JP5733029B2 - Inspection device and inspection method for underwater transmitter - Google Patents

Description

  The present invention relates to an inspection apparatus and an inspection method for an underwater transmitter that transmits sound waves in water.

  In general, in order to measure the acoustic performance of underwater transmitters that transmit sound waves such as ultrasonic waves into the water, a wide water field, underwater or a dedicated test water tank facility for acoustic testing, is used, and the receiving sensitivity performance is An obvious standard receiver is used.

  The underwater transmitter and the standard receiver are arranged to face each other at a predetermined distance in water, and the standard wave receiver receives the sound wave emitted from the underwater transmitter. The acoustic performance of the underwater transmitter is obtained by analyzing the received signal. In general, measurement is performed using a test water tank facility having a deep water depth and a small fluctuation in water flow and water temperature so that the water pressure characteristic of impedance is stabilized.

  FIG. 10 is a block diagram of the measuring apparatus 100 used when measuring the acoustic performance of the underwater transmitter. The measuring apparatus 100 includes an oscillator 101, a power amplifier 102, a standard receiver 111, a preamplifier 112, a band filter 113, and an oscilloscope 114. The underwater transmitter 103 and the standard receiver 111 are installed in a large test water tank, and the standard receiver 111 receives sound waves from the underwater transmitter 103.

  With such a configuration, a sine wave inspection signal having a predetermined frequency is output from the oscillator 101, and this inspection signal is amplified by the power amplifier 102 and output to the underwater transmitter 103. The underwater transmitter 103 radiates sound waves having a frequency corresponding to the power-amplified inspection signal into water.

  The sound wave radiated into the water is received by the standard receiver 111 separated by a distance W. Since the sound wave has a predetermined sound speed, it is received with a delay corresponding to the distance W.

  The signal received by the standard receiver 111 is amplified by the preamplifier 112 and input to the oscilloscope 114, and the oscilloscope 114 performs waveform observation and the like.

  The measurement results obtained by these measuring devices 100 are calculated as the wave transmission sensitivity of the underwater wave transmitter 103 based on the following formula 1.

Sv = Vout−Vin−Mv−PG + 20 log (W) (1)
here,
Sv: Transmission sensitivity [dB re 1 μPa / V; W = 1 m]
Vout: Standard receiver output voltage [dB]
Vin: Underwater transmitter input voltage [dB]
Mv: Received voltage sensitivity of standard receiver [dB]
PG: Preamplifier gain [dB]
W: Distance between transmitter and receiver [m]
It is.

  Such a transmission sensitivity inspection method for an underwater transmitter is disclosed, for example, in JP-A-8-79898. In JP-A-8-79898, an unknown sensitivity transducer and a known sensitivity reference underwater transducer are combined and suspended in water at a predetermined distance to test the unknown sensitivity transducer. Is the method.

Japanese Patent Laid-Open No. 8-79898

  However, in the inspection method as described above, it is necessary to install not only the underwater transmitter but also the standard receiver in the water. In particular, since it is necessary to install the underwater transmitter and the standard receiver so as to maintain a predetermined distance in water, a lot of work time is required. The reason why these are installed so as to maintain a predetermined distance in the water is that the sound wave radiated from the underwater transmitter is input to the standard receiver through a member other than water (reflected, etc.). It is for preventing.

  Accordingly, a main object of the present invention is to provide an underwater transmitter inspection device and a water inspection method capable of measuring performance of an underwater transmitter easily and with high accuracy.

  In order to solve the above-described problems, an invention relating to an underwater transmitter inspection device includes an oscillator that generates a predetermined inspection signal, a power amplifier that amplifies the inspection signal to drive the underwater transmitter, and a predetermined amount from the water surface. And a vibration measuring device that is installed in the atmosphere at a height of 5 mm and measures the vibration amplitude of the acoustic radiation surface of the driven underwater transmitter.

  Further, the invention relating to the inspection method of the underwater transmitter includes a driving procedure for driving the underwater transmitter installed in the water, and radiating detection light from the atmosphere to the water, so that the acoustic radiation in the underwater transmitter is emitted. A measurement procedure for measuring the vibration amplitude of the surface.

  Since the vibration measuring device is installed in the atmosphere, the performance of the underwater transmitter can be measured easily and with high accuracy.

1 is a block diagram of an inspection apparatus according to a first embodiment of the present invention. It is a flowchart which shows the test | inspection procedure using the test | inspection apparatus concerning 1st Embodiment. It is a figure which shows the vibration state in the piezoelectric type underwater transmitter driven by the test | inspection apparatus concerning 1st Embodiment, (a) is the state which swelled, (b) is a figure which shows the contracted state. It is a figure which shows a mode that several points | pieces are measured with the test | inspection apparatus concerning 1st Embodiment. The transmission sensitivity (solid curve) with respect to the frequency of the inspection signal measured using the inspection apparatus according to the first embodiment and the transmission sensitivity (dotted curve) with respect to the frequency of the inspection signal measured by a known inspection method. It is the figure compared. It is a figure which shows a mode that the point with the largest amplitude is measured by the test | inspection apparatus concerning the 2nd Embodiment of this invention. It is the figure which compared the transmission sensitivity (solid curve) obtained by the inspection method concerning a 2nd embodiment, and the transmission sensitivity (dotted curve) obtained by measuring by a publicly known method. It is a graph which shows the example of the measured value with respect to the measurement depth concerning the 3rd Embodiment of this invention, (a) is a case where a measured value is a vibration speed, (b) is a case where a measured value is a resonant frequency. It is a block diagram of the inspection apparatus concerning the 3rd Embodiment of this invention. It is a block diagram of the measuring device concerning related technology.

<First Embodiment>
A first embodiment of the present invention will be described. FIG. 1 is a block diagram of an underwater transmitter inspection apparatus 2A according to a first embodiment of the present invention.

  The inspection apparatus 2A includes an oscillator 11 that generates an inspection signal having a predetermined frequency, a power amplifier 12 that amplifies the inspection signal, and a vibration measurement apparatus 13 that measures the vibration amplitude of the acoustic radiation surface of the underwater transmitter 5 using infrared rays or the like. I have. The underwater transmitter 5 is installed in a water tank 21 filled with water 22, and a test signal is input to the underwater transmitter 5 from the power amplifier 12. The water depth of the underwater transmitter 5 is set to a preset water depth D1, and the height of the vibration measuring device 13 from the water surface is set to a preset height D2.

  Hereinafter, a case where a test signal such as a sine wave is generated from the oscillator 11 will be described, but the present invention is not limited to a sine wave as the test signal.

  In this embodiment, a bent disk type omnidirectional underwater wave transmitter using a piezoelectric vibrator is described as an example of the underwater wave transmitter 5, but the underwater wave transmitter 5 is not limited to such a wave transmitter. .

  The operation of the underwater transmitter inspection apparatus 2A having such a configuration will be described with reference to the flowchart of FIG. First, a continuous sinusoidal inspection signal is output from the oscillator 11 (step S1), and power is amplified by the power amplifier 12 (step S2). The amplified inspection signal is input to the underwater transmitter 5 (step S3), thereby causing the underwater transmitter 5 to continuously vibrate and radiating sound waves into the water (step S4).

  FIG. 3 is a diagram showing a vibration state of the underwater transmitter 5. FIG. 3A shows a state in which the underwater transmitter 5 is swollen by the inspection signal, and FIG. 3B shows a contracted state. Such vibration becomes a sound wave and is radiated into the water. Note that the underwater transmitter 5 uses a piezoelectric vibrator, and the radiated sound wave is an ultrasonic wave.

  The sound pressure P of the sound wave radiated into the water is given by Equation 2 below.

P = ρfU / 2d (2)
here,
ρ: density of acoustic medium f: frequency U: volume velocity d: distance from sound source to receiving point.

  Sound waves with this sound pressure are radiated into the water. That is, when radiating sound waves into water, the vibrating acoustic radiation surface vibrates water, which is an acoustic medium, and the greater the amplitude, the greater the sound pressure. Since the volume velocity U can be calculated from the acoustic radiation area and its vibration velocity, the sound pressure is obtained by measuring the amplitude over the entire acoustic radiation surface with the vibration measuring device 13. And by measuring this vibration amplitude, the transmission sensitivity can be converted (steps S5 and S6).

  In order to obtain a more accurate transmission sensitivity, it is desirable to measure the amplitude distribution of the entire acoustic radiation surface (step S7). FIG. 4 shows how to measure at a large number of measurement points in order to measure the vibration distribution. In FIG. 4, the code | symbol P has shown the measurement point. Reference numeral 5a denotes an acoustic radiation surface.

  Since the vibration amplitude at this time has a frequency characteristic corresponding to the underwater impedance characteristic of the underwater transmitter 5, the frequency characteristic of the transmission sensitivity can be obtained by measuring the amplitude for each frequency.

  Based on these conditions, in the present embodiment, an optical non-contact vibrometer with high measurement accuracy is used as the vibration measurement device 13 among the displacement sensors. This optical non-contact vibrometer irradiates the acoustic radiation surface of the underwater transmitter 5 with a laser (detection light), and includes physical information (for example, the reflected light reflected by the acoustic radiation surface 5a (for example, Measure the amplitude etc. using the Doppler effect, delay time).

  FIG. 5 compares the transmission sensitivity (dotted curve) obtained by measurement with a known inspection method and the transmission sensitivity (solid curve) obtained using the inspection apparatus 2A according to the present embodiment. It is the result. As inspection conditions, the same underwater transmitter is installed at the same water depth, and the frequency within a predetermined range (± 0.1 [kHz] and ± 0.2 [kHz] with respect to the frequency f [kHz]). A sound wave is generated by the inspection signal of (frequency).

  Thereby, it can be seen that the difference between the inspection results obtained by the two inspection methods is very small. Therefore, the inspection method according to the present invention can obtain a measurement result equivalent to a known inspection method.

  On the other hand, regarding the measurement time, the inspection method according to the present invention was able to be performed in about 1/5 of the time compared with the known inspection method.

From the above, it was proved that the inspection method according to the present invention can be inspected with a small number of inspection steps without causing a decrease in measurement accuracy.
<Second Embodiment>
Next, a second embodiment of the present invention will be described. In addition, about the same structure as 1st Embodiment, description is abbreviate | omitted suitably using the same code | symbol.

  In the first embodiment, measurement accuracy is improved by measuring the amplitude of the entire acoustic radiation surface of the underwater transmitter. However, increasing the number of measurement points increases measurement time and analysis time. In addition, the number of measurement points and the measurement accuracy do not show a linear proportional relationship, and the measurement accuracy asymptotically approaches a certain value (true value) with respect to the number of measurement points. Here, the true value means a true value that does not include a measurement error.

  There is a required range (required accuracy) for measurement accuracy. Therefore, there is no need to measure meaninglessly with high accuracy. Assuming that this required accuracy is the accuracy by a conventionally used inspection method, it can be said that the result shown in FIG. 5 of the first embodiment is an inspection method that satisfies the required accuracy. Limiting the number of measurements to satisfy the required accuracy leads to a reduction in useless measurement man-hours.

  From such a viewpoint, in this embodiment, as shown in FIG. 6, only one point is measured at the center of the acoustic radiation surface 5a where the amplitude is maximum. FIG. 6 shows the measurement point P, and the alternate long and short dash line shows the vibration of the acoustic radiation surface 5a approximated to a triangle (vibration amplitude approximate distribution) with the position of the maximum amplitude (position of the measurement point P) as a vertex.

  FIG. 7 compares the transmission sensitivity (solid curve) obtained by such one-point measurement with the transmission sensitivity (dotted curve) obtained by a known method. FIG.

  As can be seen from FIG. 7, the transmission sensitivity obtained by measuring one point shows a very good agreement with the transmission sensitivity obtained by using a known method. The time required to acquire the transmission sensitivity by the method according to the present embodiment was about 1/20 of that in the known method.

This means that if the measurement method according to the present embodiment is applied to one point with the maximum amplitude, the measurement man-hour can be greatly shortened while preventing a decrease in measurement accuracy. Therefore, the measurement work efficiency is improved.
<Third Embodiment>
Next, a third embodiment of the present invention will be described. In addition, about the same structure as 1st Embodiment, description is abbreviate | omitted suitably using the same code | symbol.

  Since the impedance characteristic of the underwater transmitter changes depending on the acoustic load, the vibration speed and resonance frequency of the acoustic radiation surface change according to the water depth where the underwater transmitter is installed. For this reason, conventionally, measurement is performed by installing an underwater transmitter at a water depth of several meters or more where the impedance characteristics are stable.

  FIG. 8 is a graph showing changes in the vibration velocity (FIG. 8A) and the resonance frequency (FIG. 8B) with respect to the measured depth. Both the vibration speed and the resonance frequency show larger values as the measurement depth becomes shallower, and it is understood that it is difficult to obtain an accurate transmission sensitivity.

  However, when setting an underwater transmitter in a deep water place, it is a matter of course that a large ultrasonic test water tank facility is required. Therefore, in the present embodiment, characteristics such as transmission sensitivity are obtained by a simpler inspection method than the conventional inspection method without requiring a large ultrasonic testing water tank facility and without reducing measurement accuracy. To be able to. As a specific method for this purpose, in the present embodiment, correction data is acquired in advance, and measurement data is corrected based on the correction data.

  As shown in FIG. 8, since the vibration speed and the resonance frequency change according to the water depth, these characteristics are measured in advance with respect to the water depth, and the vibration measuring device 13 is provided in the form of an approximate expression or a data table, for example. Remember.

  An example of correction will be described with reference to FIG. In FIG. 8A, it is assumed that the underwater transmitter is set at the depth D3, the measured value is m1, and the true value to be obtained is m2. The true value referred to here is a value with a deep depth and no change in impedance characteristics or a value in which a change in impedance characteristics or the like can be substantially ignored. On the other hand, when the underwater transmitter is set to the depth D3 from the correction data, it is understood that the measured value of M1 is measured due to a change in impedance characteristics or the like even if the true value is M2. Therefore, the true value m2 is calculated as m2 = m1 * (M2 / M1) using a proportional distribution method. M2 / M1 is a correction coefficient corresponding to the depth.

  By performing such correction, it is possible to obtain transmission sensitivity and the like while suppressing a decrease in measurement accuracy even in a small water tank 21 that can be installed indoors.

Also, if the correction data is applied up to a depth of several hundred meters, for example, this underwater transmitter is located at a deep depth by using the measured value of the underwater transmitter obtained at a shallow depth. Can be calculated. Therefore, it is possible to perform measurement with a simple and wide application range.
<Fourth Embodiment>
Next, a fourth embodiment of the present invention will be described. In addition, about the same structure as 1st Embodiment, description is abbreviate | omitted suitably using the same code | symbol.

  In each of the embodiments so far, the number of underwater transmitters to be measured is one. However, there may be times when you want to evaluate multiple underwater transmitters. In such a case, if the installation and replacement work is performed for each underwater transmitter, measurement efficiency deteriorates.

  Therefore, in the present embodiment, a plurality of underwater transmitters are installed at the same time, and can be measured individually while scanning the vibration measuring device.

  FIG. 9 is a block diagram of such an underwater transmitter inspection device 2B. The inspection signal generated by the oscillator 11 is amplified by the power amplifier and input to the plurality of underwater transmitters 5a to 5n installed at the position of the water depth D1. Thereby, each underwater transmitter 5a-5n radiates | emits a sound wave.

  Therefore, the vibration measuring device 13 is scanned by the scanning device 16. When the vibration measuring device 13 is positioned directly above one underwater transmitter 5, the vibration measuring device 13 performs measurement by irradiating the acoustic radiation surface of the underwater transmitter 5 with laser light. . Thereafter, the scanning device 16 performs measurement by moving the vibration measuring device 13 to a position directly above the next underwater transmitter. Such movement and measurement of the vibration measuring device 13 are repeated by the number corresponding to each of the underwater transmitters 5a to 5n.

  As a result, the transmission sensitivity of a plurality of underwater transmitters can be acquired continuously, and the number of measurement steps can be greatly reduced.

  In addition, this invention is not limited to each embodiment demonstrated until now, It can change suitably according to the system and shape of a submerged transmitter, and the intended purpose.

2A, 2B Inspection device 5, 5a-5n Underwater transmitter 11 Oscillator 12 Power amplifier 13 Vibration measuring device 16 Scanning device 21 Water tank

Claims (8)

An inspection device that measures the transmission sensitivity of an underwater transmitter,
An oscillator for generating a predetermined inspection signal;
A power amplifier that amplifies the inspection signal and drives the underwater transmitter;
A vibration measuring device that is installed in the atmosphere at a predetermined height from the water surface and measures the vibration amplitude of the acoustic radiation surface in the driven underwater transmitter; and
The vibration measurement device prestores correction data corresponding to the water depth of said water wave transmitter is installed, the inspection device of the underwater transmitters characterized that you correct the measurement value based on the correction data . An inspection apparatus for an underwater transmitter according to claim 1,
When measuring the vibration amplitude of an acoustic radiation surface by the vibration measuring device, a plurality of points on the acoustic radiation surface are measured. An inspection apparatus for an underwater transmitter according to claim 1,
When measuring the vibration amplitude of an acoustic radiation surface by the vibration measuring device, one point having the largest amplitude among the acoustic radiation surfaces is measured. An inspection device for an underwater transmitter according to any one of claims 1 to 3 ,
A scanning device for moving the vibration measuring device parallel to the water surface;
The power amplifier outputs inspection signals to the plurality of submersible transmitters;
An inspection apparatus for an underwater transmitter, wherein the scanning device moves the vibration measuring device to sequentially measure the vibration amplitude of an acoustic radiation surface in the underwater transmitter. An inspection method for measuring the transmission sensitivity of an underwater transmitter,
A driving procedure for driving an underwater transmitter installed in the water;
Measuring procedure for irradiating detection light into the water from the atmosphere and measuring the vibration amplitude of the acoustic radiation surface in the underwater transmitter;
A procedure for storing correction data corresponding to the water depth in which the underwater transmitter is installed;
And a procedure for correcting the measurement value based on the correction data .
An inspection method for an underwater transmitter according to claim 5 ,
The measuring procedure for measuring the vibration amplitude of the acoustic radiation surface in the underwater transmitter includes a procedure for measuring a plurality of points on the acoustic radiation surface. An inspection method for an underwater transmitter according to claim 5 ,
The measuring procedure for measuring the vibration amplitude of the acoustic radiation surface in the underwater transmitter includes a procedure for measuring one point having the largest amplitude in the acoustic radiation surface. . An inspection method for an underwater transmitter according to any one of claims 5 to 7 ,
A procedure for outputting inspection signals to a plurality of the underwater transmitters and emitting sound waves for each of the underwater transmitters;
A procedure for moving the vibration measuring device so that the vibration amplitude of the acoustic radiation surface in the underwater transmitter can be measured;
And a procedure for measuring the vibration amplitude of the acoustic radiation surface by the vibration measuring device.

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