Diagnosis device, diagnosis method, and diagnosis program

Abstract

To provide a diagnosis device, a diagnosis method, and a diagnosis program capable of obtaining about the same diagnosis precision as that of a diagnosis using a hammering sound without any contact.SOLUTION: A diagnosis device includes an excitation section, a sound volume indication section, a first sound reception section, a second sound reception section, an impulse response calculation section, a correlation analysis section, a differential analysis section, and a diagnosis section. The impulse response calculation section calculates an impulse response based on output of the first sound reception section and the second sound reception section when an excitation sound is radiated from the excitation section with reference sound volume and evaluation sound volume. The correlation analysis section calculates a correlation transfer function between second reference characteristics and second evaluation characteristics based on an impulse response. The difference analysis section calculates a difference between first evaluation characteristics and first reference characteristics based on an impulse response on the basis of a correlation transfer function. The diagnosis section diagnoses a measurement object on the basis of the difference, and features in which sound volume of a vibration radiation sound is shifted to a dead zone, a rising area, a linear area, and a saturation zone in this order following a change in the sound volume of an excitation sound.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] An embodiment of the present invention relates to a diagnostic device, a diagnostic method, and a diagnostic program. [Background technology]

[0002] In structures such as buildings and infrastructure structures, deterioration over time may occur in the form of changes in rigidity due to changes in welding or joining conditions of the structure, changes in structural damping characteristics due to peeling of internal coatings such as vibration-damping materials, and changes in strength due to rust, cracks, hollowing, etc. of internal structures. Conventionally, deterioration evaluation has been performed using periodic audible evaluation by hammering sounds as a diagnosis for such deterioration over time. In addition, automatic diagnoses using contact diagnosis by ultrasonic waves, contact diagnosis by acoustic emission (AE) sensors, contact diagnosis by magnetic sensors, deterioration evaluation by images, diagnosis by radar, diagnosis by thermography, etc. are also known. Of these automatic diagnoses, contact diagnosis is often used. Also, some of these automatic diagnoses cannot achieve the same level of diagnostic accuracy as hammering sounds. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-77684 A Summary of the Invention [Problem to be solved by the invention]

[0004] The embodiments provide a diagnostic device, a diagnostic method, and a diagnostic program for a structure that can obtain diagnostic accuracy equivalent to that of a non-contact diagnosis using hammering sounds. [Means for solving the problem]

[0005] A diagnostic device according to one embodiment includes a vibration unit, a volume instruction unit, a first sound receiving unit, a second sound receiving unit, an impulse response calculation unit, a correlation analysis unit, a difference analysis unit, and a diagnosis unit. The vibration unit radiates a vibration sound to a measurement object. The volume instruction unit instructs the vibration unit to a plurality of different volumes. The first sound receiving unit is disposed near the measurement object and receives a sound including a vibration radiation sound of the measurement object due to the radiation of the vibration sound. The second sound receiving unit is disposed near the vibration unit and receives the vibration sound. The impulse response calculation unit calculates a first reference impulse response based on a first reference signal output from the first sound receiving unit when a vibration sound of a reference volume is radiated from the measurement target object without radiating vibration radiation sound, a second reference impulse response based on a second reference signal output from the second sound receiving unit when a vibration sound of a reference volume is radiated, a first evaluation impulse response based on a first evaluation signal output from the first sound receiving unit when a vibration sound of at least two evaluation volumes larger than the reference volume is radiated, and a second evaluation impulse response based on a second evaluation signal output from the second sound receiving unit when a vibration sound of an evaluation volume is radiated. The correlation analysis unit calculates a correlation transfer function between a second reference characteristic based on the second reference impulse response and a second evaluation characteristic based on the second evaluation impulse response. The difference analysis unit calculates a difference between the first evaluation characteristic based on the first evaluation impulse response and the first reference characteristic based on the first reference impulse response based on the correlation transfer function. The diagnosing unit diagnoses the measurement object based on the difference and a feature that the volume of the vibration radiation sound changes in the order of a dead zone, a rise zone, a linear zone, and a saturation zone in accordance with a change in the volume of the excitation sound. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a diagram for explaining the principle of the embodiment. [Diagram 2] FIG. 2 is a diagram showing the volume change characteristics of the sound from the measurement object when the measurement object is vibrated by the vibration unit. [Diagram 3] FIG. 3 is a block diagram showing an example of a configuration of a diagnostic device according to an embodiment. [Figure 4]FIG. 4 is a diagram illustrating a hardware configuration of an example of the control device. [Diagram 5] FIG. 5 is a flowchart showing the operation of the diagnostic method by the diagnostic device according to the embodiment. [Figure 6A] FIG. 6A is a diagram showing an example of measurement results of frequency characteristics of vibration-radiated sound at each evaluated sound volume for sample A. [Figure 6B] FIG. 6B is a diagram showing an example of measurement results of frequency characteristics of vibration-radiated sound at each evaluated sound volume for sample B. [Figure 6C] FIG. 6C is a diagram showing an example of measurement results of frequency characteristics of vibration-radiated sound at each evaluated sound volume for sample C. [Figure 6D] FIG. 6D is a diagram showing an example of measurement results of frequency characteristics of vibration-radiated sound at each evaluated sound volume for sample D. [Figure 7] FIG. 7 is a schematic diagram of the sample used in the measurement. [Figure 8] FIG. 8 is a diagram showing a comparison result of the volume change characteristics of the vibration-radiated sound of 1250 Hz for each sample. [Figure 9] FIG. 9 is a diagram showing a comparison between the volume change characteristics of vibration radiated sound without volume correction and the volume change characteristics of vibration radiated sound with volume correction. [Figure 10A] FIG. 10A is a diagram showing an example of frequency characteristics of vibration-radiated sound at each evaluated sound volume for sample A. [Figure 10B] FIG. 10B is a diagram showing an example of the frequency characteristics of vibration-radiated sound at each evaluated sound volume for sample B. [Figure 10C] FIG. 10C is a diagram showing an example of the frequency characteristics of vibration-radiated sound at each evaluated sound volume for sample C. [Figure 10D] FIG. 10D is a diagram showing an example of the frequency characteristics of vibration-radiated sound at each evaluated sound volume for sample D. [Figure 11]FIG. 11 is a diagram showing a comparison of the frequency characteristics of the vibration radiated sound of sample A, the frequency characteristics of the vibration radiated sound of sample B, the frequency characteristics of the vibration radiated sound of sample C, and the frequency characteristics of the vibration radiated sound of sample D in terms of the volume at which volume linearity is maintained. [Figure 12] FIG. 12 is a block diagram showing a configuration of an example of a diagnostic device according to a first modified example of the embodiment. [Figure 13] FIG. 13 is a diagram showing the measurement of vibration-radiated sound with an added mass attached to an object to be measured. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, an embodiment will be described with reference to the drawings. First, an overview of the diagnostic device of the embodiment will be described. The diagnostic device according to the embodiment obtains diagnostic accuracy equivalent to that of tapping sound by non-contact diagnosis. Disadvantages of tapping sound include that it is a contact diagnosis, so there is a possibility of damaging the target, and that the tapping force and audibility evaluation are based on the operator's many years of experience and therefore vary.

[0008] In contrast, in the embodiment, the measurement object is vibrated by emitting a vibration sound of a certain volume from a vibration unit such as a speaker. Then, the measurement object is diagnosed using a minute vibration radiation sound emitted from the measurement object in association with the vibration of the measurement object. Here, in the embodiment, the characteristic that the volume of the vibration radiation sound from the measurement object changes in the order of dead zone, rising region, linear region, and saturation zone according to the change in the volume of the excitation sound is utilized for diagnosis. Specifically, the measurement object is acoustically vibrated while changing the volume, and the normality or abnormality of the measurement object is determined by capturing the change in the volume of the vibration radiation sound for each excitation volume. The vibration radiation sound also reflects changes in the internal structure. Therefore, in the diagnosis of the measurement object in the embodiment, changes that cannot be determined from an image of the surface of the structure can be captured.

[0009] 1 is a diagram for explaining the principle of the embodiment. The diagnostic device 1 has a vibration unit S and a sound receiving unit R. The vibration unit S is disposed to face a measurement object O, which is a structure such as a building or an infrastructure structure, and emits a vibration sound to the measurement object O, and is, for example, a speaker. The sound receiving unit R is, for example, a microphone that receives a vibration radiation sound from the measurement object O.

[0010] 2(a) and (b) are diagrams showing the volume change characteristics of the sound from the measurement object O when the measurement object O is vibrated by the vibration unit S. The horizontal axis of FIG. 2(a) and (b) is the volume of the vibration sound, that is, the sound pressure level of the vibration sound relative to the reference sound. Here, the sound pressure level of the reference sound is set to a sound pressure level at which no vibration radiation sound is generated even by acoustic vibration by the vibration unit S. On the other hand, the vertical axis of FIG. 2(a) and (b) is the volume of the sound from the measurement object O, that is, the sound pressure level of the sound relative to the reference sound.

[0011] In reality, the sound from the measurement object O when the measurement object O is vibrated by the vibration unit S includes vibration radiated sound and reflected sound. Vibration radiated sound is sound emitted from the measurement object O in association with the vibration of the measurement object O due to the emission of excitation sound to the measurement object O. Reflected sound is sound reflected from the measurement object O due to the emission of excitation sound to the measurement object O. Figure 2(a) shows the volume change characteristics of vibration radiated sound, and Figure 2(b) shows the volume change characteristics of reflected sound.

[0012] When the measurement object O is acoustically excited by the vibration unit S, the volume of the vibration radiation sound from the measurement object O progresses through the dead zone, rise region, linear region, and saturation zone in this order according to the change in volume of the excitation sound, as shown in (a) of FIG. 2. The dead zone is a region where the volume of the vibration radiation sound is approximately at the reference volume. The rise region is a region after the dead zone where the volume of the vibration radiation sound rises sharply from the reference volume. The linear region is a region after the rise region where the volume of the vibration radiation sound rises approximately linearly with the change in the excitation volume. The saturation zone is a region after the linear region where the volume of the vibration radiation sound is saturated. In an embodiment, the normality or abnormality of the measurement object is determined by capturing the change in the vibration radiation sound for each excitation volume.

[0013] Vibration-radiated sound is weaker than reflected sound. Therefore, in the sound acquired by the sound receiving unit R, the vibration-radiated sound is buried in the reflected sound. Here, as shown in (b) of Figure 2, the volume of the reflected sound changes linearly with the volume of the excitation sound. Since the volume of the excitation sound is known, only the vibration-radiated sound can be extracted by applying a sound pressure difference to the signal received by the sound receiving unit R. This makes it possible to perform diagnosis using the vibration-radiated sound.

[0014] The specific configuration of the diagnostic device according to the embodiment will be described below. Fig. 3 is a block diagram showing the configuration of an example of the diagnostic device according to the embodiment. The diagnostic device 1 has a speaker 2, microphones 3a and 3b, and a control device 4.

[0015] The speaker 2 is an example of the excitation unit S, and is disposed to face the measurement object O, radiating an excitation sound to the measurement object O. An acoustic excitation signal for generating the excitation sound of the speaker 2 is applied by the excitation instruction unit 41 of the control device 4. The volume of the excitation sound is instructed by the volume instruction unit 42 of the control device 4. The speaker 2 generates the excitation sound by amplifying the acoustic excitation signal applied from the excitation instruction unit 41 by a gain corresponding to the volume instructed by the volume instruction unit 42. The speaker 2 then radiates the generated excitation sound to the measurement object O.

[0016] The microphone 3a is an example of the sound receiving unit R, and is disposed near the measurement object O to receive sound from the measurement object O and generate a received sound signal. The microphone 3b is disposed near the speaker 2 to receive the excitation sound directly emitted from the speaker 2 and generate a received sound signal. Here, it is preferable that both the microphones 3a and 3b are microphones having directionality. As the microphone having directionality, a unidirectional microphone having a microphone cap or the like having a cardioid directional characteristic attached to the microphone, a gun microphone, a line array microphone, or other superdirectional microphone may be used.

[0017] As described above, in the embodiment, the volume of the speaker 2 is changed to extract the vibration radiation sound. However, the volume of the vibration sound radiated from the speaker 2 does not change precisely linearly with respect to the change in the volume of the speaker 2. For example, even if the gain of the acoustic excitation signal is increased by 3 dB, the volume of the vibration sound radiated from the speaker 2 does not increase by 3 dB at all frequencies. Therefore, it becomes necessary to monitor the change in the volume of the vibration sound radiated from the speaker 2 with respect to the change in the volume of the speaker 2. The microphone 3b is provided for monitoring this change.

[0018] The control device 4 is a computer that processes the received signals of the microphones 3a and 3b to diagnose the measurement object O. The control device 4 has a vibration instruction unit 41, a volume instruction unit 42, an impulse response calculation unit 43, an analysis unit 44, a diagnosis unit 45, and an output unit 46.

[0019] The excitation instruction unit 41 applies an acoustic excitation signal to the speaker 2 to instruct the speaker 2 to emit an excitation sound. The acoustic excitation signal may be any signal. For example, the acoustic excitation signal may be a TSP (Time stretched Pulse) signal or a random signal.

[0020] The volume instruction unit 42 instructs the speaker 2 on the volume of the vibration sound. The volume is selected from among predetermined volumes. Here, in the embodiment, the volume instruction unit 42 instructs the speaker 2 on a different volume each time the speaker 2 radiates the vibration sound. The predetermined volumes may include a reference volume and at least two evaluation volumes that are greater than the reference volume. However, as described above, in the embodiment, in order to fully utilize the feature that the volume of the vibration radiation sound changes in the order of the dead zone, the rising region, the linear region, and the saturation zone in accordance with the change in the volume of the vibration sound, it is desirable that the number of evaluation volumes is large.

[0021] The impulse response calculation unit 43 calculates an impulse response between the acoustic excitation signal applied by the excitation instruction unit 41 and the sound reception signal obtained by the microphone 3a. The impulse response calculation unit 43 also calculates an impulse response between the acoustic excitation signal applied by the excitation instruction unit 41 and the sound reception signal obtained by the microphone 3b. In the following description, the impulse response calculated from the sound reception signal obtained by the microphone 3a when the vibration sound of the reference volume is radiated is described as a first reference impulse response. The impulse response calculated from the sound reception signal obtained by the microphone 3b when the vibration sound of the reference volume is radiated is described as a second reference impulse response. The impulse response calculated from the sound reception signal obtained by the microphone 3a when the vibration sound of the evaluation volume is radiated is described as a first evaluation impulse response. The impulse response calculated from the sound reception signal obtained by the microphone 3b when the vibration sound of the evaluation volume is radiated is described as a second evaluation impulse response.

[0022] The analysis unit 44 executes an analysis of the impulse response calculated by the impulse response calculation unit 43. The analysis unit 44 has a removal unit 441, a reference characteristic creation unit 442, an evaluation characteristic creation unit 443, a correlation analysis unit 444, a power difference analysis unit 445, a volume correction unit 446, and an evaluation unit 447.

[0023] The removal unit 441 removes multiple reflection components between the speaker 2 and the measurement object O in each of the first reference impulse response, the second reference impulse response, the first evaluation impulse response, and the second evaluation impulse response, and outputs each impulse response from which the multiple reflection components have been removed to the reference characteristic creation unit 442 and the evaluation characteristic creation unit 443. Specifically, the removal unit 441 leaves components up to a predetermined time including peak components in each of the first reference impulse response, the second reference impulse response, the first evaluation impulse response, and the second evaluation impulse response, and removes components beyond the predetermined time as multiple reflection components. The removal can be performed, for example, by filling the multiple reflection components with zeros.

[0024] The reference characteristic creating unit 442 creates a reference characteristic based on the first reference impulse response and the second reference impulse response. For example, the reference characteristic creating unit 442 holds the first reference impulse response from which the multiple reflection components are removed and output from the removing unit 441 as the first reference characteristic, and holds the second reference impulse response from which the multiple reflection components are removed and output from the removing unit 441 as the second reference characteristic. Alternatively, the reference characteristic creating unit 442 may hold, as the first reference characteristic and the second reference characteristic, frequency characteristics obtained by converting each of the first reference impulse response and the second reference impulse response.

[0025] The evaluation characteristic creating unit 443 creates an evaluation characteristic based on the first evaluation impulse response and the second evaluation impulse response. For example, the evaluation characteristic creating unit 443 holds the first evaluation impulse response for each evaluation volume from which the multiple reflection components are removed and output from the removal unit 441 as the first evaluation characteristic, and holds the second evaluation impulse response for each evaluation volume from which the multiple reflection components are removed and output from the removal unit 441 as the second evaluation characteristic. Alternatively, the evaluation characteristic creating unit 443 may hold, as the first evaluation characteristic and the second evaluation characteristic, frequency characteristics obtained by converting the first evaluation impulse response and the second evaluation impulse response, respectively.

[0026] The correlation analysis unit 444 performs correlation analysis of the impulse response for the microphone 3b that receives the vibration sound from the speaker 2. Specifically, the correlation analysis unit 444 performs correlation processing between the second reference characteristic and the second evaluation characteristic for each evaluation volume, and derives a correlation transfer function corresponding to the ratio between the second reference characteristic and each second evaluation characteristic.

[0027] The power difference analysis unit 445 calculates the power difference between the first evaluation characteristic and the first reference characteristic for each evaluation volume. Since the first reference characteristic corresponds to the characteristic of the reflected sound from the measurement object O, the power difference between the first evaluation characteristic and the signal obtained by multiplying the first reference characteristic by the volume difference between the reference volume and the evaluation volume corresponds to the power of only the vibration radiation sound from the measurement object O. However, as described above, the volume of the excitation sound radiated from the speaker 2 does not change precisely linearly with respect to the change in the volume of the speaker 2, so the power difference analysis unit 445 calculates the power difference using the correlation transfer function derived by the correlation analysis unit 444. Specifically, the power difference analysis unit 445 calculates the power difference from (first evaluation characteristic)-(first reference characteristic)×(correlation transfer function). Although the accuracy of diagnosis is lower than when two microphones are used, microphone 3b can be omitted by treating the power difference between the first evaluation characteristic and the signal obtained by multiplying the first reference characteristic by the volume difference between the reference volume and the evaluation volume as the power of only the vibration radiation sound from the measurement object O.

[0028] The volume correction unit 446 performs volume correction on the power of the vibration radiated sound obtained by the power difference analysis unit 445. As the evaluated volume increases, the volume of the vibration radiated sound increases. In order to make it easier to compare the vibration radiated sounds with each other, the volume correction unit 446 calculates (power of vibration radiated sound)-((evaluated volume)-(reference volume)) as the volume correction. The evaluated volume and the reference volume are the reference volume and the evaluated volume instructed by the volume instruction unit 42.

[0029] In order to evaluate the power of the vibration radiation sound, the evaluation unit 447 converts the power characteristics corrected by the volume correction unit 446 into frequency characteristics of the power in an octave band or 1 / 3 octave band. For example, the evaluation unit 447 obtains the frequency characteristics of the power using FFT (Fast Fourier Transformation).

[0030] The diagnosis unit 45 diagnoses the measurement object O by using the frequency characteristics of the vibration radiated sound obtained by the evaluation unit 447. The diagnosis of the measurement object O will be described in detail later.

[0031] The output unit 46 outputs the diagnosis result by the diagnosis unit 45. The output can be performed by various methods such as displaying the diagnosis result on a display device, printing the diagnosis result on a printer, etc. The diagnosis result can include information such as the presence or absence of an abnormality in the measurement object O, and the position of the abnormality when an abnormality is present.

[0032] 4 is a diagram showing an example of a hardware configuration of the control device 4. The control device 4 may be a computer having a processor 101, a memory 102, a storage 103, an input device 104, a display device 105, and a communication device 106 as hardware. The processor 101, the memory 102, the storage 103, the input device 104, the display device 105, and the communication device 106 are connected to a bus 107. The control device 4 may be mounted on a terminal device such as a personal computer (PC), a smartphone, or a tablet terminal.

[0033] The processor 101 is a processor that controls the overall operation of the control device 4. The processor 101 operates as a vibration instruction unit 41, a volume instruction unit 42, an impulse response calculation unit 43, an analysis unit 44, a diagnosis unit 45, and an output unit 46, for example, by executing a diagnostic program 1031 stored in the storage 103. The processor 101 is, for example, a CPU. The processor 101 may be an MPU, a GPU, an ASIC, an FPGA, or the like. The processor 101 may be a single CPU or the like, or may be multiple CPUs or the like.

[0034] The memory 102 includes a ROM and a RAM. The ROM is a non-volatile memory. The ROM stores a startup program for the control device 4 and the like. The RAM is a volatile memory. The RAM is used as a working memory during processing in the processor 101, for example.

[0035] The storage 103 is, for example, a storage such as a flash memory, a hard disk drive, or a solid state drive. The storage 103 stores various programs executed by the processor 101, such as a diagnostic program. The storage 103 may also be configured to store a diagnosis result for the measurement object O.

[0036] The input device 104 is an input device such as a touch panel, a keyboard, a mouse, etc. When the input device 104 is operated, a signal corresponding to the operation content is input to the processor 101 via the bus 107. The processor 101 performs various processes in response to this signal.

[0037] The display device 105 is a display device such as a liquid crystal display, an organic EL display, etc. The display device 105 displays various images.

[0038] The communication device 106 is a communication device for the control device 4 to communicate with an external device. The communication device 106 may be a communication device for wired communication or a communication device for wireless communication. The communication device 106 may be used, for example, to transmit an acoustic excitation signal and a gain corresponding to a volume to the speaker 2, and to receive a sound signal from the microphones 3a and 3b.

[0039] 5 is a flowchart showing the operation of the diagnostic method by the diagnostic device 1 according to the embodiment. The operation in FIG.

[0040] In step S1, the control device 4 causes the speaker 2 to emit a vibration sound to the measurement object O. First, the volume instruction unit 42 instructs the reference volume as the volume for the speaker 2. Then, the vibration instruction unit 41 instructs the speaker 2 to emit the vibration sound by the reference volume by inputting an acoustic excitation signal to the speaker 2. Next, the volume instruction unit 42 instructs one of the evaluated volumes as the volume for the speaker 2. Then, the vibration instruction unit 41 instructs the speaker 2 to emit the vibration sound by the evaluated volume by inputting an acoustic excitation signal to the speaker 2. Thereafter, in the same manner, the volume instruction unit 42 sequentially instructs the volume of the evaluated volume as the volume for the speaker 2, and the vibration instruction unit 41 instructs the speaker 2 to emit the vibration sound by the evaluated volume by inputting an acoustic excitation signal to the speaker 2.

[0041] In step S2, the impulse response calculation unit 43 acquires the received sound signals from the microphones 3a and 3b every time the vibration sound is emitted from the speaker 2 to the measurement object O.

[0042] In step S3, the impulse response calculation unit 43 calculates impulse responses for each of the microphones 3a and 3b from the sound reception signals acquired from the microphones 3a and 3b.

[0043] In step S4, the removal unit 441 removes the multiple reflection components in the impulse responses for each of the microphones 3a and 3b by, for example, zero padding.

[0044] In step S5, the reference characteristic creating unit 442 creates a reference characteristic based on the first reference impulse response and the second reference impulse response obtained by the elimination unit 441 when the vibration sound of the reference volume is emitted. Alternatively, in step S5, the evaluation characteristic creating unit 443 creates an evaluation characteristic for each evaluation volume based on the first evaluation impulse response and the second evaluation impulse response obtained by the elimination unit 441 when the vibration sound of each evaluation volume is emitted. For example, the first time, i.e., when the vibration sound of the reference volume is emitted, the reference characteristic creating unit 442 holds the output of the elimination unit 441 as the reference characteristic, and from the second time onwards, i.e., when the vibration sound of the evaluation volume is emitted, the evaluation characteristic creating unit 443 holds the output of the elimination unit 441 as the evaluation characteristic. Alternatively, the reference characteristic creating unit 442 may convert each of the first reference impulse response and the second reference impulse response into frequency characteristics and hold them as reference characteristics, and the evaluation characteristic creating unit 443 may convert each of the first evaluation impulse response and the second evaluation impulse response into frequency characteristics and hold them as evaluation characteristics.

[0045] In step S6, the correlation analysis unit 444 performs correlation processing between the second reference characteristic for the microphone 3b and the second evaluation characteristic for each evaluated volume to derive a correlation transfer function for each evaluated volume.

[0046] In step S7, the power difference analysis unit 445 uses the correlation transfer function for each evaluation characteristic to calculate the power difference between the first evaluation characteristic for the microphone 3a stored in the evaluation characteristic creation unit 443 and the first reference characteristic for the microphone 3a stored in the reference characteristic creation unit 442.

[0047] In step S8, the volume correcting unit 446 performs volume correction on the power calculated by the power difference analyzing unit 445 based on the evaluation volume and the reference volume instructed by the volume instructing unit 42.

[0048] In step S9, the evaluation unit 447 converts the power characteristics corrected by the volume correction unit 446 into octave band frequency characteristics.

[0049] In step S10, the diagnosing unit 45 performs a diagnosis on the measurement object O from the power characteristics for each evaluated volume obtained by the evaluating unit 447. The details of the diagnosis will be described later.

[0050] In step S11, the output unit 46 outputs the diagnosis result to, for example, a display device. After that, the process of Fig. 5 ends. The output unit 46 displays, as the diagnosis result, for example, information on the presence or absence of an abnormality in the measurement object O, and, if an abnormality is present, information such as the position of the abnormality, on the display device. In addition, the output unit 46 may display a graph of the volume change characteristic and a graph of the frequency characteristic, which will be described later, on the display device.

[0051] The diagnosis in step S10 will be described below. The diagnosis in the embodiment includes a first diagnosis and a second diagnosis. Either the first diagnosis or the second diagnosis may be performed, or both may be performed.

[0052] First, the first diagnosis will be described. Figures 6A, 6B, 6C, and 6D are diagrams showing measurement results of an example of the frequency characteristics (including volume correction by the volume correction unit 446) of vibration-radiated sound at each evaluation volume obtained by the evaluation unit 447. The horizontal axis of Figures 6A, 6B, 6C, and 6D is 1 / 3 octave band frequency, and the vertical axis of Figures 6A, 6B, 6C, and 6D is the power of vibration-radiated sound. Figure 6A shows the frequency characteristics of vibration-radiated sound for sample A simulating a structure without an abnormality. On the other hand, Figures 6B, 6C, and 6D show the frequency characteristics of vibration-radiated sound for samples B, C, and D simulating structures with an abnormality.

[0053] Here, the measurement conditions for the frequency characteristics in Figures 6A, 6B, 6C, and 6D are that the distance between the microphone 3a and the measurement object O is 15 mm, and the distance between the microphone 3b and the speaker 2 is 60 mm. The distance between the speaker 2 and the measurement object O is 330 mm. Furthermore, the reference volume is -18 dB, and the evaluation volumes are -15 dB, -12 dB, -9 dB, ..., 0 dB, 3 dB, and 6 dB (9 levels in 3 dB increments).

[0054] FIG. 7 is a schematic diagram of the samples used in the measurements. As samples, concrete pieces that are often used in buildings and the like are used. Sample A is a concrete piece that has not been subjected to any particular processing. On the other hand, samples B, C, and D are concrete pieces that contain styrene boards that mimic the internal cavities of buildings in order to simulate defects in buildings. The styrene boards are contained in the positions indicated by the dashed lines in FIG. 7. The diameters of the styrene boards are different between samples B, C, and D. On the other hand, the embedding positions of the styrene boards, i.e., the cover thickness, are the same between samples B, C, and D. The conditions of each sample used in the measurements are summarized below. Sample A (normal): No styrene board Sample B (abnormal): Cover thickness 5mm, φ200 Sample C (abnormal): Cover thickness 5mm, φ100 Sample D (abnormal): Cover thickness 5mm, φ50

[0055] As shown in Figures 6A, 6B, 6C, and 6D, when the volume of the vibration excitation sound is increased, the lines roughly overlap. This means that when the volume increases to a certain extent, the volume linearity of the vibration emission sound is maintained. The state in which the volume linearity is maintained corresponds to a state in which the relationship between the power of the vibration emission sound and the volume of the vibration excitation sound belongs to the linear region of the volume change characteristics described above. For example, in Figure 6A, the lines of -6 dB, -3 dB, 0 dB, +3 dB, and +6 dB roughly overlap. Also, in Figures 6B, 6C, and 6D, the lines of -9 dB, -6 dB, -3 dB, 0 dB, +3 dB, and +6 dB roughly overlap.

[0056] In the first diagnosis, a frequency band with high power of vibration radiation sound is set as a frequency band of interest, and the volume change characteristics of vibration radiation sound for each sample are compared for frequencies included in the frequency band of interest. For example, in Figures 6A, 6B, 6C, and 6D, the frequency band with high power of vibration radiation sound is approximately 1000Hz-1600Hz. Therefore, the diagnosis unit 45 compares the volume change characteristics of vibration radiation sound for each sample at frequencies included in this frequency band. Specifically, the diagnosis unit 45 extracts the power of vibration radiation sound at a specific frequency in the frequency band of interest for each volume of excitation sound in the frequency characteristics of vibration radiation sound for each sample, and replots the extracted power of vibration radiation sound with the horizontal axis representing the volume of excitation sound and the vertical axis representing the power of vibration radiation sound.

[0057] FIG. 8 is a diagram showing a comparison result of the volume change characteristics of the vibration radiation sound (volume corrected by the volume correction unit 446) of 1250 Hz (1 / 3 octave band) for each sample. Sample A without an abnormality and samples B, C, and D with an abnormality have different volume ranges in which the volume linearity is maintained, that is, volumes transitioning from the rising region to the linear region. Since the volume correction process of step S8 has been performed, in FIG. 8 corresponding to the diagnosis of step S10 based on the octave band evaluation of step S9, the linear region is classified as a region with a slope close to 0 (vibration volume -4 dB or more in FIG. 8). Therefore, the power line in the rising region of sample A does not overlap with the power lines of samples B, C, and D. The presence or absence of an abnormality in the measurement object O can be diagnosed by such a difference in the volume change characteristics. In addition, the position of the abnormality when it is diagnosed that there is an abnormality can be identified, for example, from the position on the measurement object O where the vibration sound is radiated.

[0058] In actual diagnosis, the control device 4 collects vibration radiation sound from a sample without abnormality in advance, identifies a frequency band of interest in which power of a predetermined level or more is obtained in the frequency characteristics obtained as a result of collecting the vibration radiation sound, and stores the volume change characteristics of the identified frequency band of interest.The control device 4 then collects vibration radiation sound from the measurement object O, and diagnoses the presence or absence of an abnormality in the measurement object O by comparing the volume change characteristics of the frequency band of interest of the measurement object O with the volume change characteristics of the sample without abnormality.For example, when the control device 4 compares the volume change characteristics between the sample without abnormality and the measurement object O, and finds that there is a volume range in which the volume change characteristics differ by a predetermined level or more, it diagnoses that the measurement object O has an abnormality.

[0059] In the first diagnosis described above, the way in which the vibration radiation sound transitions from the dead zone to the rising zone, the linear zone, and the saturation zone in association with the volume change of the excitation sound differs depending on whether or not the measurement object has an abnormality, so the volume change characteristics of the measurement object in the frequency band of interest are compared with the volume change characteristics of a sample without an abnormality to diagnose whether or not the measurement object has an abnormality. Therefore, the presence or absence of an abnormality in the measurement object can be diagnosed without contact. In addition, since the vibration radiation sound also reflects changes inside the measurement object, it is possible to capture changes that cannot be determined from an image of the surface of the measurement object.

[0060] Furthermore, by removing the components of the reflected sound from the measurement object O by the power difference analysis section 445, it is possible to compare the volume change characteristics using minute vibration radiation sound.

[0061] Furthermore, by performing the volume correction by the volume correction unit 446, the difference in the volume change characteristic for each sample becomes easier to grasp. The effect of the volume correction unit 446 will be specifically described below. FIG. 9 is a diagram showing a comparison between the volume change characteristic of vibration radiated sound without volume correction and the volume change characteristic of vibration radiated sound with volume correction. The upper graph of FIG. 9 shows the volume change characteristic of vibration radiated sound without volume correction, and the lower graph shows the volume change characteristic of vibration radiated sound with volume correction. Vibration radiated sound increases linearly as the volume increases. Therefore, if the volume change characteristic is compared as it is, it becomes difficult to grasp the difference in the volume change characteristic for each sample. By correcting the linear increase by the volume correction, it becomes easier to grasp the difference in the volume change characteristic for each sample. In the example of FIG. 9, the difference between the power change of sample A, which is the rising region, and the power changes of samples B, C, and D, which are the linear region, is large.

[0062] Here, in the above-mentioned first diagnosis example, the volume change characteristics are compared for 1250 Hz in the frequency band of interest, but the volume change characteristics may be compared for multiple frequencies in the frequency band of interest. By comparing the volume change characteristics for multiple frequencies in the frequency band of interest, it is expected that the presence or absence of an abnormality can be diagnosed more easily.

[0063] Moreover, the samples used as examples of the first diagnosis described above are concretes with different diameters of styrene boards, simulating measurement objects O with different sizes of defects. Meanwhile, the applicant has also performed a similar first diagnosis on multiple types of concretes with different cover thicknesses of styrene boards, simulating measurement objects O with different depths of defects. As a result, the applicant has confirmed that the first diagnosis can diagnose the presence or absence of abnormalities. In other words, the first diagnosis can diagnose the presence or absence of various abnormalities.

[0064] Next, the second diagnosis will be described. In the first diagnosis, the presence or absence of an abnormality in the measurement object O is diagnosed from the difference in the volume change characteristics. In the second diagnosis, the volume where the volume linearity is maintained is set as the target evaluation volume, and the diagnosis is performed by comparing the frequency characteristics of the vibration radiation sound of the target evaluation volume.

[0065] 10A, 10B, 10C, and 10D are diagrams showing an example of the frequency characteristics of the power of vibration-radiated sound at each evaluation volume (volume at which volume linearity is maintained) obtained by the evaluation unit 447. The horizontal axis of FIG. 10A, 10B, 10C, and 10D is 1 / 3 octave band frequency, and the vertical axis of FIG. 10A, 10B, 10C, and 10D is the power of vibration-radiated sound. FIG. 10A shows the frequency characteristics of vibration-radiated sound for sample A simulating a structure without an abnormality. Meanwhile, FIG. 10B, 10C, and 10D show the frequency characteristics of vibration-radiated sound for samples B, C, and D simulating structures with an abnormality, respectively. Here, the measurement conditions of the frequency characteristics of FIG. 10A, 10B, 10C, and 10D are the same as the measurement conditions of the frequency characteristics of FIG. 6A, 6B, 6C, and 6D. In addition, Figures 10A, 10B, 10C and 10D only show frequency characteristics for volumes where volume linearity is maintained among Figures 6A, 6B, 6C and 6D, i.e., volumes where the power lines overlap.

[0066] Fig. 11 is a diagram showing a comparison of the frequency characteristics of the vibration radiated sound of sample A, the frequency characteristics of the vibration radiated sound of sample B, the frequency characteristics of the vibration radiated sound of sample C, and the frequency characteristics of the vibration radiated sound of sample D for the volume levels where volume linearity is maintained. Here, in Fig. 11, +6 dB is selected as the target evaluation volume among the volume levels where volume linearity is maintained. The volume selected as the target evaluation volume may be another volume where volume linearity is maintained.

[0067] As shown in Figure 11, the frequency characteristics below the 2 kHz band are roughly consistent regardless of the sample. However, there are significant differences in the frequency characteristics for each sample in the 2.5 kHz and 3.1 kHz bands. Specifically, the power of sample A without anomalies is significantly lower than the power of samples B, C, and D with anomalies. This shows that the presence or absence of anomalies in the measurement object O can be diagnosed by comparing the frequency characteristics for volumes where volume linearity is maintained.

[0068] In addition, in FIG. 11, there is a noticeable difference in the frequency characteristics of samples B, C, and D that have an abnormality in the 2.5 kHz band and the 3.1 kHz band. As mentioned above, the diameter of the styrene board is different in samples B, C, and D. In other words, the fact that there is a noticeable difference in the frequency characteristics of samples B, C, and D that have an abnormality in the 2.5 kHz band and the 3.1 kHz band indicates that it may be possible to diagnose the degree of abnormality in the measurement object O by comparing the frequency characteristics of the volume where volume linearity is maintained. For example, the degree of abnormality may be diagnosed by accumulating a database of the relationship between the degree of abnormality and frequency characteristics, and comparing the similarity between the frequency characteristics of this database and the frequency characteristics of the diagnosis object.

[0069] In an actual diagnosis, the control device 4 collects vibration radiated sound from a sample without abnormality in advance, and stores the frequency characteristics of the volume at which volume linearity is maintained for the sample without abnormality from the vibration radiated sound collection results in the diagnosis unit 45. The control device 4 then collects vibration radiated sound from the measurement object O, and diagnoses the presence or absence of an abnormality in the measurement object O by comparing the frequency characteristics of the volume at which a predetermined volume linearity is maintained for the measurement object O with the frequency characteristics of the sample without abnormality. For example, when the control device 4 compares the frequency characteristics of the sample without abnormality and the measurement object O, and there is a frequency range in which the frequency characteristics differ by a predetermined level or more, the control device 4 diagnoses that the measurement object O has an abnormality.

[0070] In the second diagnosis described above, the frequency characteristics of the measurement object at a volume where volume linearity is maintained are compared with the frequency characteristics of a sample without an abnormality to diagnose the presence or absence of an abnormality in the measurement object. Therefore, the presence or absence of an abnormality in the measurement object can be diagnosed without contact. In addition, since the vibration radiation sound also reflects changes inside the measurement object, it is possible to capture changes that cannot be determined from an image of the surface of the measurement object.

[0071] Moreover, the components of the reflected sound from the measurement object O can be removed by the power difference analysis section 445. Therefore, it is possible to compare the volume change characteristics of minute vibration radiation sounds.

[0072] Here, in the above-mentioned second diagnostic example, the frequency characteristics are compared for a volume of +6 dB as the volume for which volume linearity is maintained, but the frequency characteristics may be compared for multiple volumes within the volume range for which volume linearity is maintained. By comparing the frequency characteristics for multiple volumes within the volume range for which volume linearity is maintained, it is expected that it will be easier to diagnose whether or not there is an abnormality.

[0073] Moreover, the samples used as examples of the second diagnosis are three types of concrete with different diameters of styrene boards, simulating the measurement objects O with different sizes of defects. On the other hand, the applicant has performed a similar second diagnosis on multiple types of concrete with different cover thicknesses of styrene boards, simulating the measurement objects O with different depths of defects. As a result, the applicant has confirmed that the second diagnosis can diagnose the presence or absence of abnormalities. In other words, the second diagnosis can diagnose the presence or absence of various abnormalities. In addition, in order to distinguish between the difference in frequency characteristics due to the difference in size of the defect and the difference in frequency characteristics due to the difference in the defect and the depth, for example, the relationship between the degree of abnormality and the frequency characteristics for each type of abnormality is stored in a database, and by comparing the similarity between the frequency characteristics of the database and the frequency characteristics of the diagnosis target, not only the degree of abnormality but also the type of abnormality can be diagnosed.

[0074] As described above, according to the embodiment, the volume of the vibration radiation sound from the measurement object when the measurement object is excited by the excitation sound changes in the order of the dead zone, the rising area, the linear area, and the saturation area according to the volume of the excitation sound, to diagnose an abnormality in the measurement object. This allows for the diagnosis of a structure with the same degree of accuracy as a diagnosis by tapping sound without contact.

[0075] (Modification) Modifications of the embodiment will be described below. (First Modification) 12 is a block diagram showing the configuration of an example of a diagnostic device according to a first modified example of the embodiment. As in the embodiment, the diagnostic device 1 of the first modified example also has a speaker 2, microphones 3a and 3b, and a control device 4. In the first modified example, the configuration of the control device 4 is different.

[0076] The control device 4 of the first modification has a gain instruction unit 47 in addition to the excitation instruction unit 41, the volume instruction unit 42, the impulse response calculation unit 43, the analysis unit 44, the diagnosis unit 45, and the output unit 46. The gain instruction unit 47 instructs the amplifier gain of the microphones 3a and 3b based on the volume instructed by the volume instruction unit 42. Specifically, when the volume instruction unit 42 instructs to increase the volume of the vibration sound, the gain instruction unit 47 decreases the amplifier gain of the microphones 3a and 3b. For example, when the volume of the vibration sound is set to +3 dB, the gain instruction unit 47 sets the amplifier gain of the microphones 3a and 3b to -3 dB. By such an operation, the range of the sound reception signal at the microphones 3a and 3b is constant regardless of the volume of the vibration sound. Therefore, the SN of the sound reception signal is maintained. Here, the standard of the amplifier gain of the microphones 3a and 3b is set to be in the range of ±0.1V or more and 1.0V or less based on the volume standard of the vibration sound of the speaker 2.

[0077] In the configuration of Fig. 12, since the gain of the received signal is reduced, in order to obtain a correct frequency characteristic, it is necessary to correct the reduction in the gain of the received signal. For this purpose, the evaluation characteristic creating unit 443 holds, as the first evaluation characteristic and the second evaluation characteristic, the first evaluation impulse response and the second evaluation impulse response, which are respectively subjected to gain correction. Specifically, the evaluation characteristic creating unit 443 adds a gain for the evaluation volume to each of the first evaluation impulse response and the second evaluation impulse response, and holds these as the first evaluation characteristic and the second evaluation characteristic.

[0078] The first modified example described above improves the signal-to-noise ratio of the received sound signal, which is expected to improve diagnostic accuracy.

[0079] (Second Modification) In the embodiment, diagnosis is performed on the measurement object O in a completely non-contact manner. In contrast, as shown in FIG. 13, an added mass M may be attached to the measurement object O to measure the vibration radiation sound. It is expected that attaching the added mass M to the measurement object O makes it easier to capture the transition of the dead zone, rise zone, linear zone, and saturation zone of the vibration radiation sound. Here, the added mass M may be anything that can increase the mass of the measurement object O. Also, the attached mass M may be attached to the measurement object O by various methods suited to the measurement object O, such as pasting or coating on the measurement object O.

[0080] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0081] 1 diagnostic device, 2 speaker, 3a, 3b microphones (microphones), 4 control device, 41 vibration instruction unit, 42 volume instruction unit, 43 impulse response calculation unit, 44 analysis unit, 45 diagnostic unit, 46 output unit, 47 gain instruction unit, 101 processor, 102 memory, 103 storage, 104 input device, 105 display device, 106 communication device, 107 bus, 441 removal unit, 442 reference characteristic creation unit, 443 evaluation characteristic creation unit, 444 correlation analysis unit, 445 power difference analysis unit, 446 volume correction unit, 447 evaluation unit, 1031 diagnostic program.

Claims

1. A vibration unit that radiates a vibration sound to the measurement object; A volume instruction unit that instructs the vibration unit to have a plurality of different volumes; a first sound receiving unit that is disposed near the measurement object and receives a sound including a vibration radiation sound of the measurement object due to the emission of the excitation sound; A second sound receiving unit is disposed near the vibration unit and receives the excitation sound; an impulse response calculation unit that calculates a first reference impulse response based on a first reference signal output from the first sound receiving unit when a vibration sound of a reference volume from which the vibration radiation sound is not radiated is radiated from the measurement object, a second reference impulse response based on a second reference signal output from the second sound receiving unit when the vibration sound of the reference volume is radiated, a first evaluation impulse response based on a first evaluation signal output from the first sound receiving unit when vibration sounds of at least two evaluation volumes larger than the reference volume are radiated, and a second evaluation impulse response based on a second evaluation signal output from the second sound receiving unit when the vibration sound of the evaluation volume is radiated; a correlation analysis unit that calculates a correlation transfer function between a second reference characteristic based on the second reference impulse response and a second evaluation characteristic based on the second evaluation impulse response; a difference analysis unit that calculates a difference between a first evaluation characteristic based on the first evaluation impulse response and a first reference characteristic based on the first reference impulse response based on the correlation transfer function; a diagnosis unit that diagnoses the measurement object based on the difference and a feature that the volume of the vibration radiation sound changes in the order of a dead zone, a rise zone, a linear zone, and a saturation zone in accordance with a change in the volume of the excitation sound; A diagnostic device comprising:

2. The diagnosis unit includes: Identifying a frequency band of interest in which the difference in frequency characteristics is equal to or greater than a predetermined level; Diagnosing the measurement object based on the difference in the manner in which the volume of the vibration radiation sound in the frequency band of interest changes from a dead zone to a rise zone to a linear zone to a saturation zone in that order in response to a change in the volume of the excitation sound for each measurement object. The diagnostic device of claim 1 .

3. The diagnosis unit includes: Identifying a target evaluation volume whose difference value belongs to the linear region within a certain frequency range in the frequency characteristic of the difference; diagnosing the measurement object based on a difference for each measurement object in the frequency characteristic of the difference for the noticeable evaluation volume; The diagnostic device of claim 1 .

4. The diagnostic device according to claim 1 , further comprising a volume correction unit that performs volume correction on the difference based on a difference between the reference volume and the evaluated volume.

5. a gain instruction unit that decreases gains of the first sound receiving unit and the second sound receiving unit in response to an instruction to increase a volume by the volume instruction unit; an evaluation characteristic creating unit that performs gain correction of the first evaluation impulse response and the second evaluation impulse response according to gains of the first sound receiving unit and the second sound receiving unit; The diagnostic device of claim 1 further comprising:

6. Further comprising an applied mass attached to the measurement object. The diagnostic device of claim 1 .

7. Emitting a vibration sound from a vibration unit to a measurement object; Instructing the vibration unit to have a plurality of different volume levels; Calculating a first reference impulse response based on a first reference signal output from a first sound receiving unit arranged in the vicinity of the measurement object when a vibration sound of a reference volume from which vibration radiation sound is not radiated from the measurement object is radiated, a second reference impulse response based on a second reference signal output from a second sound receiving unit arranged in the vicinity of the excitation unit when the vibration sound of the reference volume is radiated, a first evaluation impulse response based on a first evaluation signal output from the first sound receiving unit when vibration sounds of at least two evaluation volumes larger than the reference volume are radiated, and a second evaluation impulse response based on a second evaluation signal output from the second sound receiving unit when the vibration sound of the evaluation volume is radiated; Calculating a correlation transfer function between a second reference characteristic based on the second reference impulse response and a second evaluation characteristic based on the second evaluation impulse response; calculating a difference between a first evaluation characteristic based on the first evaluation impulse response and a first reference characteristic based on the first reference impulse response based on the correlation transfer function; Diagnosing the measurement object based on the difference and a feature that the volume of the vibration radiation sound changes in the order of a dead zone, a rising region, a linear region, and a saturation zone in accordance with a change in the volume of the excitation sound; A diagnostic method comprising:

8. Emitting a vibration sound from a vibration unit to a measurement object; Instructing the vibration unit to have a plurality of different volume levels; Calculating a first reference impulse response based on a first reference signal output from a first sound receiving unit arranged in the vicinity of the measurement object when a vibration sound of a reference volume from which vibration radiation sound is not radiated from the measurement object is radiated, a second reference impulse response based on a second reference signal output from a second sound receiving unit arranged in the vicinity of the excitation unit when the vibration sound of the reference volume is radiated, a first evaluation impulse response based on a first evaluation signal output from the first sound receiving unit when vibration sounds of at least two evaluation volumes larger than the reference volume are radiated, and a second evaluation impulse response based on a second evaluation signal output from the second sound receiving unit when the vibration sound of the evaluation volume is radiated; Calculating a correlation transfer function between a second reference characteristic based on the second reference impulse response and a second evaluation characteristic based on the second evaluation impulse response; calculating a difference between a first evaluation characteristic based on the first evaluation impulse response and a first reference characteristic based on the first reference impulse response based on the correlation transfer function; Diagnosing the measurement object based on the difference and a feature that the volume of the vibration radiation sound changes in the order of a dead zone, a rising region, a linear region, and a saturation zone in accordance with a change in the volume of the excitation sound; A diagnostic program that allows a computer to run

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