JP2009042142A - 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 movable mechanism section 11 and a measuring pipe 12 is connected to a pipe 3, a sound reception signal sent from a microphone 103 arranged so that howling occurs in a measuring pipe is received from a speaker 102. Until sound waves of a large amplitude by the speaker 102 and microphone 103 occur in the pipe 3, a driving section 104 is controlled, and a stationary wave spectrum is detected, they are simultaneously adjusted while the interval between the speaker 102 and microphone 103 is kept constant. Using temperature data about the pipe and peak frequency of stationary wave, the pipe length is calculated by a control section 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 measurement system and a measurement method therefor, and in particular, calculates a length of a pipe using a frequency obtained by generating a standing wave with respect to an embedded pipe and obtaining a Fourier transform. The present invention relates to a pipe 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 a tube length measurement system for measuring the length of a tube to be measured using a standing wave, in a measurement mechanism connected to the tube to be measured, and outputs a sound wave, Howling generating means for receiving the output sound wave to generate howling, temperature acquiring means for acquiring a temperature related to the inside of the tube to be measured, and frequency data of standing wave obtained by generating howling by the howling generating means And a measuring device for calculating the length of the tube to be measured based on a predetermined relational expression using the temperature data obtained from the temperature acquisition means.

In a preferred example, the howling generation means 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. Drive means that moves the position of the howling generator in a predetermined direction until the measuring device detects the frequency of the standing wave, and amplifies the power to output the received sound wave again A power amplifying unit.
Preferably, the measurement apparatus includes a signal amplification unit that amplifies the signal received by the howling generation unit, and an A / D conversion unit that converts the signal amplified by the signal amplification unit from analog to digital. And calculating means for calculating the length of the tube to be measured using the frequency data of the standing wave obtained from the A / D converter and the temperature data.
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 a tube length measurement method for measuring the length of a tube to be measured using a standing wave, the step of connecting a measurement mechanism having a measurement tube to the tube to be measured, and the device to be measured Outputting a sound wave to the tube, receiving the output sound wave to generate howling, obtaining a temperature related to the inside of the tube to be measured, and a standing wave obtained by generating the howling And a step of calculating the length of the tube to be measured based on a predetermined formula using a processing device using the obtained frequency data and the obtained temperature data.

  In a preferred example, in a tube length measurement method for measuring the length of a tube to be measured using a standing wave, the tube to be measured and the measurement tube are coupled, and a sound wave is output into the measurement tube to The sound is received and amplified, and the sound wave is output again to generate howling. The sound is received and amplified, and data is collected from a plurality of signals obtained by converting from analog to digital. Control how to change the position of the howling generator until a wave is generated, and convert the measurement data collected from analog to digital again to detect the standing wave from the data over time. When a 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 temperature data inside the tube to be measured and the data. Configured as a measurement method.

  According to the present invention, with the measurement tube connected to the tube to be measured, the peak frequency of the standing wave is changed over time while generating howling using the sound wave output unit and the sound reception unit arranged in the measurement tube. It is possible to measure and use the peak frequency data of the standing wave and the temperature data related to the tube to be measured to calculate the tube length. 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 movable mechanism unit 11. A temperature sensor 105 that measures the temperature in the pipe is disposed inside the measurement pipe 12.

  The movable mechanism 11 has an accordion structure at the outer periphery thereof, and is movable by the drive unit 104 in the direction of arrow a. In addition, this movable mechanism part 11 may be called an expansion-contraction joint. Inside the movable mechanism unit 11, a speaker 102 that is connected to the power amplifier 101 and outputs sound waves is disposed. In such a mechanism, the speaker 102 and the microphone 103 are paired and configured as a howling generation unit that keeps them constant at intervals at which a high ring occurs. The bellows structure can be moved in the direction of arrow a by driving the drive unit 104, and the howling generation unit can be moved and adjusted until a 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 power amplifying unit 101, provided to the speaker 102, and input to the signal amplifying unit 24 for amplification. Then, a signal converted from an analog signal to a digital signal by the A / D conversion unit 25 is input to the control unit 21. The controller 21 also receives a temperature signal from the temperature sensor 105.
The control unit 21 performs a Fourier transform on the acquired acoustic signal, and uses the obtained frequency data x and temperature data y to process based on a predetermined relational expression to calculate a condition for detecting a standing wave. When no standing wave is detected, the control signal z is output to the drive unit 104. The drive unit 104 drives the movable mechanism unit 11 to move in the a direction by a predetermined amount according to the received control signal z. Such an operation is repeated until a standing wave is detected. When the standing wave is finally detected, data L (= L ₀ + L ₁ ) calculated from the frequency data and temperature data obtained therefrom. Ask for.

Here, the principle of tube length measurement according to the present invention will be described in more detail.
In a state where the measuring tube 12 is connected to the piping 3, a howling phenomenon occurs in the microphone 103 set in a position where howling is generated in advance when the power is turned on and the speaker 102 connected via the power amplifier 101 outside the measuring tube 12. To generate a large amplitude sound wave.
In the control unit 21, the sound reception signal from the microphone 103 is amplified by the signal amplification unit 24 and converted from an analog signal to a digital signal by the A / D conversion unit 25 to obtain the acoustic signal x. In order to project this time series signal to the frequency domain, Fourier transform is performed. Control signal z is output to control drive unit 104 until a standing wave is detected in the Fourier transformed frequency domain. 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.

Regarding the processing operation in the control unit 21, the composite wave signal converted into a digital signal and inputted is Fourier-transformed and projected to the frequency domain, the peak frequency f (Hz) is selected, and the sound velocity c from the tube temperature t (° C.) is selected. (M / s) is calculated, and the tube length L _n (m), which is the reflection distance, is calculated 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. Look for it.

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 a coupling part length L ₀ (m) for coupling the pipe 3 to the measurement pipe 12 via an expansion joint 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 obtained as

  As described above, the tube length measurement system according to the present embodiment controls the driving unit 104 so that the point where the spectrum peculiar to the standing wave is obtained can be adjusted between the speaker 102 and the microphone 103 in the movable mechanism unit 11 that can be expanded and contracted. While keeping the interval constant, it is possible to measure over time while adjusting these two simultaneously.

In measurement of the tube length, when the measurement tube 12 is viewed from the exterior by the processing of the control unit 21, for example, when measurement is started from a state where the expansion joint (movable mechanism unit 11) of the measurement tube 12 is contracted, measurement over time is performed. And the Fourier transform process are repeated, and the expansion joint moves in the direction of arrow a several centimeters in the direction of arrow a. When the spectrum specific to the standing wave is obtained, the drive unit 104 stops moving the expansion joint. To do. 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 necessarily 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 as necessary.

Next, the tube length calculation process will be described with reference to FIG.
This calculation process is realized mainly by executing a predetermined program in the CPU 211, and the execution result is controlled by the drive unit 104, standing wave detection judgment and tube length calculation, and display to the display unit 22. With display.
When the measuring tube 12 having the movable mechanism 11 is coupled to the piping 3 and the measuring device 2 is powered on, the speaker 102 that outputs sound waves connected to the power amplifier 101 and the signal from the speaker 102 are received. The microphone 103 adjusts these two at the same time while keeping the distance between them constant to generate a howling phenomenon (S201).

  From here, it becomes processing operation by CPU211 of the control part 21. FIG. In step S201, the speaker 102 and the microphone 103 are mounted in advance at a position where the howling phenomenon occurs, and at that time, the measurement is started from the state where the expansion joint of the measurement tube 12 is contracted. While generating a howling phenomenon in step S201, the sound wave from the microphone 103 is amplified, converted from analog to digital, and Fourier-transformed to project this signal to the frequency domain. The detection of the standing wave in the frequency domain is monitored over time, and the drive unit 104 is controlled from the output of the position adjustment signal (S202).

When the peak frequency of the standing wave is detected, the tube length is calculated based on the temperature data from the temperature sensor 105 in the pipe 3 and conversion from analog to digital, and the frequency data obtained from the standing wave detection. And the calculation result is displayed on the display unit 22 (S203).
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, is related thereto. The calculation is performed using the formula (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 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 place. 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 drive unit 104 is shown to be outside the movable mechanism unit 11 in FIG. 1, but the drive unit 104 may be provided in the movable drive unit 11. In short, it is important for the drive unit 104 to be able to move and adjust these two at the same time while keeping the distance between the speaker 102 and the microphone 103 constant until a standing wave is detected. It is not limited to the above embodiment.

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

DESCRIPTION OF SYMBOLS 1: Measuring mechanism 2: Measuring apparatus 3 Piping 11: Movable mechanism part 12: Measuring pipe | tube 101: Power amplifier 102: Speaker 103: Microphone 104: Drive part 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 (8)

In a tube length measurement system that measures the length of a tube to be measured using a standing wave,
A measuring mechanism connected to the tube to be measured, which outputs a sound wave, receives a sound wave that is output, and generates a howling phenomenon, howling generation means,
Temperature acquisition means for acquiring a temperature related to the inside of the tube to be measured;
Frequency data of a standing wave obtained by generating howling by the howling generating means;
A tube length measuring system comprising: a measuring device that calculates the length of a tube to be measured based on a predetermined relational expression using temperature data obtained from the temperature acquisition means. The howling generation means includes a howling generation unit that is disposed in the measurement mechanism and generates a howling with a pair of a sound wave output means that outputs a sound wave and a sound reception means that receives the output sound wave. Driving means for moving the position of the howling generator in a predetermined direction until the measuring device detects the frequency of the standing wave;
A power amplification unit for continuing howling with the received signal;
The tube length measuring system according to claim 1, wherein The measurement apparatus includes a signal amplifying unit that amplifies a signal received by the howling generation unit;
An A / D converter that converts the signal amplified by the signal amplifier from analog to digital;
A standing wave frequency data obtained by Fourier transform of the signal obtained from the A / D converter and a calculation means for calculating the length of the tube to be measured using the temperature data;
3. The pipe length measuring system according to claim 2, wherein the driving means adjusts the means while keeping the distance between the sound wave output means and the sound receiving means constant according to the calculation result by the calculating means. 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 pipe length measuring system according to claim 2 or claim 3. In the tube length measurement method that measures the length of the tube to be measured using standing waves,
Connecting a measuring mechanism having a measuring tube to the tube to be measured;
Outputting sound waves to the tube to be measured and receiving the output sound waves to generate howling;
Obtaining temperature data relating to the inside of the tube to be measured;
And a step of calculating the length of the tube to be measured based on a predetermined relational expression in the processing device using the frequency data of the standing wave obtained by generating the howling and the obtained temperature data. A tube length measuring method characterized by the above. In the generation of the howling, a howling generation unit that is disposed in the measurement mechanism and that outputs a sound wave and a sound receiving unit that receives the output sound wave is kept constant, and the howling is generated. 6. The tube length measuring method according to claim 5, wherein the predetermined frequency data is obtained by moving and controlling the position of the section so as to generate a standing wave inside the tube to be measured. In the tube length measurement method that measures the length of the tube to be measured using standing waves,
The measurement target tube is connected to the measurement tube, and a sound wave is output into the measurement tube, the sound is received and amplified, and howling is generated by outputting the sound wave again, and the sound is received and amplified. Then, data is collected from the signal obtained by converting from analog to digital, and the position of the howling generator is moved and controlled from there until a standing wave is generated, and the standing wave is generated from the collected measurement data. When the data to be detected is selected over time and a standing wave is detected, the temperature data in the tube to be measured and these data are used in the processing device based on a predetermined relational expression. A tube length measuring method characterized by calculating a length of a measuring tube. In the calculation by the processing device, the time series signal obtained by converting from analog to digital is Fourier transformed and projected to the frequency domain, the peak frequency f (Hz) is selected, and the temperature t (° C.) in the tube to be measured. ) Is calculated from the sound velocity c (m / s), and the tube length L _n (m), which is the reflection distance, is calculated therefrom using the relational expression (L _n = c / 2f). Or the pipe length measuring method of Claim 7.

Images