JP2006275666A - Covered damage analyzer, method therefor, and program therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a covered damage analyzer dispensing with analysis for analyzing a waveform visually by a user, and capable of detecting precisely a damaged point. <P>SOLUTION: In this covered damage analyzer, a plurality of continuous sections is set in the waveform in a ground surface potential distribution (step S205), an inclination of the waveform in the ground surface potential distribution is drawn out in every of set sections (step S207), and the damaged point is detected based on a tendency of inclinations drawn out in the respective section. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a coating damage analysis apparatus and method for analyzing a coating damage of a metal pipe embedded in the ground with an anticorrosion coating on the outer surface, and a program thereof.

  In general, a metal pipe buried in the ground is prevented from being corroded by an anti-corrosion coating on the outer surface. As this anticorrosion coating, various insulators are used. For example, a bituminous material such as asphalt or a thermoplastic resin such as polyethylene is preferably used as the insulator.

  When such an anticorrosion coating is damaged for some reason, and the metal surface of the embedded metal tube is in direct contact with an electrolyte such as soil, the portion is corroded. Therefore, in order to prevent corrosion, it is important to keep the anticorrosion coating on the metal tube intact. For this purpose, it is necessary to detect the damaged portion of the coating as early as possible, and when the damaged portion of the coating is detected, it is necessary to excavate and repair it immediately. Therefore, traditionally, damage position detection technology for detecting the position of the damaged portion of the buried metal pipe from the ground surface has been regarded as important, and various damage position detection technologies have been developed and applied in practice. Yes.

  Patent Document 1 discloses an example of a damage position detection technique. In this damage position detection technique, an AC signal current flows between a metal tube and a counter electrode that is an electrode embedded in the ground. Here, if a coating damage portion exists in the metal tube, an AC signal current flows between the coating damage portion and the counter electrode. And the ground surface potential distribution produced by the damaged portion of the metal pipe by measuring the ground surface potential difference with the two wheel electrodes in the measuring device (receiver) that moves on the ground surface directly above the metal tube and processing the signal. Is calculated.

  Specifically, the potential difference between the two wheel electrodes is input to the lock-in amplifier, and a signal having the same component as the AC signal current is extracted. Then, the change in polarity of the amplitude A and the phase φ of the signal is measured. Further, the sine Asinφ or cosine Acosφ is calculated, and the ground surface potential distribution is obtained by integrating the calculated sine Asinφ or cosine Acosφ. Here, according to the damage position detection technique of Patent Document 1, the obtained ground surface potential distribution waveform is drawn on a display device such as a recorder. Then, the user visually analyzes the drawn waveform, whereby the position of the anticorrosion coating portion is detected.

  Further, Patent Document 2 discloses a damage position detection technique that can accurately know the position of a coating damage portion by using AC signal currents having two different types of frequencies. Also in this case, since some of the obtained waveforms are drawn on a display device such as a recorder, it is necessary for the user to visually analyze the drawn waveforms.

  However, depending on the user's visual analysis, it is judged that the coating damage portion exists even though the coating damage portion does not exist, and no damage is confirmed even if excavation is performed. Cases may arise. In addition, the waveform may be overlooked, so that it may not be detected even if it is damaged.

In addition, since it is necessary to mount a display device such as a recorder on the measuring device, there is a problem that it becomes an obstacle to miniaturization of the measuring device.
JP 2003-004686 A JP 2003-004687 A

  The present invention has been made to solve the above problems. Accordingly, an object of the present invention is to provide a coating damage analysis apparatus and method capable of automatically executing the determination of the presence / absence of a coating damage portion and the position detection of a coating respect portion without the need to visually analyze the waveform by the user Is to provide a program. In particular, there is no cover damage analysis in which there is no risk of deciding that there is a damaged part of the coating, even though there is no damaged part of the coating, or overlooking even though there is a damaged part of the coating. The purpose is to provide technology.

  Another object of the present invention is to eliminate the need to mount a display device such as a recorder on the measuring device, and to reduce the size of the measuring device.

  Means for solving the above-described problems are configured as follows.

  (1) The covering damage analyzing apparatus according to the present invention passes an AC signal current between a covering damaged portion of a metal pipe embedded in the ground with an anti-corrosion coating on the outer surface and a counter electrode embedded in the ground. Further, a covering damage analyzing apparatus for analyzing covering damage based on a ground surface potential distribution produced by the covering damage portion, and setting means for setting a plurality of continuous sections in the waveform of the ground surface potential distribution And a deriving means for deriving the slope of the waveform of the ground surface potential distribution for each section, and a detecting means for detecting the position of the covering damaged portion from the inclination tendency derived for each section, To do.

  (2) The setting means moves the plurality of sections relatively with respect to the waveform of the ground surface potential distribution, and the derivation means separates the sections for each section each time the plurality of sections are moved. The slope of the ground potential distribution waveform is derived.

  (3) The detecting means integrates a plurality of position detection results obtained by moving the plurality of sections, and detects the position of the covering damage portion.

  (4) The setting means sets the section with a plurality of widths.

  (5) The detection means detects a position of the covering damage portion by integrating a plurality of position detection results obtained by setting the section with a plurality of widths.

  (6) Two types of AC signal currents having different frequencies are used as the AC signal current, and the detection means has a plurality of positions obtained by passing two types of AC signal currents having different frequencies. The detection result is integrated to detect the position of the coating damage portion.

  (7) The covering damage analysis apparatus further moves the ground surface directly above the metal pipe, detects a potential difference on the ground surface by a wheel electrode to be mounted, and extracts a signal having the same component as the AC signal current. Then, the communication means for communicating with the measuring device for measuring the amplitude and phase of the signal, and the ground potential distribution is calculated based on the amplitude and phase data received via the communication means. And calculating means.

  (8) The covering damage analysis method of the present invention is the case where an AC signal current is passed between a covering damage portion of a metal pipe embedded in the ground with an anticorrosion coating on the outer surface and a counter electrode embedded in the ground. A covering damage analysis method for analyzing covering damage based on a ground surface potential distribution produced by the covering damage portion, wherein a plurality of continuous sections are set in a waveform of the ground surface potential distribution. The method includes a step of deriving a slope of the waveform of the ground surface potential distribution for each section, and a step of detecting the position of the covering damage portion from the tendency of the slope derived for each section.

  (9) The covering damage analysis program according to the present invention passes an AC signal current between a covering damage portion of a metal pipe embedded in the ground with an anti-corrosion coating on the outer surface and a counter electrode embedded in the ground. And a covering damage analysis program for analyzing covering damage based on a ground surface potential distribution produced by the covering damage portion, and a procedure for setting a plurality of continuous sections in the waveform of the ground surface potential distribution, and The computer is caused to execute a procedure for deriving the slope of the waveform of the ground surface potential distribution for each section and a procedure for detecting the position of the covering damaged portion from the tendency of the slope derived for each section.

  According to the covering damage analysis apparatus and method and the program of the present invention, a plurality of continuous sections are set in the ground potential distribution waveform, and the slope of the ground potential distribution waveform is derived for each set section. Further, since the position of the covering damage portion is detected from the inclination tendency derived for each section, it is not necessary for the user to visually analyze the waveform, and the position of the covering damage portion can be detected with high accuracy. Accordingly, it is possible to reduce the possibility of an error in determining whether there is a coating damage and an error in detecting the position of the coating damage portion. Further, since there is no need to mount a display device such as a recorder on the measuring device, the measuring device can be miniaturized.

  FIG. 1 is a diagram showing a schematic configuration of a damage position detection system according to the present embodiment.

  As shown in FIG. 1, an anticorrosion-coated metal tube 12 configured by applying an anticorrosion coating 1 to the outer surface of a metal tube 2 is embedded in the ground. And the counter electrode 5 and the counter electrode 7 are embed | buried in the ground 4 of the both ends of the investigation object range of the embed | buried anticorrosion coating | coated metal pipe | tube 12. FIG.

  The counter electrode 5 is connected to the metal tube 2 via the first measurement signal generator 6, and the counter electrode 7 is connected to the metal-to-metal 2 via the second measurement signal generator 8. Here, the first measurement signal generator 6 generates a first AC signal current having a first frequency, and the second measurement signal generator 8 has a second frequency having a second frequency different from the first frequency. An AC signal current is generated. In other words, the first measurement signal generator 6 and the second measurement signal generator 8 pass the first and second AC signal currents between the coating damaged portion 3 of the metal tube 2 and the counter electrodes 5 and 7, respectively. is there.

  Here, the first and second frequencies used in the first measurement signal generator 6 and the second measurement signal generator 8 are selected from a frequency range of several tens to 750 Hz. However, use of frequencies multiplied by 50 Hz and 60 Hz, which are commercial frequencies, causes noise to be superimposed, so it is desirable to avoid using these frequencies. Also, if the difference between the first and second frequencies used is too small, the signal of the other frequency may be detected, so the first and second frequencies used must be separated by several tens of Hz or more. There is. For example, a preferable result is obtained by setting the first frequency used in the first measurement signal generator 6 to 220 Hz and setting the second frequency used in the second measurement signal generator 8 to 320 Hz.

  When the first measurement signal generator 6 is connected to one end of the metal tube 2 and the second measurement signal generator 8 is connected to the other end of the metal tube 2 and the first and second AC signal currents flow, AC signal current flows from one measurement signal generator to the other measurement signal generator, and there is a risk that signal accuracy may be degraded due to signal interference. Therefore, in each of the first measurement signal generator 6 and the second measurement signal generator 8, a notch filter (not shown) and a resistor (not shown) are installed in the middle of the connection circuit with the metal tube 2, You may prevent an alternating current signal from flowing in.

  The measuring device 9 is disposed on the ground surface directly above the metal tube 2. The measuring device 9 includes a wheel electrode 10 made of conductive rubber and disposed at intervals along the longitudinal direction of the metal tube 2. This measuring device 9 is moved along the metal tube 2 on the ground surface immediately above the metal tube 2, and the potential difference between the two wheel electrodes 10 at each point (hereinafter referred to as “ground surface potential difference”) sequentially. Measured. The measuring device 9 extracts a signal having the same component as the AC signal current from the ground surface potential difference at each point, and wirelessly transmits the amplitude A and phase φ data of the signal extracted at each point on the metal tube 2. Send.

  The analysis device (coverage damage analysis device) 11 calculates the ground surface potential distribution based on the data of the amplitude A and the phase φ received from the measurement device 9 described above, and calculates a plurality of continuous sections in the waveform of the ground surface potential distribution. Set. Then, the position of the covered damage portion (hereinafter referred to as “damage point”) is detected from the tendency of the slope of the waveform of the ground surface potential distribution derived for each section. This is one of the characteristic points of the coating damage analysis apparatus of the present invention. The processing content of the analysis device 11 will be described later.

  FIG. 2 is a block diagram illustrating the configuration of the measurement device 9 and the analysis device 11. First, the measuring device 9 will be described.

  The measuring device 9 includes a reference signal transmitter 13, a lock-in amplifier 14, an encoder 15, a wireless interface 16, and a control unit 17. The measuring device 9 includes a battery 18 that is used as a power source.

The reference signal transmitter 13 transmits the first reference signal and the second reference signal independently. Here, the first reference signal is a signal having the same frequency as the first frequency of the first AC signal current and having a phase different from that of the first AC signal current by φ _1. This is a signal having a frequency similar to the second frequency of the second AC signal current and having a phase different from that of the second AC signal current by φ ₂ . In the present embodiment, since the phase change is taken into account when the position of the coating damage part 3 is known, the frequency of the first reference signal and the frequency of the first AC signal current must be very close to each other. First, the frequency of the second reference signal and the frequency of the second AC signal current must be very close.

The reference signal transmitter 13 is attached to the lock-in amplifier 14, and the phases φ ₁ and φ ₂ are appropriately adjusted using a phase adjustment circuit (not shown) provided in the lock-in amplifier 14. The For example, it is desirable to adjust so that the absolute values of φ ₁ and φ ₂ are 90 degrees.

The lock-in amplifier 14 is an amplifier that uses a synchronous rectification method and extracts a minute signal of a specific frequency that is buried in noise. In the present embodiment, two wheel electrodes 10 are connected to the lock-in amplifier 14 and a ground surface potential difference that is a potential difference between the two wheel electrodes 10 is input. The lock-in amplifier 14 uses the first reference signal generated by the reference signal transmitter 13 to generate a signal having the same first frequency component as the first AC signal current (hereinafter, “ (Referred to as “first frequency signal”) to derive the amplitude A ₁ and the phase φ ₁ of the first frequency signal. Further, the lock-in amplifier 14 uses the second reference signal generated by the reference signal transmitter 13 and uses the second frequency component signal (hereinafter referred to as the second AC signal current) from the ground surface potential difference signal. , Referred to as “second frequency signal”) to derive the amplitude A ₂ and the phase φ ₂ of the second frequency signal.

  The encoder 15 is a rotation signal generator that generates a signal according to the rotation angle of the wheel electrode 10. When the measuring device 9 is moved a predetermined distance and the wheel electrode 10 rotates, the encoder 15 generates a pulse signal according to the rotation angle of the wheel electrode 10. A voltage value of the pulse signal from the encoder 15 is converted as necessary, and is input to the control unit 17.

The wireless interface 16 is a wireless interface for communicating with the analysis apparatus 11. The wireless interface 16 corresponds to, for example, a wireless LAN standard. The wireless interface 16 wirelessly transmits the amplitude A ₁ and phase φ ₁ of the first frequency signal obtained by the measuring device 9 and the amplitude A ₂ and phase φ _{2 of} the second frequency signal to the analysis device 11. .

  The control unit 17 is, for example, a PLC (programmable logic controller), and controls each unit of the measuring device 9.

  Next, the analysis device 11 will be described. The analysis device 11 is a computer such as a personal computer or an engineering workstation, for example. The analysis device 11 includes a CPU (Central Processing Unit) 20, a memory 21, an operation unit 22, a display 23, a hard disk 24, and a wireless interface 25.

  The CPU 20 is for executing various calculations and controls. The CPU 20 plays various roles by executing a coating damage analysis program stored in the hard disk 24. Specifically, the CPU 20 functions as a calculation unit, a setting unit, a derivation unit, and a detection unit.

Here, the calculation unit calculates the ground surface potential distribution based on the data of the amplitudes A ₁ and A ₂ and the phases φ ₁ and φ ₂ of the first frequency signal and the second frequency signal received via the wireless interface 25. It is a calculation means to do. The setting unit is setting means for setting a plurality of continuous sections in the waveform of the ground surface potential distribution. The deriving unit is deriving means for deriving the slope of the waveform of the ground surface potential distribution for each set section. The detection unit is detection means for detecting a damage point from the inclination tendency derived for each section. The function of each unit will be described in detail in the flowchart described later.

  The memory 21 includes, for example, a ROM (Read only memory) and a RAM (Random access memory). The ROM stores control programs and parameters. The RAM stores various data and also functions as a work area for the CPU 20.

  The operation unit 22 is a pointing device such as a keyboard, a touch panel, and a mouse, and is used, for example, when a user instructs the start of processing.

  The display 23 is a liquid crystal panel or a CRT display, and displays various information. For example, the display 23 can display numerically the presence / absence of the damaged portion of the coating and the damage point.

The hard disk 24 stores a coating damage analysis program and various data and parameters. The data stored in the hard disk 24 includes data for defining individual section widths (hereinafter referred to as “section width data”) when setting a plurality of consecutive sections in the ground potential distribution waveform, and Data on the predetermined ranges D ₁ , D ₂ , D ₃ used when integrating a plurality of position detection results is included.

The wireless interface 25 is a wireless interface for communicating with the measuring device 9. The wireless interface 25 functions as a communication unit for communicating with the measurement device 9. The amplitude A ₁ and phase φ ₁ of the first frequency signal obtained by the measuring device 9 and the amplitude A ₂ and phase φ _{2 of} the second frequency signal are received via the wireless interface 25.

  The damage position detection system configured as described above performs processing as follows. In addition, since the damage position detection system is roughly divided into the measurement device 9 and the analysis device 11, the processing contents of each of these two devices will be described below.

<Processing by measuring device>
First, the processing content by the measuring device 9 will be described. FIG. 3 is a flowchart illustrating a processing procedure performed by the measurement apparatus 9 according to the present embodiment. The processing procedure shown in the flowchart of FIG. 3 is stored as a control program in a storage unit (not shown) of the control unit 17, and is executed by the control unit 17 (particularly the CPU in the control unit 17).

  First, a pulse signal is received from the encoder 15 (step S101). Then, based on the received pulse signal, it is determined whether or not a predetermined sampling interval has been reached (step S102). When the predetermined sampling interval is reached (step S102: YES), the process proceeds to step S103. If the predetermined sampling interval has not been reached (step S102: NO), step S103 is skipped and the process proceeds to step S104.

In step S103, the amplitude and phase of the first frequency signal received from the lock-in amplifier 14 are sampled. Therefore, the amplitudes A ₁ and A ₂ and the phases φ ₁ and φ _{2 of} the first and second frequency signals are acquired at predetermined sampling intervals by the processing of step S102 and step S103.

The process of step S103 will be specifically described as follows. A ground surface potential difference, that is, a potential difference between the two wheel electrodes 10 is always input from the wheel electrode 10 to the lock-in amplifier 14. The lock-in amplifier 14 uses the first reference signal generated by the reference signal transmitter 13 to extract the first frequency signal from the ground surface potential difference signal, and the amplitude A _{1 of} the first frequency signal. And the phase φ ₁ is derived. Similarly, the lock-in amplifier 14 extracts the second frequency signal from the ground potential difference signal by using the second reference signal generated by the reference signal transmitter 13, and extracts the second frequency signal. The amplitude A ₂ and phase φ ₂ of the signal are derived.

The derived amplitudes A ₁ and A ₂ and phases φ ₁ and φ ₂ are input to the control unit 17. In step S103, the control unit 17 samples the amplitudes A ₁ and A ₂ and the phases φ ₁ and φ ₂ at a constant sampling interval.

For example, the sampling interval can be about 1 cm in terms of distance units. Therefore, every time the measuring device advances about 1 cm along the longitudinal direction directly above the metal tube 2, the amplitudes A ₁ and A ₂ and the phases φ ₁ and φ _{2 at that time} are acquired. Each acquired data is temporarily stored in a memory (not shown) in the control unit 17 or the like.

Next, in step S104, sequentially the amplitude A ₁ and phase phi ₁ the data of the first frequency signal is sampled, the second frequency signal and the amplitude A ₂ and the phase phi ₂ the data via the radio interface 16 The transmission process is executed. A position number is added to each data. This position number is a number indicating the number of sampled data. The position number multiplied by the sampling interval corresponds to the distance from the initial position.

In step S105, it is determined whether or not the processing has been completed for all investigation target ranges of the metal pipe 2. For example, when it is received through the operation unit (not shown) that the user has instructed the end of the process, it is determined that the process has been completed for all the survey target ranges (step S105: YES). Is completed.

On the other hand, if the processing has not been completed for all the investigation target ranges (step S105: NO), the process returns to step S101, and the amplitudes A ₁ and A ₂ and the phases φ ₁ and φ ₂ are set at predetermined sampling intervals. The sampling process continues. Eventually, amplitudes A ₁ and A ₂ and phases φ ₁ and φ _{2 corresponding} to the number obtained by dividing the length of the investigation target range of the metal tube 2 by the sampling interval (n _total ) are obtained.

In this embodiment, the amplitudes A ₁ and A ₂ and the phases φ ₁ and φ ₂ are sequentially transmitted. However, after the processing is completed for all the investigation target ranges, n _total amplitudes A ₁ and A ₂ and phases φ ₁ and φ ₂ may be transmitted together.

<Processing by analysis device>
Next, the coating damage analysis process by the analysis apparatus 11 will be described. FIG. 4 and FIG. 5 are flowcharts showing the contents of the coating damage analysis process by the analysis apparatus of this embodiment, that is, the contents of the coating damage analysis method of this embodiment. The processing procedure shown in the flowcharts of FIGS. 4 and 5 is stored in the hard disk 24 as a coating damage analysis program, and is executed by the CPU 20.

In the following description, each process will be described with reference to FIG. 6 showing the waveform of the first frequency signal (amplitude A ₁ , phase φ ₁ , sine A ₁ sin φ ₁ , ground surface potential distribution). Although only various waveforms in the first frequency signal are shown in FIG. 6, similar waveforms can be obtained for the second frequency signal.

In the analysis apparatus 11 of the present embodiment, the data of the amplitude A ₁ and the phase φ ₁ of the first frequency signal and the data of the amplitude A ₂ and the phase φ ₂ of the second frequency signal are changed from the position number 1 to n _total . Are sequentially received from the measuring device 9. The analysis device 11 can repeatedly execute the following processing in real time each time data corresponding to each position number is sequentially received.

In the following description, the amplitude A ₁ and phase φ ₁ data of the first frequency signal up to the position number n (n is a natural number of 1 to n _total ), and the amplitude A ₂ and phase φ of the second frequency signal. The processing at the time when the _second data is received from the measuring device 9 will be described as an example.

First, in step S201, the position number n, and the amplitude A ₁ and phase phi ₁ the data of a first frequency signal, and the amplitude A ₂ and the phase phi ₂ the data of the second frequency signal is received from the measuring device 9 The

Here, FIG. 6A and FIG. 6B show waveforms of the amplitude A ₁ and the phase φ ₁ . The horizontal axis of FIG. 6 is the distance (m). This is obtained by multiplying the position number by the sampling interval and converting it to a distance value. As is known in the art, the amplitude A ₁ takes a minimum value at the damaged point (FIG. 6 (A)). Further, the polarity of the phase φ ₁ is reversed at the damage point. For example, phase φ ₁ reverses from +90 degrees to −90 degrees at the damage point.

  The processing in the following steps S202 to S212 will be described by taking the case of processing the first frequency signal as an example for the sake of simplicity of explanation, but the same processing is also executed for the second frequency signal.

In step S202, a sine A ₁ sin φ ₁ is calculated using the amplitude A ₁ and the phase φ ₁ of the first frequency signal. Note that the sine A ₁ sin φ ₁ is calculated for all amplitudes A ₁ and phases φ _{1 at} position numbers 1 to n.

FIG. 6C shows a waveform of A ₁ sinφ ₁ . When the phase adjustment circuit is adjusted so that the phase φ ₁ is inverted from +90 degrees to −90 degrees at the damage point, sin (−90 degrees) is −1 and sin (90 degrees) is +1. Therefore, the waveform of the sine A ₁ sinφ ₁ is the waveform itself of the amplitude A ₁ shown in FIG. 6A on the one side with respect to the damage point, and the waveform of the amplitude A ₁ is horizontally displayed on the other side. The waveform is folded around the axis.

Next, in step S203, the value of the sine A ₁ sinφ ₁ obtained in step S202 is sequentially accumulated along the position number order, thereby calculating the ground potential distribution waveform. At the position corresponding to the position number i (where i is an integer from 1 to n), the ground surface potential P is calculated by the following equation (1).

  A ground surface potential distribution can be obtained by calculating the ground surface potential at each position corresponding to the position numbers 1 to n.

  FIG. 6D shows the waveform of the ground surface potential distribution. The ground surface potential distribution has a mountain-shaped waveform that shows a peak at the damage point.

Processing of steps S202 and step S203 corresponds to the step of calculating the earth surface potential distribution P based on the amplitude A ₁ and phase phi ₁ data. After waiting for the ground surface potential distribution P to be calculated in this way, the process proceeds to damage determination processing in step S204 and subsequent steps.

In step S204, the section width (section pitch) is set. First, section width data is read from the hard disk 24. In the present embodiment, the section width data is given as the half width S of the section. Specifically, four types of S ₁ , S ₂ , S ₃ , and S ₄ are prepared in advance as the half width S. Here, corresponding to the case of the narrow section S ₁ is the most wide, corresponds to the case of the wider S ₄ are the most wide section.

When the half width is S ₄ , the section width (full width) W ₄ is W ₄ = 2S ₄ +1. When the opposite width is S ₃ , S ₂ , and S ₁ , the section widths W ₃ , W ₂ , and W ₁ are given by the same relational expression. Here, 1 is added because the position number of the center of the section is taken into consideration.

In this embodiment, as an initial value, for example, (the half-width when the S ₄₎ widest section width is set, the section width becomes W _4. Unlike the present embodiment, as an initial value, for example, the narrowest section width may be set (the half-width when the S ₁₎ is.

Next, in step S205, a plurality of continuous sections 1 to 5 are set in the ground surface potential distribution P calculated in step S203. At this time, the section width of each section is W ₄ set in step S204.

  FIG. 7 shows an example of section setting. In FIG. 7, a total of five continuous sections 1 to 5 are set around the position number i of interest. The section 3 is a section in which the section 3 is located at the center (hereinafter referred to as “center section”). Then, with reference to the central section 3, the sections 1 and 2 are arranged on one side, and the sections 4 and 5 are arranged on the other side.

In section 3, position number i is the center. In the section 2 and the section 1, the position number (i−W ₄ ) and the position number (i−2W ₄ ) are centered. In the section 4 and the section 5, the position number (i + W ₄ ) and the position number (i + 2W ₄ ), respectively. ) Is the center.

As will be described later, the position number i of interest is variable as long as sections 1 to 5 can be set. For example, since the minimum position number corresponding to the end point of section 1 in the figure is (i−2W ₄ ) −S ₄ , if this position number is not 1 or more, a part of section 1 is lost. Therefore, it is necessary that (i−2W ₄ ) −S ₄ ≧ 1. Similarly, since the maximum position number corresponding to the end point of the section 5 in the figure is (i + 2W ₄ ) + S ₄ , if this position number is not less than n, a part of the section 5 is lost. That is, it is necessary that (i + 2W ₄ ) + S ₄ ≦ n. In summary, as long as i satisfies the condition of 1 + 2W ₄ + S ₄ ≦ i ≦ n−2W ₄ −S ₄ , it is possible to set the sections 1 to 5 without loss.

In this embodiment, i = 1 + 2W ₄ + S ₄ is set as an initial value, and i is sequentially incremented every time data is received, as will be described later. However, unlike this embodiment, another initial value may be adopted.

  The processes in steps S204 and S205 described above correspond to the step of setting a plurality of continuous sections in the waveform of the ground surface potential distribution.

Next, in step S206, it is determined whether or not a condition for preventing the sections 1 to 5 from being lost is satisfied. That is, when processing is performed in real time, when the number of data of the amplitude A ₁ , the phase φ ₁ , the amplitude A ₂ , and the phase φ ₂ received up to the processing time point is small (when n is small), Depending on the section width, there may be a case where the five sections, section 1 to section 5, cannot be set without loss. Therefore, when the conditions for not missing the sections 1 to 5 are not satisfied and the missing occurs (step S206: NO), the process proceeds to step S211 and step S212, and processing for other section widths can be performed. On the other hand, when the conditions for not missing the sections 1 to 5 are satisfied (step S206: YES), the process proceeds to step S207.

Next, in step S207, the slope a of the waveform of the ground surface potential distribution P is derived for each section 1-5. The slope a of the waveform for each section is derived by the least square method. Further, in the process of deriving the gradient a of the waveform, the average value P _a of the ground surface potential distribution P for each interval is also derived.

As an example, FIG. 8 shows the result of deriving the slope of the waveform of the ground surface potential distribution P in section 1. As described above, section 1 is a section in which the center position number j is (i−2W ₄ ) and the section width (number of data) is W ₄ . In other words, the section 1 is a section in which the position number j is included in the range of i−2W ₄ −S ₄ ≦ j ≦ −2W ₄ + S ₄ .

First, the average value j _a of the position numbers j in the section 1 is obtained. The average value j _a of the position number j is given by the following equation (2).

The average value P _a of the ground surface potential P in the section 1 is obtained. Mean value P _a of the ground surface potential P is given by the following equation (3).

  Next, the sum of squares Tx of the position numbers in section 1 is obtained using equation (2). The square sum Tx of the position numbers is given by equation (4).

  Next, the product sum of the position number j and the ground surface potential P is obtained. The product sum Txy of the position number j and the ground surface potential P is given by equation (5).

  Finally, the slope a of the waveform of the ground surface potential distribution in the section 1 is calculated based on the sum of squares Tx of the positions indicated by the equation (4) and the product sum Txy of the positions indicated by the equations (5) and the ground surface potential. And are derived as shown in Equation (6).

  Note that the slope of the slope a of the waveform of the ground surface potential distribution can be similarly derived for the sections 2 to 5. The processing in step S207 described above corresponds to the step of deriving the slope of the ground potential distribution waveform for each set section.

Next, in step S208, it is determined whether or not the tendency of the slope a in each of the sections 1 to 5 obtained in step S207 and the average value Pa of the ground surface potential satisfy _a specified condition. Specifically, the average value P _a trend and earth surface potential of the slope a of the respective sections 1 to 5, it is determined whether the following conditions 1, satisfy either condition 2 or condition 3, The Hereinafter, Condition 1, Condition 2, and Condition 3 will be described.

  Condition 1 is required to satisfy all of the following (1-1) to (1-3).

  (1-1) The slope a in the central section (section 3) is negative, the slope a in the sections (sections 1 and 2) arranged on one side with respect to the central section is positive, and on the other side The slope a in the arranged section (sections 4 and 5) is negative. If this is expressed by an equation, a (section 1)> 0, slope a (section 2)> 0, slope a (section 3) <0, slope a (section 4) <0, slope a (section 5) < 0.

(1-2) according to become closer section to the center section, the mean value P _a of the ground surface potential P becomes higher. If this is expressed by an equation, P _a (section 1) <P _a (section 2) and P _a (section 4)> P _a (section 5).

  (1-3) The absolute value of the slope a in the central section (section 3) is smaller than the absolute value of the slope a in the adjacent section. As an adjacent section, it is desirable to adopt a section having a slope with a sign different from the slope a in the central section. In this condition, since the slope a in the central section is negative, the section having the positive slope a (section 2) is adopted. If this is expressed by an equation, | a (section 3) | <| a (section 2) |.

  Condition 2 is required to satisfy all of the following (2-1) to (2-3).

  (2-1) The slope a in the central section (section 3) is positive, the slope a in the sections (sections 1 and 2) arranged on one side with respect to the central section is positive, and on the other side The slope a in the arranged section (sections 4 and 5) is negative. If this is expressed by an equation, a (section 1)> 0, slope a (section 2)> 0, slope a (section 3)> 0, slope a (section 4) <0, slope a (section 5) < 0.

(2-2) according to become closer section to the center section, the mean value P _a of the ground surface potential P becomes higher. If this is expressed by an equation, P _a (section 1) <P _a (section 2) and P _a (section 4)> P _a (section 5).

  (2-3) The absolute value of the slope a in the central section (section 3) is smaller than the absolute value of the slope a in the adjacent section. As an adjacent section, it is desirable to adopt a section having a slope with a sign different from the slope a in the central section. In this condition, since the slope a in the central section is positive, a section (section 4) having a negative slope a is adopted. If this is expressed by an expression, | a (section 3) | <| a (section 4) |.

  Condition 3 is required to satisfy the following (3-1) to (3-2).

  (3-1) The slope a in the central section (section 3) is 0, the slope a in the sections (sections 1 and 2) arranged on one side with respect to the central section is positive, and on the other side The slope a in the arranged section (sections 4 and 5) is negative. If this is expressed by an equation, a (section 1)> 0, slope a (section 2)> 0, slope a (section 3) = 0, slope a (section 4) <0, slope a (section 5) < 0.

(3-2) according to become closer section to the center section, the mean value P _a of the ground surface potential P is high. If this is expressed by an equation, P _a (section 1) <P _a (section 2) and P _a (section 4)> P _a (section 5).

As described above, when the average value _{P a} trend and earth surface potential of the slope a of the section 1-5 provisions condition (Condition 1, Condition 2, or Condition 3) satisfy (Step S208: YES) The process proceeds to step S209. Next, in step S209, the position number i of interest is stored in the memory 21 as a damage point candidate, and the process proceeds to step S210. On the other hand, if the average value _{P a} trend and the ground surface potential of the slope a of a section 1-5 does not satisfy the specified condition (step S208: NO), the process proceeds to step S210 by skipping step S209.

  The plurality of sections 1 to 5 are moved relative to the waveform of the ground surface potential distribution every time data is sequentially received from the measuring device 9. As a result, every time the plurality of sections 1 to 5 are moved, the slope of the waveform of the ground surface potential distribution is derived for each section, and a damage point candidate is detected from the tendency of the slope.

In step S210, processing predetermined range (first predetermined range) more damage point candidates is recorded in the past contained within D ₁ integrates regarded as correspond to the same fault location is performed. That is, since the plurality of sections 1 to 5 are moved relatively to the waveform of the ground surface potential distribution, one damaged point can be originally stored as a separate damaged point candidate in step S209. Accordingly, multiple lesions point candidates included in the first predetermined range D ₁ is the inherent assumption that a single fault location is separately stored, are integrated into one. For example, among the plurality of fault location candidates included in the first predetermined range D _1, leaving what gradient a of the center section (section 3) is the smallest as a damage point candidates, remove the others from damage point candidates Can be integrated.

Next, in step S211, it is determined whether or not the processing in steps S205 to S210 has been executed for all the section widths W ₄ , W ₃ , W ₂ , and W ₁ . If there is a section width that has not been processed yet (step S211: NO), a different section width is adopted in step S212, the process returns to step S205, and the processes in and after step S205 are repeated.

  As described above, in this embodiment, since it is possible to set and process sections with a plurality of widths, it becomes possible to analyze the ground potential distribution of various waveforms, and to cover with various sizes and shapes. Damaged part can be detected.

  Damage point candidates are derived by processing the first frequency signal and the second frequency signal in accordance with the processing in steps S201 to S212 described above.

  Next, in step S213 (FIG. 5), it is determined whether a damage point candidate is stored. When no damage point candidates are stored (step S213: NO), there is no covering damage portion, and the process ends. On the other hand, when the damage point candidate is stored (step S213: YES), the process proceeds to step S214.

In step S214, the damage point candidate derived in the first frequency signal (hereinafter referred to as “first damage point candidate”) and the damage point candidate derived in the second frequency signal (hereinafter referred to as “second damage point candidate”). More. Specifically referred) are compared, within a predetermined range (second predetermined range) D _2, whether the first damage point candidate and the second damage point candidates are both present or not When only one of the first damage point candidate and the second damage point candidate exists (step S214: NO), noise or interference is present even though there is actually no covering damage portion. It is the effect is determined that the damage point candidate is detected, the processing is terminated. on the other hand, within a predetermined range D _2, if the first damage point candidate and the second damage point candidates exist together (step S214: YES), step S215 Proceed to the bottom of the processing.

Incidentally, in a predetermined range D _2, when the first damage point candidate and the second damage point candidates are both present, it and the first damage point candidate and the second damage point candidates included in the predetermined range D ₂ It is also possible to execute a process of integrating by regarding that they correspond to the same damage point. In this case, essentially one damaged point is detected and stored by processing both the first frequency signal and the second frequency signal. Accordingly, the first damage point candidate and the second damage point candidates included in the predetermined range D _2, is inherently as a single damaged points are separately stored, it can be integrated into one . For example, only the first damage point candidate may be left as the damage point candidate and the second damage point candidate may be deleted.

  The processing after step S215 is processing for integrating a plurality of position detection results obtained by setting sections with a plurality of widths. FIG. 9 shows an outline of processing for integrating a plurality of position detection results obtained by setting sections with a plurality of widths. Hereinafter, with reference to FIG. 9, the processing after step S215 will be described.

First, in step S215, the one section width, for example, if the narrowest section width W ₁ is selected. In this case, all the damage point candidates detected during the adoption narrowest section width W ₁ is read. Next, in step S216, one damage point candidate is selected from the damage point candidates read in step S215.

Next, in step S217, has been damaged point candidates (e.g., i ₁ in Figure ₉₎ selected in step S216 in a predetermined range relative to the (third predetermined range) D _3, detected upon the adoption of another section width It is determined whether or not there is a damaged point candidate (for example, i ₂ and i ₄ in FIG. 9). If there is a damage point candidate detected at the time of adopting another section width (step S217: YES), the process proceeds to step S218. On the other hand, when there is no damage point candidate detected when the section is set with another section width (step S217: NO), the process of step S218 is skipped and the process proceeds to step S219.

In step S218, a flag (see FIG. 9) is regarded as a plurality of fault location candidates included in a predetermined range D ₃ is detected when the adoption of the section width corresponds to the same fault location, integrates Processing is executed. Specifically, for example, among the plurality of fault location candidates included in a predetermined range D _3, leaving a detected fault location candidates during adoption of the narrowest section width, it is removed others from damage point candidates .

  In step S219, it is determined whether or not selection has been completed for all damage point candidates read in step S215. If there is a damage point candidate that has not yet been selected (step S219: NO), the process returns to step S216, another damage point candidate is selected, and the process is repeated. On the other hand, if selection has been completed for all the damage point candidates read in step S215 (step S219: YES), the process proceeds to step S220.

  In step S220, it is determined whether selection of all section widths has been completed. If there is an unselected section width (step S220: NO), the process returns to step S215, one other section width is selected, and the processing from step S216 onward is repeated. On the other hand, if all the section widths have been selected (step S220: YES), the process proceeds to step S221.

  In step S221, the damage point candidates remaining after the integration are finally listed as damage points, and then in step S222, the distance to the covered damaged part is calculated by multiplying the position number of the damage point by the sampling interval. Is done. Then, the result is displayed on the display 23, and the process is completed.

The above processing is performed each time the amplitude A ₁ and phase φ ₁ data of the first frequency signal and the amplitude A ₂ and phase φ ₂ data of the second frequency signal are sequentially received from the measuring device 9. The damage point is finally stored in the hard disk 24 when the measurement device 9 completes the measurement of the investigation target range. If there is no damaged portion of the coating, that fact may be displayed on the screen of the display.

  In this way, the position of the coating damage portion can be grasped in real time by sequentially receiving the data measured by the measuring device 9 and performing the above processing.

As described above, each processing in step S202 and step S203 includes a calculation unit that calculates the ground surface potential distribution P based on the data of the amplitudes A ₁ and A ₂ and the phases φ ₁ and φ ₂ received via the communication unit. Corresponds to the function of. Each process of step S204, step S205, step S211, and step S212 corresponds to the function of a setting unit that sets a plurality of continuous sections in the waveform of the ground surface potential distribution. Furthermore, the process of step S207 corresponds to the function of a derivation unit that derives the slope of the waveform of the ground surface potential distribution for each set section. And the process of step S208, step S209, step S210, and step S213-S222 respond | corresponds to the function of the detection part which detects a damage point from the inclination tendency derived | led-out according to each area.

  According to the coating damage analysis technique of the present embodiment, the following effects can be obtained.

  (A) In the waveform of the ground surface potential distribution, a plurality of continuous sections 1 to 5 are set, the slope a of the ground surface potential distribution waveform is derived for each set section, and the slope a derived for each section is derived. Since the damage point is detected from the tendency, it is not necessary for the user to visually analyze the waveform, and the damage point can be detected with high accuracy.

  (B) The plurality of sections 1 to 5 are moved relative to the ground potential distribution waveform, and each time the plurality of sections 1 to 5 are moved, the slope a of the ground surface potential distribution waveform for each section Therefore, the processing can be applied to most of the ground potential distribution.

  (C) Since a damage point is detected by integrating a plurality of position detection results obtained by moving a plurality of sections 1 to 5, a single covering damage portion is essentially a plurality of covering damage portions. It can be prevented from being detected.

(D) Since sections 1 to 5 are set with a plurality of widths W ₄ , W ₃ , W ₂ , and W ₁ , it becomes possible to analyze the ground surface potential distribution of various waveforms, and various sizes and shapes It is possible to detect a damaged part of the coating having

(E) Since a damage point is detected by integrating a plurality of position detection results obtained by setting sections 1 to 5 with a plurality of widths W ₄ , W ₃ , W ₂ , and W ₁ , Specifically, it is possible to prevent a single coating damage portion from being detected as a plurality of coating damage portions. In particular, by integrating the position detection result detected when the narrowest section is set, the damage point can be detected with high accuracy.

  (F) Two types of AC signal currents having different frequencies are used as the AC signal current, and when a damage point candidate is detected only when an AC signal current of one frequency is used, noise or interference Since it is determined that a damage point candidate has been detected due to the influence, the influence of noise or interference can be eliminated.

  (G) Since a damage point is detected by integrating a plurality of position detection results obtained by passing AC signal currents of two different frequencies, a single covering damage portion is inherently a plurality of coverings. It can prevent being detected as a damaged part.

  (H) Since there is no need to mount a display device such as a recorder in the measuring device 9, the measuring device 9 can be miniaturized.

  (I) The present invention can be implemented on various computers by installing a coating damage analysis program for executing the processing procedure shown in the flowcharts of FIGS. 4 and 5 on the computer.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to these cases, and various modifications, omissions, and additions can be made by those skilled in the art.

For example, in the above description, the analysis device 11 acquires data of the amplitudes A ₁ and A ₂ and the phases φ ₁ and φ ₂ of the first frequency signal and the second frequency signal from the measurement device 9 via the wireless interface 25. Although described, the present invention is not limited to this case. For example, a damage position detection system such as the modification shown in FIG. 10 may be employed.

In this modification, the measurement device 9 is provided with a memory card writing unit 27 instead of the wireless interface 16, and the analysis device 11 is provided with a memory card reading unit 28 instead of the wireless interface 25. The memory card writing unit 27 writes the amplitude A ₁ and phase φ ₁ of the first frequency signal and the amplitude A ₂ and phase φ ₂ of the second frequency signal obtained by the measuring device 9 into the memory card 26. is there. On the other hand, the memory card reading unit 28 reads the amplitude A ₁ and phase φ ₁ of the first frequency signal and the amplitude A ₂ and phase φ ₂ of the second frequency signal from the memory card 26.

As described above, the analysis device 11 acquires the data of the amplitudes A ₁ and A ₂ and the phases φ ₁ and φ ₂ of the first frequency signal and the second frequency signal from the measurement device 9 through the memory card 26. May be.

  In the above description, the case where the measuring device 9 and the analyzing device 11 are configured separately is shown. From the viewpoint of reducing the size of the measuring device 9, it is desirable to configure the measuring device 9 and the analyzing device 11 separately, but the present invention is not limited to this case, and the measuring device 9 and the analyzing device 11 are integrated. It can also be configured. Also in this case, it is useful because the burden on the user to visually analyze the waveform can be eliminated and the position of the covering damage portion can be displayed numerically.

  The processing procedure shown in the flowcharts of FIGS. 4 and 5 is an example, and a plurality of continuous sections are set in the ground surface potential distribution waveform, and the slope of the ground surface potential distribution waveform is set for each set section. As long as the damage point is detected from the inclination tendency derived for each section, some steps can be omitted or the order between the steps can be changed.

  In the above description, the case where five sections are set has been described, but the present invention is not limited to this case. The present invention can be applied when a plurality of sections are set regardless of the number of sections. However, from the viewpoint of using the analysis method shown in step S208 of FIG. 4 described above, the number of sections is preferably an odd number, and more preferably, the number of sections is an odd number of five or more.

  In the above description, the case where two types of alternating signal currents having different frequencies are used has been described, but the present invention is not limited to this case. It is clear that the present invention can be applied even when an AC signal having a single frequency is used.

  In the above description, the case where the CPU 20 functions as a calculation unit, a setting unit, a derivation unit, and a detection unit by executing a coating damage analysis program has been described as an example. However, hardware such as a logic integrated circuit is used. A part of each of these parts can also be configured.

  The coating damage analysis program of the present invention may be provided by a recording medium such as a CD-ROM or may be provided via a network such as the Internet.

It is a figure which shows schematic structure of the damage position detection system which is embodiment of this invention. It is a block diagram which shows the structure of the measuring apparatus and analysis apparatus which are shown by FIG. It is a flowchart which shows the process sequence by the measuring apparatus shown by FIG. It is a flowchart which shows the process sequence by the analyzer shown by FIG. It is a flowchart following FIG. It is a figure which shows the waveform of the amplitude of a 1st frequency signal, a phase, a sine, and ground surface potential. It is a figure which shows the example of a setting of the area in the waveform of a ground surface potential. It is a figure which shows typically the result of having derived | led-out the inclination of the waveform of the ground surface potential according to the area. It is a figure which shows the outline | summary of the process which integrates the several position detection result obtained by setting an area with multiple widths. It is a block diagram which shows the structure of the measuring apparatus and analysis apparatus in the damage position detection system of a modification.

Explanation of symbols

1 anticorrosion coating,
2 metal tubes,
3 Damaged parts of the coating,
4 Ground,
5 counter electrode,
6 first signal generator,
7 Counter electrode,
8 Second signal generator,
9 Measuring device,
10 wheel electrodes,
11 Analysis device,
12 Anticorrosion coated metal tube,
13 Reference signal transmitter,
14 Lock-in amplifier,
15 encoder,
16 wireless interface,
17 control unit,
18 battery,
19 converter,
20 CPU (calculation means, setting means, derivation means, and detection means)
21 memory,
22 Operation part,
23 display,
24 hard disk,
25 Wireless interface (communication means)
26 Memory card,
27 Memory card writing unit,
28 Memory card reading unit.

Claims (9)

Ground surface potential distribution created by the damaged portion of the sheath when the AC signal current is passed between the damaged portion of the metal pipe embedded in the ground with anticorrosive coating on the outer surface and the counter electrode embedded in the ground A coating damage analysis device for analyzing coating damage based on
Setting means for setting a plurality of continuous sections in the waveform of the ground surface potential distribution;
Deriving means for deriving the slope of the waveform of the ground surface potential distribution for each set section;
And a detecting means for detecting a position of the covering damage portion from the inclination tendency derived for each section. The setting means moves the plurality of sections relative to the waveform of the ground surface potential distribution,
2. The covering damage analysis apparatus according to claim 1, wherein the deriving unit derives a slope of a waveform of the ground surface potential distribution for each section each time the plurality of sections are moved.   3. The covering damage analysis according to claim 2, wherein the detecting unit integrates a plurality of position detection results obtained by moving the plurality of sections to detect the position of the covering damaged portion. apparatus.   The coating damage analysis apparatus according to claim 1, wherein the setting unit sets the section with a plurality of widths.   The said detection means integrates the several position detection result obtained by setting the said area by several widths, and detects the position of the said covering damaged part. Cover damage analyzer. As the AC signal current, AC signal currents of two different frequencies are used,
2. The detection unit according to claim 1, wherein the position of the damaged portion is detected by integrating a plurality of position detection results obtained by passing AC signal currents having two different frequencies. Coating damage analysis equipment. Further, the ground surface just above the metal pipe is moved, the potential difference of the ground surface is detected by the mounted wheel electrode, the signal having the same component as the AC signal current is extracted, and the amplitude and phase of the signal are measured. A communication means for communicating with the measuring device;
The covering damage analysis apparatus according to claim 1, further comprising a calculation unit that calculates a ground surface potential distribution based on the amplitude and phase data received via the communication unit. Ground surface potential distribution created by the damaged portion of the sheath when the AC signal current is passed between the damaged portion of the metal pipe embedded in the ground with anticorrosive coating on the outer surface and the counter electrode embedded in the ground A coating damage analysis method for analyzing a coating damage based on
Setting a plurality of consecutive sections in the waveform of the ground surface potential distribution;
Deriving the slope of the ground potential distribution waveform for each set section;
Detecting the position of the damaged portion of the covering from the inclination tendency derived for each section. Ground surface potential distribution created by the damaged portion of the sheath when the AC signal current is passed between the damaged portion of the metal pipe embedded in the ground with anticorrosive coating on the outer surface and the counter electrode embedded in the ground A coating damage analysis program for analyzing coating damage based on
A procedure for setting a plurality of continuous sections in the ground potential distribution waveform;
A procedure for deriving the slope of the waveform of the ground surface potential distribution for each set section,
A covering damage analysis program for causing a computer to execute a procedure of detecting the position of the covering damage portion from the inclination tendency derived for each section.

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