JP6408929B2 - Analysis data creation method, water leakage position detection device, and water leakage position identification method - Google Patents

Description

  The present invention relates to an analysis data creation method, a water leakage position detection device, and a water leakage position identification method.

  Conventionally, as a method of determining the position of a pipe leak, vibration is detected by a sensor, a cross-correlation function is generated from the detected signal, analysis data is created using the acoustic propagation velocity, and abnormal noise such as water leakage is detected. There is a method for specifying the occurrence position of the.

  For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 8-226865) discloses that in a noisy environment where no excavation is easy and noisy, a disturbing noise source is eliminated in a non-intrusive manner, and the leakage of the conduit is accurately detected. A method for determining the position of a conduit leak for determining position is disclosed.

  The method of determining the leak position of a conduit described in Patent Document 1 (Japanese Patent Application Laid-Open No. 8-226865) includes: a) first sensors arranged along a conduit so as to obtain a raw plot of a first time difference; Calculating a cross-correlation function from leakage noise data obtained from the pair; and b) from leakage noise data obtained from a second pair of sensors spaced apart along the conduit to obtain a raw plot of the second time difference. Calculating a cross-correlation function; c) smoothing each raw plot of the time difference to obtain a time difference peak for each plot; and d) a known time interval between the first time difference peak and the first sensor pair. To determine the propagation speed for conduit leakage noise, and e) to determine the location of the leakage by using the propagation speed, the second time difference peak, and the spacing between the second sensor pair. The position of the leakage of the conduit is determined.

  Patent Document 2 (Japanese Patent Publication No. 2003-502678) describes a method and apparatus for detecting and locating leakage in a fluid conveyance pipe using a technique based on correlation.

  In the position specifying method described in Patent Document 2 (Japanese translations of PCT publication No. 2003-502678), a method for detecting and specifying a common signal of two input signals using a correlation-based technique, Analyzing the phase of the input signal, preparing at least one filter, filtering the input signal in the frequency domain using the at least one filter, and cross-correlating the filtered signals Common signal detection comprising the steps of:

JP-A-8-226865 Special table 2003-502678 gazette

  Thus, the aging of waterworks or gas pipes has progressed, and fluid leakage from defects has become a problem. Therefore, it is conceivable to apply the method described in Patent Document 1 (Japanese Patent Laid-Open No. 8-226865) or Patent Document 2 (Japanese Patent Publication No. 2003-502678) to specify the defect position.

However, in an actual leakage site, there is a problem that external noise such as automobile traffic noise and other noises are input in addition to abnormal sounds.
Further, when the amount of fluid leaking is small and the abnormal sound is small, there is a problem that the leak position is separated from the vibration sensor position and the detected abnormal sound is small.
For this reason, the method described in Patent Document 2 attempts to detect abnormal sounds by enhancing or reducing the cross-correlation peak by removing or blocking frequencies that do not exhibit sufficient coherence.

However, in the method described in Patent Document 2, since noise with extremely high correlation is included as a result of incomplete digitization, the noise is deleted using an automatic band filter.
As a result of the deletion, there is a problem that a necessary waveform component is removed when an abnormal sound smaller than noise is input, such as a minute water leak in a synthetic resin tube.

  An object of the present invention is to provide a highly reliable analysis data creation method, a water leak position detection device, and a water leak position specifying method.

(1)
An analysis data creation method according to one aspect includes a measurement step of measuring vibrations for a predetermined time at a plurality of times at the same time by at least two sensors, and a cross correlation for obtaining a plurality of cross correlations from a plurality of waveforms measured in the measurement step. A calculation step, a division step for dividing the cross-correlation calculated in the cross-correlation calculation step for each predetermined span, and a specific span having a maximum value or a predetermined correlation value or more in each span divided in the division step. It includes a span specifying step for specifying, and a frequency calculating step for calculating the frequency of the specific span specified in the span specifying step.

  In this case, the cross-correlation is divided into predetermined spans by the dividing step, and a specific span equal to or greater than the maximum value of each span or a predetermined correlation value is specified by the span specifying step. Then, the frequency of the specific span is calculated by the frequency calculation step. As a result, it is possible to remove the influence of disturbance or the like included in the correlation function, increase the accuracy of the analysis data, and obtain highly reliable analysis data.

(2)
The analysis data creation method according to the second invention may include a cross-correlation selection step of selecting a cross-correlation including a specific span whose frequency is calculated to be a certain value or more in the frequency calculation step in the analysis data creation method according to one aspect. Good.

  In this case, the cross-correlation including the specific span whose frequency is calculated to be a certain level or higher is selected by the cross-correlation selecting step. Therefore, it is possible to extract only the cross-correlation having a high influence degree and to remove the cross-correlation having a low influence degree or including a disturbance. As a result, the accuracy of the analysis data can be increased.

(3)
The analysis data creation method according to the third invention is the analysis data creation method according to the second invention, wherein the cross-correlation including a plurality of specific spans among the cross-correlations including the specific span selected in the cross-correlation selection step is averaged. You may use it.

  In this case, since the cross-correlation including a plurality of specific spans is averaged and used, the cross-correlation averaging process having a high influence can be performed. As a result, the accuracy of the analysis data can be further increased.

(4)
The analysis data creation method according to a fourth aspect of the present invention is the analysis data creation method according to one aspect, wherein the frequency calculation step includes a span selection step of selecting a cross-correlation in a specific span where the frequency is calculated to be a certain value or more. Good.

  In this case, since the cross-correlation is selected for the specific span whose frequency is calculated to be a certain value or more by the span selection process, only the specific span with a high impact level is extracted, and the specific span with a low impact level or a disturbance is included. Can be removed. As a result, the accuracy of the analysis data can be increased.

(5)
The analysis data creation method according to the fifth invention is the analysis data creation method according to the fourth invention, wherein the cross-correlation in a plurality of specific spans among the specific spans selected in the span selection step is averaged and used. Good.

  In this case, since the cross-correlation including a plurality of specific spans is averaged and used, it is possible to perform the average processing of specific spans having a high degree of influence. As a result, the accuracy of the analysis data can be further increased.

(6)
A water leakage detection device according to another aspect is configured using analysis data created by the analysis data creation method according to any one of claims 1 to 5.

  In this case, water leakage detection can be performed using the analysis data created by the analysis data creation method. Therefore, since the analysis data with high accuracy is used, the certainty of the leak position can be increased.

(7)
Furthermore, the water leak position specifying method according to another aspect specifies the water leak position using the analysis data created by the analysis data creating method according to any one of claims 1 to 5.

  In this case, water leakage detection can be performed using the analysis data created by the analysis data creation method. Therefore, since the analysis data with high accuracy is used, the certainty of the leak position can be increased.

It is a schematic diagram for demonstrating the condition of the water leak location specifying method. It is a schematic diagram which shows an example of the water leak position detection apparatus containing a vibration sensor. It is a schematic diagram which shows an example of the characteristic of the vibration sensor of FIG. It is a flowchart which shows an example of the water leak position specific method concerning this Embodiment. It is a schematic diagram which shows the intensity | strength in the frequency band of a vibration sensor. It is a schematic diagram which shows the intensity | strength in the frequency band of a vibration sensor. It is a flowchart which shows an example of frequency processing. It is a schematic diagram which shows an example of a cross correlation function. It is a schematic diagram which shows an example of a cross correlation function. It is a schematic diagram which shows an example of a cross correlation function. It is a schematic diagram which shows an example of a cross correlation function. It is a schematic diagram which shows an example of a cross correlation function. It is a schematic diagram which shows an example of a cross correlation function. It is a schematic diagram explaining the process of step S74. It is a schematic diagram which shows an example of the result of having performed the position calculation process of step S35. It is a flowchart which shows the other example of frequency processing of FIG. It is a schematic diagram explaining the process of step S74a.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

<Situation explanation of water leak location method>
FIG. 1 is a schematic diagram for explaining the situation of the water leakage position specifying method.

  As shown in FIG. 1, a pipe network 110 is provided in the ground. The pipe network 110 is provided with vertical holes (manholes) 120 at regular intervals. In the present embodiment, vertical holes 120 are provided at intervals between point A and point B. In this case, vibration sensors 200 are provided in the vertical holes 120 at point A and point B in FIG.

<Description of vibration sensor>
FIG. 2 is a schematic diagram illustrating an example of a water leakage position detection device including a vibration sensor, and FIG. 3 is a schematic diagram illustrating an example of characteristics of the vibration sensor in FIG.

As shown in FIG. 2, the abnormal sound generation specifying device 100 according to the present embodiment includes an arithmetic device 300 and at least a pair of vibration sensors 200. The pair of vibration sensors 200 is a resonance type vibration sensor 200.
The vibration sensor 200 of FIG. 2 includes a pedestal 210, support columns 220, thin film electrodes 230 and 240, lead wires 231 and 241, a piezoelectric element 250, and a weight 260.
The arithmetic device 300 includes an analog-digital conversion unit (AD conversion unit) 310 and a wireless device 320.

  As shown in FIG. 2, in the vibration sensor 200, a support 220 is fixed on an iron base 210. A piezoelectric element 250 is provided at the upper end of the support 220. One end of the piezoelectric element 250 is cantilevered by the upper end of the column 220.

A pair of upper and lower thin film electrodes 230 and 240 formed by applying silver paste on both surfaces of the piezoelectric element 250 are provided. The column 220 and the pair of thin film electrodes 230 and 240 are insulated.
A weight 260 is placed on the other end of the piezoelectric element 250 and on the thin film electrode 230.

A lead wire 231 is connected to the thin film electrode 230, a lead wire 241 is connected to the thin film electrode 240, and the lead wires 231 and 241 are connected to the arithmetic unit 300.
The potential difference output from the lead wires 231 and 241 is output as a vibration waveform by a processing device such as a computer.
In this embodiment, the lead wires 231 and 241 are used. However, the present invention is not limited to this, and a functional unit capable of transmitting and receiving with the arithmetic device 300 may be provided.

  The piezoelectric element 250 is formed of a stretched film (PVDF film) of polyvinylidene fluoride which is a polymer piezoelectric material.

  When the specific parameters are the elasticity E of the piezoelectric material, the secondary moment J of the cross section, the length L, the width b, and the height h, the spring constant k is expressed as follows.

^{k = 3EJ / L 3 (J} = bh 3/12) ··· (1)
Can be shown.

  The resonance frequency fo of the system composed of the piezoelectric element 250 and the weight 260 is expressed as follows.

  fo = √ (k / M) / 2π (2)

The resonance type vibration sensor 200 is formed so that at least one resonance frequency fo exists within a range of 60 Hz or more and less than 1000 Hz.
The resonance type vibration sensor 200 according to the present embodiment is formed so that there are four resonance frequencies fo between 100 Hz and 500 Hz as shown by the solid line in FIG. The reason for this is that abnormal sounds transmitted through the pipe network 110, particularly water leakage sounds, are often audible sounds, especially those below 1000 Hz.

Specifically, as shown in FIG. 3, the resonance frequency fo has four peaks: a peak P1 near 260 Hz, a peak P2 near 310 Hz, a peak P3 near 350 Hz, and a peak P4 near 480 Hz.
On the other hand, the broken line in FIG. 3 shows an example of a conventional vibration sensor. In this case, no peak is formed.

  In this embodiment, the resonance type vibration sensor 200 is used. However, the present invention is not limited to this, and a conventional vibration sensor indicated by a broken line in FIG. 3 may be used.

  Further, in the present embodiment, the installation position of the vibration sensor 200 is input to a processing device such as an external computer in comparison with the pipeline diagram.

<Flowchart of water leakage position specifying method>
Next, the water leakage position specifying method will be described with a specific example.

In the water leakage position specifying method according to the present embodiment, vibration sensors 200 are installed in at least two places (point A and point B) of the pipe network 110, and abnormal sounds or vibrations caused by defects in the pipe network 110 are detected as vibration sensors. 200.
A filter is created using the coherence function of the waveform input to each vibration sensor 200. When creating this filter, the processing described later is performed to improve the accuracy of the abnormal sound generation position, the filter is created, and after applying the filter, the vibration transmission time difference Td is obtained from the cross-correlation function. This is a water leakage position specifying method for specifying an abnormal sound generation position from Td and vibration propagation velocity V.

  In FIG. 1, it is assumed that fluid leakage has occurred at a distance L from the vibration sensor 200 at point A. That is, the position of the distance L is an abnormal sound generation position (fluid leakage position). In this case, the leakage sound propagates a distance (L + N) longer than the distance L of the vibration sensor 200 at the point A by a distance N before reaching the vibration sensor 200 at the point B.

  Accordingly, assuming that the distance between the vibration sensor 200 at the point A and the vibration sensor 200 at the point B is D, the transmission time difference Td at which the leakage sound arrives at the vibration sensor 200 at the point A and the vibration sensor 200 at the point B is The propagation speed V of the leaked sound and the distance between the two vibration sensors can be determined by the following equation, where D is the distance.

Td = N / V (3)
Also,
N = D-2L (4)
Can be shown.

By substituting equation (4) into equation (3),
L = (D−V · Td) / 2 (5)
It can be expressed as.
As described above, the distance L can be obtained.

Then, the specific example of the water leak position specific method concerning this Embodiment is demonstrated. FIG. 4 is a flowchart showing an example of the water leakage position specifying method according to the present embodiment.
5 and 6 are schematic diagrams showing the strength of the vibration sensor 200 in the frequency band.

First, as shown in FIG. 4, the waveform of the leakage sound is acquired from the vibration sensor 200 at point A of the pipe network 110 (step S11). Similarly, the waveform of the leakage sound is acquired from the vibration sensor 200 at the point B of the pipe network 110 (step S21).
Here, as shown in FIG. 3, the vibration sensor 200 according to the present invention has four resonance frequencies fo between 60 Hz and less than 1000 Hz, and thus detects vibration waveforms such as leakage with a small flow rate with high sensitivity. be able to. In particular, the sensitivity of the vibration waveform in the low frequency band can be maintained high. That is, the vibration sensor has extremely low sensitivity when the frequency of the target sound is greatly different from the resonance frequency, and the sensitivity can be increased as the frequency approaches the resonance frequency.

In addition, it is desirable that at least one resonance frequency fo exists at 100 Hz or more and 500 Hz or less.
In particular, the resonance frequency fo of the vibration sensor is preferably in the range of 60 Hz to less than 1000 Hz, preferably 2 to 6, and at a predetermined interval.

  Next, the waveform of the leaked sound acquired from the vibration sensor 200 at the point A is subjected to Fourier transform processing (step S12), and the Fourier spectrum A is acquired (step S13). Next, the waveform of the leaked sound acquired from the vibration sensor 200 at the point B is subjected to Fourier transform processing (step S22), and the Fourier spectrum B is acquired (step S23).

<Fourier Transform Processing (Step S12 and Step S22)>
In the Fourier transform process, a waveform of a certain time (for example, 1 second) starting from the same time is extracted from the waveforms obtained by the vibration sensor 200 at the point A and the vibration sensor 200 at the point B, and the waveform is Fourier transformed. Convert it. Assuming that the Fourier spectrum is X (f), X (f) is expressed as a complex function as shown in the following equation (6).

X (f) = ∫ _−∞ ^∞ x (t) e ^−j2πft dt (6)
Expression (6) can be expressed separately as a real part and an imaginary part, as in the following Expression (7).

X (f) = XR (f) + jX _I (f) = | X (f) | e ^{jθ (f)} (7)

  In Expression (7), | X (f) | represents the amplitude of the Fourier spectrum, and θ (f) represents the phase. The amplitude | X (f) | of the Fourier spectrum can be obtained by the following equation (8).

| X (f) | = √ {X _R (f) ² + X _I (f) ² } (8)

  Here, as shown in FIGS. 5 and 6, the sensitivity of the vibration sensor 200 with respect to each frequency band can be acquired. Here, as shown in FIGS. 5 and 6, it can be seen that the waveform acquired by the vibration sensor 200 shows a high value in the vicinity of a frequency of 250 Hz.

Next, as shown in FIG. 4, a cross spectrum is calculated from these two Fourier spectrum A and Fourier spectrum B (step S31).
Here, the cross spectrum is obtained by multiplying the frequency components of the Fourier spectrum A and the Fourier spectrum B and then averaging them.

  The fact that the cross spectrum shows a large value means that the correlation between the frequency components of the two spectra is large in the frequency band, and the magnitude of both frequency components is large.

  Here, X (f) is normalized by dividing it by the amplitude | X (f) | of the Fourier spectrum, and when this normalized one is A (f), A (f) is expressed by equation (9). I want.

A (f) = X (f) / | x (f) | = e ^{jθ (f)} (9)

  Subsequently, as shown in FIG. 4, the cross spectrum is inversely Fourier transformed (step S32) to obtain a cross-correlation function (step S33).

  The transmission time difference Td can be obtained by taking the above cross-correlation. In the present embodiment, frequency processing (step S34) is performed using cross-correlation as will be described later, and the transmission time difference Td is calculated using the cross-correlation obtained by frequency processing, and abnormal sound A position calculation process (step S35) is performed.

<Frequency processing (step S34)>
Next, frequency processing in step S34 will be described. The frequency processing in step S34 is to select or extract some cross-correlation functions from a plurality of cross-correlation functions.

FIG. 7 is a flowchart showing an example of frequency processing. 8 to 13 are schematic diagrams illustrating an example of the cross-correlation function. FIG. 14 is a schematic diagram for explaining the processing in step S74.
8 to 13, the vertical axis indicates the correlation value, and the horizontal axis indicates the transmission time difference Td (seconds). Also, (1) to (100) shown in FIG. 14 are abbreviations of the cross-correlation functions from FIG. 8 to FIG.

As shown in FIG. 7, in the frequency processing, the cross-correlation function is divided for each predetermined span (step S71). Specifically, as shown in FIGS. 8 to 13, the horizontal axis (transmission time difference Td) of the cross-correlation function is divided into predetermined spans SPa,..., SPh.
Here, the predetermined is defined by the pipe type, pipe diameter, embedding time, etc., but when used in the most cases, it is preferably 0.5 m or more and 10 m or less, more preferably 1 m in terms of distance. It is 3 m or less. The time corresponding to each distance can be obtained from the transmission speed of vibration transmitted through the tube. For example, when a pipe having a vibration transmission speed of 400 m / s is divided by a span corresponding to 1 m, the interval is 0.0025 s in terms of time. At this time, the cross-correlation may be divided by a span of 0.0025 s.
In the present embodiment, the predetermined span is constant. However, the present invention is not limited to this, and the span may be changed to an arbitrary span width, or a predetermined variable variable may be used.

Next, as shown in FIG. 7, among the divided predetermined spans, a span having a correlation value having a maximum value or a predetermined correlation value or more is specified as a specific span (step S72).
Specifically, as shown in FIG. 8, since the span including the maximum value of the cross correlation function is SPd, the specific span is specified as SPd.

  Further, in the cross-correlation function shown in FIG. 8, when a predetermined correlation value or more is 0.8 or more, SPd and SPe are applicable, and therefore the specific span is specified as SPd and SPe. In the present embodiment, the predetermined correlation value is 0.8 or more. However, the present invention is not limited to this, and an arbitrary correlation value may be used.

  Next, since there are a plurality of cross-correlation functions, the same processing of step S72 is performed for other cross-correlation functions. Specifically, as shown in FIG. 9, since the span including the maximum value of the cross-correlation function is SPd, the specific span is specified as SPd.

  In addition, in the cross-correlation function shown in FIG. 9, when a predetermined correlation value or more is 0.8 or more, SPc and SPd are applicable, so that the specific span is specified as SPc and SPd.

  Subsequently, as shown in FIG. 10, since the span including the maximum value of the cross-correlation function is SPe, the specific span is specified as SPe.

  Further, in the cross-correlation function shown in FIG. 10, when a predetermined correlation value or more is 0.8 or more, SPe and SPf are applicable, so that the specific span is specified as SPe and SPf.

  Further, as shown in FIG. 11, since the span including the maximum value of the cross correlation function is SPe, the specific span is specified as SPe.

  Further, in the cross-correlation function shown in FIG. 11, when a predetermined correlation value or more is 0.8 or more, SPd and SPe are applicable, so that the specific span is specified as SPd and SPe.

Subsequently, as shown in FIG. 12, since the span including the maximum value of the cross-correlation function is SPg, the specific span is specified as SPg.
Further, in the cross-correlation function shown in FIG. 12, when a predetermined correlation value or more is 0.8 or more, SPc, SPd, SPf, and SPg are applicable, so that the specific span is SPc, SPd, SPf, and SPg. Identify.

Subsequently, as shown in FIG. 13, since the span including the maximum value of the cross-correlation function is SPe, the specific span is specified as SPe.
In addition, in the cross-correlation function shown in FIG. 13, when a predetermined correlation value or more is 0.8 or more, SPe is applicable, so the specific span is specified as SPe.
In this way, the process of step S72 is performed.

  In steps S11 and S21, it is preferable to perform detection twice or more and 10,000 times or less. In the present embodiment, detection was performed 100 times. As a result, since 100 cross-correlation functions are obtained, the process of step S72 is performed on 100 cross-correlation functions.

As described above, a plurality of cross-correlation functions are repeated, a span having a maximum value or a predetermined correlation value or more is specified as a specific span, and the frequency of the specific span is calculated as shown in FIG. 7 (step S73).
For example, the maximum value appears in each span SPa,..., SPh. The span SPa is 0 times, the span SPb is 2 times, the span SPc is 10 times, the span SPd is 15 times, the span SPe is 12 times, and the span SPf is 3 times. The span SPg is 2 times and the span SPh is 0 times.

  In addition, although the process of step S73 was illustrated as the frequency | count of appearance of the maximum value, it is not limited to this, Appearance of each span SPa, ..., SPh more than a predetermined correlation value, for example, span SPa is 0 times and span SPb 2 times, span SPc 20 times, span SPd 35 times, span SPe 22 times, span SPf 14 times, span SPg 2 times, and span SPh 0 times.

  Subsequently, as shown in FIG. 7, a cross-correlation function of a predetermined number of times or more is selected (step S74), the selected cross-correlation function shown in FIG. 14 is averaged, and the cross-correlation function is calculated again ( Step S75) is given to the position calculation process (Step S35).

Specifically, in the present embodiment, when there are three or more appearances out of 100 detections, the cross-correlation function is added to the averaging process.
In the above example, the number of appearances is three times or more, but the present invention is not limited to this. Preferably, the number of appearances may be defined by 50 times, or two or more other times. Good.

  For example, when it is defined by another arbitrary number of times equal to or greater than 3, the cross-correlation function of FIG. 12 having the maximum value of the span SPg where the number of appearances is 2 is excluded. That is, as shown in FIG. 14, the cross-correlation function of FIG. 12 is not added to the averaging.

  As described above, the position is calculated by using a cross-correlation function that does not include disturbances or the like, excluding the cross-correlation function as shown in FIG. Therefore, highly reliable position calculation can be performed.

FIG. 15 is a schematic diagram illustrating an example of a result of the position calculation process in step S35.
The vertical axis in FIG. 15 indicates the value of the detection level of the water leakage sound in which the maximum value obtained from the cross-correlation function is set to 20, and the horizontal axis indicates the distance from one of the pair of vibration sensors 200.

  For example, as shown in FIG. 15, a case where a bar graph is shown at three positions of a detection level value 18, a detection level value 5, and a detection level value 4 will be described. Here, a detection level of 10 or higher is assumed to be determination A with a high possibility of water leakage, and a detection level of less than 10 is defined as determination B with a possibility of water leakage.

  In this case, since there is a high possibility that there is a water leak in a portion having the detection A area of the detection level value 18, a hole can be dug for repair, and the detection level value 18 or the detection level value 5 determination B Detection may be performed again for the portion having the region.

  Further, even in a portion having the region of determination B, in the case of a resin pipe or a large-diameter pipe, a leak sound may not be clearly generated, so it cannot be said that there is no possibility of water leak. As a result, there is a possibility of water leakage, so a hole may be dug to check.

  In the above description, the determination level is determined to be one of the determination A and the determination B depending on whether the detection level is 10 or less. However, the determination level may be three or more, and the detection level is determined based on the type of piping and the material. Different numerical values may be set for each aperture.

  Thus, in this embodiment, since disturbance can be removed, highly reliable position calculation can be performed.

<Second Embodiment>
Next, a second embodiment will be described. In the second embodiment, differences from the first embodiment will be mainly described.
FIG. 16 is a flowchart showing another example of the frequency processing of FIG. 7, and FIG. 17 is a schematic diagram for explaining the processing in step S74a.
Also, (1) to (100) shown in FIG. 17 are abbreviations of the cross-correlation functions from FIG. 8 to FIG.

  As shown in FIG. 16, in the frequency processing according to the second embodiment, the processes in steps S71 to S73 and step S75 are the same as those in the first embodiment. Only the span portion of the cross-correlation function is selected (step S74a).

  Specifically, the process of step S74a will be described. In the process of step S74a, only those having a predetermined correlation value of 0.8 or more are extracted. For example, only the specific spans SPd and SPe in FIG. 8 are extracted, only the specific spans SPc and SPd in FIG. 9 are extracted, only the specific spans SPe and SPf in FIG. 10 are extracted, and only the specific spans SPd and SPe in FIG. , Only the specific spans SPc, SPd, SPf and SPg in FIG. 12 are extracted, and only the specific span SPe in FIG. 13 is extracted.

  In FIG. 17, the process is performed based on whether the correlation value is equal to or greater than a predetermined correlation value, but the process may be performed based on the maximum value.

  As a result, since it is possible to perform processing for a specific span having a high influence among the spans, position calculation can be performed clearly.

  As described above, in the analysis data creation method, the water leakage position specifying method, and the water leakage position detecting device 100 according to the present embodiment, the cross-correlation in the specific span whose frequency is calculated to be a certain value or more by the span selection step is selected. Therefore, it is possible to extract only a specific span having a high influence degree and to remove a specific span having a low influence degree or including a disturbance. Furthermore, since the cross-correlation including a plurality of specific spans is averaged and used, the cross-correlation averaging process having a high influence can be performed. As a result, the accuracy of the analysis data can be increased.

  Moreover, water leak detection can be performed using the analysis data created by the analysis data creation method. Therefore, since the analysis data with high accuracy is used, the certainty of the leak position can be increased.

  Furthermore, by using the analysis data creation method, the accuracy of both the water leak position detection device 100 and the water leak position specifying method can be increased.

  Note that the water leakage position specifying method can be applied to various pipe networks 110. For example, in addition to detecting leaks from water supply pipes, it is also used for detecting leaks in various pipes other than water supply, or for detecting leakage of fluids such as chemicals in pipes for chemicals in factories. be able to.

  In the present invention, the vibration sensor 200 corresponds to “two sensors”, steps S11 and S21 correspond to “measurement process”, and the cross-correlation functions of FIGS. 8 to 13 become “a plurality of cross-correlations”. Correspondingly, the process of step S33 corresponds to a “cross-correlation calculation process”, each of the spans SPa,..., SPh corresponds to a “predetermined span”, the process of step S71 corresponds to a “division process”, and The process corresponds to a “span specifying process”, the process of step S73 corresponds to a “frequency calculation process”, and steps S11, S13, S21, S23, S23, S31, S35, S71, S75, and S75. Corresponds to the “analysis data creation method”, the process in step S74 corresponds to the “cross-correlation selection process”, the process in step S74a corresponds to the “span selection process”, and the water leakage position Intellectual device 100 is equivalent to the "water leakage position sensing device".

  A preferred embodiment of the present invention is as described above, but the present invention is not limited thereto. It will be understood that various other embodiments may be made without departing from the spirit and scope of the invention. Furthermore, in this embodiment, although the effect | action and effect by the structure of this invention are described, these effect | actions and effects are examples and do not limit this invention.

DESCRIPTION OF SYMBOLS 100 Water leak detection apparatus 110 Pipe network 200 Vibration sensor

Claims (7)

A measurement step of measuring vibrations of a predetermined time at the same time a plurality of times by at least two sensors;
A cross-correlation calculating step for obtaining a plurality of cross-correlations from a plurality of waveforms measured in the measuring step;
A dividing step of dividing the cross-correlation calculated in the cross-correlation calculating step every predetermined span;
A span specifying step for specifying a specific span having a maximum value or a predetermined correlation value or more in each span divided in the dividing step;
A frequency calculating step of calculating a frequency of the specific span specified in the span specifying step.   The analysis data creation method according to claim 1, further comprising a cross-correlation selection step of selecting a cross-correlation including a specific span whose frequency is calculated to be a certain value or more in the frequency calculation step.   The analysis data creation method according to claim 2, wherein the cross-correlation including a plurality of specific spans among the cross-correlations including the specific span selected in the cross-correlation selection step is averaged and used.   The analysis data creation method according to claim 1, further comprising a span selection step of selecting a cross-correlation in a specific span whose frequency is calculated to be a certain value or more in the frequency calculation step.   The analysis data creation method according to claim 4, wherein cross correlations in a plurality of specific spans among the specific spans selected in the span selection step are averaged and used.   The water leak position detection apparatus comprised using the analysis data created by the analysis data creation method of any one of Claims 1 thru | or 5. The water leak position specifying method of specifying a water leak position using the analysis data created by the analysis data creating method according to any one of claims 1 to 5.

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