting the structure to another structure; acquiring a second amplitude-frequency characteristic from second vibration data detected using a second sensor, among the plurality of sensors, that is different from the first sensor; acquiring a phase-frequency characteristic based on the first amplitude-frequency characteristic and the second amplitude-frequency characteristic; acquiring one or more candidate resonant frequencies that are candidates for resonant frequencies in the structure, based on the amplitude-frequency characteristic acquired based on vibration data detected using at least one of the plurality of sensors; determining whether the phase-frequency characteristic is nonlinear at the one or more candidate resonant frequencies; and determining, as a resonant frequency, a candidate resonant frequency, among the one or more candidate resonant frequencies, for which the phase-frequency characteristic is determined to be nonlinear.

[0008] A structure diagnosis method according to a second aspect of the present disclosure includes: acquiring amplitude-frequency characteristics from vibration data detected by each of a plurality of sensors, each of which detects vibrations occurring in a structure; acquiring phase-frequency characteristics based on a first amplitude-frequency characteristic acquired for a first sensor of the plurality of sensors that is located closest to an expansion joint connecting the structure to another structure, and a second amplitude-frequency characteristic acquired for a second sensor of the plurality of sensors that is different from the first sensor; acquiring one or more candidate resonance frequencies that are candidates for resonant frequencies of the structure based on the amplitude-frequency characteristic acquired for at least one of the plurality of sensors; determining, for the one or more candidate resonance frequencies, whether the phase-frequency characteristic is nonlinear at the candidate resonance frequencies; determining, among the one or more candidate resonance frequencies, a candidate resonance frequency for which the phase-frequency characteristic is determined to be nonlinear as a resonant frequency; acquiring natural vibration information of the structure at the determined resonant frequency; and diagnosing the health of the structure using the acquired natural vibration information.

[0009] A resonant frequency determination device according to a third aspect of the present disclosure includes: an amplitude characteristic acquisition unit that acquires a first amplitude-frequency characteristic from first vibration data detected using a first sensor, among a plurality of sensors each for detecting vibrations occurring in a structure, that is located closest to an expansion joint connecting the structure to another structure; and acquires a second amplitude-frequency characteristic from second vibration data detected using a second sensor, among the plurality of sensors, that is different from the first sensor; a phase characteristic acquisition unit that acquires a phase-frequency characteristic based on the first amplitude-frequency characteristic and the second amplitude-frequency characteristic; a candidate resonance frequency acquisition unit that acquires one or more candidate resonance frequencies for a resonant frequency of the structure, based on the amplitude-frequency characteristic acquired based on vibration data detected using at least one of the plurality of sensors; and a resonant frequency determination unit that determines whether the phase-frequency characteristic is nonlinear at the one or more candidate resonance frequencies, and determines, from the one or more candidate resonance frequencies, a candidate resonance frequency for which the phase-frequency characteristic is determined to be nonlinear, as a resonant frequency.

[0010] A structure diagnosis device according to a fourth aspect of the present disclosure includes: an amplitude characteristic acquisition unit that acquires, for each of a plurality of sensors that detect vibrations occurring in a structure, amplitude-frequency characteristics from vibration data detected by each sensor; a phase characteristic acquisition unit that acquires phase-frequency characteristics based on a first amplitude-frequency characteristic acquired for a first sensor of the plurality of sensors that is located closest to an expansion joint connecting the structure to another structure, and a second amplitude-frequency characteristic acquired for a second sensor of the plurality of sensors that is different from the first sensor; a candidate resonance frequency acquisition unit that acquires one or more candidate resonance frequencies that are resonant frequency candidates for the structure based on the amplitude-frequency characteristic acquired for at least one of the plurality of sensors; a resonance frequency determination unit that determines whether the phase-frequency characteristic is nonlinear at the one or more candidate resonance frequencies and determines, as a resonant frequency, a candidate resonance frequency determined to have a nonlinear phase-frequency characteristic at the one or more candidate resonance frequencies; and a natural vibration information acquisition unit that acquires natural vibration information of the structure at the determined resonant frequencies. and a diagnosis unit that diagnoses the soundness of the structure using the acquired natural vibration information.

[0011] A program according to a fifth aspect of the present disclosure causes a computer to execute a process including: acquiring a first amplitude-frequency characteristic from first vibration data detected using a first sensor, among a plurality of sensors each for detecting vibrations occurring in a structure, the first sensor being located closest to an expansion joint connecting the structure to another structure; acquiring a second amplitude-frequency characteristic from second vibration data detected using a second sensor, different from the first sensor, among the plurality of sensors; acquiring a phase-frequency characteristic based on the first amplitude-frequency characteristic and the second amplitude-frequency characteristic; acquiring one or more candidate resonance frequencies that are candidates for resonant frequencies of the structure, based on the amplitude-frequency characteristic acquired based on vibration data detected using at least one of the plurality of sensors; determining, for the one or more candidate resonance frequencies, whether the phase-frequency characteristic is nonlinear at the candidate resonance frequencies; and determining, from the one or more candidate resonance frequencies, a candidate resonance frequency for which the phase-frequency characteristic is determined to be nonlinear, as a resonant frequency.

[0012] a phase-frequency characteristic based on a first amplitude-frequency characteristic acquired for a first sensor among the plurality of sensors that is located closest to an expansion joint connecting the structure to another structure, and a second amplitude-frequency characteristic acquired for a second sensor among the plurality of sensors that is different from the first sensor; acquiring one or more candidate resonance frequencies that are candidates for a resonance frequency of the structure based on the amplitude-frequency characteristic acquired for at least one of the plurality of sensors; determining whether or not the phase-frequency characteristic is nonlinear at the one or more candidate resonance frequencies; determining, among the one or more candidate resonance frequencies, a candidate resonance frequency whose phase-frequency characteristic is determined to be nonlinear at the candidate resonance frequency as a resonance frequency; acquiring natural vibration information of the structure at the determined resonance frequency; and diagnosing the soundness of the structure using the acquired natural vibration information. [Effects of the Invention]

[0013] The resonance frequency determination device, structure diagnosis device, resonance frequency determination method, structure diagnosis method, and program according to the present disclosure can accurately determine the frequency associated with the resonance characteristics of a structure. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a block diagram illustrating a schematic configuration example of a structure diagnosis device according to the present disclosure. [Figure 2] 1 is a block diagram illustrating an example of a configuration of a structure diagnosis device according to the present disclosure. [Figure 3] FIG. 2 is a schematic diagram showing an example of the arrangement of sensors in a structure to be diagnosed. [Figure 4] 1 is a graph showing an example of a time history waveform of acceleration detected by a sensor. [Figure 5]10 is a graph showing an example of amplitude-frequency characteristics acquired for a certain sensor. [Figure 6] 10 is a graph showing an example of a phase frequency characteristic obtained using the amplitude frequency characteristic of a sensor pair. [Figure 7] 10 is a graph showing a phase frequency characteristic and an approximation line of the phase frequency characteristic. [Figure 8] 3 is a flowchart showing an operation procedure of the structure diagnosis device. [Figure 9] 4 is a flowchart showing an operation procedure of the resonant frequency determining device. [Figure 10] FIG. 10 is a block diagram illustrating another example configuration of a structure diagnosis device according to the present disclosure. [Figure 11] FIG. 2 is a block diagram showing an example of the configuration of a sensor. [Figure 12] FIG. 1 is a block diagram illustrating an example of the configuration of a computer device. DETAILED DESCRIPTION OF THE INVENTION

[0015] Prior to describing the embodiments of the present disclosure, an overview of the present disclosure will be described. Fig. 1 is a block diagram showing a schematic configuration example of a structure diagnosis device according to the present disclosure. The structure diagnosis device 10 includes an amplitude characteristic acquisition unit 11, a phase characteristic acquisition unit 12, a candidate resonance frequency acquisition unit 13, a resonance frequency determination unit 14, a natural vibration information acquisition unit 15, and a diagnosis unit 16. In the structure diagnosis device 10, the amplitude characteristic acquisition unit 11, the phase characteristic acquisition unit 12, the candidate resonance frequency acquisition unit 13, and the resonance frequency determination unit 14 constitute a resonance frequency determination device 20.

[0016] The amplitude characteristic acquisition unit 11 acquires amplitude frequency characteristics from vibration data detected using each of a plurality of sensors, each of which detects vibrations occurring in the structure. The amplitude frequency characteristics acquired by the amplitude characteristic acquisition unit 11 include a first amplitude frequency characteristic acquired for a first sensor arranged at a position closest to an expansion joint connecting the structure to another structure, and a second amplitude frequency characteristic acquired for a second sensor different from the first sensor.

[0017] The phase characteristic acquisition unit 12 acquires the phase frequency characteristic based on the first amplitude frequency characteristic and the second amplitude frequency characteristic. The candidate resonance frequency acquisition unit 13 acquires one or more candidate resonance frequencies that are candidates for the resonance frequency of the structure based on the amplitude frequency characteristic acquired for at least one of the multiple sensors. The resonance frequency determination unit 14 determines whether or not the phase frequency characteristic is nonlinear at the acquired candidate resonance frequency. The resonance frequency determination unit 14 determines, among the one or more candidate resonance frequencies, the candidate resonance frequency whose phase frequency characteristic is determined to be nonlinear at the candidate resonance frequency as the resonance frequency.

[0018] The natural vibration information acquisition unit 15 acquires natural vibration information of the structure at the frequency determined to be the resonant frequency by the resonant frequency determination unit 14. The diagnosis unit 16 uses the acquired natural vibration information to diagnose the soundness of the structure.

[0019] In the present disclosure, the phase characteristic acquisition unit 12 acquires the phase-frequency characteristic based on the first amplitude-frequency characteristic and the second amplitude-frequency characteristic. The resonant frequency determination unit 14 determines whether the phase-frequency characteristic is nonlinear at the candidate resonant frequency. The resonant frequency determination unit 14 determines, from among the acquired candidate resonant frequencies, a candidate resonant frequency at which the phase-frequency characteristic is determined to be nonlinear, as the resonant frequency. In this manner, the resonant frequency determination device 20 can prevent erroneous determination of a frequency different from the resonant characteristic of the structure as the resonant frequency, and can accurately determine the resonant frequency associated with the resonant characteristic of the structure. Furthermore, the structure diagnosis device 10 can accurately use the resonant frequency to correctly diagnose damage, deterioration, or soundness of the structure.

[0020] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the following description and drawings have been omitted and simplified as appropriate for clarity of explanation. In addition, in each drawing, the same or similar elements are designated by the same reference numerals, and duplicate explanations are omitted as necessary.

[0021] A first embodiment of the present disclosure will be described. Fig. 2 is a block diagram showing an example of the configuration of a structure diagnosis device according to the present disclosure. The structure diagnosis device 100 shown in Fig. 2 includes a data acquisition unit 101, a data extraction unit 102, an amplitude characteristic acquisition unit 103, a phase characteristic acquisition unit 104, a resonance candidate frequency acquisition unit 105, a resonance frequency determination unit 106, a natural vibration information acquisition unit 107, and a diagnosis unit 108.

[0022] In the structure diagnosis device 100, the data acquisition unit 101, the data extraction unit 102, the amplitude characteristic acquisition unit 103, the phase characteristic acquisition unit 104, the resonance candidate frequency acquisition unit 105, and the resonance frequency determination unit 106 constitute a resonance frequency determination device 120. The structure diagnosis device 100 corresponds to the structure diagnosis device 10 shown in Fig. 1. The resonance frequency determination device 120 corresponds to the resonance frequency determination device 20 shown in Fig. 1.

[0023] The structure diagnosis device 100 is configured as, for example, a computer device or a server device having one or more memories and one or more processors. At least a part of the functions of each unit in the structure diagnosis device 100 can be realized by one or more processors executing processing in accordance with instructions read from one or more memories. The structure diagnosis device 100 does not necessarily have to be configured as a single physical device. The structure diagnosis device 100 may be configured using multiple physically separated devices.

[0024] The data acquisition unit 101 acquires sensor data from a plurality of sensors 150. Each of the plurality of sensors 150 is a sensor for detecting vibrations occurring in a structure. The plurality of sensors 150 are installed at different positions in the structure to be diagnosed. In this embodiment, an acceleration sensor is used as the sensor 150. The sensor 150 may be any sensor capable of detecting a time history waveform of displacement, and the sensor 150 is not limited to an acceleration sensor.

[0025] 3 is a schematic diagram showing an example of the arrangement of sensors 150 in a structure to be diagnosed. In this example, the structure to be diagnosed is a bridge 200. As shown in FIG. 3, five sensors 150-1 to 150-5 are attached to the bridge 200. The sensors 150-1 to 150-5 are attached to, for example, the deck of the bridge 200. The bridge 200 has an expansion joint 210 at a connection portion with another structure such as an abutment.

[0026] In this embodiment, the bridge 200 is assumed to be a bridge over which vehicles 250, which are moving objects such as trucks and trailers, can pass. Vibrations are applied to the bridge 200 as the vehicles 250 pass over. In particular, when the vehicle 250 exits the bridge 200, vibrations are applied to the bridge 200 due to elastic shock waves generated when the vehicle 250 steps over the expansion joint 210. The multiple sensors 150 detect accelerations occurring in the bridge 200 due to the vibrations at the respective positions where the sensors are installed.

[0027] The data acquisition unit 101 acquires, as sensor data, a time history waveform of acceleration occurring in a structure from a plurality of sensors 150. The sensor data acquired by the data acquisition unit 101 from the plurality of sensors 150 is assumed to be time-synchronized. The sensor data may be stored in a device such as a data logger, and the data acquisition unit 101 may acquire the sensor data from the data logger. The data acquisition unit 101 may acquire the sensor data from the plurality of sensors 150 via a wired network or a wireless network.

[0028] The data extraction unit 102 extracts, as vibration data, from each of the sensor data acquired from the multiple sensors 150, sensor data of a section of the acceleration time history waveform, i.e., a series of acceleration measurement values, that represents a damping portion of vibration of the structure due to excitation. For example, the data extraction unit 102 identifies the time when the vehicle 250 exits the bridge 200 when only one vehicle 250 is traveling on the bridge 200. The data extraction unit 102 may identify the time when the vehicle 250 last stepped on the extension / retraction device 210, i.e., the time when the last wheel of the vehicle 250 passed the extension / retraction device 210, as the time when the vehicle 250 exited the bridge 200. The data extraction unit 102 sets the time when the vehicle 250 exited the bridge 200 as the starting point, and extracts sensor data within a predetermined time from the starting time as vibration data.

[0029] As an example, the data extraction unit 102 acquires sensor data, i.e., acceleration measurement values ​​at each time, acquired from sensor 150-1, which is closest to the extension / retraction device 210 as shown in FIG. 3, among the multiple sensors 150. The data extraction unit 102 determines whether the acceleration is equal to or greater than a predetermined threshold. The data extraction unit 102 identifies the last time the acceleration became equal to or greater than the predetermined threshold as the time when the last wheel of the vehicle 250 passed the extension / retraction device 210. The data extraction unit 102 extracts, as vibration data, data within a time range of several seconds from the time when the last wheel of the vehicle 250 passed the extension / retraction device 210 from each of the sensor data acquired from sensors 150-1 to 150-5.

[0030] FIG. 4 is a graph showing an example of a time history waveform of acceleration detected by sensor 150-1 installed at a position closest to extension joint 210. In the graph shown in FIG. 4, the vertical axis represents acceleration, and the horizontal axis represents time. From changes in the detected acceleration, data extraction unit 102 identifies time t0, when the last wheel of vehicle 250 passes extension joint 210. Data extraction unit 102 defines time t1 as a predetermined time after time t0, and extracts sensor data from the time range from time t0 to time t1 as vibration data. The extracted vibration data indicates a time history waveform of damped free vibration when vehicle 250 leaves bridge 200. Data extraction unit 102 also extracts sensor data from the other sensors 150-2 to 150-5 from the time range from time t0 to time t1 as vibration data.

[0031] The amplitude characteristic acquisition unit 103 acquires amplitude-frequency characteristics from the vibration data extracted by the data extraction unit 102 for each of the multiple sensors 150. For example, the amplitude characteristic acquisition unit 103 performs a Fourier transform on the time history waveform of acceleration, i.e., the vibration data indicating the amplitude of acceleration at each time, for each sensor 150, to convert the vibration data into data in the frequency domain. The amplitude characteristic acquisition unit 103 acquires the Fourier amplitude of each frequency as the amplitude-frequency characteristic. The Fourier amplitude is expressed as a complex number. The amplitude characteristic acquisition unit 103 corresponds to the amplitude characteristic acquisition unit 11 shown in FIG. 1.

[0032] The phase characteristic acquisition unit 104 acquires phase frequency characteristics, i.e., phase frequency characteristics, based on the amplitude frequency characteristics of a sensor pair including, among the multiple sensors 150, a sensor 150 used as a phase reference sensor and another sensor 150 used as a diagnostic sensor. In acquiring the phase frequency characteristics, the phase characteristic acquisition unit 104 calculates a transfer function based on the amplitude frequency characteristics acquired for the phase reference sensor and the amplitude frequency characteristics acquired for the diagnostic sensor. The phase reference sensor is also referred to as a first sensor. Vibration data extracted from the sensor data of the phase reference sensor is also referred to as first vibration data. The amplitude frequency characteristics acquired for the phase reference sensor are also referred to as first frequency characteristics. The diagnostic sensor is also referred to as a second sensor. Vibration data extracted from the sensor data of the diagnostic sensor is also referred to as second vibration data. The amplitude frequency characteristics acquired for the diagnostic sensor are also referred to as second amplitude frequency characteristics. The phase characteristic acquisition unit 104 calculates the phase frequency characteristics based on the calculated transfer function. The phase characteristic acquisition unit 104 corresponds to the phase characteristic acquisition unit 12 shown in FIG.

[0033] In this embodiment, the phase reference sensor is the sensor among the multiple sensors 150 that is installed at a position closest to the extension joint 210 on the exit side. The diagnostic sensor is one sensor selected from the multiple sensors 150 other than the phase reference sensor. The diagnostic sensor may be appropriately selected from the sensors 150 other than the phase reference sensor depending on the vibration mode used for diagnosis. The diagnostic sensor is not necessarily limited to one, and multiple sensors may be selected sequentially as the diagnostic sensor. In this case, the phase characteristic acquisition unit 104 may acquire phase frequency characteristics for multiple sensor pairs.

[0034] An example of acquiring phase frequency characteristics will be described. Here, the phase reference sensor is sensor 150-1 shown in FIG. 3, and the diagnostic sensor is sensor 150-3. The time history waveform of acceleration acquired by phase reference sensor 150-1, i.e., the sensor response, is defined as x(t). The time history waveform of acceleration acquired by diagnostic sensor 150-3, i.e., the sensor response, is defined as y(t). Here, t represents time. The amplitude characteristics acquisition unit 103 Fourier transforms the sensor response x(t) of sensor 150-1, converting the sensor response x(t) into a Fourier amplitude X(f). The amplitude characteristics acquisition unit 103 also Fourier transforms the sensor response y(t) of sensor 150-1, converting the sensor response y(t) into a Fourier amplitude Y(f). Here, f represents frequency.

[0035] The phase characteristic acquisition unit 104 calculates a transfer function to the diagnostic sensor when the sensor response of the phase reference sensor is used as a pseudo input signal. Specifically, the phase characteristic acquisition unit 104 calculates the transfer function G(f) by G(f)=Y(f) / X(f). Since the Fourier amplitude X(f) and the Fourier amplitude Y(f) are both complex numbers, the transfer function G(f) is expressed as a complex number. G r Let (f) be the real part of the transfer function G(f), and G i With (f) as the imaginary part of the transfer function G(f), the phase characteristic acquisition unit 104 obtains the phase frequency characteristic φ(f) as φ(f)=tan -1 (G i (f) / G r (f)) is calculated.

[0036] The candidate resonance frequency acquisition unit 105 acquires one or more candidate resonance frequencies for the structure to be diagnosed, i.e., one or more candidate resonance frequencies, based on the amplitude frequency characteristics acquired for at least one of the multiple sensors 150. The candidate resonance frequency acquisition unit 105 acquires one or more candidate resonance frequencies based on, for example, the amplitude frequency characteristics acquired for the sensor 150 used as a diagnostic sensor. For example, the candidate resonance frequency acquisition unit 105 acquires, as the candidate resonance frequencies, frequencies whose spectral intensity is equal to or greater than a predetermined threshold in the amplitude frequency characteristics. The candidate resonance frequency acquisition unit 105 corresponds to the candidate resonance frequency acquisition unit 13 shown in FIG. 1.

[0037] The resonance frequency determination unit 106 determines whether or not a candidate resonance frequency is a resonance frequency based on the phase-frequency characteristic acquired by the phase characteristic acquisition unit 104. In this determination, the resonance frequency determination unit 106 determines whether or not the phase-frequency characteristic is nonlinear at the candidate resonance frequency. The resonance frequency determination unit 106 determines, as a resonance frequency, a candidate resonance frequency whose phase-frequency characteristic is nonlinear at the candidate resonance frequency, among one or more candidate resonance frequencies acquired by the candidate resonance frequency acquisition unit 105. The resonance frequency determination unit 106 corresponds to the resonance frequency determination unit 14 shown in FIG. 1.

[0038] The determination of the resonant frequency will now be described. FIG. 5 is a graph showing an example of amplitude-frequency characteristics acquired for a certain sensor. In the graph shown in FIG. 5, the vertical axis represents the magnitude of the amplitude, and the horizontal axis represents the frequency. The candidate resonance frequency acquisition unit 105 detects the peak of the frequency spectrum in the amplitude-frequency characteristics, i.e., the frequency domain data converted into a frequency domain signal. In the example shown in FIG. 5, the candidate resonance frequency acquisition unit 105 acquires frequencies f1 to f5 as candidate resonance frequencies.

[0039] Fig. 6 is a graph showing an example of phase-frequency characteristics acquired using the amplitude-frequency characteristics of a sensor pair. In the graph shown in Fig. 6, the vertical axis represents phase, and the horizontal axis represents frequency. The phase characteristic acquisition unit 104 calculates a transfer function from the sensor response of the phase reference sensor and the sensor response of the diagnostic sensor, and acquires the phase-frequency characteristics from the transfer function. As shown in Fig. 6, the acquired phase-frequency characteristics include a section where the phase changes linearly with frequency and a section where the phase does not change linearly with frequency.

[0040] Let us assume that the sensor response of the phase reference sensor is expressed as a sine wave. Specifically, let us assume that the sensor response of the phase reference sensor is Acos(ωt+φ0). Here, A represents the amplitude, ω represents the angular frequency, and t represents the time. The angular frequency ω is expressed as 2πf, where f represents the frequency. φ0 represents the initial phase, and ωt+φ0 represents the phase. In the diagnostic sensor, there is a time delay T with respect to the above sine wave. delay In this case, the sensor response of the diagnostic sensor is Acos{ω(tT delay )+φ0}. In this case, the phase difference between the sensor response of the phase reference sensor and the sensor response of the diagnostic sensor is ωt+φ0-{ω(tT delay )+φ0}=ωT delay From this, it can be seen that the phase difference is proportional to ω, that is, the frequency f. This indicates that the frequency characteristics of the phase difference have a linear relationship with the frequency.

[0041] As described above, when vibration is simply detected with a delay between the position of the phase reference sensor and the position of the diagnostic sensor, the frequency characteristic of the phase difference is linear. On the other hand, at the resonant frequency of a structure, the phase exhibits a nonlinear characteristic with respect to frequency. The resonant frequency determination unit 106 utilizes this property to determine whether a frequency acquired as a candidate resonant frequency is a resonant frequency. If the phase-frequency characteristic is linear at the candidate resonant frequency, the candidate resonant frequency is considered not to be a resonant frequency. On the other hand, if the phase-frequency characteristic is nonlinear at the candidate resonant frequency, the candidate resonant frequency is considered to be a resonant frequency.

[0042] FIG. 7 is a graph showing the phase-frequency characteristics and an approximation line of the phase-frequency characteristics. In the graph shown in FIG. 7, the vertical axis represents phase and the horizontal axis represents frequency. The resonant frequency determination unit 106 obtains an approximation formula that linearly approximates the phase-frequency characteristics, i.e., an approximation line. The resonant frequency determination unit 106 calculates the difference between the phase in the phase-frequency characteristics and the phase calculated using the approximation formula for each of frequencies f1 to f5, which are candidate resonance frequencies. If the difference exceeds a threshold, the resonant frequency determination unit 106 determines that the phase-frequency characteristics at the candidate resonance frequency are nonlinear. If the difference is equal to or less than the threshold, the resonant frequency determination unit 106 determines that the phase-frequency characteristics at the candidate resonance frequency are linear.

[0043] 7, the resonance frequency determination unit 106 determines that the phase-frequency characteristics are linear at frequencies f2 and f4. The resonance frequency determination unit 106 also determines that the phase-frequency characteristics are nonlinear at frequencies f1, f3, and f5. In this case, the resonance frequency determination unit 106 determines that frequencies f1, f3, and f5 are resonance frequencies, and that frequencies f2 and f4 are not resonance frequencies. The spectra of frequencies f2 and f4 in the amplitude-frequency characteristics are not spectra associated with resonance, but are considered to be spectra associated with external disturbances, i.e., mechanical vibrations of the surrounding environment or the vehicle.

[0044] 2, the natural vibration information acquisition unit 107 uses the determined resonant frequency information to acquire information on the natural vibrations occurring in the structure, i.e., natural vibration information. The natural vibration information includes the resonant frequency, i.e., the natural vibration mode and natural damping factor of the structure vibrating at the natural frequency.

[0045] The natural vibration information acquisition unit 107 acquires natural vibration information about vibrations that occur when a structure, such as a beam with both ends fixed, is excited to cause free damped vibration in the structure. For example, the natural vibration information acquisition unit 107 acquires the amplitude spectrum of a frequency determined to be a resonant frequency from each of the amplitude-frequency characteristics acquired by multiple sensors. The natural vibration information acquisition unit 107 may create a spatial distribution of the amplitude spectrum at the resonant frequency and determine the vibration mode at the resonant frequency based on the spatial distribution of the amplitude spectrum. The natural vibration information acquisition unit 107 corresponds to the natural vibration information acquisition unit 15 shown in FIG. 1.

[0046] The diagnosing unit 108 diagnoses the deterioration or soundness of the structure using the natural vibration information acquired by the natural vibration information acquiring unit 107. The diagnosing unit 108 determines, for example, whether a vibration occurring in the structure includes a vibration mode of a predetermined order. The order of a vibration mode is defined by the number of antinodes, where the point at which the amplitude is maximum is defined as an antinode and the point at which the amplitude is zero is defined as a node. In other words, the order of a vibration mode is defined by the number of positions at which the amplitude is large in a structure vibrating at a certain resonant frequency. The diagnosing unit 108 determines, for example, whether a third-order vibration mode is included in the vibration occurring in the structure. If the diagnosing unit 108 determines that the third-order vibration mode is included, it determines that the structure is not deteriorated and is sound.

[0047] The diagnosing unit 108 may compare the shape of the vibration mode with a theoretical shape or a reference shape of the vibration mode in a healthy structure and determine the health of the structure based on the comparison result. For example, if the shape of the vibration mode significantly deviates from the theoretical shape of the vibration mode, the diagnosing unit 108 may determine that the structure is not healthy. Alternatively, the diagnosing unit 108 may compare the shape of the vibration mode with shapes of vibration modes observed in the structure in the past and determine the health of the structure based on the comparison result. For example, if the shape of the vibration mode has changed from the shape of the vibration mode at a reference time, the diagnosing unit 108 may determine that the structure is not healthy. The method of diagnosing deterioration based on the natural vibration information in the diagnosing unit 108 is not limited to a specific method. The diagnosing unit 108 corresponds to the diagnosing unit 16 shown in FIG. 1.

[0048] Next, the operation procedure will be described. Fig. 8 is a flowchart showing the operation procedure of the structure diagnosis device 100. The operation procedure of the structure diagnosis device 100 corresponds to a structure diagnosis method. The data acquisition unit 101 acquires sensor data measured by a plurality of sensors 150 (step A1). In step A1, the data acquisition unit 101 may acquire the sensor data of the plurality of sensors 150 via a network such as the Internet, for example.

[0049] The data extraction unit 102 extracts vibration data from the sensor data acquired in step A1 (step A2). In step A2, the data extraction unit 102 extracts, for each of the multiple sensors 150, data on a portion of the time history waveform of damped free vibration included in the sensor data as vibration data. The vibration data extraction may be performed manually. In the structure diagnosis device 100, the resonant frequency determination device 120 determines the resonant frequency using the vibration data extracted in step A2 (step A3).

[0050] 9 is a flowchart showing the operation procedure of the resonant frequency determination device 120. The operation procedure of the resonant frequency determination device 120 corresponds to a resonant frequency determination method. The amplitude characteristic acquisition unit 103 acquires amplitude frequency characteristics from the vibration data extracted by the data extraction unit 102 (step B1). The phase characteristic acquisition unit 104 calculates a transfer function between the phase reference sensor and the diagnostic sensor based on the amplitude frequency characteristics acquired for the phase reference sensor and the amplitude frequency characteristics acquired for the diagnostic sensor (step B2). The phase characteristic acquisition unit 104 acquires the phase frequency characteristics, i.e., the frequency characteristics of the phase difference between the phase reference sensor and the diagnostic sensor, based on the calculated transfer function (step B3).

[0051] The candidate resonance frequency acquisition unit 105 acquires one or more candidate resonance frequencies based on the amplitude frequency characteristics acquired in step B1 (step B4). In step B4, the candidate resonance frequency acquisition unit 105 acquires, for example, frequencies whose spectrum intensity is equal to or greater than a threshold value in the amplitude frequency characteristics as candidate resonance frequencies.

[0052] The resonant frequency determination unit 106 determines whether the phase-frequency characteristic at the candidate resonance frequency obtained in step B4 is nonlinear, using the phase-frequency characteristic obtained in step B3 (step B5). If the resonant frequency determination unit 106 determines that the phase-frequency characteristic at the candidate resonance frequency is nonlinear in step B5, it determines that the candidate resonance frequency is a resonant frequency (step B6). If the resonant frequency determination unit 106 determines that the phase-frequency characteristic at the candidate resonance frequency is not nonlinear in step B5, it determines that the candidate resonance frequency is not a resonant frequency (step B7).

[0053] Returning to Fig. 8, the natural vibration information acquisition unit 107 uses the determined resonant frequency information to acquire information on the natural vibrations occurring in the structure, i.e., natural vibration information (step A4). In step A4, the natural vibration information acquisition unit 107 acquires, as natural vibration information, the natural vibration mode and natural damping rate of the structure vibrating at the resonant frequency, for example, based on the amplitude frequency characteristics acquired by the amplitude characteristics acquisition unit 103. The diagnosis unit 108 uses the natural vibration information acquired in step A4 to diagnose the deterioration, damage, or soundness of the structure (step A5).

[0054] In this embodiment, the data acquisition unit 101 acquires time-synchronized sensor data from multiple sensors 150. The data extraction unit 102 extracts, from the sensor data, data within the time range of damped free vibration when a vehicle exits a structure such as a bridge as vibration data. The phase characteristic acquisition unit 104 uses the sensor 150 installed closest to the extension joint on the exit side as a phase reference sensor and acquires the frequency characteristics of the phase difference between the phase reference sensor and the diagnostic sensor. In this way, phase information at each frequency can be obtained starting from the time when the impact elastic wave caused by the rear wheel is generated.

[0055] If the phase-frequency characteristics at a candidate resonance frequency are nonlinear, the resonance frequency determination unit 106 determines that the candidate resonance frequency is a resonant frequency. In other words, if a nonlinear phase change different from a time delay occurs at the candidate resonance frequency, the resonance frequency determination unit 106 determines that the candidate resonance frequency is a resonant frequency. In this manner, the resonance frequency determination unit 106 can correctly determine the resonant frequency, which is a characteristic of the structure, even if the structure vibrates due to a disturbance or the like. In addition, in this embodiment, the diagnosing unit 108 diagnoses damage, deterioration, or soundness of the structure using natural vibration information of the frequency determined to be a resonant frequency. In this embodiment, the resonant frequency can be correctly determined, and therefore the damage, deterioration, or soundness of the structure can be correctly determined.

[0056] Here, when the excitation force can be measured, such as when vibrating a structure using a hammer, it is possible to determine whether a spectral peak represents a resonance by focusing on the phase characteristics of the transfer function. However, in bridge measurements, it is difficult to quantitatively measure the excitation force, i.e., the force applied to the bridge due to vehicle traffic. Furthermore, when vibration is not intentionally applied to the structure, how to set the initial phase in a structure diagnosis system is also an issue. Therefore, when the excitation force is unknown, a structure diagnosis system cannot obtain a transfer function including the phase, and cannot correctly determine whether resonance, i.e., natural vibration, occurs. As a result, a structure diagnosis system may erroneously determine the resonant frequency and erroneously diagnose damage to the structure.

[0057] In contrast, the resonant frequency determination device 120 according to this embodiment can determine whether a candidate resonance frequency is a resonant frequency based on the occurrence of a nonlinear phase change using responses from multiple sensors 150 installed on a structure. In determining the resonant frequency, it is not necessary to measure the excitation force applied to the structure or to set an initial phase. Even in this case, the resonant frequency determination device 120 can accurately determine the resonant frequency even in an environment with external disturbances. Furthermore, the structure diagnosis device 100 can diagnose damage to the structure using the determined resonant frequency. The determination of the resonant frequency according to this embodiment can also be used in application fields such as railway bridges and aqueducts, and has high industrial utility value.

[0058] An example will be described below. The inventors conducted an experiment to confirm the effect of the structure diagnosis device 100 according to this embodiment. In the experiment, bridge damage was diagnosed for a bridge whose presence or absence of damage was known, both in the case where the resonant frequency was determined based on the phase frequency characteristics and in the case where the determination was not performed. In the experiment, sensor data was acquired from multiple sensors attached to a bridge deck whose presence or absence of damage, i.e., whose change in natural frequency between the initial state and the time of diagnosis, was known, and the acquired sensor data was input into the structure diagnosis device.

[0059] In the comparative example, sensor 150 installed at the center of the deck span was used as the diagnostic sensor, and the natural frequency was extracted from the damped vibration immediately after the vehicle left. The presence or absence of damage was diagnosed based on whether the natural frequency changed between the initial state and the time of diagnosis. On the other hand, in the example, the sensor installed closest to the expansion joint was used as the phase reference sensor, and the sensor installed at the center of the deck span was used as the diagnostic sensor. Phase frequency characteristics were obtained from the sensor responses of the phase reference sensor and the diagnostic sensor for the damped vibration immediately after the vehicle left, and the obtained phase frequency characteristics were used to determine whether the natural frequency extracted from the damped vibration immediately after the vehicle left was a resonant frequency. The presence or absence of damage was diagnosed based on whether the natural frequency determined to be a resonant frequency changed between the initial state and the time of diagnosis.

[0060] In the comparative example, the frequency of vibration due to disturbance was extracted as the natural frequency. As a result, a bridge that was not actually damaged was mistakenly diagnosed as damaged. In contrast, in the example, the phase frequency characteristic was used to determine the resonant frequency, so the frequency of vibration due to disturbance was not extracted as the natural frequency. As a result, the natural frequency could be correctly extracted, and the presence or absence of damage could be correctly diagnosed.

[0061] Next, a second embodiment will be described. Fig. 10 is a block diagram showing another example of the configuration of a structure diagnosis device according to the present disclosure. In a structure diagnosis device 100a shown in Fig. 10, a resonant frequency determination device 120a has a phase correction unit 109 in addition to the configuration of the resonant frequency determination device 120 shown in Fig. 2.

[0062] 11 is a block diagram showing an example configuration of a sensor 150. In this example, each of the multiple sensors 150 has a detection unit 151, which is a sensor main body, and an electronic circuit 152. The electronic circuit 152 may include an amplifier that amplifies the detection signal of the detection unit 151. The electronic circuit 152 may also include a frequency band filter that passes or blocks signals of a specific frequency from the detection signal of the detection unit 151. The electronic circuit 152 is typically configured as an analog electronic circuit.

[0063] The electronic circuit 152 does not necessarily have to be built into the sensor 150. The electronic circuit 152 may be included in the data acquisition unit 101 that acquires measurement data from multiple sensors 150. For example, the data acquisition unit 101 has an analog-to-digital converter for each channel that converts the detection signal of each sensor 150 from an analog signal to a digital signal. In each channel, the electronic circuit 152 may perform frequency band filtering and signal amplification on the detection signal of each sensor 150, which is an analog signal, in accordance with the specifications of the digital signal, such as the sampling frequency. The electronic circuit 152 may be inserted in a signal path from each sensor 150 to the data acquisition unit 101.

[0064] Each electronic circuit 152 may have its own phase characteristic. The phase characteristic indicates, for example, the frequency characteristic of the phase. Due to the phase characteristic of the electronic circuit 152, the phase characteristic of the measurement value, i.e., the phase characteristic of the measurement data, may differ between one sensor 150 and another sensor 150. When the phase characteristics differ between the sensors, the phase frequency characteristic acquired by the phase characteristic acquisition unit 104 may include the difference in the frequency characteristic of the phase between the sensors.

[0065] In this embodiment, the phase correction unit 109 corrects the phase characteristics of the measurement data of the multiple sensors 150. The phase correction unit 109 corrects the phase characteristics of the measurement data of each sensor acquired by the data acquisition unit 101 for each sensor, for example, by using the phase-frequency characteristics of the electronic circuit 152 of each sensor 150 that have been determined in advance. The amplitude characteristic acquisition unit 103 and the phase characteristic acquisition unit 104 acquire the amplitude-frequency characteristics and the phase-frequency characteristics, respectively, using the data whose phase characteristics have been corrected. The resonant frequency determination unit 106 determines the resonant frequency using the phase-frequency characteristics acquired from the data whose phase characteristics have been corrected.

[0066] In this embodiment, the phase correction unit 109 corrects the phase-frequency characteristics using the phase-frequency characteristics of the electronic circuit 152 of each sensor 150. In this manner, even if each individual sensor 150 has a different phase-frequency characteristic, the phase-frequency characteristics between a sensor pair can be correctly acquired. In this embodiment, since the phase-frequency characteristics can be correctly acquired, the resonant frequency can be accurately determined. Furthermore, in this embodiment, the diagnosis of the structure is performed using the accurately determined resonant frequency, so the soundness of the structure can be correctly diagnosed.

[0067] Next, a description will be given of the hardware configuration of the structure diagnosis device 100 and the resonant frequency determination device 120. Fig. 12 is a block diagram showing an example configuration of a computer device that can be used as the structure diagnosis device 100 or the resonant frequency determination device 120. The computer device 500 has a processor 510 such as a CPU (Central Processing Unit), a storage unit 520, a ROM (Read Only Memory) 530, a RAM (Random Access Memory) 540, a communication interface (IF: Interface) 550, and a user interface 560.

[0068] The communication interface 550 is an interface for connecting the computer device 500 to a communication network via wired communication means or wireless communication means, etc. The user interface 560 includes a display unit such as a display, and an input unit such as a keyboard, a mouse, and a touch panel.

[0069] The storage unit 520 is an auxiliary storage device that can store various types of data. The storage unit 520 can be used as the product information DB 110. The storage unit 520 does not necessarily have to be a part of the computer device 500, but may be an external storage device or a cloud storage connected to the computer device 500 via a network.

[0070] The ROM 530 is a non-volatile storage device. For example, a semiconductor storage device such as a flash memory with a relatively small capacity is used for the ROM 530. The programs executed by the CPU 510 can be stored in the storage unit 520 or the ROM 530. The storage unit 520 or the ROM 530 stores programs for realizing the functions of each unit of the structure diagnosis device 100 or the resonant frequency determination device 120.

[0071] The program includes instructions (or software code) that, when loaded into a computer, cause the computer to perform one or more functions described in the embodiments. The program may be stored in a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, computer-readable media or tangible storage media include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technologies, compact discs (CDs), digital versatile discs (DVDs), Blu-ray discs or other optical disk storage, magnetic cassettes, magnetic tapes, magnetic disk storage or other magnetic storage devices. The program may also be transmitted on a transitory computer-readable medium or communication medium. By way of example and not limitation, transitory computer-readable media or communication media include electrical, optical, acoustic, or other forms of propagated signals.

[0072] The RAM 540 is a volatile storage device. Various semiconductor memory devices such as a DRAM (Dynamic Random Access Memory) or an SRAM (Static Random Access Memory) are used for the RAM 540. The RAM 540 can be used as an internal buffer for temporarily storing data and the like. The CPU 510 loads a program stored in the storage unit 520 or the ROM 530 into the RAM 540 and executes it. The CPU 510 executes the program, thereby realizing the functions of each unit of the structure diagnosis device 100 or the resonant frequency determination device 120. The CPU 510 may have an internal buffer for temporarily storing data and the like.

[0073] Although the present disclosure has been described above with reference to the embodiments, the present disclosure is not limited to the above-described embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure. Each embodiment can be combined with other embodiments as appropriate.

[0074] Each drawing is merely an example for describing one or more embodiments. Each drawing may relate not only to one particular embodiment, but also to one or more other embodiments. As will be understood by those skilled in the art, various features or steps described with reference to any one drawing can be combined with features or steps shown in one or more other drawings to create, for example, an embodiment not explicitly shown or described. Not all features or steps shown in any one drawing are necessary to describe an exemplary embodiment, and some features or steps may be omitted. The order of steps described in any drawing may be changed as appropriate.

[0075] A part or all of the above-described embodiments can be described as, but not limited to, the following supplementary notes.

[0076] [Appendix 1] acquiring a first amplitude-frequency characteristic from first vibration data detected using a first sensor arranged closest to an expansion joint connecting the structure to another structure, among a plurality of sensors each for detecting vibration occurring in the structure; acquiring a second amplitude-frequency characteristic from second vibration data detected using a second sensor different from the first sensor among the plurality of sensors; obtaining a phase frequency characteristic based on the first amplitude frequency characteristic and the second amplitude frequency characteristic; acquiring one or more candidate resonance frequencies that are candidates for a resonance frequency of the structure based on amplitude-frequency characteristics acquired based on vibration data detected using at least one of the plurality of sensors; determining whether the phase-frequency characteristic is nonlinear at the one or more candidate resonance frequencies; a resonance frequency determining method comprising determining, as a resonance frequency, a candidate resonance frequency among the one or more candidate resonance frequencies, the candidate resonance frequency at which the phase-frequency characteristic is determined to be nonlinear.

[0077] [Appendix 2] The resonance frequency determination method according to claim 1, wherein acquiring the candidate resonance frequency includes acquiring, as the candidate resonance frequency, a frequency whose spectral intensity is equal to or greater than a threshold value in an amplitude-frequency characteristic acquired from vibration data detected by one or more of the plurality of sensors.

[0078] [Appendix 3] acquiring the first amplitude-frequency characteristic includes Fourier transforming the first vibration data; acquiring the second amplitude-frequency characteristic includes Fourier transforming the second vibration data; 3. The method for determining a resonance frequency according to claim 1 or 2.

[0079] [Appendix 4] The resonance frequency determination method according to any one of appendixes 1 to 3, wherein acquiring the candidate resonance frequency includes extracting, in the second amplitude-frequency characteristic, a frequency whose spectral intensity is equal to or greater than a threshold as the candidate resonance frequency.

[0080] [Appendix 5] 5. The resonant frequency determination method according to claim 1, wherein acquiring the phase frequency characteristic includes calculating a transfer function based on the first amplitude frequency characteristic and the second amplitude frequency characteristic, and acquiring the phase frequency characteristic based on the transfer function.

[0081] [Appendix 6] The resonance frequency determination method according to any one of Supplementary Note 1 to 4, wherein determining whether the phase-frequency characteristic is nonlinear includes calculating, for each of the one or more candidate resonance frequencies, a difference between a phase indicated by the phase-frequency characteristic and a phase calculated using an approximation formula that linearly approximates the phase-frequency characteristic, and determining that the phase at the candidate resonance frequency is nonlinear if the difference is equal to or greater than a threshold value.

[0082] [Appendix 7] Identifying the time when a moving object traveling on the structure passed through the extension joint based on the measurement value of the first sensor; extracting, from the measurement values ​​of the first sensor and the measurement values ​​of the second sensor, measurement values ​​within a predetermined time range from the specified time as the first vibration data and the second vibration data, respectively. 7. A method for determining a resonance frequency according to any one of claims 1 to 6.

[0083] [Appendix 8] the measurement values ​​of the plurality of sensors each have a phase characteristic; The method further includes correcting phase characteristics of the measurement values ​​of the plurality of sensors. 8. A method for determining a resonance frequency according to any one of claims 1 to 7.

[0084] [Appendix 9] For each of a plurality of sensors for detecting vibrations occurring in a structure, an amplitude-frequency characteristic is obtained from vibration data detected by each sensor; acquiring a phase frequency characteristic based on a first amplitude frequency characteristic acquired for a first sensor, among the plurality of sensors, that is disposed at a position closest to an expansion joint that connects the structure to another structure, and a second amplitude frequency characteristic acquired for a second sensor, among the plurality of sensors, that is different from the first sensor; acquiring one or more candidate resonance frequencies that are candidates for a resonance frequency of the structure based on the amplitude-frequency characteristics acquired for at least one of the plurality of sensors; determining whether the phase-frequency characteristic is nonlinear at the one or more candidate resonance frequencies; Among the one or more resonance candidate frequencies, a resonance candidate frequency at which the phase-frequency characteristic is determined to be nonlinear is determined to be a resonance frequency; acquiring natural vibration information of the structure at the determined resonant frequency; A structure diagnosis method comprising diagnosing the soundness of the structure using the acquired natural vibration information.

[0085] [Appendix 10] 10. A structure diagnosis method according to claim 9, wherein diagnosing the health of the structure includes comparing the acquired natural vibration information with natural vibration information acquired in the past.

[0086] [Appendix 11] 11. A structure diagnosis method according to claim 9, wherein the natural vibration information includes at least one of a natural vibration mode and a natural damping rate.

[0087] [Appendix 12] an amplitude characteristic acquisition unit that acquires a first amplitude frequency characteristic from first vibration data detected using a first sensor, among a plurality of sensors each for detecting vibrations occurring in a structure, that is located closest to an expansion joint that connects the structure to another structure, and acquires a second amplitude frequency characteristic from second vibration data detected using a second sensor, different from the first sensor, among the plurality of sensors; a phase characteristic acquisition unit that acquires a phase frequency characteristic based on the first amplitude frequency characteristic and the second amplitude frequency characteristic; a candidate resonance frequency acquisition unit that acquires one or more candidate resonance frequencies that are candidates for a resonance frequency of the structure based on amplitude-frequency characteristics acquired based on vibration data detected using at least one of the plurality of sensors; a resonance frequency determination unit that determines whether or not the phase-frequency characteristic is nonlinear at the one or more candidate resonance frequencies, and determines, among the one or more candidate resonance frequencies, a candidate resonance frequency for which the phase-frequency characteristic is determined to be nonlinear, as a resonance frequency.

[0088] [Appendix 13] an amplitude characteristic acquisition unit that acquires amplitude frequency characteristics from vibration data detected by each of a plurality of sensors, each of which is used to detect vibrations occurring in a structure; a phase characteristic acquisition unit that acquires a phase frequency characteristic based on a first amplitude frequency characteristic acquired for a first sensor among the plurality of sensors that is located closest to an expansion joint that connects the structure to another structure, and a second amplitude frequency characteristic acquired for a second sensor among the plurality of sensors that is different from the first sensor; a candidate resonance frequency acquisition unit that acquires one or more candidate resonance frequencies that are candidates for a resonance frequency of the structure based on the amplitude-frequency characteristic acquired for at least one of the plurality of sensors; a resonance frequency determination unit that determines whether or not the phase-frequency characteristic is nonlinear at the one or more candidate resonance frequencies, and determines, among the one or more candidate resonance frequencies, a candidate resonance frequency at which the phase-frequency characteristic is determined to be nonlinear, as a resonance frequency; a natural vibration information acquisition unit that acquires natural vibration information of the structure at the determined resonant frequency; a diagnosis unit that diagnoses the soundness of the structure using the acquired natural vibration information.

[0089] [Appendix 14] acquiring a first amplitude-frequency characteristic from first vibration data detected using a first sensor arranged closest to an expansion joint connecting the structure to another structure, among a plurality of sensors each for detecting vibration occurring in the structure; acquiring a second amplitude-frequency characteristic from second vibration data detected using a second sensor different from the first sensor among the plurality of sensors; obtaining a phase frequency characteristic based on the first amplitude frequency characteristic and the second amplitude frequency characteristic; acquiring one or more candidate resonance frequencies that are candidates for a resonance frequency of the structure based on amplitude-frequency characteristics acquired based on vibration data detected using at least one of the plurality of sensors; determining whether the phase-frequency characteristic is nonlinear at the one or more candidate resonance frequencies; A program for causing a computer to execute a process including determining, among the one or more candidate resonance frequencies, a candidate resonance frequency for which the phase-frequency characteristic is determined to be nonlinear, as a resonance frequency.

[0090] [Appendix 15] For each of a plurality of sensors for detecting vibrations occurring in a structure, an amplitude-frequency characteristic is obtained from vibration data detected by each sensor; acquiring a phase frequency characteristic based on a first amplitude frequency characteristic acquired for a first sensor, among the plurality of sensors, that is disposed at a position closest to an expansion joint that connects the structure to another structure, and a second amplitude frequency characteristic acquired for a second sensor, among the plurality of sensors, that is different from the first sensor; acquiring one or more candidate resonance frequencies that are candidates for a resonance frequency of the structure based on the amplitude-frequency characteristics acquired for at least one of the plurality of sensors; determining whether the phase-frequency characteristic is nonlinear at the one or more candidate resonance frequencies; Among the one or more resonance candidate frequencies, a resonance candidate frequency at which the phase-frequency characteristic is determined to be nonlinear is determined to be a resonance frequency; acquiring natural vibration information of the structure at the determined resonant frequency; A program for causing a computer to execute a process including diagnosing the soundness of the structure using the acquired natural vibration information.

[0091] Some or all of the elements (e.g., configurations and functions) described in Supplementary Notes 2 to 8 that are dependent on Supplementary Notes 1 may also be dependent on Supplementary Notes 9 and Supplementary Notes 12 to 15 in the same dependent relationship as Supplementary Notes 2 to 8. Also, some or all of the elements described in Supplementary Notes 10 and 11 that are dependent on Supplementary Notes 9 may also be dependent on Supplementary Notes 13 and 15 in the same dependent relationship as Supplementary Notes 10 and 11. Some or all of the elements described in any Supplementary Note may be applicable to various hardware, software, recording means for recording software, systems, and methods. [Explanation of symbols]

[0092] 10: Structural diagnostic equipment 11: Amplitude characteristic acquisition section 12: Phase characteristic acquisition section 13: Resonance candidate frequency acquisition unit 14: Resonance frequency determination section 15: Natural vibration information acquisition unit 16: Diagnostic Department 20: Resonant frequency determination device 100: Structural diagnostic equipment 101: Data acquisition section 102: Data extraction unit 103: Amplitude characteristic acquisition unit 104: Phase characteristic acquisition section 105: Resonance candidate frequency acquisition unit 106: Resonant frequency determination section 107: Natural vibration information acquisition unit 108: Diagnostic Department 109: Phase correction section 120: Resonant frequency determination device 150: Sensor 151: Detection unit 152:Electronic circuit 200: Bridge 210: Telescopic device 250: Vehicle

Claims

1. a first amplitude-frequency characteristic is acquired from first vibration data detected using a first sensor, among a plurality of sensors each for detecting vibration occurring in a structure, the first sensor being arranged at a position closest to an expansion joint connecting the structure to another structure; acquiring a second amplitude-frequency characteristic from second vibration data detected using a second sensor different from the first sensor among the plurality of sensors; obtaining a phase frequency characteristic based on the first amplitude frequency characteristic and the second amplitude frequency characteristic; acquiring one or more candidate resonance frequencies that are candidates for a resonance frequency of the structure based on amplitude-frequency characteristics acquired based on vibration data detected using at least one of the plurality of sensors; determining whether the phase-frequency characteristic is nonlinear at the one or more candidate resonance frequencies; a resonance frequency determining method comprising determining, as a resonance frequency, a resonance candidate frequency at which the phase-frequency characteristic is determined to be nonlinear, among the one or more resonance candidate frequencies.

2. 2. The resonance frequency determination method according to claim 1, wherein acquiring the candidate resonance frequency includes acquiring, as the candidate resonance frequency, a frequency whose spectral intensity is equal to or greater than a threshold value in an amplitude-frequency characteristic acquired from vibration data detected by one or more of the plurality of sensors.

3. 3. The resonant frequency determination method according to claim 1, wherein acquiring the phase frequency characteristic includes calculating a transfer function based on the first amplitude frequency characteristic and the second amplitude frequency characteristic, and acquiring the phase frequency characteristic based on the transfer function.

4. identifying a time when a moving object traveling on the structure passed through the extension joint based on the measurement value of the first sensor; The method further includes extracting, from the measurement values ​​of the first sensor and the measurement values ​​of the second sensor, measurement values ​​within a predetermined time range from the specified time as the first vibration data and the second vibration data, respectively. The method for determining a resonance frequency according to claim 1 or 2.

5. the measurement values ​​of the plurality of sensors each have a phase characteristic; The method further includes correcting phase characteristics of the measurement values ​​of the plurality of sensors. The method for determining a resonance frequency according to claim 1 or 2.

6. For each of a plurality of sensors for detecting vibrations occurring in a structure, an amplitude-frequency characteristic is obtained from vibration data detected by each sensor; acquiring a phase frequency characteristic based on a first amplitude frequency characteristic acquired for a first sensor, among the plurality of sensors, that is disposed at a position closest to an expansion joint that connects the structure to another structure, and a second amplitude frequency characteristic acquired for a second sensor, among the plurality of sensors, that is different from the first sensor; acquiring one or more candidate resonance frequencies that are candidates for a resonance frequency of the structure based on the amplitude-frequency characteristics acquired for at least one of the plurality of sensors; determining whether the phase-frequency characteristic is nonlinear at the one or more candidate resonance frequencies; Among the one or more resonance candidate frequencies, a resonance candidate frequency at which the phase-frequency characteristic is determined to be nonlinear is determined to be a resonance frequency; acquiring natural vibration information of the structure at the determined resonant frequency; A structure diagnosis method comprising diagnosing the soundness of the structure using the acquired natural vibration information.

7. an amplitude characteristic acquisition unit that acquires a first amplitude frequency characteristic from first vibration data detected using a first sensor, among a plurality of sensors each for detecting vibrations occurring in a structure, that is located closest to an expansion joint connecting the structure to another structure, and acquires a second amplitude frequency characteristic from second vibration data detected using a second sensor, different from the first sensor, among the plurality of sensors; a phase characteristic acquisition unit that acquires a phase frequency characteristic based on the first amplitude frequency characteristic and the second amplitude frequency characteristic; a candidate resonance frequency acquisition unit that acquires one or more candidate resonance frequencies that are candidates for a resonance frequency of the structure based on an amplitude-frequency characteristic acquired based on vibration data detected using at least one of the plurality of sensors; a resonance frequency determination unit that determines whether or not the phase-frequency characteristic is nonlinear at the one or more candidate resonance frequencies, and determines, among the one or more candidate resonance frequencies, a candidate resonance frequency for which the phase-frequency characteristic is determined to be nonlinear, as a resonance frequency.

8. an amplitude characteristic acquisition unit that acquires amplitude frequency characteristics from vibration data detected by each of a plurality of sensors, each of which is used to detect vibrations occurring in a structure; a phase characteristic acquisition unit that acquires a phase frequency characteristic based on a first amplitude frequency characteristic acquired for a first sensor, among the plurality of sensors, that is located closest to an expansion joint that connects the structure to another structure, and a second amplitude frequency characteristic acquired for a second sensor, among the plurality of sensors, that is different from the first sensor; a candidate resonance frequency acquisition unit that acquires one or more candidate resonance frequencies that are candidates for a resonance frequency of the structure based on the amplitude-frequency characteristic acquired for at least one of the plurality of sensors; a resonance frequency determination unit that determines whether or not the phase-frequency characteristic is nonlinear at the one or more candidate resonance frequencies, and determines, among the one or more candidate resonance frequencies, a candidate resonance frequency for which the phase-frequency characteristic is determined to be nonlinear, as a resonance frequency; a natural vibration information acquisition unit that acquires natural vibration information of the structure at the determined resonant frequency; a diagnosis unit that diagnoses the soundness of the structure using the acquired natural vibration information.

9. a first amplitude-frequency characteristic is acquired from first vibration data detected using a first sensor, among a plurality of sensors each for detecting vibration occurring in a structure, the first sensor being arranged at a position closest to an expansion joint connecting the structure to another structure; acquiring a second amplitude-frequency characteristic from second vibration data detected using a second sensor different from the first sensor among the plurality of sensors; obtaining a phase frequency characteristic based on the first amplitude frequency characteristic and the second amplitude frequency characteristic; acquiring one or more candidate resonance frequencies that are candidates for a resonance frequency of the structure based on amplitude-frequency characteristics acquired based on vibration data detected using at least one of the plurality of sensors; determining whether the phase-frequency characteristic is nonlinear at the one or more candidate resonance frequencies; A program for causing a computer to execute a process including determining, as a resonance frequency, a resonance candidate frequency at which the phase-frequency characteristic is determined to be nonlinear, among the one or more resonance candidate frequencies.

10. For each of a plurality of sensors for detecting vibrations occurring in a structure, an amplitude-frequency characteristic is obtained from vibration data detected by each sensor; acquiring a phase frequency characteristic based on a first amplitude frequency characteristic acquired for a first sensor, among the plurality of sensors, that is disposed at a position closest to an expansion joint that connects the structure to another structure, and a second amplitude frequency characteristic acquired for a second sensor, among the plurality of sensors, that is different from the first sensor; acquiring one or more candidate resonance frequencies that are candidates for a resonance frequency of the structure based on the amplitude-frequency characteristics acquired for at least one of the plurality of sensors; determining whether the phase-frequency characteristic is nonlinear at the one or more candidate resonance frequencies; Among the one or more resonance candidate frequencies, a resonance candidate frequency at which the phase-frequency characteristic is determined to be nonlinear is determined to be a resonance frequency; acquiring natural vibration information of the structure at the determined resonant frequency; A program for causing a computer to execute a process including diagnosing the soundness of the structure using the acquired natural vibration information.

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