Equipment inspection device and equipment inspection method

Abstract

Even under the influence of obstacles and walls, it can accurately identify equipment emitting abnormal noises. [Solution] An equipment inspection device according to one embodiment includes: a plurality of microphones for measuring sound waveforms emitted from a plurality of devices; an abnormal sound detection unit for detecting abnormal sounds from the sound waveforms; a database storage unit for storing a database that includes the relationship between the frequency of the test sound for each sound source position and a feature quantity that indicates at least one of the phase difference and sound pressure ratio between the plurality of microphones, when the test sound emitted individually from each position of the plurality of devices is measured by the plurality of microphones; and an abnormal sound source identification unit that, when an abnormal sound is detected, identifies the device that emitted the abnormal sound from among the plurality of devices based on the dominant frequency of the abnormal sound and the feature quantity at the dominant frequency of the abnormal sound.

Description

Technical Field

[0001] Embodiments of the present invention relate to an equipment inspection device and an equipment inspection method.

Background Art

[0002] In plants such as factories and power plants, a large number of devices such as prime movers, gearboxes, generators, control motors, and pumps are used. Among these, sensors such as vibration meters are installed on major devices for condition monitoring. However, it is difficult to install sensors on all devices for condition monitoring because the monitoring system becomes complex. Therefore, for non-major devices, people usually perform inspections regularly and take measures if abnormalities are found.

[0003] In recent years, in order to reduce the labor costs required for inspection work, it has been desired to unmanned the inspection of equipment in the plant. However, as described above, it is difficult to install sensors such as vibration meters on all devices. Therefore, a technique has been proposed in which a plurality of microphones are installed in the plant, the sound waveforms emitted by a plurality of devices are simultaneously acquired, and the occurrence of abnormal sounds and the identification of the devices that emitted the abnormal sounds are performed. For example, a technique for identifying a device that emitted an abnormal sound based on the phase difference between a plurality of microphones has been proposed.

[0004] However, for example, when devices are installed in a narrow space such as inside the nacelle of a wind turbine in a wind power plant or inside a small-scale hydroelectric power plant, it may be difficult to measure the phase difference proportional to the sound path difference due to the influence of obstacles and wall surfaces. Therefore, there are cases where the device that emitted the abnormal sound cannot be correctly identified.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

[0006] The embodiment of the present invention aims to provide an equipment inspection device and equipment inspection method that can accurately identify equipment emitting abnormal noises, even under the influence of obstacles or walls. [Means for solving the problem]

[0007] An equipment inspection device according to one embodiment includes: multiple microphones for measuring sound waveforms emitted from multiple devices; an abnormal sound detection unit for detecting abnormal sounds from the sound waveforms; a database storage unit for storing a database that includes the relationship between the frequency of the test sound for each sound source location and a feature quantity indicating at least one of the phase difference and sound pressure ratio between the multiple microphones, when the test sound emitted individually from each location of the multiple devices is measured by the multiple microphones; and an abnormal sound source identification unit that, when an abnormal sound is detected, identifies the device that emitted the abnormal sound from among the multiple devices based on the dominant frequency of the abnormal sound and the feature quantity at the dominant frequency of the abnormal sound.

[0008] A device inspection method according to one embodiment includes a database creation step of creating a database that includes the relationship between the frequency of the test sound for each sound source position and a feature quantity that indicates at least one of the phase difference and sound pressure ratio between the multiple microphones, when the test sound emitted individually from each position of multiple devices is measured by multiple microphones; a sound waveform measurement step of measuring the sound waveforms emitted from each of the multiple devices by multiple microphones; an abnormal sound detection step of detecting abnormal sounds from the sound waveforms; and, if an abnormal sound is detected, an abnormal sound source identification step of identifying the device that emitted the abnormal sound from among the multiple devices based on the dominant frequency of the abnormal sound and the feature quantity at the dominant frequency of the abnormal sound, based on the database. [Effects of the Invention]

[0009] According to embodiments of the present invention, equipment emitting abnormal noises can be accurately identified even under the influence of obstacles or walls. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram showing an equipment inspection device according to the first embodiment. [Figure 2] This is a block diagram showing the configuration of the equipment inspection device according to the first embodiment. [Figure 3] This figure shows an example of the frequency spectrum of a normal sound waveform. [Figure 4] This figure shows an example of the frequency spectrum of a sound waveform when an abnormal sound occurs. [Figure 5] This is a diagram illustrating the method for creating a database in the first embodiment. [Figure 6] This figure shows an example of a database in the first embodiment. [Figure 7] This is a flowchart showing the equipment inspection method according to the first embodiment. [Figure 8] This is a flowchart showing the database creation process in the first embodiment. [Figure 9] This figure shows an example of a database in the second embodiment. [Figure 10] This figure shows an example of a database in the third embodiment. [Figure 11] This is a schematic diagram showing an equipment inspection device according to the fourth embodiment. [Figure 12] This is a flowchart showing the database creation process in the fifth embodiment. [Figure 13] This figure shows an example of a graph representing the phase difference between the moving microphone and the reference microphone with respect to the position of the moving microphone at sound source position A. [Figure 14] This figure shows an example of a graph representing the phase difference between the moving microphone and the reference microphone with respect to the position of the moving microphone at sound source position B. [Figure 15]It is a diagram showing an example of a graph representing the absolute value of the difference in the phase difference between sound source positions A and B with respect to the position of the moving microphone.

Embodiment for Carrying Out the Invention

[0011] Hereinafter, with reference to the drawings, an equipment inspection apparatus and an equipment inspection method according to an embodiment of the present invention will be described.

[0012] (First Embodiment) First, with reference to FIGS. 1 to 6, an equipment inspection apparatus according to the first embodiment will be described.

[0013] FIG. 1 is a schematic diagram showing an equipment inspection apparatus according to the present embodiment. The equipment inspection apparatus 10 according to the present embodiment is installed in the plant 1. The plant 1 is, for example, a wind power plant or a hydroelectric power plant. The equipment inspection apparatus 10 is installed in a narrow space such as inside the nacelle of a wind turbine of a wind power plant or inside a small-scale hydroelectric power plant.

[0014] A plurality of devices 2A, 2B, 2C, 2D are also installed in the plant 1. In the example shown in FIG. 1, four devices 2A, 2B, 2C, 2D are installed in the plant 1. Each of the devices 2A, 2B, 2C, 2D may be a rotating device. Each of the devices 2A, 2B, 2C, 2D is, for example, a prime mover, a transmission, a generator, a control motor, a pump, or the like. The equipment inspection apparatus 10 is used for inspecting a plurality of devices 2A, 2B, 2C, 2D installed in the plant 1.

[0015] [ FIG. 2 is a block diagram showing the configuration of the equipment inspection apparatus according to the present embodiment. The equipment inspection apparatus 10 includes a plurality of microphones 11, 12, 13, 14, sound waveform processing units 21, 22, 23, 24, an abnormal sound detection unit 30, a database storage unit 40, and an abnormal sound source identification unit 50. In the example shown in FIGS. 1 and 2, the equipment inspection apparatus 10 includes four microphones 11, 12, 13, 14.

[0016] Microphones 11, 12, 13, and 14 are placed within Plant 1. Microphones 11, 12, 13, and 14 may be placed at any location within Plant 1. Microphones 11, 12, 13, and 14 may be placed at different distances from each of the devices 2A, 2B, 2C, and 2D. In the example shown in Figure 1, for example, microphone 12 is placed at a position such that the distance from device 2C to microphone 12 is longer by a distance difference dL than the distance from device 2C to microphone 11.

[0017] Microphones 11, 12, 13, and 14 measure the sound waveforms emitted from multiple devices 2A, 2B, 2C, and 2D, respectively. The sound waveforms measured by microphones 11, 12, 13, and 14 are transmitted to their respective sound waveform processing units 21, 22, 23, and 24.

[0018] The sound waveform processing units 21, 22, 23, and 24 are connected to the microphones 11, 12, 13, and 14. The equipment inspection device 10 may include multiple sound waveform processing units 21, 22, 23, and 24. In the example shown in Figure 2, the equipment inspection device 10 includes four sound waveform processing units 21, 22, 23, and 24 corresponding to the four microphones 11, 12, 13, and 14. Each sound waveform processing unit 21, 22, 23, and 24 is connected to the corresponding microphone 11, 12, 13, and 14, respectively.

[0019] The sound waveform processing units 21, 22, 23, and 24 perform signal processing on the sound waveforms measured by the microphones 11, 12, 13, and 14. For example, the sound waveform processing units 21, 22, 23, and 24 perform a Fourier transform on the sound waveforms measured by the microphones 11, 12, 13, and 14 to calculate the frequency spectrum (see Figures 3 and 4). The sound waveforms processed by the sound waveform processing units 21, 22, 23, and 24 are transmitted to the abnormal sound detection unit 30.

[0020] In the example described above, the equipment inspection device 10 included multiple sound waveform processing units 21, 22, 23, and 24, but it may also include only one sound waveform processing unit. In this case, multiple microphones 11, 12, 13, and 14 may be connected to the single sound waveform processing unit. The single sound waveform processing unit may then perform signal processing on each of the sound waveforms measured by the multiple microphones 11, 12, 13, and 14.

[0021] The abnormal sound detection unit 30 is connected to the sound waveform processing units 21, 22, 23, and 24. The abnormal sound detection unit 30 detects abnormal sounds from the sound waveform. That is, the abnormal sound detection unit 30 detects abnormal sounds emitted from any of the multiple devices 2A, 2B, 2C, and 2D. For example, the abnormal sound detection unit 30 detects abnormal sounds from the frequency spectrum of the sound waveform.

[0022] Figure 3 shows an example of the frequency spectrum of a sound waveform under normal conditions. Figure 4 shows an example of the frequency spectrum of a sound waveform when an abnormal sound is generated. In Figures 3 and 4, the horizontal axis represents frequency [Hz] and the vertical axis represents sound pressure [Pa].

[0023] The frequency spectrum shown in Figure 3 contains dominant frequencies f1 and f2, where the sound pressure at those frequencies shows a peak value. These dominant frequencies f1 and f2 are the frequency components of the mechanical sound emitted during normal operation of the equipment. On the other hand, the frequency spectrum shown in Figure 4 contains a dominant frequency f3 in addition to these dominant frequencies f1 and f2. This dominant frequency f3 is the frequency component of abnormal sound emitted from one of the pieces of equipment.

[0024] The abnormal sound detection unit 30 may detect abnormal sounds by comparing the frequency spectrum of the sound waveform when an abnormal sound occurs with the frequency spectrum of the sound waveform when it is normal. For example, the abnormal sound detection unit 30 may calculate the difference between the frequency spectrum of the sound waveform when an abnormal sound occurs and the frequency spectrum of the sound waveform when it is normal, and if there is a frequency component in which the sound pressure difference is greater than a preset reference value, it may determine that the sound waveform contains an abnormal sound. That frequency component corresponds to the dominant frequency of the abnormal sound.

[0025] Information regarding abnormal sounds detected by the abnormal sound detection unit 30 is transmitted to the abnormal sound source identification unit 50.

[0026] The database storage unit 40 stores the database. The database contains the relationship between the frequency of the test sound and the feature quantity for each sound source position, when the test sound emitted individually from each of the positions of the multiple devices 2A, 2B, 2C, and 2D is measured by multiple microphones 11, 12, 13, and 14. In this embodiment, the feature quantity is the phase difference between the multiple microphones 11, 12, 13, and 14.

[0027] Figure 5 is a diagram illustrating the method for creating a database in this embodiment. When creating a database, as shown in Figure 5, first, test sound sources 41 are placed at the respective locations of multiple devices 2A, 2B, 2C, and 2D. In the example shown in Figure 5, a test sound source 41 is placed at the location of device 2C. Multiple test sound sources 41 may be placed simultaneously to correspond to the respective locations of multiple devices, or one test sound source 41 may be placed at the location of one device, and after measurement at that location is completed, that test sound source 41 may be sequentially placed at the locations of the other devices.

[0028] Next, test sounds are individually emitted from the test sound source 41, and the sound waveforms of these test sounds are measured by multiple microphones 11, 12, 13, and 14. The test sound source 41 may emit a single-frequency test sound. The test sound source 41 may sequentially emit multiple different single-frequency test sounds.

[0029] Next, feature quantities are calculated from the sound waveforms of the test sound. Specifically, the phase difference between the multiple microphones 11, 12, 13, and 14 is calculated from the sound waveforms of the test sound measured by the multiple microphones 11, 12, 13, and 14. For example, the phase difference between microphones 11 and 12, the phase difference between microphones 11 and 13, and the phase difference between microphones 11 and 14 are calculated, with microphone 11 as the reference.

[0030] Subsequently, a database is created that includes the relationship between the frequency of the test sound and its features for each sound source location. Specifically, a database is created that includes the relationship between the frequency of the test sound for each sound source location and the phase difference between multiple microphones 11, 12, 13, and 14. Figure 6 shows an example of the database in this embodiment. In the database 42 shown in Figure 6, the relationship between the frequency of the test sound [Hz] and the phase difference [deg] between multiple microphones 11, 12, 13, and 14 is shown for each sound source location A, B, C, and D.

[0031] In Figure 6, the sound source position is the position where the test sound source 41 emitted sound. The sound source position corresponding to device 2A is denoted by symbol A, the sound source position corresponding to device 2B by symbol B, the sound source position corresponding to device 2C by symbol C, and the sound source position corresponding to device 2D by symbol D. In Figure 6, the phase difference between microphones is the phase difference with respect to microphone 11. Microphone 1 is the phase difference between microphones 11, 11. Microphone 2 is the phase difference between microphones 11 and 12. Microphone 3 is the phase difference between microphones 11 and 13. Microphone 4 is the phase difference between microphones 11 and 14.

[0032] In Figure 6, the frequency interval of the test tones is 100 Hz, but this is just an example, and finer frequency intervals (e.g., 10 Hz) may be used. Also, in the database 42 shown in Figure 6, for frequencies located between the test tones (e.g., 150 Hz), the phase difference between microphones may be interpolated by linear interpolation or spline interpolation.

[0033] The abnormal sound source identification unit 50 is connected to the abnormal sound detection unit 30 and the database storage unit 40, respectively. When an abnormal sound is detected by the abnormal sound detection unit 30, the abnormal sound source identification unit 50 identifies the device that emitted the abnormal sound from among multiple devices based on the dominant frequency of the abnormal sound and the characteristic quantities at the dominant frequency of the abnormal sound, using the database 42 stored in the database storage unit 40.

[0034] More specifically, first, the abnormal sound source identification unit 50 calculates the dominant frequency of the abnormal sound detected by the abnormal sound detection unit 30 and the phase difference between the multiple microphones 11, 12, 13, and 14 at that dominant frequency. Next, the abnormal sound source identification unit 50 refers to the database 42 and identifies the sound source location from the dominant frequency of the abnormal sound and the phase difference between the multiple microphones 11, 12, 13, and 14 at that dominant frequency. Then, the abnormal sound source identification unit 50 identifies the equipment that emitted the abnormal sound from this identified sound source location.

[0035] For example, consider a case where the dominant frequency of the abnormal sound is 200 Hz, the phase difference between microphones 11 and 12 is 45 degrees, the phase difference between microphones 11 and 13 is 30 degrees, and the phase difference between microphones 11 and 14 is 15 degrees. In this case, referring to the database 42 shown in Figure 6, the sound source location can be identified as B. Therefore, the device that emitted the abnormal sound can be identified as device 2B.

[0036] If the phase difference between multiple microphones 11, 12, 13, and 14 at the dominant frequency of the abnormal sound does not match the phase difference between microphones in database 42, the sound source location is identified from the closest phase difference at that frequency. For example, consider the case where the dominant frequency of the abnormal sound is 100 Hz, the phase difference between microphones 11 and 12 is 8 degrees, the phase difference between microphones 11 and 13 is 19 degrees, and the phase difference between microphones 11 and 14 is 33 degrees. In this case, by referring to database 42 shown in Figure 6, the sound source location can be identified as A from the relationship between the closest frequency and the phase difference between microphones. Also, if the dominant frequency of the abnormal sound does not match the frequency in database 42, the sound source location is identified from the phase difference between microphones interpolated by linear interpolation or spline interpolation at that frequency, for example.

[0037] Next, the equipment inspection method according to the first embodiment will be described with reference to Figures 7 and 8.

[0038] The equipment inspection method according to this embodiment is a method for inspecting multiple pieces of equipment 2A, 2B, 2C, and 2D installed in Plant 1. In the equipment inspection method according to this embodiment, the above-described equipment inspection device 10 is used to inspect multiple pieces of equipment 2A, 2B, 2C, and 2D installed in Plant 1.

[0039] Figure 7 is a flowchart illustrating the equipment inspection method according to this embodiment. As shown in Figure 7, the equipment inspection method according to this embodiment includes a database creation step (step S1 in Figure 7), a sound waveform measurement step (step S2 in Figure 7), an abnormal sound detection step (step S3 in Figure 7), and an abnormal sound source identification step (step S4 in Figure 7). The equipment inspection method according to this embodiment may further include an equipment monitoring step (step S5 in Figure 7). The equipment inspection method according to this embodiment will be described below in accordance with the flowchart in Figure 7.

[0040] First, in the database creation process of step S1, a database is created. The database contains the relationship between the frequency of the test sound and the feature quantity for each sound source position, when the test sound emitted individually from each of the positions of multiple devices 2A, 2B, 2C, and 2D is measured by multiple microphones 11, 12, 13, and 14. In this embodiment, the feature quantity is the phase difference between the multiple microphones 11, 12, 13, and 14.

[0041] In the database creation process of step S1, a database 42 as shown in Figure 6 is created. Figure 8 is a flowchart of the database creation process in this embodiment. The database creation process in this embodiment will be explained in more detail using Figure 8.

[0042] First, in step S11, test sound sources 41 are placed at the respective locations of the multiple devices 2A, 2B, 2C, and 2D. Multiple test sound sources 41 may be placed simultaneously to correspond to the respective locations of the multiple devices, or one test sound source 41 may be placed at the location of one device, and after the measurement in step S13 described later at that location is completed, that test sound source 41 may be sequentially placed at the locations of the other devices.

[0043] Next, in step S12, test sounds are individually emitted from the installed test sound sources 41. The test sound sources 41 may emit a single-frequency test sound. Alternatively, the test sound sources 41 may sequentially emit multiple different single-frequency test sounds.

[0044] Next, in step S13, the sound waveform of the test sound is measured using multiple microphones 11, 12, 13, and 14. If one test sound source 41 was placed at the location of one piece of equipment in step S11, after this measurement is completed, the process returns to step S11 and the test sound source 41 is placed at the location of the other piece of equipment. Steps S11 to S13 are then repeated until measurements for all pieces of equipment 2A, 2B, 2C, and 2D are completed.

[0045] Subsequently, in step S14, feature quantities are calculated from the sound waveform of the test sound. Specifically, the phase difference between the multiple microphones 11, 12, 13, and 14 is calculated from the sound waveform of the test sound measured by the multiple microphones 11, 12, 13, and 14. For example, the phase difference between microphones 11 and 12, the phase difference between microphones 11 and 13, and the phase difference between microphones 11 and 14 are calculated, with microphone 11 as the reference.

[0046] Then, in step S15, a database is created that includes the relationship between the frequency of the test sound and the feature quantity for each sound source position. That is, a database 42 is created that includes the relationship between the frequency of the test sound for each sound source position A, B, C, D and the phase difference between multiple microphones 11, 12, 13, 14, as shown in Figure 6.

[0047] Step S1, the database creation process, is a preliminary test conducted before the operation of equipment 2A, 2B, 2C, and 2D. After the completion of this preliminary test, equipment 2A, 2B, 2C, and 2D installed in Plant 1 are put into operation. Steps S2 and beyond are performed during the operation of equipment 2A, 2B, 2C, and 2D.

[0048] Returning to the explanation of the flowchart in Figure 7, after the database creation process in step S1, in the sound waveform measurement process in step S2, the sound waveforms emitted from multiple devices 2A, 2B, 2C, and 2D are measured using multiple microphones 11, 12, 13, and 14. In step S2, the sound waveforms of the multiple devices 2A, 2B, 2C, and 2D are measured during operation.

[0049] Here, we consider the case where the number of microphones 11, 12, 13, and 14 used to measure the sound waveform in the sound waveform measurement process of step S2 is the same as the number of microphones 11, 12, 13, and 14 used to measure the sound waveform of the test sound in step S13 described above. We also consider the case where the installation positions of microphones 11, 12, 13, and 14 in the sound waveform measurement process of step S2 are the same as the installation positions of microphones 11, 12, 13, and 14 in step S13.

[0050] After the sound waveform measurement step in step S2, in the abnormal sound detection step in step S3, abnormal sounds are detected from the sound waveforms measured by the multiple microphones 11, 12, 13, and 14. In the abnormal sound detection step in step S3, abnormal sounds may also be detected by comparing the frequency spectrum of the sound waveform when an abnormal sound occurs with the frequency spectrum of a normal sound waveform. For example, the difference between the frequency spectrum of the sound waveform when an abnormal sound occurs and the frequency spectrum of a normal sound waveform may be calculated, and if there is a frequency component in which the sound pressure difference is greater than a preset reference value, it may be determined that the sound waveform contains an abnormal sound.

[0051] If no abnormal sound is detected in the abnormal sound detection step S3 (NO in step S3), the sound waveform is measured again in step S2. On the other hand, if an abnormal sound is detected in the abnormal sound detection step S3 (YES in step S3), the process proceeds to the abnormal sound source identification step S4.

[0052] In step S4, the abnormal sound source identification process, the device that emitted the abnormal sound is identified from among multiple devices 2A, 2B, 2C, and 2D based on the database 42, using the dominant frequency of the abnormal sound and the features at that dominant frequency. More specifically, first, for the detected abnormal sound, the dominant frequency of the abnormal sound and the phase difference between multiple microphones 11, 12, 13, and 14 at that dominant frequency are calculated. Next, the sound source location is identified by referring to the database 42, using the dominant frequency of the abnormal sound and the phase difference between multiple microphones 11, 12, 13, and 14 at that dominant frequency. Then, the device that emitted the abnormal sound is identified from this identified sound source location.

[0053] After the abnormal sound source identification step in step S4, the equipment monitoring step in step S5 monitors the equipment identified as emitting the abnormal sound. For example, the status of the equipment identified as emitting the abnormal sound is monitored in detail using a microphone placed closest to the equipment. Alternatively, the microphone is moved closer to the equipment identified as emitting the abnormal sound, and its status is monitored in detail using that microphone. Another example is installing a sensor such as a vibration meter on the equipment identified as emitting the abnormal sound, and its status is monitored in detail using that sensor. Such detailed monitoring makes it possible to estimate the maintenance or replacement timing of the equipment.

[0054] As described above, according to this embodiment, when an abnormal sound is detected, the device that emitted the abnormal sound is identified from among the multiple devices 2A, 2B, 2C, and 2D based on the database 42, using the dominant frequency of the abnormal sound and the feature quantities at the dominant frequency of the abnormal sound. The database 42 includes the relationship between the frequency and feature quantities of the test sound for each sound source location, when the test sounds emitted individually from each location of the multiple devices 2A, 2B, 2C, and 2D are measured by multiple microphones 11, 12, 13, and 14. Here, the feature quantities of the database 42 also reflect the effects of obstacles and walls. Therefore, even under the influence of obstacles and walls, the device that emitted the abnormal sound can be identified with high accuracy.

[0055] In particular, according to this embodiment, the feature quantity is the phase difference between multiple microphones 11, 12, 13, and 14. In general methods of identifying sound sources using the phase difference between multiple microphones, it is necessary to assume that the phase difference between microphones is proportional to the path difference of the sound from the sound source, and the microphones are required to measure only the direct sound from the sound source. For this reason, if there is reflected sound from obstacles or walls, the phase of the sound changes, and it may not be possible to accurately measure the phase difference between microphones. In contrast, according to this embodiment, the phase difference between microphones in the database 42 also reflects the effects of obstacles and walls, so the above assumption can be eliminated. For this reason, even under the influence of obstacles and walls, equipment emitting abnormal sounds can be identified with high accuracy.

[0056] In the example described above, the number of microphones used to measure the sound waveform in the sound waveform measurement step S2 was the same as the number of microphones used to measure the sound waveform of the test sound in step S13. However, this embodiment is not limited to this example, and for example, the number of microphones used to measure the sound waveform in the sound waveform measurement step S2 may be less than the number of microphones used to measure the sound waveform of the test sound in step S13. For example, eight microphones may be used in step S13 and four microphones may be used in the sound waveform measurement step S2. In this case, the microphone placement positions in the sound waveform measurement step S2 may be appropriately selected from the microphone placement positions in step S13. For example, from the microphone placement positions in step S13, a position where the difference in feature quantities between sound source positions is large and makes it easier to identify the sound source position may be selected as the microphone placement position in the sound waveform measurement step S2.

[0057] (Second Embodiment) Next, with reference to Figure 9, a second embodiment of the equipment inspection device and equipment inspection method will be described.

[0058] In the second embodiment shown in Figure 9, the main difference is that the feature quantity is the sound pressure ratio between multiple microphones. The other configurations are substantially the same as those of the first embodiment shown in Figures 1 to 8.

[0059] In this embodiment, the feature quantity is the sound pressure ratio between multiple microphones 11, 12, 13, and 14. Figure 9 shows an example of a database in this embodiment. In the database 43 shown in Figure 9, the relationship between the frequency [Hz] of the test sound and the sound pressure ratio between multiple microphones 11, 12, 13, and 14 is shown for each sound source position A, B, C, and D.

[0060] In Figure 9, the sound pressure ratio between microphones is the sound pressure ratio with respect to microphone 11. Microphone 1 is the sound pressure ratio between microphones 11, 11 (the sound pressure ratio of microphone 11 relative to microphone 11). Microphone 2 is the sound pressure ratio between microphones 11, 12 (the sound pressure ratio of microphone 12 relative to microphone 11). Microphone 3 is the sound pressure ratio between microphones 11, 13 (the sound pressure ratio of microphone 13 relative to microphone 11). Microphone 4 is the sound pressure ratio between microphones 11, 14 (the sound pressure ratio of microphone 14 relative to microphone 11).

[0061] In the equipment inspection device 10 according to this embodiment, first, the abnormal sound source identification unit 50 calculates the dominant frequency of the abnormal sound detected by the abnormal sound detection unit 30 and the sound pressure ratio between the multiple microphones 11, 12, 13, and 14 at that dominant frequency. Next, the abnormal sound source identification unit 50 refers to the database 43 and identifies the sound source location from the dominant frequency of the abnormal sound and the sound pressure ratio between the multiple microphones 11, 12, 13, and 14 at that dominant frequency. Then, the abnormal sound source identification unit 50 identifies the equipment that emitted the abnormal sound from this identified sound source location.

[0062] For example, consider the case where the dominant frequency is 200 Hz, the sound pressure ratio between microphones 11 and 12 is 3, the sound pressure ratio between microphones 11 and 13 is 0.5, and the sound pressure ratio between microphones 11 and 14 is 0.2. In this case, referring to database 43 shown in Figure 9, the sound source location can be identified as B. Therefore, the device that emitted the abnormal sound can be identified as device 2B.

[0063] If the sound pressure ratio between multiple microphones 11, 12, 13, and 14 at the dominant frequency of the abnormal sound does not match the sound pressure ratio between microphones in database 42, the sound source location is identified from the closest sound pressure ratio at that frequency. For example, consider the case where the dominant frequency of the abnormal sound is 100 Hz, the sound pressure ratio between microphones 11 and 12 is 1.8, the sound pressure ratio between microphones 11 and 13 is 3.1, and the sound pressure ratio between microphones 11 and 14 is 5.3. In this case, by referring to database 43 shown in Figure 9, the sound source location can be identified as A from the relationship between the closest frequency and the sound pressure ratio between microphones. Furthermore, if the dominant frequency of the abnormal sound does not match the frequency in database 43, the sound source location is identified from the sound pressure ratio between microphones interpolated by linear interpolation or spline interpolation at that frequency, for example.

[0064] In the equipment inspection method according to this embodiment, in the database creation process, a database 43 is created that includes the relationship between the frequency of the test sound for each sound source position A, B, C, and D and the sound pressure ratio between multiple microphones 11, 12, 13, and 14, as shown in Figure 9.

[0065] Furthermore, in the equipment inspection method according to this embodiment, in the abnormal sound source identification step, first, for the detected abnormal sound, the dominant frequency of the abnormal sound and the sound pressure ratio between the multiple microphones 11, 12, 13, and 14 at that dominant frequency are calculated. Next, by referring to the database 42, the sound source location is identified from the dominant frequency of the abnormal sound and the sound pressure ratio between the multiple microphones 11, 12, 13, and 14 at that dominant frequency. Then, the equipment that emitted the abnormal sound is identified from this identified sound source location.

[0066] Thus, according to this embodiment, the feature quantity is the sound pressure ratio between multiple microphones 11, 12, 13, and 14. Based on general theory, it is difficult to identify the sound source location from the sound pressure difference. However, if a database created in advance under the same environment is used, as in this embodiment, it is possible to identify the sound source location from the sound pressure ratio. Therefore, in this embodiment as well, it is possible to accurately identify equipment emitting abnormal sounds under the influence of obstacles and walls.

[0067] (Third embodiment) Next, with reference to Figure 10, a third embodiment of equipment inspection apparatus and equipment inspection method will be described.

[0068] The third embodiment shown in Figure 10 differs mainly in that the feature quantities are both the phase difference and the sound pressure ratio between multiple microphones. The other configurations are substantially the same as those of the first embodiment shown in Figures 1 to 8.

[0069] In this embodiment, the feature quantities are both the phase difference and the sound pressure ratio between the multiple microphones 11, 12, 13, and 14. Figure 10 shows an example of a database in this embodiment. In the database 44 shown in Figure 10, the relationship between the frequency of the test sound and the phase difference and sound pressure ratio between the multiple microphones 11, 12, 13, and 14 is shown for each sound source position A, B, C, and D.

[0070] In Figure 10, the phase difference / sound pressure ratio between microphones is the phase difference and sound pressure ratio relative to microphone 11, respectively. Microphone 1 is the phase difference and sound pressure ratio between microphones 11, 11. Microphone 2 is the phase difference and sound pressure ratio between microphones 11 and 12. Microphone 3 is the phase difference and sound pressure ratio between microphones 11 and 13. Microphone 4 is the phase difference and sound pressure ratio between microphones 11 and 14.

[0071] In the equipment inspection device 10 according to this embodiment, first, the abnormal sound source identification unit 50 calculates the dominant frequency of the abnormal sound detected by the abnormal sound detection unit 30, as well as the phase difference and sound pressure ratio between the multiple microphones 11, 12, 13, and 14 at that dominant frequency. Next, the abnormal sound source identification unit 50 refers to the database 44 to identify the sound source location from the dominant frequency of the abnormal sound and the phase difference and sound pressure ratio between the multiple microphones 11, 12, 13, and 14 at that dominant frequency. Then, the abnormal sound source identification unit 50 identifies the equipment that emitted the abnormal sound from this identified sound source location.

[0072] In the equipment inspection method according to this embodiment, in the database creation step, a database 44 is created that includes the relationship between the frequency of the test sound for each sound source position A, B, C, D and the phase difference and sound pressure ratio between multiple microphones 11, 12, 13, 14, as shown in Figure 10.

[0073] In the equipment inspection method according to this embodiment, in the abnormal sound source identification step, first, for the detected abnormal sound, the dominant frequency of the abnormal sound and the phase difference and sound pressure ratio between the multiple microphones 11, 12, 13, and 14 at that dominant frequency are calculated. Next, by referring to the database 42, the sound source location is identified from the dominant frequency of the abnormal sound and the phase difference and sound pressure ratio between the multiple microphones 11, 12, 13, and 14 at that dominant frequency. Then, the equipment that emitted the abnormal sound is identified from this identified sound source location.

[0074] Thus, according to this embodiment, the feature quantities are both the phase difference and the sound pressure ratio between the multiple microphones 11, 12, 13, and 14. By using both the phase difference and the sound pressure ratio between the microphones 11, 12, 13, and 14, the sound source location can be identified with even greater accuracy. Therefore, even under the influence of obstacles and walls, equipment emitting abnormal sounds can be identified with even greater accuracy.

[0075] (Fourth Embodiment) Next, with reference to Figure 11, a fourth embodiment of equipment inspection apparatus and equipment inspection method will be described.

[0076] The fourth embodiment shown in Figure 11 differs mainly in that one of the microphones among the multiple microphones is configured to be movable. The other configurations are substantially the same as those of the first embodiment shown in Figures 1 to 8.

[0077] In the equipment inspection device 10 according to this embodiment, one of the microphones among the multiple microphones is configured to be movable. Figure 11 is a schematic diagram showing the equipment inspection device according to this embodiment. In the example shown in Figure 11, the equipment inspection device 10 includes two microphones 11 and 12.

[0078] Microphone 11 is a fixed microphone; that is, its position is fixed. Microphone 11 may be fixed in the position of microphone 11 in the first embodiment.

[0079] Microphone 12 is a portable microphone. That is, microphone 12 is configured to be movable. Microphone 12 may be moved to the positions of microphones 12, 13, and 14 in the first embodiment. Microphone 12 may also be moved to a position near devices 2A, 2B, 2C, and 2D.

[0080] The microphone 12 may be mounted on a cart or a drone. The microphone 12 may be mobile by being mounted on a cart or a drone. In the example shown in Figure 11, the microphone 12 is mounted on a cart 60. The cart 60 may be configured to be movable by human intervention, or it may be configured to be movable by remote control or automatic piloting.

[0081] In the equipment inspection method according to this embodiment, during the database creation process, the sound waveform of the test sound is measured while moving the microphone 12 to multiple positions. For example, the microphone 12 is moved to the positions of microphones 12, 13, and 14 in the first embodiment, and the sound waveform of the test sound is measured at each position.

[0082] Furthermore, in the equipment inspection method according to this embodiment, in the sound waveform measurement step, the microphone 12 is moved to multiple positions while measuring the sound waveforms emitted from multiple devices 2A, 2B, 2C, and 2D. For example, the microphone 12 is moved to the positions of microphones 12, 13, and 14 in the first embodiment, and the sound waveforms emitted from multiple devices 2A, 2B, 2C, and 2D are measured at each position.

[0083] Furthermore, in the equipment inspection method according to this embodiment, during the equipment monitoring process, the microphone 12 is moved to the vicinity of the equipment that has been identified as emitting an abnormal sound, and the condition of that equipment is monitored in detail using the microphone 12.

[0084] As described above, in this embodiment, one of the multiple microphones is configured to be movable. This reduces the number of microphones used for measuring sound waveforms. Furthermore, it increases the degree of freedom in detailed monitoring of equipment during the equipment monitoring process.

[0085] (Fifth embodiment) Next, with reference to Figures 12 to 15, a fifth embodiment of equipment inspection apparatus and equipment inspection method will be described.

[0086] In the fifth embodiment shown in Figures 12 to 15, the main difference is that in the database creation process, the fixed position of the microphone is determined from among multiple locations based on the difference in feature quantities between different sound source locations. The other configurations are substantially the same as those of the fourth embodiment shown in Figure 11.

[0087] In the equipment inspection device 10 according to this embodiment, similar to the fourth embodiment, one of the multiple microphones is configured to be movable. Similar to the fourth embodiment, the equipment inspection device 10 may include two microphones 11 and 12, a fixed microphone 11 and a movable microphone 12.

[0088] In the equipment inspection method according to this embodiment, the fixed position of the microphone 12 is determined from among multiple positions based on the difference in feature quantities between different sound source positions during the database creation process. Figure 12 is a flowchart of the database creation process in this embodiment. In the flowchart shown in Figure 12, steps S11 and S12 are the same as in the first embodiment.

[0089] In the equipment inspection method according to this embodiment, in step S23 following step S12, the sound waveform of the test sound is measured while moving the microphone 12 to multiple positions. The microphone 12 is moved, for example, by predetermined distances in the X and Y directions in a horizontal plane.

[0090] Next, in step S24, feature quantities are calculated from the sound waveform of the test sound. For example, at each position where microphone 12 is moved, the phase difference between microphones 11 and 12 is calculated with respect to microphone 11.

[0091] Next, in step S25, the fixed position of microphone 12 is determined from among multiple positions based on the difference in feature quantities between different sound source locations. That is, the fixed position of microphone 12 is determined from among multiple positions to which microphone 12 has been moved, based on the difference in phase difference between microphones 11 and 12 between different sound source locations. For example, the fixed position of microphone 12 is determined to be a position where the absolute value of the difference in phase difference between microphones 11 and 12 between different sound source locations is greater than a preset threshold.

[0092] Figure 13 shows an example graph representing the phase difference δa between the moving microphone and the reference microphone with respect to the position of the moving microphone at sound source position A. Figure 14 shows an example graph representing the phase difference δb between the moving microphone and the reference microphone with respect to the position of the moving microphone at sound source position B. Here, the reference microphone refers to a fixed microphone 11, and the moving microphone refers to a movable microphone 12. The position of the moving microphone is represented by its position in the X direction and the Y direction. Graphs like those shown in Figures 13 and 14 can be obtained in step S24 by calculating the phase difference between microphones 11 and 12 at each position of microphone 12.

[0093] Figure 15 shows an example of a graph representing the absolute value of the phase difference between sound source positions A and B with respect to the position of the moving microphone. Figure 15 shows the absolute value of the difference between the phase difference δa shown in Figure 13 and the phase difference δb shown in Figure 14, at each position shown in the graphs of Figures 13 and 14.

[0094] In the graph shown in Figure 15, the absolute value of the phase difference shows a maximum value at positions P and Q of the moving microphone, and these maximum values ​​are greater than a preset threshold. Therefore, these positions P and Q can be determined as the fixed positions of the microphone 12.

[0095] In the example above, we explained the case with two sound source positions A and B for ease of understanding, but the same method can be applied to cases with more sound source positions. For example, if there are four sound source positions A, B, C, and D, the absolute difference in phase difference between each of the sound source positions A, B, C, and D can be calculated, and their sum can be found. The position where this sum is greater than a predetermined threshold can then be determined as the fixed position for the microphone 12.

[0096] Furthermore, although the above example described the case where the feature quantity is the phase difference between microphones 11 and 12, as in the second embodiment, the feature quantity may also be the sound pressure ratio between microphones 11 and 12. That is, the fixed position of microphone 12 may be determined from among a plurality of positions where microphone 12 has been moved, based on the difference in the sound pressure ratio between microphones 11 and 12 at different sound source locations.

[0097] Subsequently, in step S26, a database is created that includes the relationship between the frequency of the test sound and the feature quantities for each sound source position at the fixed position of microphone 12. That is, a database is created that includes the relationship between the frequency of the test sound for each sound source position A, B, C, D and the phase difference between multiple microphones 11, 12, 13, 14 when microphone 12 is moved to its fixed position and measured.

[0098] In the equipment inspection method according to this embodiment, in the sound waveform measurement step, the microphone 12 is moved to a predetermined fixed position and the sound waveforms emitted from multiple devices 2A, 2B, 2C, and 2D are measured.

[0099] As described above, in this embodiment, during the database creation process, the fixed position of the microphone 12 is determined from among multiple locations based on the difference in feature quantities between different sound source locations. This makes it easier to distinguish the difference in feature quantities between sound source locations, thereby enabling more accurate identification of the sound source location. As a result, equipment emitting abnormal sounds can be identified with even greater accuracy, even under the influence of obstacles or walls.

[0100] According to the embodiments described above, even under the influence of obstacles or walls, equipment emitting abnormal noises can be accurately identified.

[0101] 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 variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of symbols]

[0102] 2A, 2B, 2C, 2D: Equipment, 10: Equipment inspection device, 11, 12, 13, 14: Microphone, 30: Abnormal sound detection unit, 40: Database storage unit, 41: Test sound source, 42, 43, 44: Database, 50: Abnormal sound source identification unit, A, B, C, D: Sound source location

Claims

1. Multiple microphones to measure the sound waveforms emitted from multiple devices, An abnormal sound detection unit that detects abnormal sounds from the sound waveform, A database storage unit stores a database that includes the relationship between the frequency of the test sound for each sound source position and a feature quantity that represents at least one of the phase difference and sound pressure ratio between the multiple microphones, when the test sound emitted individually from each position of the multiple devices is measured by the multiple microphones, An equipment inspection device comprising: an abnormal sound source identification unit that, when the abnormal sound is detected, identifies the equipment that emitted the abnormal sound from among the plurality of equipment based on the dominant frequency of the abnormal sound and the characteristic quantity at the dominant frequency of the abnormal sound, based on the database.

2. The equipment inspection device according to claim 1, wherein the aforementioned feature quantity is the phase difference between the plurality of microphones.

3. The equipment inspection device according to claim 1, wherein the aforementioned feature quantity is the sound pressure ratio between the plurality of microphones.

4. The equipment inspection device according to claim 1, wherein the aforementioned feature quantities are both the phase difference and the sound pressure ratio between the plurality of microphones.

5. The equipment inspection device according to claim 1, wherein one of the microphones among the plurality of microphones is configured to be movable.

6. A database creation step involves creating a database that includes the relationship between the frequency of the test sound for each sound source position and a feature quantity that represents at least one of the phase difference and sound pressure ratio between the multiple microphones, when the test sound emitted individually from each position of multiple devices is measured using multiple microphones. A sound waveform measurement step in which the sound waveforms emitted from each of the aforementioned multiple devices are measured by the aforementioned multiple microphones, An abnormal sound detection step for detecting abnormal sounds from the sound waveform, A device inspection method comprising: when the aforementioned abnormal sound is detected, an abnormal sound source identification step, based on the database, identifying the device that emitted the abnormal sound from among the plurality of devices based on the dominant frequency of the abnormal sound and the characteristic quantity at the dominant frequency of the abnormal sound.

7. The equipment inspection method according to claim 6, wherein in the database creation step, test sound sources are installed at each of the multiple pieces of equipment, test sounds are emitted individually from the test sound sources, the sound waveform of the test sounds is measured by the multiple microphones, the feature quantities are calculated from the sound waveform of the test sounds, and a database is created that includes the relationship between the frequency of the test sounds and the feature quantities for each sound source location.

8. The equipment inspection method according to claim 6, further comprising an equipment monitoring step of monitoring the equipment that has been identified as having emitted the abnormal sound.

9. The equipment inspection method according to claim 6, wherein the feature quantity is the phase difference between the plurality of microphones.

10. The equipment inspection method according to claim 6, wherein the feature quantity is the sound pressure ratio between the plurality of microphones.

11. The equipment inspection method according to claim 6, wherein the characteristic quantities are both the phase difference and the sound pressure ratio between the plurality of microphones.

12. The equipment inspection method according to claim 7, wherein in the database creation step, the sound waveform of the test sound is measured while moving one of the multiple microphones to multiple positions.

13. The equipment inspection method according to claim 12, wherein in the database creation step, a fixed position for the microphone is determined from among the plurality of positions based on the difference in the feature quantities between different sound source positions.

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