JP2009216585A - System and method for measuring pipe length - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To be immune to noise, to transmit sound wave to a distance, to prevent attenuation of the waveform, and to accurately measure the pipe length. <P>SOLUTION: In a state where a measuring mechanism 1 having a measuring part 11 and a measuring pipe 12 is connected to a pipe 3, a sound reception signal emitted from a microphone 103 arranged so that howling occurs in the measuring pipe is received from a speaker 102. Until a sound wave having a large amplitude by a speaker 102 and the microphone 103 occurs in the pipe 3 and a standing wave vector is detected, the frequency of a signal generated from a signal generation part 104 is changed and controlled, By using temperature data in the pipe and the peak frequency of the standing wave at that time, the pipe length is calculated by a control part 21 of a measuring device 2 based on a predetermined expression. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pipe length measuring system and a measuring method thereof, and in particular, generates and measures a standing wave with respect to an embedded pipe, and calculates the length of the pipe using a frequency obtained by Fourier transform. The present invention relates to a tube length measuring system and a measuring method thereof.

  As a means for measuring the length of a gas pipe or water pipe buried underground, a method of measuring the pipe length using pulsed sound waves or noise is known. In the method using pulsed sound waves, the tube length is obtained by dividing the time difference between the generation time of the incident sound wave and the reception time of the reflected sound wave by the sound velocity. A method using noise is to obtain the tube length by dividing the generation time of the peak value in the autocorrelation of the received sound signal by the speed of sound. The former is disclosed in Patent Document 1, for example.

  In Non-Patent Document 1, as a distance measurement method using a standing wave, a principle of measuring a distance using a standing wave generated by interference between a sound radiated from a speaker and a reflected sound from an object is used. Has been proposed.

JP-A-10-132540 Nakasako, Kamiho, and Mori: "Fundamental study of distance estimation using standing waves" Proceedings of the Acoustical Society of Japan (September 2006, pp.435-436)

  In the conventional method of measuring the tube length using pulsed sound waves, it is difficult to accurately determine the tube length in an environment with a lot of external noise and extremely long piping, since the energy of the sound waves propagating in the piping is small. . In addition, tube length measurements using broadband signals such as white noise (sounds containing almost the same amount of all frequency components) are measured using their autocorrelation, which is high when the autocorrelation is weak. Since the peak value cannot be obtained, it is difficult to obtain the peak occurrence time which is a parameter necessary for obtaining the tube length.

  As described above, in the prior art, it is weak against noise, it is difficult to reach a sound wave far away, and it is difficult to accurately obtain the tube length because there is a fear of waveform attenuation. Further, the above Non-Patent Document 1 discloses the principle of the distance measurement method using the standing wave, but how to apply the method using the standing wave for measuring the tube length. Not mentioned.

  An object of the present invention is to provide a tube length measurement system and a measurement method using a standing wave, which can transmit sound waves far away to noise and can accurately measure the tube length while preventing waveform attenuation. It is to provide.

  The tube length measurement system according to the present invention is preferably a tube length measurement system in which a measurement mechanism is connected to a tube to be measured and the length of the tube to be measured is measured using a standing wave. A signal generation unit that controls the frequency of the signal, a howling generation mechanism that receives the output sound wave to generate a howling phenomenon, and frequency data of standing waves obtained by generating howling by the howling generation mechanism; And a measuring device for calculating the length of the tube to be measured based on a predetermined relational expression using temperature data relating to the tube to be measured.

  In a preferred example, the howling generation mechanism generates howling by generating a pair of sound wave output means for outputting a sound wave and sound receiving means for receiving the output sound wave, which are arranged in the measurement mechanism. The signal generator is connected to a power amplifying unit for continuing howling with the received signal until the measurement device detects the frequency of the standing wave. Control the frequency of the signal.

  Preferably, the measurement apparatus includes a signal amplification unit that amplifies the signal received by the howling generation mechanism, an A / D conversion unit that converts the signal amplified by the signal amplification unit from analog to digital, and A calculation means for calculating the length of the tube to be measured using the frequency data of the standing wave obtained by Fourier-transforming the signal obtained from the A / D converter and the temperature data, and the calculation means The output frequency of the signal of the signal generator is controlled according to the calculation according to.

  Preferably, a temperature sensor that detects the temperature inside the tube to be measured is provided, and the measuring device uses temperature data about the tube to be measured detected by the temperature sensor based on a predetermined relational expression. The length of the tube to be measured is calculated.

Preferably, the calculation means Fourier-transforms the time series signal obtained by the conversion by the A / D conversion unit and projects it to the frequency domain, selects the peak frequency f (Hz), and measures The speed of sound c (m / s) is calculated from the temperature t (° C.) in the tube, and the tube length L _n (m), which is the reflection distance, is calculated using the relational expression (L _n = c / 2f).

The tube length measurement method according to the present invention is preferably a tube length measurement method for measuring the length of a tube to be measured using a standing wave.
For the tube to be measured, output the sound wave by controlling the frequency of the signal to output the sound wave,
Receiving the output sound wave to generate howling,
The length of the tube to be measured is calculated based on a predetermined relational expression by a processing device using the frequency data of the standing wave obtained by generating the howling and the temperature data regarding the obtained tube to be measured. It is constituted as a tube length measuring method characterized by obtaining the thickness.

  Preferably, in the generation of the howling, the signal generator changes and controls the output frequency of the signal to output a sound wave, and the inside of the tube to be measured is in a standing wave generation state to obtain the predetermined frequency data.

Preferably, in the tube length measurement method for connecting the measurement mechanism to the tube to be measured and measuring the length of the tube to be measured using a standing wave,
Obtaining the temperature in the tube to be measured, controlling the frequency of the output signal of the sound wave to emit a sound wave to the tube to be measured, and repeatedly receiving the sound wave to generate howling,
Amplify the received signal, measure the data converted from analog to digital,
While detecting and changing the frequency of the output signal from the signal generator, it is detected whether the standing wave is generated with respect to the measured data,
A tube length characterized in that, when a standing wave is detected, the length of the tube to be measured is calculated based on a predetermined relational expression by the processing device using the acquired temperature data in the tube to be measured and the measurement data. Configured as a measurement method.

  According to the present invention, a measuring mechanism is connected to a tube to be measured, and the frequency of a standing wave is measured over time while generating howling in the measuring tube by controlling the frequency of a signal output from a signal generator. In addition, the tube length can be calculated using the peak frequency data of the standing wave and the temperature data related to the tube to be measured. As a result, it is possible to transmit sound waves far away against noise, and to accurately measure the tube length while preventing waveform attenuation.

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a configuration diagram of a tube length measurement system in an embodiment of the present invention.
This measurement system includes a pipe 3 that is a pipe to be measured, a measurement mechanism 1 connected to the pipe 3, and a measurement device 2 that processes a signal obtained from the measurement mechanism 1.

The measurement mechanism 1 includes a measurement tube 12 connected to the pipe 3 and a measurement unit 11. A temperature sensor 105 that measures the temperature in the pipe is disposed inside the measurement pipe 12.
In the measurement unit 11, a speaker 102 that outputs sound waves and a microphone 103 that receives a signal from the speaker 102 are arranged. A signal generator 104 that generates a signal for outputting sound waves is connected to the speaker 102 via a power amplifier 101 that amplifies the signal. The signal generation unit 104 changes the frequency based on a signal from the control unit 21 and generates a sound wave having the changed frequency.

  Here, the speaker 102 and the microphone 103 are paired to constitute a howling generation mechanism. When the signal generator 104 sequentially changes the frequency of the signal, howling occurs at a certain timing. That is, the standing wave can be obtained by changing and controlling the frequency of the signal by the signal generation unit 104 until the standing wave is detected.

  The measuring apparatus 2 mainly includes a control unit 21, a display unit 22, an input unit 23, a signal amplification unit 24, and an A / D conversion unit 25. Here, the control unit 21 may preferably be a personal computer (PC), and includes a CPU 211 that executes a program for calculating the tube length, and a memory 212 that stores the program and various processing data. The calculated tube length data is displayed on the display unit 22. Although not shown, preferably, a storage device such as an HD (hard disk) for storing various data and programs is connected to the control unit 21.

Here, the signal received by the microphone 103 is amplified by the signal amplifier 24, converted from an analog signal to a digital signal by the A / D converter 25, and sent to the controller 2. The sound reception signal of the microphone 103 is also combined with the output of the signal generation unit 104 and sent to the power amplification unit 101, where it is amplified and sent to the speaker 102. The temperature signal y detected by the temperature sensor 105 is also input to the control unit 21. (Hereinafter, the temperature signal y converted into a digital signal is referred to as temperature data.)
The control unit 21 uses the frequency data (acoustic signal) x and temperature data y obtained by performing Fourier transform on the acquired sound reception signal, calculates based on a predetermined relational expression, and a condition for detecting a standing wave Ask for. As a result, if no standing wave is detected, the control signal z is output to the signal generator 104. The signal generator 104 performs change control so as to increase or decrease the frequency of the output signal based on the received control signal z.
Such an operation is repeated until a standing wave is detected when howling occurs. Then, when a standing wave is finally detected, data L (= L ₀ + L ₁ ) is calculated using the frequency data and temperature data obtained therefrom.

Here, the principle of tube length measurement according to the present invention will be described in more detail.
The control unit 21 amplifies the sound reception signal from the microphone 103 by the signal amplification unit 24 and converts the analog signal to the digital signal by the A / D conversion unit 25 to obtain the frequency data x. In order to project this time series signal to the frequency domain, Fourier transform is performed. In the frequency domain subjected to Fourier transform, the control signal z is output until the standing wave is detected, and change control is performed so as to increase or decrease the frequency of the signal of the signal generation unit 104. Further, when the peak frequency of the standing wave is detected, the pipe length is calculated using the temperature data y inside the pipe 3 and the frequency data obtained by digital conversion. This calculation is realized by the CPU 211 executing a predetermined program.

The calculation processing operation in the control unit 21 will be described. The synthesized wave signal converted into a digital signal and Fourier-transformed is projected onto the frequency domain, the peak frequency f (Hz) is selected, and the tube temperature t (° C.). The sound speed c (m / s) is calculated from the calculated value, and the tube length L _n (m), which is the reflection distance, is calculated from the calculated value using the relational expression (L _n = c / 2f).
As an example, the tube temperature t (° C.) is measured to calculate the sound velocity c (m / s), the peak frequency f (Hz) is selected from a plurality of measured data, and the tube length L _n (m) is calculated. Ask.

When the sound velocity c (m / s) is the tube temperature t (° C.), the relational expression is
c = 331.5 + 0.61t (1)
When the tube internal temperature t (° C.) is 20 degrees, the sound velocity c (m / s) is expressed by the relational expression (1) as follows:
c = 331.5 + 0.61 × 20 = 343.7 (m / s) (2)
It becomes.

Next, if the measured value of the standing wave peak frequency f (Hz) is f = 52.08 (Hz), from the measured value and the result of (2),
L _n = c / 2f = 343.7 ÷ 2 × 52.08) ≈3.3 (m) (3)
Thus, the tube length L _n (m) is obtained.

The value obtained here is a value including the coupling portion length L ₀ (m) for coupling the pipe 3 to the measuring pipe 12 and measuring.
In this case, the relational expression between the coupling part length L ₀ (m) and the desired tube length L ₁ (m) is
L _n = L ₀ + L ₁ (4)
Assuming that the coupling portion length L ₀ (m) is set to 0.3 (m), the pipe length L ₁ (m) of the pipe 3 from the relational expression (4) is
_{L 1 = L n -L 0 =} 3.3-0.3 = 3.0 (m)
Can be calculated as

As described above, in the tube length measurement system according to the present embodiment, by changing and controlling the frequency of the signal of the signal generation unit 104, the point where the spectrum peculiar to the standing wave is obtained is determined by the speaker 102 and the microphone in the measurement unit 11. 103 can be measured over time.
In the measurement of the tube length, the signal generator 104 controls the change of the frequency of the signal when the spectrum specific to the standing wave is obtained by repeating the measurement with time and the Fourier transform process by the processing of the control unit 21. To stop.

At that time, the CPU 211 of the control unit 21 executes tube length measurement calculation based on the temperature data from the temperature sensor 105 in the pipe and the measured frequency, and displays the result on the display unit 22.
Note that displaying the calculation result on the display unit 22 is not an essential function. For example, the calculation result of the tube length may be stored in the database or the memory 212, and later transferred to another computer, displayed on another display device, or printed out as necessary.

Next, the tube length calculation process will be described with reference to FIG.
This calculation process is realized mainly by the CPU 211 executing a predetermined program. That is, according to the calculation processing of the program in the CPU 211, the signal generator 104 controls the change of the signal frequency, detects and determines the standing wave, calculates the tube length, and finally displays the processing result on the display unit 22. Execute the process. This will be described in detail below.

  First, the measuring tube 12 having the measuring unit 11 is connected to the piping 3 and the measuring device 2 is turned on (S2011). When the signal generator 104 generates a signal for outputting a sound wave, the power amplifier 101 receives the signal and amplifies the power. Then, a howling phenomenon occurs between the speaker 102 and the microphone 103 (S2012). Here, it is assumed that the speaker 102 and the microphone 103 are mounted in advance at a position where a howling phenomenon occurs, and measurement starts from this state.

  Thereafter, the processing operation by the CPU 211 of the control unit 21 is performed. In step S201, a sound wave signal is obtained from the microphone 103 while generating a howling phenomenon. The sound wave signal is amplified by the signal amplifier 24 and converted from analog to digital by the A / D converter 25 (S2021). In order to project this signal to the frequency domain, Fourier transform is performed (S2022). The detection of the standing wave in the frequency domain is monitored over time, and the signal frequency of the signal generator 104 is changed and controlled from the output of the position adjustment signal (S2023).

  Then, it is determined whether the peak frequency of the standing wave has been detected (S2024). If it is detected, the tube length is calculated based on the temperature data obtained from the temperature sensor 105 in the pipe 3 and the maximum peak frequency data obtained from the standing wave detection (S2032). Finally, the calculation result is displayed on the display unit 22 (S2033).

Here, in the process of step S203, the peak frequency f (Hz) is selected, the sound velocity c (m / s) is calculated from the tube temperature t (° C.), and the tube length L _n (m) which is the reflection distance therefrom. Is calculated using the relational expression (L _n = c / 2f).
For example, the pipe length L ₁ (m) of the pipe 3 is calculated using the above formulas (1) to (4).

FIG. 3 is a schematic diagram of the spectrum level in the frequency domain in standing wave generation.
In the measurement of the pipe length according to this example, the pipe length is calculated based on the temperature data inside the pipe and the peak frequency when the standing wave waveform is detected (a high peak waveform is observed only at a certain frequency).
In the measurement of the tube length according to the present embodiment, the standing wave in a state where howling is generated is the high peak waveform at a certain level or higher in the spectrum (A) before the generation in the frequency region from the low frequency to the high frequency. It can be seen that is not detected.
On the other hand, in the spectrum (B) when the standing wave is generated, it can be seen that a sharp high peak waveform is observed at a specific frequency.

As mentioned above, although one Example of this invention was described, this invention is not limited to the said Example, It can implement in various deformation | transformation.
For example, the temperature sensor 105 that measures the temperature in the pipe is not necessarily limited to being arranged in the measurement pipe 12 of FIG. The temperature sensor 105 may be inserted into the pipe 3 and disposed at an appropriate location. As another example, temperature data separately measured as the temperature in the pipe 3 may be used. In addition, when the temperature in the pipe is known in advance, the temperature data may be used.

  As another example, the signal generation unit 104 is shown to be outside the measurement unit 11 in FIG. 1, but the signal generation unit 104 may be provided in the measurement unit 11. In short, it is important that the signal generation unit 104 can change and control the frequency of the generated signal until a standing wave is detected, and the present invention is not limited to the above embodiment as long as the function or means can be realized.

The block diagram of the pipe length measurement system in one Example, Process flowchart showing tube length measurement in one embodiment, Schematic of the spectrum level in the frequency domain in standing wave generation.

Explanation of symbols

1: measurement mechanism, 2: measurement device, 3 piping, 11: measurement unit, 12: measurement tube, 101: power amplifier, 102: speaker, 103: microphone, 104: signal generation unit, 105: temperature sensor, 21: control Unit 22: display unit 23: input unit 24: signal amplification unit 25: A / D conversion unit 211: CPU 212: memory

Claims (9)

In a tube length measurement system for connecting a measurement mechanism to a tube to be measured and measuring the length of the tube to be measured using a standing wave,
A signal generator for controlling the frequency of a signal for outputting a sound wave;
A howling generation mechanism that receives the output sound wave and generates a howling phenomenon;
A measuring device for calculating the length of the tube to be measured based on a predetermined relational expression using frequency data of a standing wave obtained by generating howling by the howling generation mechanism and temperature data about the tube to be measured And a tube length measuring system comprising: The howling generation mechanism includes a howling generation unit that is disposed in the measurement mechanism and generates a howling by a pair of a sound wave output unit that outputs a sound wave and a sound reception unit that receives the output sound wave. ,
The signal generator is connected to a power amplifier for continuing howling with the received signal, and controls the signal frequency of the signal generator until the measuring device detects the frequency of the standing wave. The tube length measuring system according to claim 1, wherein: The measurement apparatus includes a signal amplification unit that amplifies a signal received by the howling generation mechanism, an A / D conversion unit that converts the signal amplified by the signal amplification unit from analog to digital, and the A / D conversion. And a calculation means for calculating the length of the tube to be measured using the frequency data of the standing wave obtained by Fourier transforming the signal obtained from the section and the temperature data,
3. The tube length measurement system according to claim 1, wherein the output frequency of the signal of the signal generator is controlled according to the calculation by the calculation means. A temperature sensor for detecting the temperature inside the tube to be measured;
4. The measuring apparatus according to claim 1, wherein the measuring device calculates the length of the pipe to be measured based on a predetermined relational expression using temperature data about the pipe to be measured detected by the temperature sensor. Either tube length measurement system. The calculation means Fourier-transforms the time series signal obtained by the conversion by the A / D conversion unit and projects it to the frequency domain, selects the peak frequency f (Hz), and selects the temperature t ( The sound velocity c (m / s) is calculated from the temperature (° C.), and the tube length L _n (m), which is the reflection distance, is calculated using the relational expression (L _n = c / 2f). The tube length measurement system according to claim 3 or claim 4. In the tube length measurement method that measures the length of the tube to be measured using standing waves,
For the tube to be measured, output the sound wave by controlling the frequency of the signal to output the sound wave,
Receiving the output sound wave to generate howling,
The length of the tube to be measured is calculated based on a predetermined relational expression by a processing device using the frequency data of the standing wave obtained by generating the howling and the temperature data regarding the obtained tube to be measured. A method for measuring the length of a tube, wherein the length is obtained. In the howling generation, the signal generation unit changes and controls the output frequency of the signal to output a sound wave, and the predetermined frequency data is obtained by setting the inside of the tube to be measured to a standing wave generation state. Item 6. The pipe length measuring method according to item 6. In a tube length measurement method for connecting a measurement mechanism to a tube to be measured and measuring the length of the tube to be measured using a standing wave,
Get the temperature inside the tube to be measured,
Controlling the frequency of the output signal of the sound wave to emit a sound wave to the tube to be measured, and repeatedly receiving the sound wave to generate howling,
Amplify the received signal, measure the data converted from analog to digital,
While detecting and changing the frequency of the output signal from the signal generator, it is detected whether the standing wave is generated with respect to the measured data,
A tube length characterized in that, when a standing wave is detected, the length of the tube to be measured is calculated based on a predetermined relational expression by the processing device using the acquired temperature data in the tube to be measured and the measurement data. Measuring method. In the calculation by the processing device, the time-series signal obtained by converting the received signal from analog to digital is Fourier-transformed and projected to the frequency domain, the peak frequency f (Hz) is selected, and the measured pipe The sound speed c (m / s) is calculated from the temperature t (° C.), and the tube length L _n (m), which is the reflection distance, is calculated using the relational expression (L _n = c / 2f). The tube length measuring method according to any one of claims 6 to 8.

Images