JP3573584B2 - Sonic pipeline inspection system - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sound wave type pipeline inspection system for inspecting the inside of a pipeline such as a buried pipe using sound waves.
[0002]
[Prior art]
Pipes such as gas pipes and water pipes buried in the ground may deteriorate due to corrosion due to long-term laying, or may be damaged by external force. Therefore, it is necessary to investigate the inside of the pipes and take measures for repairs such as repairs.
2. Description of the Related Art Conventionally, as one of systems used for investigation inside a pipeline of this type, there is a system in which a device such as a camera or a fiberscope is inserted into the pipeline so that the state in the pipeline can be directly visually recognized.
However, the method of inserting such equipment requires ancillary equipment such as a cable to be inserted into the pipeline and insertion work, which may require a large amount of work and equipment for investigation. In addition, if there is a broken point, a branch, or the like in the middle of the pipeline, it is difficult to guide the devices at the location, and there is a problem that the investigation over the entire pipeline cannot be performed accurately.
Therefore, instead of such a method, a system is proposed in which a sound wave is transmitted from the end of the pipe and the state of reflection of the sound wave is observed, so that the situation inside the pipe can be easily inspected from both ends or one end of the pipe. (Eg, JP-A-61-29757 and JP-A-61-202158).
In the above publication, a sound-generating means and a sound-collecting means are arranged at the end of a pipe, and a sound wave transmitted from the sound-generating means is detected to be reflected at a cross-sectional area changing portion generated in the pipe, and a cross-sectional area is detected. A technique capable of observing a position up to a changing portion is disclosed. Such a technique can not only detect a cross-sectional area change portion in a pipe, but also can investigate the position of a joint or the like installed in the pipe by observing a position where a reflected sound wave is generated.
[0003]
[Problems to be solved by the invention]
However, when conducting an investigation inside a pipeline using sound waves, even if a signal forming a one-cycle sine wave is output as an output signal to the speaker, which is a sound generating means, the frequency characteristic due to mechanical inertia in the speaker is obtained. Therefore, the transmitted sound wave does not have a waveform of one cycle. Specifically, as shown in FIG. 4 (A), even when a sound wave generation voltage is applied to the speaker as a one-cycle sine wave, the waveform of the sound wave from the speaker is increased as shown in FIG. 4 (B). Does not converge in one cycle due to the frequency characteristics of the loudspeaker, and a so-called drifted waveform is obtained until the convergence.
For this reason, since the reflected sound wave is different from a sound wave waveform that forms a one-cycle sine wave, the resolution when identifying the reflected sound wave is low.
[0004]
SUMMARY OF THE INVENTION An object of the present invention is to provide a sound wave type pipeline survey system capable of transmitting a sound wave without lowering the resolution for identifying reflected sound waves reflected in a pipeline in view of the above-mentioned problems in the conventional sound wave type pipeline survey system. Is to do.
[0005]
[Means for Solving the Problems]
In order to achieve this object, the invention according to claim 1 is a sound generating means for transmitting a pulsed sound wave from one end of a pipeline into the pipeline, and a pulse-like sound reflected in the pipeline at one end of the pipeline. In the sound wave type pipe line survey system for examining the inside of the pipe line from the time from when the above-mentioned pulsed sound wave is transmitted to when the sound is collected by using the sound collecting means that collects the sound wave, Means is connected to an output side, and an input side is provided with a control unit to which a pipe diameter selection unit and a frequency selection unit of a sound wave transmitted from the sound generation unit are connected, respectively, wherein the control unit has a predetermined sound wave waveform. In order to obtain, a voltage waveform set with the pipeline diameter and the frequency of the sound wave is registered in advance, and the voltage waveform is selected and output from the selected pipeline diameter and the frequency of the sound wave. Features.
[0010]
[Action]
According to the first aspect of the present invention, by selecting the diameter of the pipeline to be investigated and the frequency of the transmitted sound wave, a voltage waveform from which a predetermined sound wave waveform corresponding to the diameter and the frequency is obtained is extracted. Voltage control corresponding to the voltage waveform is performed.
[0013]
【Example】
Hereinafter, the present invention will be described in detail with reference to illustrated embodiments.
FIG. 1 is a block diagram for explaining the configuration of the first aspect of the present invention.
In FIG. 1, a sound wave type pipeline survey system includes a speaker 1 which is a sound generating means disposed at one end of a pipe S, and collects reflected sound waves transmitted from the speaker 1 and reflected from a reflection source. A microphone 2 serving as a sound collecting unit and a control unit 3 to which the speaker 1 is connected on the output side and the microphone 2 is connected on the input side are provided. The speaker 1 and the microphone 2 are connected to the control unit 3 via an I / O interface including an A / D converter and a D / A converter (not shown).
The control unit 3 is configured by a microcomputer that calculates the distance to the reflection source in the pipeline S using the reception timing of the reflected sound wave by the microphone 2 in addition to the generation of the pulsed sound wave transmitted from the speaker 1. Have been.
[0014]
On the input side of the control unit 3, a pipeline diameter input key 4 and a sound frequency input key 5 are connected, so that the pipeline diameter and the frequency are input.
The control unit 3 has a storage unit that stores various basic data including an arithmetic processing program, and the storage unit stores the diameter of the pipe S to be investigated as shown in FIG. (Indicated by reference symbol D in FIG. 2) and the frequency of the sound wave (indicated by reference character f in FIG. 2) are output to the speaker 1 so that a predetermined sound wave waveform consisting of one cycle of a sine wave is obtained. A waveform table 6 in which a voltage waveform is set is registered.
The waveform table 6 is obtained by selecting the diameter of the pipeline used for the investigation and the frequency of the sound wave and observing the waveform of the sound wave by applying various voltages in advance. The voltage waveform at the time when it is confirmed that the voltage is obtained as a wave is registered.
Since the present embodiment is configured as described above, when the diameter of the pipeline S to be investigated and the frequency of the used sound wave are input by the pipeline diameter input key 4 and the frequency input key 5, the control unit 3 Using the input pipe diameter and frequency as parameters, a voltage waveform that can obtain a predetermined sound waveform (one-cycle sound waveform) is extracted from the waveform table 6, and the voltage waveform is output to the speaker 1.
[0015]
Next, another embodiment will be described. This is the same as the example shown in FIG. 1 except that the pipe diameter selection means 4 is not provided in the configuration shown in FIG. 1, the speaker 1, the microphone 2, the control unit 3, and the frequency selection means. 5 is used. In the present embodiment , the controller 3 selects only the frequency from the parameters of the waveform table 6 shown in FIG. Since the frequency of the sound wave is correlated with the voltage applied to the speaker 1, this is used as a parameter for selecting a voltage waveform. In the present embodiment , when the frequency of the sound wave to be transmitted is input by the frequency selection unit 5, the control unit 3 uses the input frequency as a parameter to obtain a predetermined sound wave waveform (one cycle of sound wave waveform). The waveform is extracted from the waveform table 6, and the voltage waveform is output to the speaker 1.
[0016]
Next, still another embodiment will be described. This is characterized in that while observing the transmitted sound waveform, voltage control is performed so that the waveform becomes a predetermined sound waveform. As a form for obtaining this feature, as in the example shown in FIG. 1, the functions are different, but a speaker 1 that is a sound generator, a microphone 2 that is a sound collector, and a controller 3 are used. In this case, the control unit 3 includes an amplifier such as an operational amplifier having a function as a comparator, and controls the signal level of the sound wave reception signal obtained from the microphone 2 on the time axis and the signal level corresponding to a predetermined sound wave waveform. The waveform of the output voltage is changed while observing. In this case , the waveform of the output voltage is sequentially changed so that the sound wave waveform obtained by the microphone 2 matches a predetermined sound wave waveform.
[0017]
According to this , since analog control using an operational amplifier is performed, the shaping process for the target waveform can be performed at an extremely high speed, so that the response time to the shaping process can be shortened. Can be performed.
[0018]
Next, still another embodiment will be described. This is characterized in that a sound wave waveform transmitted from the sound generating means is compared with a predetermined sound wave waveform, and a voltage output to the sound generating means to the sound generating means is controlled so that the waveforms match each other. The form for obtaining this feature is different from that of the example shown in FIG. 1 in function, but uses a speaker 1 as a sound generator, a microphone 2 as a sound collector, and a control unit 3. In this case, the control unit 3, a signal level corresponding to the signal level and a predetermined acoustic waveform of an amplifier such as an operational amplifier, the received signal waves obtained from the microphone 2 on the time axis which functions as a comparator Are compared, and the amplitude of the output voltage is controlled according to the comparison result. As shown in FIG. 3, the transmitted sound wave waveform is compared with a one-cycle sine wave corresponding to a predetermined sound wave waveform shown on the right side of FIG. 3C, and the output voltage waveform is changed so that the waveforms match. Is done.
[0019]
Next, still another embodiment will be described. This is characterized in that the change of the voltage waveform is repeated a plurality of times so that the waveform of the transmitted sound wave matches the predetermined sound wave waveform. As a mode for obtaining this feature, a configuration similar to the above-described mode is used. Here, the relationship between the output voltage to the speaker 1 and the sound wave waveform shown in FIG. 3C, that is , the output voltage to the speaker 1 is set such that the sound wave waveform is obtained as a sine wave of a predetermined cycle. Therefore, as shown in FIGS. 3A and 3B, the control of the output voltage is repeated a plurality of times.
[0020]
As a method of eliminating the deviation described in the above embodiment , as an example, a proportional control or a PID control that finds an amplitude difference between waveforms on a time axis and adjusts a voltage output according to the amplitude difference is used. .
[0021]
Further, the above method is an analog method, but digital signal processing is also possible. In this case, a microcomputer capable of arithmetically processing a deviation and an output voltage based on the deviation is used as the control unit 3, and the speaker 1 and the microphone 2 are not shown with respect to the output unit and the input unit of the control unit 3. It is connected via an I / O interface including a D / A converter and an A / D converter.
The control unit 3 calculates a deviation between the waveform of the received sound wave and a predetermined waveform (one cycle of a sine wave) based on the output signal from the microphone 2, and outputs the deviation to the speaker 1 to eliminate the deviation. A voltage correction amount for the voltage is set and output to the speaker 1.
In digital control, control time is longer than in analog control. However, this problem can be processed in a short time by using a commonly used sampling theorem (sampling theorem).
[0022]
【The invention's effect】
According to the first aspect of the present invention, by selecting the diameter of the pipeline to be investigated and the frequency of the sound wave to be transmitted, a voltage waveform from which one cycle of a sine wave sound wave corresponding to the diameter and the frequency is obtained is extracted. Then, voltage control corresponding to the voltage waveform is performed. As a result, it is possible to prevent the resolution at the time of identifying the reflected sound wave from being lowered.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a sound wave type pipeline inspection system according to the present invention.
FIG. 2 is a table showing a waveform table used in the configuration shown in FIG. 1; FIG. 3 is a timing chart for explaining the operation of the system shown in FIG. 1;
FIG. 4 is a timing chart showing a waveform of a transmitted sound wave in a pipeline and a waveform of a voltage applied for transmitting the sound wave.
[Explanation of symbols]
1 Speaker as sounding means 2 Microphone as sound collecting means 3 Control unit 4 Pipe diameter input key 5 Frequency input key

Claims (1)

The sound generating means for transmitting a pulsed sound wave from one end of the pipe into the pipe, and the pulse-shaped sound collecting means for collecting the pulsed sound wave reflected in the pipe at one end of the pipe. In a sound wave type pipe line survey system for investigating the inside of a pipe line from the time until the sound is collected after the sound wave is transmitted and the sound velocity value,
The sound generating means is connected to an output side, and the input side includes a control unit to which a pipe diameter selecting means and a frequency selecting means of a sound wave transmitted from the sound generating means are connected, respectively.
The control unit previously registers a voltage waveform set with the pipeline diameter and the frequency of the sound wave in order to obtain a predetermined sound waveform, and calculates the voltage based on the selected pipeline diameter and the frequency of the sound wave. A sonic pipeline inspection system characterized by selecting and outputting a waveform.

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