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JP2009147871

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DESCRIPTION JP2009147871
The present invention provides a sound pressure stabilization method and apparatus for an
underwater sound source in which sound pressure is stabilized regardless of long-term use or
change in environmental conditions and there is no unbalance between diaphragms. SOLUTION:
A sound wave sensor 7 for detecting a sound wave outside the enclosure 3 and amplitudes of
signals given to a plurality of actuators 6 when the sound pressure level of the sound wave
detected by the sound wave sensor 7 is different from a predetermined target sound pressure
level The sound pressure adjusting means 11 adjusts the sound pressure of the sound wave
detected by the sound wave sensor 7 to be equal to the predetermined target sound pressure
level. [Selected figure] Figure 1
Method and apparatus for stabilizing sound pressure of underwater sound source
[0001]
The present invention relates to a method and apparatus for stabilizing the sound pressure of an
underwater sound source, in which the sound pressure level is stabilized regardless of long-term
use or change in environmental conditions, and there is no unbalance between the diaphragms.
[0002]
Acoustics can be used in oceans, lakes, rivers, etc. to conduct various academic and technical
surveys.
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1
For example, when sound waves are emitted in water, the sound waves reflected and returned
can be measured to investigate the topography of the bottom of the water and the properties of
the material constituting the bottom of the water.
[0003]
A sound source used for this purpose is called an underwater sound source, and a diaphragm is
attached to the opening of the enclosure, and a hydraulic actuator for vibrating the diaphragm is
provided inside the enclosure to vibrate the diaphragm in water Emits sound waves in the water.
In the case where the frequency of the sound wave is low frequency, in order to excite the
diaphragm at such low frequency in water, hydraulic actuators that reciprocate hydraulically are
used.
[0004]
The underwater sound source of Patent Document 1 is the underwater sound source configured
as described above, which detects the sound pressure of sound waves radiated from the
diaphragm into the water with a hydrophone disposed in the water, and inputs the sound
pressure detection signal and the hydraulic servo circuit By comparing the signal with the signal
and increasing or decreasing the amplitude of the signal supplied to the hydraulic actuator so
that the sound pressure detection signal becomes equal to the input signal, the sound pressure
corresponding to the input signal can be obtained.
[0005]
In the underwater sound source of Patent Document 2, two loudspeakers (diaphragm and
hydraulic actuator) are provided to input a signal common to both loudspeakers in order to make
the output sound wave strong. By detecting an error of the pressure waveform and adjusting a
transfer function for an input signal of one of the speakers using an adaptive algorithm so as to
reduce the error, the sound pressure waveform is matched.
However, when the sound pressures of the two speakers are measured in water, they interfere
with each other. Therefore, the sound pressure is not measured in water, and the acceleration or
displacement of each diaphragm is detected to detect an error.
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2
[0006]
JP-A-8-280088 JP-A-8-280089
[0007]
By the way, in the conventional underwater sound source, in order to vibrate a diaphragm
directly connected to a piston rod of a hydraulic actuator, a hydraulic servo system which feeds
back a displacement of the piston rod is configured.
A diaphragm that generates sound waves is driven by an input signal to a hydraulic servo system.
In such a hydraulic underwater sound source, the temperature of the hydraulic oil changes due
to the degree of heat generation of the hydraulic equipment, the change of the cooling capacity
due to the water temperature, and the like. In addition, even if sound waves are generated under
certain conditions, it is inevitable that the properties of oil such as viscosity and the
characteristics of hydraulic equipment change due to the influence of the ambient temperature in
the enclosure. The sound pressure level changes as a result of the temperature change and
property change of the hydraulic fluid and the characteristic change of the hydraulic equipment.
As these environmental conditions change slowly in time, the sound pressure level also changes
slowly in time.
[0008]
Also, in the conventional underwater sound source, the displacement of the piston rod is fed back
to the servo valve in the hydraulic servo system to vibrate the diaphragm while maintaining the
localization within a limited stroke, but the vibration frequency is several hundred It is difficult to
directly feed back the sound pressure and acceleration to the servo valve because it extends to
Hz, which is beyond the limits of the hydraulic servo system and is difficult. Therefore, the
conventional underwater sound source performs open loop control (control without feedback of
sound pressure) regarding sound. For this reason, it can not be avoided that effects such as
temperature change and property change of the hydraulic oil and characteristic change of the
hydraulic equipment affect the sound pressure level.
[0009]
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For example, the underwater sound source in Patent Document 1 compares the sound pressure
detection signal detected by the hydrophone in water with the input signal to the hydraulic servo
circuit, adjusts the amplitude of the input signal and gives a signal to the hydraulic actuator.
Although acquired, since the relationship between the sound pressure in the water and the input
signal can not be clearly understood, it is unclear whether the sound pressure has actually
reached the target sound pressure. Therefore, when the sound pressure level changes due to the
temperature change or property change of the hydraulic oil as described above, the characteristic
change of the hydraulic equipment, etc., the sound pressure level can not be stabilized to the
originally desired value.
[0010]
However, since an underwater sound source is used as a measuring instrument in academic and
technical surveys, it is desirable that the sound pressure level be stable even when used for a
long time.
[0011]
If the technique of installing the hydrophone in the water near the diaphragm as in the
underwater sound source of Patent Document 1 is applied to the case where two diaphragms are
provided as in Patent Document 2, the number of hydrophones installed and We are troubled
with setting place.
[0012]
In addition, when the sound pressure by the underwater sound source provided with a plurality
of diaphragms is detected by a hydrophone in water, a sound pressure level obtained by
combining the sound waves radiated from the plurality of diaphragms is detected.
Therefore, even if there is a variation in sound pressure level for each diaphragm, it can not be
known.
For example, even if the sound pressure level of a sound wave from one diaphragm is very large
and the sound pressure level of a sound wave from another diaphragm is small, a large sound
pressure level is detected overall. Thus, if the sound pressure level of each diaphragm varies, the
underwater sound source will not be an ideal nondirectional point sound source.
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[0013]
Therefore, an object of the present invention is to solve the above problems and stabilize the
sound pressure regardless of long-term use or change in environmental conditions, and the
sound pressure stabilization method and apparatus for underwater sound source without
imbalance between diaphragms. To provide.
[0014]
In order to achieve the above object, the method of the present invention comprises each
vibration based on an enclosure having a plurality of openings, a plurality of diaphragms closing
each opening, and an input signal from the same signal input device in the enclosure. In an
underwater sound source provided with a plurality of actuators for exciting a plate, when a
sound wave is detected by a sound wave sensor outside the enclosure and the sound pressure
level of the sound wave detected by the sound wave sensor is different from a predetermined
target sound pressure level The amplitudes of the signals given to the plurality of actuators are
increased or decreased to adjust the sound pressure of the sound wave detected by the sound
wave sensor to be equal to the predetermined target sound pressure level.
[0015]
The method of the present invention also excites each diaphragm based on an enclosure having a
plurality of openings, a plurality of diaphragms closing each opening, and an input signal from
the same signal input device in the enclosure. In an underwater sound source provided with a
plurality of actuators, the acceleration of each diaphragm is detected by an acceleration sensor,
and when the acceleration levels of the accelerations detected by the acceleration sensors are
different, the amplitude of the signal given to one or more actuators is determined. The
acceleration level is adjusted so that the acceleration levels detected by the acceleration sensor
become equal to each other by increasing or decreasing.
[0016]
The method of the present invention also excites each diaphragm based on an enclosure having a
plurality of openings, a plurality of diaphragms closing each opening, and an input signal from
the same signal input device in the enclosure. In an underwater sound source including a
plurality of actuators, sound waves due to vibrations of the plurality of diaphragms are detected
by a sound sensor outside the enclosure, and the sound pressure level of the sound waves
detected by the sound sensor is a predetermined target sound pressure level When different, the
amplitudes of the signals given to the plurality of actuators are increased or decreased to adjust
the sound pressure of the sound wave detected by the sound wave sensor to be the same as the
predetermined target sound pressure level. When the acceleration levels detected by each
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acceleration sensor are different from each other, increase or decrease the amplitude of the
signal given to one or more actuators. The acceleration sensor detects that the acceleration levels
detected by the acceleration sensor are equal to each other, the displacement of each diaphragm
is detected by the displacement sensor, and the displacement sensor of the diaphragm is used as
a signal given to the actuator that excites the diaphragm. The sum of the detected displacement
signals is given to the actuator.
[0017]
The apparatus according to the present invention comprises an enclosure having a plurality of
openings, a plurality of diaphragms closing each opening, and a plurality of vibrators vibrating
based on input signals from the same signal input unit in the enclosure. The amplitudes of the
signals given to the plurality of actuators are increased or decreased by changing the amplitudes
of the signals supplied to the plurality of actuators when the sound pressure level of the sound
wave detected by the sound wave sensor is different from the predetermined target sound
pressure level. Sound pressure adjusting means for adjusting the sound pressure of the sound
wave detected by the sound wave sensor to be equal to the predetermined target sound pressure
level.
[0018]
Further, the apparatus according to the present invention excites each diaphragm based on an
enclosure having a plurality of openings, a plurality of diaphragms closing each opening, and an
input signal from the same signal input unit in the enclosure. When the acceleration levels of the
plurality of actuators, the plurality of acceleration sensors for detecting the acceleration of each
diaphragm, and the acceleration levels detected by the respective acceleration sensors are
different from each other, the amplitude of the signal given to one or more actuators is increased
or decreased. And an acceleration adjustment unit configured to adjust the acceleration levels of
the accelerations detected by the sensor to be the same.
[0019]
Further, the apparatus according to the present invention excites each diaphragm based on an
enclosure having a plurality of openings, a plurality of diaphragms closing each opening, and an
input signal from the same signal input unit in the enclosure. A plurality of actuators, an acoustic
wave sensor for detecting an acoustic wave by vibration of the plurality of diaphragms outside
the enclosure, and the plurality of actuators when the sound pressure level of the acoustic wave
detected by the acoustic sensor is different from a predetermined target sound pressure level
Sound pressure adjusting means for adjusting the sound pressure of the sound wave detected by
the sound wave sensor to be the same as the predetermined target sound pressure level by
increasing or decreasing the amplitude of the signal applied to the plurality of When the
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acceleration sensor and the acceleration levels of the accelerations detected by the acceleration
sensors are different from each other, the amplitude of the signal given to one or more actuators
is increased or decreased to Acceleration adjustment means for adjusting the acceleration levels
of the acceleration detected by the degree sensor to be the same, a plurality of displacement
sensors for detecting the displacement of each diaphragm, and a signal to be supplied to an
actuator for exciting the diaphragm And displacement feedback means for adding to the actuator
the signals of displacement detected by the displacement sensor of the plate.
[0020]
The present invention exhibits the following excellent effects.
[0021]
(1) Sound pressure is stabilized regardless of long-term use or changes in environmental
conditions.
[0022]
(2) There is no imbalance between the diaphragms.
[0023]
Hereinafter, an embodiment of the present invention will be described in detail based on the
attached drawings.
[0024]
As shown in FIG. 1, the sound pressure stabilizing device 1 for an underwater sound source
according to the present invention includes an enclosure 3 having a plurality of openings 2, a
plurality of diaphragms 4 closing the openings 2, and an enclosure 3. A plurality of actuators 6
for vibrating the respective diaphragms 4 based on input signals supplied by the same signal
input device 5, and a sound wave sensor 7 for detecting sound waves due to vibrations of the
plurality of diaphragms 4 outside the enclosure 3; A sound pressure level calculator 8 for
calculating a sound pressure level from the sound wave detected by the sound wave sensor 7 and
a sound pressure level comparator for comparing the sound pressure level with a predetermined
target sound pressure level set by the target value setting unit 9 10 When the sound pressure
level and the target sound pressure level are different, the amplitudes of the signals given to the
plurality of actuators 6 are increased or decreased so that the sound pressure of the sound wave
detected by the sound sensor 7 becomes the same as the target sound pressure level Key Sound
pressure adjusting means 11, a plurality of acceleration sensors 12 for detecting the acceleration
04-05-2019
7
of each diaphragm 4, an acceleration level calculator 13 for calculating the acceleration level
from the accelerations detected by each acceleration sensor 12, and the acceleration levels When
the acceleration levels are different from each other, the amplitudes of the signals given to the
one or more actuators 6 are increased or decreased, and the acceleration levels of the
accelerations detected by the acceleration sensors 12 become the same. And the displacement
sensor 16 for detecting the displacement of each diaphragm 4, and the displacement sensor 16
of the diaphragm 4 detects the signal given to the actuator 6 for exciting the diaphragm 4
Displacement feedback means 17 consisting of an adder that sums up displacement signals and
gives them to the actuator 6, and finally the signals given to the actuator 6 To amplify and a
servo amplifier 18.
[0025]
The sound pressure stabilizing device 1 of the underwater sound source in the present
embodiment is provided with two diaphragms 4.
To this end, the enclosure 3 is substantially cylindrical and has openings 2 at both ends.
The diaphragm 4 of each opening 2 is formed to be smaller in diameter than the diameter of the
opening 2 and is held in a freely vibrating and watertight manner by a diaphragm disposed
between the outer periphery of the diaphragm 4 and the inner periphery of the opening 2 ing.
[0026]
The actuator 6 slidably accommodates the piston rod 21 whose one end (fixed end) is fixed to the
inner surface of the diaphragm 4, the piston head 22 attached to the middle of the piston rod 21,
and the piston head 22. The cylinder 23, the servo valve 24 for adjusting operation oil supply
and discharge to the one side chamber and the opposite surface side chamber of the piston head
22 of the cylinder 23, and an operation oil source not shown, the servo amplifier 18 adjusts the
servo valve 24 By doing this, it is possible to give the piston rod 21 motion in the reciprocation
direction, that is, displacement, velocity, and acceleration.
[0027]
The acceleration sensor 12 and the displacement sensor 16 are attached, for example, to the free
end of the piston rod 21 which protrudes through the cylinder 23.
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8
[0028]
The two actuators 6 have the central axis of the enclosure 3 as a common operating axis, and the
central axes of the piston rod 21, the piston head 22 and the cylinder 23 coincide with this
operating axis.
The two actuators 6 are arranged back to back.
That is, one actuator 6 has a piston rod 21 extending from the diaphragm 4 placed at one end of
the enclosure 3 to the opposite end of the enclosure 3 and the other actuator 6 placed at the
opposite end of the enclosure 3 A piston rod 21 extends from the plate 4 towards one end of the
enclosure 3, with the free ends of the piston rod 21 facing one another.
[0029]
This actuator arrangement is such that the two actuators 6 cancel each other's reaction force.
That is, when one of the actuators 6 pushes the diaphragm 4 so as to protrude outward, the
other actuator 6 also pushes the diaphragm 4 so as to protrude outward, and the one actuator 6
dents the diaphragm 4 inward The two actuators 6 can cancel each other's reaction force by
causing the other actuator 6 to move in the opposite direction to draw the diaphragm 4 so as to
be recessed inward.
[0030]
The sound wave sensor 7 is made of, for example, a hydrophone.
The acoustic wave sensor 7 is attached to the outer periphery of the enclosure 3 at the center of
both ends of the enclosure 3.
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[0031]
In the present embodiment, since the two diaphragms 4 are provided, the acceleration adjusting
means 15 is provided only in the path of the signal given to one of the actuators 6 so as to
increase or decrease the amplitude of only the signal given to one of the actuators 6. .
[0032]
Hereinafter, the operation of the sound pressure stabilizing device 1 of the underwater sound
source will be described.
[0033]
Two actuators 6 arranged in the enclosure 3 so as to cancel each other's reaction force excite the
diaphragm 4 by reciprocating the piston rod 21 respectively.
As the diaphragm 4 vibrates, sound waves are emitted into the water.
[0034]
At this time, in each of the actuators 6, the displacement sensor 16 attached to the piston rod 21
detects the displacement of the diaphragm 4.
The displacement signal is added to the signal given to the actuator 6 in the displacement
feedback means 17.
Since both signals have opposite signs, the difference between the signal of displacement and the
signal applied to the actuator 6 is obtained, and the signal of the difference is amplified by the
servo amplifier 18 and applied to the servo valve 24 of the actuator 6.
This constitutes a servo system in which displacement is negatively fed back.
[0035]
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The sound wave radiated into the water is detected by the sound wave sensor 7.
Since the sound wave sensor 7 is disposed at the center of both ends of the enclosure 3, the
synthesized sound wave of the sound waves output from both diaphragms 4 can be detected at
an equal distance from both diaphragms 4.
[0036]
The sound pressure level calculator 8 calculates the sound pressure level from the sound wave
detected by the sound wave sensor 7.
On the other hand, the target value setting unit 9 outputs a predetermined target sound pressure
level set in advance.
The sound pressure level comparator 10 compares the sound pressure level of the sound wave
detected by the sound sensor 7 with the target sound pressure level.
The sound pressure level comparator 10 generates a signal of the difference between the sound
pressure level and the target sound pressure level.
[0037]
The sound pressure adjusting means 11 supplies the actuator 6 with the input signal supplied by
the signal input unit 5, but when there is a difference between the sound pressure level and the
target sound pressure level, the sound pressure adjusting means 11 supplies it to the actuator 6
according to the signal of this difference. Increase or decrease the amplitude of the signal.
Specifically, when the sound pressure level of the sound wave detected by the sound wave sensor
7 is higher than the target sound pressure level, the sound pressure level is lowered by reducing
the amplitude of the signal given to the actuator 6, and the sound wave sensor 7 detects When
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the sound pressure level of the generated sound wave is lower than the target sound pressure
level, the sound pressure level is increased by increasing the amplitude of the signal given to the
actuator 6.
This control corresponds to adjusting the sound pressure level and the target sound pressure
level to be the same.
[0038]
In each of the actuators 6, an acceleration sensor 12 attached to the piston rod 21 detects an
acceleration of the diaphragm 4. The acceleration level calculator 13 calculates an acceleration
level from the detected acceleration of the diaphragm 4. The acceleration levels of the
accelerations of the two diaphragms 4 are compared in the acceleration level comparator 14.
When the acceleration levels are different from each other, a signal of the difference is output to
the acceleration adjusting means 15. The acceleration adjusting means 15 increases or decreases
the amplitude of the signal given to the actuator 6 to adjust so that the acceleration levels of the
accelerations detected by the acceleration sensors 12 become the same. Specifically, when the
acceleration level of the actuator 6 placed in the signal path is higher than the acceleration level
of the other actuator 6, the actuator placed in the signal path is the actuator placed in the signal
path. If the amplitude of the signal given to 6 is reduced and the acceleration level of the actuator
6 placed in the signal path by the acceleration adjusting means 15 is smaller than the
acceleration level of the other actuator 6, the acceleration adjusting means 15 takes the signal
path. The amplitude of the signal given to the placed actuator 6 is increased.
[0039]
According to the present invention, sound pressure is stabilized regardless of long-term use or
environmental condition change. Conventionally, sound pressure could not be stabilized when
environmental conditions change, that is, temperature changes or property changes of hydraulic
fluid, or property changes of hydraulic equipment occur, but in the present invention, the sound
of the detected sound is detected. Since the pressure level and the desired target sound pressure
level are compared, the sound pressure level can be stabilized to the originally desired value.
[0040]
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According to the present invention, the acceleration levels of the two actuators 6 are compared,
and the input signal is differentiated in the direction in which the acceleration difference
disappears. Therefore, the sound pressure levels of the sound waves radiated from the two
diaphragms 4 It can be the same. In this way, when the sound pressure levels of the sound waves
radiated from the two diaphragms 4 are aligned, in combination with the above-described
stabilization of the sound pressure level, a stable and ideal nondirectional point sound source is
realized.
[0041]
The acceleration level and the sound pressure level are in a proportional relationship. The sound
pressure level and acceleration level referred to in the present specification indicate the
magnitude (amplitude) of the sound pressure and the fundamental wave of acceleration when the
diaphragm is driven with a sine wave. In general, sound pressure levels are called in units of dB.
[0042]
It is a control circuit diagram of the sound pressure stabilization device of the underwater sound
source which shows one embodiment of the present invention.
Explanation of sign
[0043]
DESCRIPTION OF SYMBOLS 1 sound pressure stabilization apparatus 2 opening part 3 enclosure
4 diaphragm 5 signal input device 6 actuator 7 sound wave sensor 8 sound pressure level
calculator 9 target value setting device 10 sound pressure level comparator 11 sound pressure
adjustment means 12 acceleration sensor 13 acceleration Level calculator 14 Acceleration level
comparator 15 Acceleration adjustment means 16 Displacement sensor 17 Displacement
feedback means 18 Servo amplifier 21 Piston rod 22 Piston head 23 Cylinder 24 Servo valve
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