Vibration analysis processing device

Abstract

The purpose of the present invention is to provide a vibration analysis processing device that is capable of identifying the location of occurrence of an event without being affected by an installation environment of an optical fiber.　A vibration analysis processing device 10 comprises: an input unit 11 that receives input of vibration data which is transmitted to an optical fiber cable 50 and which has been measured by a vibration measuring instrument 20; and a computation processing unit 12 that divides the optical fiber cable 50 into a plurality of sections in a distance direction, and, on the basis of the vibration data, generates, for each of the sections, a bit sequence in which bits are given indicating whether or not a specific vibration of a specific frequency component is occurring, that generates a determination value sequence in which moving average values calculated for the bit sequence with an arbitrary window size in the distance direction are arranged in the distance direction, and that detects a point or an area where the moving average value exceeds an arbitrary threshold value in the determination value sequence.

Description

Vibration analysis processing device

[0001] The present disclosure relates to a vibration analysis processing device that analyzes vibration data of an optical fiber cable.

[0002] Research has been underway on a technique for acquiring vibrations transmitted through an optical fiber using DAS (Distributed Acoustic Sensing) technology and detecting an event that generates the vibration (see, for example, Non-Patent Document 1). There is also a technique for monitoring vibrations using an optical fiber and DAS and detecting a location where an event has occurred by capturing specific vibration characteristics (see, for example, Non-Patent Document 2).

[0003] Lasertec Corporation Technical Information "Optical Fiber Distributed Vibration Sensor (DAS)", https: / / lazoc.jp / technical / das / (searched on October 25, 2024) Fermi Tanimola et.al. "Distributed fibre optic sensors for pipeline protection", Journal of Natural Gas Science and Engineering 1 (2009), P134 - 143

[0004] The vibration data of the optical fiber by DAS changes its characteristics depending on the installation environment of the optical fiber. Since the disclosed vibration analysis does not consider the installation environment of the optical fiber, there is a problem that it is difficult to suppress the change in the event detection rate due to the difference in the installation environment of the optical fiber.

[0005] Therefore, an object of the present invention is to provide a vibration analysis processing device that can specify the location where an event occurs without being affected by the installation environment of the optical fiber in order to solve the above problems.

[0006] In order to achieve the above object, the vibration analysis processing device according to the present invention normalizes vibration data by DAS by generating a specific vibration presence / absence bit sequence and a specific vibration presence / absence coefficient (determination value) sequence.

[0007] Specifically, the vibration analysis processing apparatus according to the present invention comprises: an input unit that receives vibration data transmitted to an optical fiber cable measured by a vibration measuring instrument; and a processing unit that divides the optical fiber cable into a plurality of sections in the distance direction, generates a bit sequence based on the vibration data, assigns bits to each of the sections indicating whether or not singular vibrations of singular frequency components are occurring; generates a determination value sequence by arranging moving average values ​​calculated with an arbitrary window size in the distance direction for the bit sequence in the distance direction; and detects a point or range in the determination value sequence where the moving average value exceeds an arbitrary threshold.

[0008] By standardizing the vibration data of optical fibers, the influence of the optical fiber installation environment can be reduced. Therefore, the present invention can provide a vibration analysis processing device that can identify the location of events without being affected by the optical fiber installation environment. Note that "dividing the optical fiber cable into multiple sections in the distance direction" means the following: Due to the principle of DAS, vibrations are measured discretely along the longitudinal distance of the optical fiber. For this reason, a "section" is either "a section divided for each discretely occurring vibration" or "a section divided into multiple discrete vibrations". In the latter case, the number of vibrations to be grouped is arbitrary to the user, and it is determined whether or not a singular vibration is occurring by treating the multiple vibrations included in each section as a single data point.

[0009] Here, the arithmetic processing unit is characterized by generating the bit sequence by performing a bit assignment operation for each section, the bit assignment operation involves: obtaining the frequency spectrum of time-series data of the vibration data at an arbitrary time; calculating the average intensity of the frequency spectrum for each predetermined band; determining whether there is a specific band at the arbitrary time in which the ratio of the average intensity of the adjacent band is greater than a predetermined value; and assigning a bit indicating that the singular vibration is "present" to the section if the specific band exists at a predetermined or higher rate in a plurality of consecutive arbitrary time periods, and a bit indicating that the singular vibration is "absent" in other cases.

[0010] The vibration analysis processing device according to the present invention may further include an output unit that outputs the location or range as the vibration generation location of the optical fiber cable.

[0011] The vibration analysis processing apparatus according to the present invention may further include: an identification unit that compares information on the route along which the optical fiber cable is laid with the distance of the point or range in the longitudinal direction of the optical fiber cable from the vibration measuring instrument to identify the geographical location of the point or range; and an output unit that outputs the geographical location.

[0012] The present invention is a program for causing a computer to function as the vibration analysis processing device described above. The vibration analysis processing device of the present invention can also be realized by a computer and a program, and the program can be recorded on a recording medium or provided via a network.

[0013] Furthermore, the above inventions can be combined as much as possible.

[0014] The present invention provides a vibration analysis processing device that can identify the location of an event without being affected by the installation environment of the optical fiber.

[0015] This is a diagram illustrating a system for identifying the location of a specific vibration, equipped with a vibration analysis processing device according to the present invention. This is a diagram illustrating the vibration analysis processing device according to the present invention. This is a flowchart illustrating the vibration location estimation method performed by the vibration analysis processing device according to the present invention. This is time-series data from 0 to 1 second from the start of measurement at a point located at a longitudinal distance X [m] from the vibration measuring instrument 20 to the optical fiber cable 50. This is a frequency spectrum obtained by frequency analysis of vibration data (time-series data) every second. This is a table listing the average values ​​of the frequency spectrum intensity for each band. This is a diagram illustrating the process of detecting the band bits suspected of specific vibrations for each band. This is a diagram illustrating a series of suspected specific vibrations at an arbitrary point and time. This is a table listing the series of suspected specific vibrations at an arbitrary point in order of measurement time. This is a diagram illustrating a method for determining specific vibration sections.

[0016] Embodiments of the present invention will be described with reference to the attached drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to these embodiments. In this specification and in the drawings, components with the same reference numerals refer to the same components.

[0017] Figure 1 is a diagram illustrating a system for identifying the location of a unique vibration, which includes a vibration analysis processing device 10 according to this embodiment. The system for identifying the location of a unique vibration according to the present invention comprises an optical fiber cable 50, a vibration measuring instrument 20, and a vibration analysis processing device 10.

[0018] The optical fiber cable 50 is installed above, on the surface of, or underground of the road 40 to be subjected to vibrations. The vibration measuring instrument 20 measures the vibrations received by the optical fiber cable 50 as a distribution along the longitudinal direction of the optical fiber cable 50, for example, using DAS. The vibration analysis processing device 10 detects the location along the longitudinal direction of the optical fiber where vibrations of a specific frequency component are particularly large, based on the vibration distribution measured by the vibration measuring instrument 20, as a unique vibration generation point. The vibration analysis processing device 10 then estimates the vicinity of the unique vibration generation point on the road 40 based on the positional relationship between the longitudinal position of the optical fiber cable 50 and the road 40. A map may be displayed on the monitor 15, and the unique vibration generation point may be displayed on the map.

[0019] The vibration analysis processing device 10 will be described in more detail. Figure 2 is a diagram illustrating the vibration analysis processing device 10. The vibration analysis processing device 10 includes an input unit 11 into which vibration data transmitted to the optical fiber cable 50 measured by the vibration measuring instrument 20 is input, and an arithmetic processing unit 12 which divides the optical fiber cable 50 into a plurality of sections in the distance direction, generates a bit sequence that assigns bits to each of the sections based on the vibration data to indicate whether or not singular vibrations of singular frequency components are occurring, generates a judgment value sequence by arranging moving average values ​​calculated with an arbitrary window size in the distance direction for the bit sequence in the distance direction, and detects a point or range in the judgment value sequence where the moving average value exceeds an arbitrary threshold.

[0020] Here, the arithmetic processing unit 12 is characterized by generating the bit sequence by performing a bit assignment operation for each section, and the bit assignment operation is characterized by: obtaining the frequency spectrum of time-series data of arbitrary time from the vibration data; calculating the average intensity of the frequency spectrum for each predetermined band; determining whether there is a specific band at the arbitrary time in which the ratio of the average intensity of adjacent bands is greater than a predetermined value; and assigning a bit (e.g., "1") indicating that the singular vibration is "present" to the section if the specific band exists at a predetermined or higher rate in a plurality of consecutive arbitrary time periods, and assigning a bit (e.g., "0") indicating that the singular vibration is "absent" to the section otherwise.

[0021] The output unit 14 outputs the aforementioned location or area as the vibration generation point of the optical fiber cable 50. Alternatively, if the vibration analysis processing device 10 includes a identification unit 13 that compares information on the route along which the optical fiber cable 50 is laid with the distance of the aforementioned location or area from the vibration measuring instrument 20 in the longitudinal direction of the optical fiber cable 50 to identify the geographic location of the aforementioned location or area, the output unit 14 outputs the geographic location. The information output by the output unit 14 is displayed on the display unit 15.

[0022] Figure 3 is a flowchart illustrating the vibration location estimation method performed by the vibration analysis processing device 10. [Step S1] Understanding the positional relationship between the fiber and the road The positional relationship between the optical fiber cable 50 and the road or ocean is understood. The position of the fiber length in the longitudinal direction of the optical fiber cable 50 laid above the road, on the road surface, or underground is investigated to determine where it is laid on the road. It may be the ocean instead of a road. [Step S2] Vibration acquisition The vibration transmitted to the optical fiber cable 50 is measured for a certain period of time using the DAS of the vibration measuring instrument 20. The vibration data measured for a certain period of time is input from the input unit 11. [Step S3] Frequency component analysis (Sub-step S3-1) The calculation processing unit 12 divides the vibration data acquired in step S2 into arbitrary points (sections) and arbitrary time intervals (e.g., 1 second). Figure 4 shows the time-series data of the vibration data for an arbitrary time (1 second from 0 to 1 second) at an arbitrary point X (distance X [m] from the vibration measuring instrument 20 in the longitudinal direction of the optical fiber cable 50). The arithmetic processing unit 12 performs frequency analysis on this time-series data and calculates the vibration frequency spectrum for each position (section) along the longitudinal direction of the optical fiber cable 50 (Figure 5). (Small step S3-2) The arithmetic processing unit 12 extracts only an arbitrary band (e.g., 20-80 Hz) from the vibration frequency spectrum for each position (section), divides the extracted band into arbitrary bandwidths (e.g., 3 Hz), and calculates the average value of the spectral intensity for each divided band. Figure 6 shows the result of extracting only the data in the 20-80 Hz band from the frequency spectrum of Figure 5, dividing it into 3 Hz intervals, and calculating the average value. (Small step S3-3) The arithmetic processing unit 12 creates a series of the calculated spectral intensity average values ​​arranged in order of frequency, and compares the magnitude of each data in each band of the series data with the data adjacent to it in the frequency direction. If the data is larger than adjacent data by a predetermined ratio (e.g., 3 times) or more, that band data is set as the suspected band data for the occurrence of anomalous vibration, and the band data that does not exceed the ratio is set as the suspected band data for the occurrence of non-anomalous vibration. Figure 7 illustrates the process of detecting suspected anomalous vibration band bits for each bandwidth.This figure compares adjacent bandwidth data from the table in Figure 6, and if there is data that is three times or more larger, it is marked as "Yes" as the bandwidth data suspected of causing anomalous vibration. Other data are marked as "No". At this time, the comparison can be made with either the bandwidth adjacent to the bandwidth being compared on the lower or higher side of the bandwidth, or both. (Small step S3-4) If one or more bandwidth data become bandwidth data suspected of causing anomalous vibration, the calculation processing unit 12 marks that series of data as the series suspected of causing anomalous vibration. As shown in Figure 7, the data in the 23-26 Hz range is the bandwidth suspected of causing anomalous vibration, so the series suspected of causing anomalous vibration from 0 to 1 second in the interval of distance X [m] is marked as "Yes" (Figure 8).

[0023] [Step S4] Creation of a bit sequence indicating the presence or absence of anomalous vibration (Sub-step S4-1) The arithmetic processing unit 12 performs the anomalous vibration suspicion determination on vibration data acquired for each fiber distance (each section) over an arbitrary time (e.g., 30 seconds). If an arbitrary percentage (e.g., 70%) or more of the sequence data included in the time are sequences suspected of anomalous vibration, the longitudinal position (section) of the optical fiber cable 50 is designated as the location suspected of anomalous vibration. Figure 9(A) is a table showing sequences suspected of anomalous vibration in a section of distance X [m] arranged in order of measurement time. In the section of distance X+3, the time for "Yes" exceeds 70%, so the section of distance X [m] is designated as the location suspected of anomalous vibration. The arithmetic processing unit 12 performs the above process at all data acquisition positions along the entire length or a portion of a desired range in the longitudinal direction of the optical fiber cable 50. (Small step S4-2) Subsequently, the arithmetic processing unit 12 assigns a bit "1" to the location (section) that was suspected of being affected by the unusual vibration and a bit "0" to the location (section) that was not suspected of being affected by the unusual vibration in the sequence data with the horizontal axis representing the longitudinal distance of the optical fiber cable 50 (Figure 9(B) "Bit assignment operation"). The sequence data with the horizontal axis representing the longitudinal distance (section) of the optical fiber cable 50 and the vertical axis representing bits related to the location suspected of being affected by the unusual vibration is called the unusual vibration presence / absence bit sequence (Figure 9(C)).

[0024] [Step S5] The calculation processing unit 12 calculates a moving average of an arbitrary number of points (for example, 10 points) in the longitudinal direction of the optical fiber for the singular vibration presence / absence bit sequence (Figure 10(A)) created in step S4 (Figure 10(B)). This moving average value is defined as the singular vibration presence / absence coefficient. The calculation processing unit 12 creates a series of data (judgment value series) with the distance in the longitudinal direction of the optical fiber on the horizontal axis and the singular vibration presence / absence coefficient on the vertical axis (Figure 10(C)). [Step S6] The threshold exceedance judgment processing unit 12 detects the distance in the longitudinal direction of the optical fiber that exceeds an arbitrary threshold (for example, 0.8) in the series of data (judgment value series) of the singular vibration presence / absence coefficient calculated in step S5, and estimates the point or section in the longitudinal direction of the optical fiber that exceeds the threshold as a singular vibration section. [Step S7] The anomalous vibration location estimation processing unit 12 estimates where the anomalous vibration location is by correlating the distance of the optical fiber cable 50, for which the presence or absence coefficient of anomalous vibration recorded in step S6 was confirmed to exceed a threshold, with the relationship between the position of the fiber length in the longitudinal direction of the optical fiber cable 50 and the position of the road, which was grasped in step S1.

[0025] The arithmetic processing unit 12 may output the waveform shown in Figure 10(C) to the display unit 15 from the output unit 14, or it may output data indicating the anomalous vibration section. Alternatively, the arithmetic processing unit 12 may query the identification unit 13 for the distance of the anomalous vibration section (the distance of the optical fiber cable 50 from the vibration measuring instrument 20), and output the map location corresponding to the distance answered by the identification unit 13, along with map data, to the display unit 15 from the output unit 14. The display unit 15 displays this information to the operator. Based on the displayed information, the operator can recognize the specific vibration location occurring in the optical fiber cable 50 as the location where the event occurred.

[0026] [Note] The present invention is characterized in that the vibration analysis processing device represents the locations where vibrations with unique frequency components are transmitted in the optical fiber cable using a "singular vibration presence / absence bit sequence," and determines the location of the singular vibration using a "singular vibration presence / absence coefficient sequence" obtained by moving average of the bit sequence.

[0027] Specifically, the present invention is characterized by using DAS to acquire vibrations transmitted to optical fiber cables laid along a road, dividing the acquired vibration data into fixed time intervals and analyzing them, determining the locations where peculiar vibrations are transmitted based on whether a certain proportion of peculiar frequency components are included in the divided vibration data over time, creating a series of data for the longitudinal distance of the optical fiber cable, with locations where peculiar vibrations are transmitted in the analysis set to "1" and locations where they are not set to "0", calculating a moving average of an arbitrary window size in the distance direction of the series of data, and determining that locations or sections where the value of the calculated moving average exceeds an arbitrary threshold are locations or sections where peculiar vibrations are occurring.

[0028] Vibrations characterized by having a unique frequency peak that persists for a certain period of time are rare as natural vibrations and are highly likely to be caused by unusual events such as construction work. The key point of this invention is that the location of the unique vibration is estimated by observing this characteristic using vibration measurement with DAS.

[0029] The present invention makes it possible to provide a system for estimating the location of events accompanied by peculiar vibrations while reducing the influence of the optical fiber installation environment. In other words, the present invention can perform peculiar vibration location determination without being affected by the magnitude of acquired vibrations due to the different vibration propagation characteristics of each road, as in the conventional method.

[0030] 10: Vibration analysis processing unit 11: Input unit 12: Calculation processing unit 13: Identification unit 14: Output unit 15: Display unit 20: Vibration measuring instrument 40: Road 50: Fiber optic cable

Claims

1. A vibration analysis processing device comprising: an input unit that receives vibration data transmitted to an optical fiber cable measured by a vibration measuring instrument; and a processing unit that divides the optical fiber cable into a plurality of sections in the distance direction, generates a bit sequence based on the vibration data, assigning bits to each of the sections to indicate whether or not singular vibrations of singular frequency components are occurring; generates a judgment value sequence by arranging moving average values ​​calculated with an arbitrary window size in the distance direction for the bit sequence in the distance direction; and detects a point or range in the judgment value sequence where the moving average value exceeds an arbitrary threshold.

2. The arithmetic processing unit is characterized by generating the bit sequence by performing a bit assignment operation for each section, wherein the bit assignment operation is characterized by: obtaining the frequency spectrum of time-series data of the vibration data at an arbitrary time; calculating the average intensity of the frequency spectrum for each predetermined band; determining whether there is a specific band at the arbitrary time in which the ratio of the average intensity of adjacent bands is greater than a predetermined value; and assigning a bit indicating that the singular vibration is "present" to the section if the specific band exists at a predetermined or higher rate in a plurality of consecutive arbitrary time periods, and assigning a bit indicating that the singular vibration is "absent" to the section otherwise.

3. The vibration analysis processing apparatus according to claim 1, further comprising an output unit that outputs the aforementioned location or range as the vibration generation location of the optical fiber cable.

4. The vibration analysis processing apparatus according to claim 1, further comprising: an identification unit that compares information on the route along which the optical fiber cable is laid with the distance of the point or area in the longitudinal direction of the optical fiber cable from the vibration measuring instrument to identify the geographic location of the point or area; and an output unit that outputs the geographic location.

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