JPH08280088A - Underwater sound source controller - Google Patents

Abstract

PURPOSE: To provide an underwater sound source controller for stabilizing sound pressure without being controlled by an environment. CONSTITUTION: In this controller 1 of an underwater sound source for which input signals are inputted to a hydraulic servo circuit, a diaphragm 5 is attached to an actuator 6 driven back and forth by the hydraulic servo circuit and sound waves are emitted underwater by the diaphragm 5, a hydrophone 22 for detecting the sound pressure is disposed underwater and a control circuit 23 for comparing the sound pressure detection signals with the input signals (i) and controlling the drive of the actuator 6 so as to attain the sound pressure corresponding to the input signals (i) is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an underwater sound source using a hydraulic servo, and more particularly to an underwater sound source control device which has a stable sound pressure regardless of the environment.

[0002]

BACKGROUND OF THE INVENTION Acoustics are sometimes used to probe underwater such as oceans, rivers and ponds. In contrast to the fact that light and electromagnetic waves do not reach far in water, sound propagates better in water than in air, making it suitable for remote exploration. In the acoustics, low frequencies below the audible band have been attracting attention in recent years, but a sound source that generates low frequencies with high sound pressure is required to reach a long distance.

The underwater sound source device developed for this purpose inputs an input signal to a hydraulic servo circuit, attaches a diaphragm to an actuator reciprocally driven by the hydraulic servo circuit, and radiates sound waves into the water from the diaphragm. It is a thing. For example, a rigid plate with one surface facing underwater, an enclosure that encloses the opposite side of this rigid plate to allow reciprocating motion of the rigid plate in the direction of water, compressed gas enclosed in the enclosure, and the rigid plate underwater. A first hydraulic chamber for pushing in the direction, a second hydraulic chamber for returning it in the opposite direction, and a servo valve for mutually supplying and discharging hydraulic oil between these first and second hydraulic chambers are provided. The underwater sound source device can reciprocate the rigid plate by supplying and discharging the operating oil. Since the reciprocating motion of the rigid plate can be regarded as low-frequency vibration, the rigid plate is hereinafter referred to as a diaphragm. This enclosure is placed in water and the reciprocating motion of the diaphragm sends sound into the water.

[0004]

By the way, since the underwater sound source device is used in a natural environment, it is affected by various environmental changes. For example, when it is used in a place where the water temperature is low, the temperature of the hydraulic oil decreases, and its viscosity increases. Such a change in the viscosity of the hydraulic fluid affects the operating characteristics of the actuator driven by the hydraulic servo. As a result, the sound pressure of the sound wave radiated into the water from the diaphragm changes.

On the other hand, in underwater exploration, it is necessary to keep the sound pressure stable at the target sound pressure level. If the sound pressure changes and the target sound pressure level cannot be maintained, exploration becomes inaccurate or hinders.

In the conventional sound source device used in the air, the change in environment is small, and such a change in sound pressure does not cause much problem.

Therefore, an object of the present invention is to solve the above problems and to provide an underwater sound source control device in which the sound pressure is stable regardless of the environment.

[0008]

In order to achieve the above-mentioned object, the present invention is to input an input signal to a hydraulic servo circuit, attach a diaphragm to an actuator reciprocally driven by the hydraulic servo circuit, and use the diaphragm. In a control device for an underwater sound source that emits sound waves in water, a hydrophone that detects the sound pressure is placed in water, the sound pressure detection signal and the input signal are compared, and the above-described sound pressure is obtained so as to obtain a target sound pressure. A control circuit for controlling the drive of the actuator is provided.

The input signal is a sine wave, and the control circuit compares the amplitude of the sound pressure detection signal with the amplitude of the input signal,
An input signal whose amplitude is adjusted according to the comparison result may be input to the hydraulic servo circuit.

[0010]

With the above structure, the detected sound pressure is fed back to the drive control of the actuator.
Even if the environment changes, the sound pressure is stably maintained at the target sound pressure level according to the input signal.

If the input signal is a sine wave, the sound pressure detection signal is also a sine wave, so that the target sound pressure level can be obtained by comparing and adjusting the amplitudes.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

As shown in FIG. 1, the underwater sound source device 1
Has a hollow gas chamber 3 incorporated into a submersible housing 2 that is towed or underwater. The gas chamber 3 is formed in a tubular shape, and one side of the gas chamber 3 is open to the outside of the diving housing 2. This opening is covered with the vibration transmitting film 4 made of a flexible thin film. During diving, the vibration transmitting film 4 serves as a boundary with water. A vibration plate 5 is provided in the gas chamber 3 so as to face the vibration transmission film 4.
Therefore, the vibrating plate 5 faces one surface in the water through the vibration transmitting film 4, and the opposite surface side is surrounded by the gas chamber 3. The size of the vibration plate 5 is the same as that of the gas chamber 3.
Is substantially equal to the inner diameter of the diaphragm 5, and the reciprocating motion of the diaphragm 5 in the water direction is allowed by sliding the peripheral portion of the diaphragm 5 along the inner wall of the gas chamber 3. Vibration transmission film 4
A vibration transmitting oil having an acoustic impedance equal to that of water is enclosed between the diaphragm 5 and the diaphragm 5. Also, the gas chamber 3
Is filled with compressed gas, and the internal pressure of the gas chamber 3 is balanced with the water pressure.

The diaphragm 5 is attached to the actuator 6. The actuator 6 supplies and discharges a hydraulic cylinder 7 provided outside the gas chamber 3, a piston 8 that reciprocates in the hydraulic cylinder 7 by hydraulic pressure, a rod 9 integrated with the piston 8, and operating oil. It is composed of a servo valve 10. The rod 9 penetrates the hydraulic cylinder 7 and is fixed to the center of the diaphragm 5 in the gas chamber 3. The inside of the hydraulic cylinder 7 is partitioned by a piston 8 into a first hydraulic chamber 11 and a second hydraulic chamber 12. The first hydraulic chamber 11 is for pushing the diaphragm 5 in the underwater direction, and the second hydraulic chamber 12 is for returning the diaphragm 5 to the contrary. The first and second hydraulic chambers are connected via a servo valve 10, and the servo valve 10 can mutually supply and discharge operating oil between the first and second hydraulic chambers. The actuator 6 switches the supply / discharge operation by the servo valve 10 at a low frequency to move the operating oil between the first and second hydraulic chambers, and transmits the reciprocating motion of the piston 8 thereby to the diaphragm 5. .

The underwater sound source control device 21 of the present invention is mainly composed of
Hydrophone 22 mounted on the outside of the dive housing 2
And a control circuit 23 mounted on the dive housing 2. The hydrophone 22 is an underwater acoustic sensor, and is arranged in an appropriate positional relationship so as to detect the sound pressure of the sound wave radiated into the water from the diaphragm 5 via the vibration transmitting film 4. Although it is arranged around the opening of the gas chamber 3 in FIG. 1, it is not limited to this. The control circuit 23 is an amplitude detection circuit 2 that detects the amplitude of the sound pressure detection signal of the hydrophone 22.
4 and an amplitude detection circuit 25 for detecting the amplitude of the input signal i
A comparator 26 that compares the amplitudes of the two, and an amplitude adjuster 27 that adjusts the amplitude of the input signal according to the comparison result.
The driver 28 drives the servo valve 10 with the input signal j whose amplitude is adjusted. The input signal i gives a target sound pressure level, waveform and frequency to the underwater sound source control device 21 from a setting device (not shown). The driver 28 forms a servo circuit together with the servo valve 10 and the rod 9, and responds to the input signal j of the servo valve 10 by the servo valve 10.
The hydraulic servo can be performed by controlling the supply / discharge direction and the supply / discharge amount of the operating oil and feeding back the displacement of the rod 9 and the like.

A concrete circuit example of the control circuit 23 is shown in FIG. An amplitude detection circuit 24 for detecting the amplitude of the sound pressure detection signal and an amplitude detection circuit 2 for detecting the amplitude of the input signal i.
The output of 5 is a subtracter (adder in which one sign is inverted) 31
Is input to the calculator 32 which calculates the control amount by proportionality / integration or the like. The control amount from the calculator 32 is input to the multiplier 33 to obtain the product of the input signal i. The product and the input signal i are input to the adder 34, and the sum is output to the driver 28 as the input signal j. The subtractor 31 corresponds to the comparator 26, and the calculator 3
2. The multiplier 33 and the adder 34 correspond to the amplitude adjuster 27. In this circuit example, the control circuit 23 adjusts the input signal i with a control amount proportional to the difference between the target sound pressure level and the actual sound pressure level.

Although the single-sided drive type sound source has been described in this embodiment, in practice, two sound sources are used and arranged so as to cancel the driving reaction force of the diaphragm. It is not limited to the examples.

Next, the operation of the embodiment will be described.

A setting device (not shown) provides a sine wave input signal i indicating the target sound pressure level, waveform and frequency to the underwater sound source control device 21. If there is no influence of the environment, the driver 28 controls the supply / discharge direction and supply / discharge amount of the operating oil of the servo valve 10 according to the input signal j equal to the input signal i, and feeds back the displacement of the rod 9 and the like to control the hydraulic pressure. Servo. Since the input signal i is a sine wave, the operating oil is mutually supplied and discharged between the first and second hydraulic chambers, and the piston 8 reciprocates according to the hydraulic pressure of the operating oil. As the piston 8 reciprocates, the rod 9 and the diaphragm 5 reciprocate. The reciprocating motion of the vibrating plate 5, that is, the low frequency vibration is radiated into the water as a sound wave through the vibration transmitting oil and the vibration transmitting film 4. The sound pressure, waveform, and frequency of this sound wave will be as set in the target if there is no environmental influence.

When the environment changes, for example, the water temperature decreases, the temperature of the hydraulic operating oil decreases, and its viscosity increases, so that the operation of the actuator changes, resulting in a change in the sound pressure. The hydrophone 22 attached to the outside of the dive housing 2 detects the sound pressure of this sound wave. Amplitude detection circuit 24
Detects the amplitude of the sound pressure detection signal, and the amplitude detection circuit 25 detects the amplitude of the input signal i. Based on the difference obtained by the subtractor 31, the arithmetic unit 32 calculates the control amount by proportionality / integration or the like. The multiplier 33 and the adder 34 add or subtract a control amount proportional to the difference between the target sound pressure level and the actual sound pressure level to the input signal i. For example, when the actual sound pressure level is lower than the target sound pressure level, a positive control amount is added to the input signal i and the amplitude is increased. Since the input signal j whose amplitude has been increased in this way is output to the driver 28,
When the driver 28 performs the hydraulic servo according to the input signal j, the amplitude of the reciprocating motion of the diaphragm 5 increases and the sound pressure increases.

In this way, the sound pressure is stably maintained at the target sound pressure level according to the input signal even if there is a change in the environment, and sound waves of a constant sound pressure level suitable for underwater exploration are emitted.

[0022]

The present invention exhibits the following excellent effects.

(1) Since the sound pressure is stable regardless of the environment, there are no restrictions on the environment in which the underwater sound source device is used, and the accuracy of underwater exploration is improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an underwater sound source device and an underwater sound source control device showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing an embodiment of a control circuit of the underwater sound source control device of the invention.

[Explanation of symbols]

 5 Vibration plate 6 Actuator 10 Servo valve 22 Hydrophone 23 Control circuit

Claims (2)

[Claims] 1. A control device for an underwater sound source that inputs an input signal to a hydraulic servo circuit, attaches a vibration plate to an actuator that is reciprocally driven by the hydraulic servo circuit, and emits sound waves into the water from the vibration plate. A hydrophone for detecting pressure is arranged in water, and a control circuit for controlling the drive of the actuator so as to obtain a target sound pressure by comparing the sound pressure detection signal with the input signal is provided. Underwater sound source control device. 2. The hydraulic servo circuit, wherein the input signal is a sine wave, the control circuit compares the amplitude of the sound pressure detection signal with the amplitude of the input signal, and adjusts the amplitude according to the comparison result. The underwater sound source control device according to claim 1, wherein