Neutral buoyancy moving electrode differential capacitive vector hydrophone and frequency band expansion method thereof

Abstract

The invention discloses a neutral buoyancy moving electrode differential capacitance type vector hydrophone and a frequency band expansion method thereof, and belongs to the field of low-frequency vector hydrophone devices and frequency band expansion methods thereof. An underwater sound acquisition mechanism with a differential capacitance function is approximately suspended in compression-resistant insulating liquid in an underwater sound channel; the floater body with the moving electrode function enables the density of the neutral buoyancy moving electrode mechanism to be close to the density of the compression-resistant insulating liquid and forms an approximately suspended neutral buoyancy unit. An underwater sound vibration signal is transmitted through the compression-resistant insulating liquid and directly acts on the surface of the moving electrode which is approximately suspended, and low-frequency underwater sound vibration velocity information is obtained by detecting the displacement change of the neutral buoyancy moving electrode relative to the fixed electrode, namely inertial acceleration detection can be replaced by low-frequency displacement detection. The low-frequency underwater acoustic signal detection sensitivity is greatly improved; a linear motor formed by a magnet in a movable electrode plate and a coil in a fixed electrode plate is used as a feedback force output unit, and the frequency band range of the hydrophone is further expanded by adopting a force balance negative feedback technology.

Description

Technical Field

[0001] The present invention belongs to the field of low-frequency vector hydrophone devices and frequency band extension methods thereof, and in particular relates to a neutral buoyancy dynamic electrode differential capacitive vector hydrophone and a frequency band extension method thereof. Background Art

[0002] Vector hydrophones are sensors used to measure the velocity vector information of particles in the underwater acoustic field. Compared with scalar hydrophones, they have better resistance to coherent interference and isotropic noise, and are widely used in sonar systems, underwater target identification, ocean noise measurement, etc. Low-frequency underwater acoustic signals have the characteristics of small attenuation amplitude over long distances. Low-frequency radiated noise monitoring is the main means of long-distance passive positioning of underwater targets, and low-frequency and ultra-low-frequency vector hydrophones are key sensors.

[0003] There are many types of vector hydrophones, and the transducer principles they adopt vary greatly, resulting in significantly different structures and characteristics, as well as different advantages and disadvantages. Vector hydrophones can be divided into inertial, differential pressure, and ciliary types in terms of structure, and piezoelectric, capacitive, optical fiber, hot wire, and electrochemical types in terms of transducer method. The most frequently used vector hydrophone at present is the inertial vector hydrophone with an inertial accelerometer or velocimeter as the core unit. The inertial vector hydrophone is also called the co-oscillation vector hydrophone.

[0004] In 2016, researchers such as Sun Qindong published a paper titled "Design and Implementation of Co-Vibration Triaxial Vector Hydrophone". The co-vibration vector hydrophone is a triaxial inertial acceleration sensor that is filled into a small rigid shell in a certain structural form and its overall density is adjusted to be close to that of seawater, thus forming an inertial vector hydrophone. The inertial vector hydrophone is suspended on a rigid bracket with an elastic rubber rope to keep it free in the liquid environment being measured. Based on the known principle that the motion response of a free-moving rigid sphere in an ideal fluid medium in a low-frequency plane wave field is equal to the vibration velocity of the measured seawater, the change in the output voltage of the inertial sensor caused by the motion of the rigid object is recorded to achieve the measurement of the particle velocity in the underwater sound field. After this type of isochronous vector hydrophone is suspended on a fixed frame by a rubber rope, its force model can be approximately regarded as a typical second-order mass / spring / damping system. The essence of this vector hydrophone is to use its acceleration sensor to measure the acceleration of a moving object, but the signal of the physical quantity of the vibration acceleration of the acoustic particle corresponding to the physical quantity of the low-frequency acoustic particle velocity is extremely weak, which causes the sensitivity of the inertial vector hydrophone based on acceleration detection to decrease with the decrease of its target detection frequency in the ocean background noise environment, or the proportion of background noise in its sensitivity index increases with the decrease of the measured frequency, which is not conducive to the low-frequency measurement of the acoustic signal. In addition, the multiple groups of elastic rubber ropes used to suspend the acceleration sensor of the isochronous three-axis vector hydrophone are important components of the inertial vector hydrophone unit. The radial stiffness of the elastic component and the specific suspension angle position and other layout methods have an important influence on the overall performance of the vector hydrophone, which leads to poor consistency of indicators and poor long-term stability in the application of inertial vector hydrophone.

[0005] In 2013, researchers such as Gong Zhanjiang published a capacitive vector hydrophone in the article "Development of a New Three-Dimensional MEMS Capacitive Vector Hydrophone". Its essence is to develop an inertial accelerometer for differential capacitive vector hydrophone. The differential capacitive inertial accelerometer is encapsulated in a cylindrical rigid object to form a capacitive vector hydrophone. The hydrophone should be more accurately described as "an inertial vector hydrophone with a differential capacitive inertial accelerometer as the core unit". The acceleration sensor used in the capacitive hydrophone is based on the piezoelectric transducer principle, which leads to better low-frequency characteristics compared with the piezoelectric accelerometer, and helps to further reduce the low-frequency sensitivity of the inertial vector hydrophone, but the improvement is still unsatisfactory and difficult to meet the needs. Moreover, it does not help with the problems of poor consistency of indicators and poor long-term stability in the application process of the acceleration sensor-based inertial vector hydrophone.

[0006] The invention patent of application publication number CN 116878645 A "An electrochemical vector hydrophone with a bionic jellyfish ear structure" discloses an electrochemical vector hydrophone, the core of which is to develop a vector hydrophone based on the principle of electrochemical transduction, that is, to use the vibration of water sound particles to stimulate the vibration of the electrolyte in the hydrophone, thereby causing the electrochemical current response of the sensitive electrode to achieve the measurement of the vibration velocity of the water sound particles. It has the characteristics of high low-frequency sensitivity and convenient installation relative to inertial hydrophones. However, the electrochemical vector hydrophone needs to use electrolyte as the electrochemical reaction medium. The electrolyte is extremely corrosive, oxidizing and volatile, and requires the cavity material containing the electrolyte to be stable and well sealed. Otherwise, the concentration of effective substances in the electrolyte is easy to decay over time, causing the sensitivity of the hydrophone to decrease and the service life to shorten. In addition, this type of electrochemical vector hydrophone belongs to an open-loop measurement system and does not involve the frequency band extension control technology based on force balance negative feedback. The force balance negative feedback control of liquids is more difficult than that of solids. Summary of the invention

[0007] In order to solve the problem that the acceleration signal of the underwater acoustic particle vibration corresponding to the physical quantity of the low-frequency underwater acoustic particle vibration velocity is extremely weak, the sensitivity of the existing three-axis co-vibration inertial vector hydrophone based on acceleration detection quantity decreases as its target detection frequency decreases in the ocean background noise environment, causing its sensitivity to decrease with frequency, or the background noise ratio to increase as the measured frequency decreases, which is not conducive to the low-frequency measurement of the underwater acoustic signal; moreover, the three-axis co-vibration inertial vector hydrophone also has the inherent problem that the overall performance is significantly affected by the radial stiffness of its elastic components and the specific suspension method, resulting in poor consistency of measurement indicators and poor long-term stability.

[0008] Although the existing capacitive vector hydrophone replaces the old piezoelectric accelerometer by adopting an acceleration sensor based on the piezoelectric transducer principle with better low-frequency characteristics, and helps to further reduce the low-frequency sensitivity of the inertial vector hydrophone, the improvement in the measurement sensitivity of the hydrophone's low-frequency signal is still unsatisfactory and difficult to meet the needs; and it does not help the inherent problem of poor consistency of the indicators of the inertial vector hydrophone based on the acceleration sensor;

[0009] In order to solve the problem that the existing electrochemical vector hydrophone needs to use an electrolyte with extremely strong corrosiveness, strong oxidizing property and volatility as an electrochemical reaction medium, which requires the cavity material containing the electrolyte to be stable and well-sealed, otherwise, the concentration of effective substances in the electrolyte will easily decay over time, causing the sensitivity of the hydrophone to decrease and the service life to shorten; at the same time, since the force balance negative feedback control of liquids is more difficult than that of solids, most of the existing electrochemical vector hydrophones belong to open-loop measurement systems, do not involve frequency band extension control technology based on force balance negative feedback, and are not conducive to calibration and adjustment of measurement results, the present invention provides a neutral buoyancy dynamic electrode differential capacitive vector hydrophone and a frequency band extension method thereof.

[0010] The technical solution adopted by the present invention to solve the technical problem is as follows:

[0011] A neutral buoyancy dynamic electrode differential capacitive vector hydrophone comprises an acoustic collecting mechanism, an acoustic channel cylinder, a pressure-resistant insulating liquid, a circuit board compartment and a circuit board; a transversely penetrating acoustic channel is provided in the middle of the acoustic channel cylinder, both ends of the acoustic channel are respectively sealed by two acoustic windows in the acoustic channel cylinder, the acoustic channel is filled with pressure-resistant insulating liquid and the acoustic collecting mechanism is completely immersed in the pressure-resistant insulating liquid; the acoustic collecting mechanism is coaxially fixed to the center of the acoustic channel and is used to collect acoustic signals transmitted into the acoustic channel through the pressure-resistant insulating liquid; the circuit board compartment is located outside the acoustic channel cylinder and is waterproofly isolated therefrom, the circuit board is sealed in the circuit board compartment and is connected to the acoustic collecting mechanism signal; the circuit board is used to process and output the acoustic signals transmitted by the acoustic collecting mechanism.

[0012] The beneficial effects of the present invention are:

[0013] The neutral buoyancy moving electrode differential capacitive vector hydrophone of the present invention has a hydroacoustic channel sealed with a pressure-resistant insulating liquid, and the hydroacoustic vibration signal enters the hydroacoustic channel through the hydroacoustic window with high transmittance. The hydroacoustic collection mechanism is coaxially fixed to the center of the hydroacoustic channel and is completely immersed in the pressure-resistant insulating liquid. The neutral buoyancy moving electrode mechanism having the function of a differential capacitive sensor moving electrode plate has a density close to that of the pressure-resistant insulating liquid, so that the buoyancy and gravity acting on the neutral buoyancy moving electrode mechanism of the present invention are approximately equal, thereby obtaining the "neutral buoyancy" property.

[0014] 1. The neutral buoyancy moving electrode mechanism vibrates synchronously with the hydroacoustic particle. By utilizing the characteristic that the vibration displacement of the hydroacoustic particle increases as the frequency decreases, the displacement response of the neutral buoyancy moving electrode mechanism relative to the fixed electrode plate is detected, and the vibration velocity information of the low-frequency hydroacoustic particle is measured, thereby achieving a significant improvement in the low-frequency hydroacoustic signal detection capability.

[0015] 2. The neutral buoyancy moving electrode mechanism with "neutral buoyancy" property is suspended in the pressure-resistant insulating liquid of the underwater acoustic channel by two three-arm planar springs whose radial stiffness is much greater than the axial stiffness, thereby avoiding the inherent problems of inconsistent indicators and poor long-term stability caused by the old inertial vector hydrophone suspended by multiple groups of rubber ropes, thereby significantly improving the compactness and ease of use of the neutral buoyancy moving electrode differential capacitive vector hydrophone of the present invention.

[0016] 3. The pressure-resistant insulating liquid sealed and filled in the hydroacoustic channel does not directly participate in the detection of the hydroacoustic vibration signal. The pressure-resistant insulating liquid has loose requirements on the filling material, which completely eliminates the high standard requirements for sealing and preservation of highly corrosive and highly oxidizing electrolytes in the use of electrochemical vector hydrophones. Therefore, the neutral buoyancy dynamic electrode differential capacitive vector hydrophone of the present invention does not have the problem of reduced sensitivity or unstable indicators after long-term use.

[0017] 4. The float body of the neutral buoyancy moving electrode mechanism, the annular magnet fixed at the center and the two electromagnetic coils embedded in the fixed pole plates constitute the feedback motor of the neutral buoyancy moving electrode differential capacitive vector hydrophone, so that the neutral buoyancy moving electrode differential capacitive vector hydrophone using force balance feedback control of the present invention has a more flexible and adjustable low-frequency detection capability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the three-dimensional structure of the neutral buoyancy dynamic electrode differential capacitive vector hydrophone of the present invention;

[0019] Figure 2 It is a preliminary exploded assembly diagram of the neutral buoyancy dynamic electrode differential capacitive vector hydrophone of the present invention;

[0020] Figure 3 It is a schematic diagram of the explosion assembly of the water acoustic channel cylinder of the present invention;

[0021] Figure 4 It is a schematic diagram of the three-dimensional structure of the hydroacoustic window of the present invention;

[0022] Figure 5 It is a schematic diagram of an axial section of a water acoustic channel cylinder of the present invention;

[0023] Figure 6 yes Figure 5 AA section view in;

[0024] Figure 7 yes Figure 5 Stereoscopic image of

[0025] Figure 8 It is a three-dimensional structural schematic diagram of the water sound collection mechanism of the present invention;

[0026] Fig. 9It is a schematic diagram of the explosion assembly of the water sound collection mechanism of the present invention;

[0027] Fig.10 It is a side view of the underwater sound collection mechanism of the present invention and a partial enlarged view of part I thereof;

[0028] Fig.11 It is a schematic axial cross-sectional view of the coaxially nested float body and annular magnet of the present invention;

[0029] Fig.12 It is a front view of the three-arm plane spring of the present invention;

[0030] Fig.13 It is a schematic diagram of the three-dimensional structure of the central bearing ring of the present invention, the float body with an annular magnet embedded therein, and the two three-arm planar springs which are coaxially connected respectively;

[0031] Fig.14 yes Fig.13 Schematic diagram of the exploded assembly;

[0032] Fig.15 yes Fig.13 An axial cross-sectional view of the device and a partial enlarged view of part II in the figure;

[0033] Fig.16 It is an assembly schematic diagram and an exploded schematic diagram of the fixed pole plate and the electromagnetic coil of the present invention;

[0034] Fig.17 This is a front view of a fixed plate blank before the sound-transmitting damping hole array is formed in the present invention;

[0035] Fig.18 yes Fig.17 The three-dimensional cross-section under the middle BB;

[0036] Fig.19 It is an axial cross-sectional stereoscopic view of the assembly structure of the fixed pole plate and the electromagnetic coil of the present invention;

[0037] Fig. 20 It is an axial cross-sectional stereoscopic view of the water sound collection mechanism of the present invention;

[0038] Fig.21 It is a schematic axial cross-sectional view of a water sound channel cylinder including a water sound collection mechanism of the present invention;

[0039] Fig. 22 It is a schematic cross-sectional view of the three-dimensional structure of the neutral buoyancy dynamic electrode differential capacitive vector hydrophone of the present invention;

[0040] Fig.23 This is a principle diagram of frequency band expansion of the force balance negative feedback method of the present invention; DETAILED DESCRIPTION

[0041] The present invention is further described in detail below with reference to the accompanying drawings.

[0042] like Figures 1 to 22 As shown, the neutral buoyancy dynamic electrode differential capacitive vector hydrophone of the present invention includes an acoustic collecting mechanism A, an acoustic channel cylinder B, a pressure-resistant insulating liquid, a circuit board compartment C and a circuit board; a transversely penetrating acoustic channel is provided in the middle of the acoustic channel cylinder B, and both ends of the acoustic channel are respectively sealed by two acoustic windows B3 in the acoustic channel cylinder B, the acoustic channel is filled with pressure-resistant insulating liquid and the acoustic collecting mechanism A is completely immersed in the pressure-resistant insulating liquid; the acoustic collecting mechanism A is coaxially fixed to the center of the acoustic channel and is used to collect the acoustic signal transmitted into the acoustic channel through the pressure-resistant insulating liquid; the circuit board compartment C is located outside the acoustic channel cylinder B and is waterproofly isolated from it, the circuit board is sealed in the circuit board compartment C and is connected to the acoustic collecting mechanism A signal; the circuit board is used to process and output the acoustic signal transmitted by the acoustic collecting mechanism A.

[0043] The underwater acoustic collection mechanism A comprises two fixed pole plates 1, two spring pressure rings 2, two three-arm plane springs 3, a channel center bearing ring 4, a float body 5, an annular magnet 6 and two electromagnetic coils 7; the three-arm plane spring 3 comprises a spring disc inner ring 3-1, a spring disc outer ring 3-2 and three arc-shaped connecting ribs 3-3 which are coaxial and coplanar with each other, and the three arc-shaped connecting ribs 3-3 are evenly distributed between the spring disc inner ring 3-1 and the spring disc outer ring 3-2 in the circumferential direction; the two three-arm plane springs 3 are respectively connected to the front of the channel center bearing ring 4 through the spring disc outer ring 3-2 outside thereof. and rear end faces thereof are coaxially fixedly connected; the two three-arm planar springs 3 are coaxially fixedly connected to the front and rear end faces of the float body 5 respectively through the spring disk inner ring 3-1 at the center position thereof; the annular magnet 6 is coaxially embedded in the center of the float body 5; the two electromagnetic coils 7 are respectively embedded and coaxially fixedly connected in the coil assembly ring groove 1-2 in the middle of the outer end face of the corresponding fixed pole plate 1; the spring compression ring 2 is made of insulating material, and the two spring compression rings 2 are respectively fixedly connected to the outer end faces of the corresponding spring disk outer ring 3-2; the two fixed pole plates 1 are respectively fixedly connected to the outer end faces of the corresponding spring compression rings 2.

[0044] The hydroacoustic channel cylinder B is made of insulating material, which includes a cylindrical arc-surface shell B1, two sound-collecting rings B2, two hydroacoustic windows B3, two clamping rings B4 and a radial sealing ring B5 of the cylinder; the cylindrical arc-surface shell B1 includes an integrally formed hydroacoustic channel shell B1-1 and a connecting ring seat B1-2 radially perpendicular to it; a transversely penetrating hydroacoustic channel is provided at the axial center of the hydroacoustic channel shell B1-1, and the hydroacoustic collecting mechanism A is coaxially fixed to the transverse center position of the hydroacoustic channel shell B1-1 and is clamped and fixed by two front and rear clamping rings B4; the hydroacoustic window B3 includes an annular ring B3-1 and a sound-transmitting membrane B3-2 fixed on its inner wall, and the hydroacoustic window B3 is used to transmit the sound through its sound-transmitting membrane B3-2 to the hydroacoustic channel. Both ends of the underwater acoustic channel shell B1-1 are sealed, and the sound-permeable membrane B3-2 is used for the high transmittance of the underwater acoustic vibration signal into the underwater acoustic channel and to isolate the contact between the pressure-resistant insulating liquid and the seawater; each sound-focusing ring B2 crimps the corresponding underwater acoustic windows B3 to the front and rear end faces of the underwater acoustic channel shell B1-1 respectively; the connecting ring seat B1-2 is used for the coaxial fixed connection between the cylindrical arc shell B1 and the circuit board bin C, and an axial through-bin hole B1-1-1 is provided in the center of the end face of the connecting ring seat B1-2; the threading flange B5 is coaxially fixed to the end face of the through-bin hole B1-1-1 and seals it; the threading flange B5 is used for the electrical connection between the underwater acoustic collection mechanism A and the circuit board fixed inside the circuit board bin C.

[0045] The pressure-resistant insulating liquid is a low-viscosity liquid that has electrical insulation properties, a large bulk modulus, and a density close to that of seawater. The pressure-resistant insulating liquid fills the hydroacoustic channel shell B1-1 and completely immerses the hydroacoustic collection mechanism A in the pressure-resistant insulating liquid. The fixed pole plate 1 is made of metal material, and an axially penetrating sound-transmitting damping hole array 1-1-1 is provided on the end face of the fixed pole plate 1. A coil assembly ring groove 1-2 is provided in the middle of the fixed pole plate 1 for installing and fixing the electromagnetic coil 7. The float body 5 is made of a low-density pressure-resistant material.

[0046] The pressure-resistant insulating liquid includes castor oil, silicone oil or transformer oil; preferably, the pressure-resistant insulating liquid is 25# transformer oil; preferably, the float body 5 described in the present invention is a low-density pressure-resistant material of epoxy resin with hollow glass beads solidified inside; the sound-transmitting membrane B3-2 is a rubber membrane; the annular magnet 6 is a radially magnetized magnetic ring; the radial stiffness of the three-arm planar spring 3 is at least 10 times its axial stiffness.

[0047] The spring disk inner ring 3-1, the float body 5 and the annular magnet 6 inside the two three-arm planar springs 3 together constitute a neutral buoyancy moving electrode mechanism; the three-arm planar spring 3 is made of a metal conductor material, the two spring disk inner rings 3-1 are electrically short-circuited, and serve as the movable electrode plate of the differential capacitance sensing structure; the two fixed electrodes 1 are symmetrically and closely arranged on both sides of the neutral buoyancy moving electrode mechanism, and the moving electrode plate of the neutral buoyancy moving electrode mechanism and the two fixed electrodes 1 together constitute the differential capacitance sensing structure of the neutral buoyancy moving electrode differential capacitance vector hydrophone; the annular magnet 6 coaxially embedded in the center of the float body 5 and the two electromagnetic coils 7 coaxially embedded in the fixed electrode 1 together constitute a feedback motor for closed-loop feedback control of the neutral buoyancy moving electrode mechanism.

[0048] The sound-transmitting damping pinhole array 1-1-1 is used to apply fluid damping to the pressure-resistant insulating liquid carrying the hydroacoustic signal flowing therethrough, thereby equivalently forming motion damping to the neutrally buoyant moving electrode mechanism, thereby providing a basis for constructing the mass / damping equation.

[0049] The float body 5 is used to adjust the overall density of the neutral buoyancy moving electrode mechanism and make it close to the density of the pressure-resistant insulating liquid, and to make the difference between the overall density of the neutral buoyancy moving electrode mechanism and the density of seawater converge within the range of ±5%.

[0050] The circuit board comprises a conditioning unit and a feedback unit; the conditioning unit is used for electromechanical signal conversion of the underwater acoustic vibration signal pickup structure of the neutral buoyancy dynamic electrode differential capacitive vector hydrophone; the feedback unit is used for closed-loop feedback control of the neutral buoyancy dynamic electrode mechanism to achieve frequency band expansion of the hydrophone.

[0051] The feedback unit of the circuit board includes at least two of a second-order differential feedback circuit, a first-order differential feedback circuit and a zero-order differential feedback circuit connected in parallel with each other; preferably, the feedback unit of the circuit board includes a second-order differential feedback circuit, a first-order differential feedback circuit and a zero-order differential feedback circuit connected in parallel with each other at the same time.

[0052] like Fig.23 As shown, the frequency band extension method based on the neutral buoyancy dynamic electrode differential capacitive vector hydrophone of the present invention comprises the following steps:

[0053] Step 1: Design a pressure-resistant insulating liquid with a density close to that of seawater and a neutral buoyancy moving electrode mechanism, wherein the conditioning unit includes at least functional units such as an AC power supply, a charge amplifier unit, a phase-sensitive detection unit, and a low-pass filter unit known in the field of automatic control, and the differential capacitor operational amplifier circuit integrated on the circuit board is formed according to a known method;

[0054] Step 1: Design a pressure-resistant insulating liquid with a density close to that of seawater and a neutral buoyancy moving electrode mechanism;

[0055] Step 2: Construct the motion equation of the water acoustic particle:

[0056] Assuming that the hydroacoustic particle is located at the center of an aquatic channel with a length of l and a cross-sectional area of ​​A in the propagation direction of the hydroacoustic vibration signal, the sound pressure gradient in the hydroacoustic channel is Forces in the hydroacoustic channel The motion equation of the hydroacoustic particle constructed from this is:

[0057]

[0058] In formula (1), m W is the mass of the water sound particle, is the vibration acceleration of the water sound particle, ρ is the seawater density, s is the complex frequency, v W is the vibration velocity of the water sound particle;

[0059] Step 3: Construct the response equation of the neutral buoyancy moving electrode mechanism under the excitation of hydroacoustic vibration:

[0060]

[0061] In formula (2), x p is the displacement of the neutral buoyancy moving electrode mechanism, m s =ρlA is the mechanical mass of the neutral buoyancy moving electrode mechanism, H s is the mechanical damping of the neutral buoyancy moving electrode mechanism, C s is the parallel mechanical stiffness of two three-arm planar springs (3) and two acoustically transparent membranes (B3-2);

[0062] Step 4: Build the conditioning circuit of the underwater acoustic vibration signal pickup structure:

[0063]

[0064] In formula (3), V o is the output voltage of the conditioning unit, D is the conversion ratio of the underwater acoustic vibration signal pickup structure, and K is the signal amplification factor;

[0065] Step 5: Construct a feedback function for closed-loop control of the underwater acoustic vibration signal pickup structure:

[0066]

[0067] In formula (4), V f is the output voltage of the feedback unit, V o is the input voltage of the feedback unit, k T is the gain of the second-order differential feedback circuit, k D is the gain of the first-order differential feedback circuit, k Ris the gain of the zero-order differential feedback circuit;

[0068] Step 6: Construct the feedback motor transfer function:

[0069]

[0070] In formula (5), F f is the output force of the feedback motor, G f is the electromotive constant of the feedback motor, R is the series resistance of the two electromagnetic coils;

[0071] Step 7: Based on the force balance negative feedback control method and equations (1) to (5), the system transfer function of the neutral buoyancy dynamic electrode differential capacitive vector hydrophone including a closed-loop feedback link is obtained:

[0072]

[0073] In formula (6), m s is the mechanical mass of the neutral buoyancy moving electrode mechanism, s is the complex frequency;

[0074] is the equivalent mass generated by the feedback system;

[0075] is the equivalent damping generated by the system;

[0076] is the equivalent stiffness generated by the system;

[0077] m e , H e and C e Can be adjusted through the circuit system, The adjustment of can achieve the expansion of the frequency band of the hydrophone.

Claims

1. Neutral buoyancy dynamic electrode differential capacitive vector hydrophone, characterized by: The differential capacitive vector hydrophone comprises an underwater acoustic collection mechanism (A), an underwater acoustic channel cylinder (B), a pressure-resistant insulating liquid, a circuit board compartment (C) and a circuit board; a horizontally penetrating underwater acoustic channel is provided in the middle of the underwater acoustic channel cylinder (B), both ends of the underwater acoustic channel are respectively sealed by two underwater acoustic windows (B3) in the underwater acoustic channel cylinder (B), the underwater acoustic channel is filled with pressure-resistant insulating liquid and the underwater acoustic collection mechanism (A) is completely immersed in the pressure-resistant insulating liquid; the underwater acoustic collection mechanism (A) is coaxially fixed to the center of the underwater acoustic channel and is used to collect the underwater acoustic signal transmitted into the underwater acoustic channel through the pressure-resistant insulating liquid; the circuit board compartment (C) is located outside the underwater acoustic channel cylinder (B) and is waterproofly isolated from it, the circuit board is sealed in the circuit board compartment (C) and is connected to the underwater acoustic collection mechanism (A) signal; the circuit board is used to process and output the underwater acoustic signal transmitted by the underwater acoustic collection mechanism (A).

2. The neutral buoyancy dynamic electrode differential capacitive vector hydrophone according to claim 1, characterized in that: The underwater sound collection mechanism (A) is a cylindrical structure as a whole, and comprises two fixed pole plates (1), two spring pressure rings (2), two three-arm plane springs (3), a channel center bearing ring (4), a float body (5), an annular magnet (6) and two electromagnetic coils (7); the three-arm plane spring (3) comprises a spring disk inner ring (3-1), a spring disk outer ring (3-2) and three arc-shaped connecting ribs (3-3) which are coaxial and coplanar with each other, and the three arc-shaped connecting ribs (3-3) are evenly distributed between the spring disk inner ring (3-1) and the spring disk outer ring (3-2) in the circumferential direction; the two three-arm plane springs (3) are respectively connected to the channel through the spring disk outer ring (3-2) outside thereof. The front and rear end surfaces of the central bearing ring (4) are correspondingly coaxially fixedly connected; the two three-arm plane springs (3) are respectively coaxially fixedly connected to the front and rear end surfaces of the float body (5) through the spring disc inner ring (3-1) at the center position; the annular magnet (6) is coaxially embedded in the center of the float body (5); the two electromagnetic coils (7) are respectively embedded and coaxially fixedly connected in the coil assembly ring groove (1-2) in the middle of the outer end surface of the corresponding fixed pole plate (1); the spring pressure ring (2) is made of insulating material, and the two spring pressure rings (2) are respectively fixedly connected to the outer end surface of the corresponding spring disc outer ring (3-2); the two fixed pole plates (1) are respectively fixedly connected to the outer end surface of the corresponding spring pressure ring (2).

3. The neutral buoyancy dynamic electrode differential capacitive vector hydrophone according to claim 1, characterized in that: The water sound channel cylinder (B) is made of insulating material, and comprises a cylindrical arc surface shell (B1), two sound focusing rings (B2), two water sound windows (B3), two clamping rings (B4) and a cylinder radial sealing ring (B5); the cylindrical arc surface shell (B1) comprises an integrally formed water sound channel shell (B1-1) and a connecting ring seat (B1-2) perpendicular to the radial direction thereof; a transversely penetrating water sound channel is provided at the axial center of the water sound channel shell (B1-1); the water sound collecting mechanism (A) is coaxially fixedly connected to the transverse center position of the water sound channel shell (B1-1) and is connected by two front and rear clamping rings ( B4) is clamped and fixed; the hydroacoustic window (B3) includes an annular ring (B3-1) and a sound-transmitting membrane (B3-2) fixed on its inner wall; each sound-focusing ring (B2) presses the corresponding hydroacoustic window (B3) to the front and rear end faces of the hydroacoustic channel shell (B1-1) respectively; the connecting ring seat (B1-2) is used for coaxially fixing the cylindrical arc shell (B1) and the circuit board bin (C), and an axial through-bin hole (B1-1-1) is opened at the center of the end face of the connecting ring seat (B1-2); the threading flange (B5) is coaxially fixed to the end face of the through-bin hole (B1-1-1) and seals it.

4. The neutral buoyancy dynamic electrode differential capacitive vector hydrophone according to claim 2 or 3, characterized in that: The pressure-resistant insulating liquid is a low-viscosity liquid having electrical insulation properties, a large bulk modulus, and a density close to that of seawater. The pressure-resistant insulating liquid fills the water sound channel shell (B1-1) and completely immerses the water sound collection mechanism (A) in the pressure-resistant insulating liquid. The fixed plate (1) is made of metal material, and an array of axially penetrating sound-transmitting damping small holes (1-1-1) is provided on the end surface of the fixed plate (1) to apply fluid damping to the pressure-resistant insulating liquid flowing therethrough. A coil assembly ring groove (1-2) is provided in the middle of the fixed plate (1) for mounting a fixed electromagnetic coil (7). The float body (5) is made of a low-density pressure-resistant material.

5. The neutral buoyancy dynamic electrode differential capacitive vector hydrophone according to claim 4, characterized in that: The pressure-resistant insulating liquid includes castor oil, silicone oil or transformer oil; preferably, the pressure-resistant insulating liquid is 25# transformer oil; The float body (5) is a low-density pressure-resistant material made of epoxy resin with hollow glass beads solidified inside; The sound-transmitting membrane (B3-2) is a rubber membrane; The annular magnet (6) is a radially magnetized magnetic ring; The radial rigidity of the three-arm planar spring (3) is at least 10 times its axial rigidity.

6. The neutral buoyancy dynamic electrode differential capacitive vector hydrophone according to claim 4, characterized in that: The spring disk inner ring (3-1), the float body (5) and the annular magnet (6) inside the two three-arm planar springs (3) together constitute a neutral buoyancy moving electrode mechanism; the three-arm planar spring (3) is made of a metal conductor material, the two spring disk inner rings (3-1) are electrically short-circuited, and serve as movable pole plates of a differential capacitance sensing structure; the two fixed pole plates (1) are symmetrically and closely arranged on both sides of the neutral buoyancy moving electrode mechanism, and the moving electrode plates of the neutral buoyancy moving electrode mechanism and the two fixed pole plates (1) together constitute a differential capacitance sensing structure of a neutral buoyancy moving electrode differential capacitance vector hydrophone; the annular magnet (6) coaxially embedded in the center of the float body (5) and the two electromagnetic coils (7) coaxially embedded in the fixed pole plates (1) together constitute a feedback motor for closed-loop feedback control of the neutral buoyancy moving electrode mechanism.

7. The neutral buoyancy dynamic electrode differential capacitive vector hydrophone according to claim 6, characterized in that: The difference between the overall density of the neutral buoyancy moving electrode mechanism and the density of seawater is ±5%.

8. The neutral buoyancy dynamic electrode differential capacitive vector hydrophone according to claim 1, characterized in that: The circuit board comprises a conditioning unit and a feedback unit; the conditioning unit is used for electromechanical signal conversion of the underwater acoustic vibration signal pickup structure of the neutral buoyancy dynamic electrode differential capacitive vector hydrophone; the feedback unit is used for closed-loop feedback control of the neutral buoyancy dynamic electrode mechanism to achieve frequency band expansion of the hydrophone.

9. The neutral buoyancy dynamic electrode differential capacitive vector hydrophone according to claim 8, characterized in that: The feedback unit of the circuit board includes at least two of a second-order differential feedback circuit, a first-order differential feedback circuit and a zero-order differential feedback circuit connected in parallel with each other; preferably, the feedback unit of the circuit board includes a second-order differential feedback circuit, a first-order differential feedback circuit and a zero-order differential feedback circuit connected in parallel with each other at the same time.

10. A frequency band extension method for a neutral buoyancy dynamic electrode differential capacitive vector hydrophone according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: Step 1: Design a pressure-resistant insulating liquid with a density close to that of seawater and a neutral buoyancy moving electrode mechanism; Step 2: Construct the motion equation of the water acoustic particle: Assuming that the hydroacoustic particle is located at the center of an aquatic channel with a length of l and a cross-sectional area of ​​A in the propagation direction of the hydroacoustic vibration signal, the sound pressure gradient in the hydroacoustic channel is Forces in the hydroacoustic channel The motion equation of the water sound particle constructed from this is: In formula (1), m W is the mass of the water sound particle, is the vibration acceleration of the water sound particle, ρ is the seawater density, s is the complex frequency, v W is the vibration velocity of the water sound particle; Step 3: Construct the response equation of the neutral buoyancy moving electrode mechanism under the excitation of hydroacoustic vibration: In formula (2), x p is the displacement of the neutral buoyancy moving electrode mechanism, m s =ρlA is the mechanical mass of the neutral buoyancy moving electrode mechanism, H s is the mechanical damping of the neutral buoyancy moving electrode mechanism, C s is the parallel mechanical stiffness of two three-arm planar springs (3) and two acoustically transparent membranes (B3-2); Step 4: Build the conditioning circuit of the underwater acoustic vibration signal pickup structure: In formula (3), V o is the output voltage of the conditioning unit, D is the conversion ratio of the underwater acoustic vibration signal pickup structure, and K is the signal amplification factor; Step 5: Construct a feedback function for closed-loop control of the underwater acoustic vibration signal pickup structure: In formula (4), V f is the output voltage of the feedback unit, V o is the input voltage of the feedback unit, k T is the gain of the second-order differential feedback circuit, k D is the gain of the first-order differential feedback circuit, k R is the gain of the zero-order differential feedback circuit; Step 6: Construct the feedback motor transfer function: In formula (5), F f is the output force of the feedback motor, G f is the electromotive constant of the feedback motor, R is the series resistance of the two electromagnetic coils; Step 7: Based on the force balance negative feedback control method and equations (1) to (5), the system transfer function of the neutral buoyancy dynamic electrode differential capacitive vector hydrophone including a closed-loop feedback link is obtained: In formula (6), is the equivalent mass generated by the feedback system; is the equivalent damping generated by the system; is the equivalent stiffness generated by the system; m e , H e and C e Can be adjusted through the circuit system, The adjustment of can achieve the expansion of the frequency band of the hydrophone.

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