Expendable submarine sediment acoustic characteristic in-situ measuring instrument

Abstract

The invention provides a disposable submarine sediment acoustic characteristic in-situ measuring instrument, which belongs to the technical field of geophysical detection equipment and consists of a disposable part and a floating part. The throwing and abandoning part comprises an acoustic probe rod, a counterweight and a fusing separation mechanism, so that the instrument sinks and is in contact with the seabed; the floating part comprises a battery cabin, a fusing cabin, an electronic cabin and a buoyancy module and is used for controlling, data collecting and floating. The acoustic probe rod is provided with a receiving transducer, the counter weight provides gravity needed by sinking, and the fusing separation mechanism achieves separation of the throwing part and the floating part. The battery cabin provides a power supply, a fuse is arranged in the fusing cabin, and the electronic cabin comprises an electronic device, an underwater wet plugging connector and the like. The buoyancy module controls the sinking posture of the instrument and data transmission in the upward floating process through the empennage and the antenna. The measuring instrument solves the problems that an existing disposable measuring instrument cannot measure the acoustic characteristics of seabed sediments, the sinking process is unstable, and floating separation is unreliable.

Description

Technical Field

[0001] The invention belongs to the technical field of geophysical detection equipment, and in particular relates to a throw-away in-situ measuring instrument for acoustic characteristics of seabed sediments. Background Art

[0002] Seafloor sediments are an important object of marine environmental research, and their acoustic properties are of great significance to seafloor mapping, oil exploration, etc. At present, the main means of obtaining the acoustic properties of seafloor sediments are direct sampling analysis and inversion acoustic wave method. The former requires seafloor sampling equipment and laboratory analysis, which is complicated to operate and has a long cycle; the latter inverts the reflection and attenuation information of sound waves through hydroacoustic detection, but requires a large number of known parameters and has low accuracy. Therefore, it is of great research value to develop a simple and effective in-situ measurement method for the acoustic properties of seafloor sediments.

[0003] With the development of technologies such as unmanned underwater vehicles (AUVs) and hydroacoustic detection, the discardable acoustic measurement method has received widespread attention. This method uses a self-sinking measuring instrument to autonomously complete the measurement on the seabed and float up to recover the data, avoiding the complicated seabed sampling and hanging operations, and greatly improving the work efficiency. However, there are some problems with the existing discardable measuring instruments: 1) they can only be used to measure the physical properties of seawater layers, but not the acoustic properties of seabed sediments; 2) the sinking process is unstable and easily deviates from the ideal trajectory; 3) the floating separation is unreliable, and there is a risk of loss of measurement data. Therefore, it is necessary to propose new technical solutions to these problems. Summary of the invention

[0004] In view of this, the present invention provides a discardable in-situ measuring instrument for the acoustic characteristics of seabed sediments, which can solve the problems of existing discardable measuring instruments that cannot measure the acoustic characteristics of seabed sediments, have an unstable sinking process, and unreliable floating separation.

[0005] The present invention is achieved in that: The first aspect of the present invention provides a throwable in-situ measuring instrument for acoustic characteristics of seabed sediments, comprising: an acoustic probe rod, a counterweight, a fuse separation mechanism, a battery compartment, a fuse compartment, an electronic compartment and a buoyancy module; the acoustic probe rod, the counterweight and the fuse separation mechanism are the throwable parts, and the battery compartment, the fuse compartment, the electronic compartment and the buoyancy module are the floating parts; the acoustic probe rod is installed at the lower end of the instrument and is equipped with two receiving transducers arranged at intervals; the counterweight is a whole piece of material, used to provide the gravity required for the sinking of the throwable in-situ measuring instrument for acoustic characteristics of seabed sediments; the fuse separation mechanism is a three-link mechanism composed of a push rod, a connecting rod and a buckle driven by a spring, which drives the movement of the internal push rod through the spring to drive the connecting rod and the buckle to achieve locking and loosening; the battery compartment, The fuse compartment, electronic compartment and buoyancy module are installed in sequence in the order described and are fixedly connected to each other. The battery compartment is at the bottom and connected to the fuse separation mechanism but are not fixedly connected to each other. Batteries for providing energy are placed inside the battery compartment. The fuse compartment is used to cooperate with the fuse separation mechanism to achieve the locking and loosening of the buckle in the fuse separation mechanism, and a fuse is installed inside it. The electronic compartment is installed with electronic devices, underwater wet plug connectors and electric push rods. The two ports of the underwater wet plug connector are respectively installed on the top rod of the fuse separation mechanism and the electric push rod, and the connection and disconnection of the underwater wet plug connector are achieved through the action of the electric push rod. The buoyancy module provides the buoyancy required for the battery compartment, fuse compartment and electronic compartment to float, and its structure is designed with a tail wing for adjusting the falling posture and an antenna for sending data.

[0006] The working principle of the present invention is as follows: the measuring instrument of the present invention is directly dropped into the seawater from a mobile platform (such as a scientific research vessel), and the measuring instrument relies on its own gravity and realizes rapid and stable sinking in a vertical posture under the control of its own appearance characteristics, the position of the center of gravity and buoyancy, and the tail wing; after sinking to the seabed, the measuring instrument relies on its own kinetic energy to penetrate into the sediment, and autonomously performs in-situ measurement of the sediment through the transmitting transducer on the tail wing and the receiving transducer on the acoustic probe rod, and stores the results in the electronic cabin; after the measurement is completed, the fuse wire is blown by the fuse in the fuse cabin, and the fuse separation mechanism releases the floating part, and at the same time, the electric push rod in the electronic cabin disconnects the underwater wet plug connector, and the floating part floats to the sea surface under the action of its own buoyancy, and the measurement data is recovered through the antenna on the buoyancy module.

[0007] On the basis of the above technical solution, the disposable in-situ measuring instrument for acoustic characteristics of seabed sediments of the present invention can also be improved as follows: The acoustic probe is a rod-shaped structure with a conical tip at one end, and two annular underwater acoustic receiving transducers spaced a certain distance apart are installed on the outer wall. The acoustic probe is fixedly connected to the counterweight.

[0008] Furthermore, the counterweight is a truncated cone structure, and the longitudinal cross-section of the truncated cone structure is a trapezoid, including a short side and a long side. The short side corresponds to a section of the truncated cone structure with a smaller diameter, and the long side corresponds to a section of the truncated cone structure with a larger diameter. The acoustic probe rod is installed at the section with a smaller diameter of the circular surface, and the fuse separation mechanism is installed at the end with a larger diameter of the circular surface. There is a through hole along the axis inside the counterweight for routing the receiving transducer.

[0009] Furthermore, the fuse separation mechanism includes a push rod, a buckle, a connecting rod, a spring, and a fuse separation base, wherein the push rod, the buckle, and the connecting rod are hinged by a pin shaft and fixed on the fuse separation base; a through hole is opened at the top of the push rod column for passing the fuse wire; the mechanism controls the locking and loosening of the buckle through the up and down movement of the push rod driven by the connecting rod; a spring is installed at the bottom of the push rod at the center of the fuse separation base, and when installed and locked, the push rod drives the buckle to swing toward the inside of the instrument and buckle on the buckle on the wall of the fuse compartment, locking the counterweight with the battery compartment and the electronic compartment, while putting the bottom spring in a compressed state.

[0010] Furthermore, the battery compartment is a cylindrical sealed pressure-resistant structure with an axial through hole at the center. It is installed at the upper end of the fuse separation mechanism but is not fixed to the fuse separation mechanism. It is used to separate from the fuse separation mechanism under the action of external force. The purpose of providing a through hole in the center of the battery compartment is to leave space for the top rod and wires in the fuse separation mechanism. A battery is sealed inside the battery compartment, which is responsible for providing energy for the entire instrument.

[0011] Furthermore, the fuse compartment is an open structure for free filling of seawater. The fuse compartment is fixedly connected to the battery compartment. An opening with the same diameter as the battery compartment is opened in the center of the bottom surface of the fuse compartment for passing the wires and the top rod of the fuse separation mechanism; four axially evenly distributed bayonet slots are opened on the wall surface of the fuse compartment, and the buckles of the fuse separation mechanism can be buckled into their corresponding bayonet slots when locked; the fuse compartment is fixedly connected to the battery compartment and the electronic compartment; two symmetrically distributed fuses are installed inside the fuse compartment, and the fuse wire is installed on the fuse, and can pass through the hole at the upper end of the top rod when the top rod in the fuse separation mechanism compresses the spring, and offset the force of the spring so that the top rod cannot move up.

[0012] Furthermore, the electronic cabin is a cylindrical pressure-resistant sealed structure, with a control module and a data communication module installed inside, and fixedly connected to the fuse cabin. In addition, an electric push rod is installed inside the electronic cabin; the telescopic rod of the electric push rod is sealed and passes through from the bottom of the electronic cabin and extends into the fuse cabin, and underwater wet plug connectors are respectively installed on the telescopic rod of the electric push rod and the top rod of the fuse separation mechanism; the electric push rod is initially in an extended state, and after the measurement of the abandonable seabed sediment acoustic characteristics in situ measuring instrument is completed, the telescopic rod of the electric push rod is retracted to drive the underwater wet plug connector, thereby realizing the line separation of the floating part and the abandonable part.

[0013] Furthermore, in addition to providing the buoyancy required for the floating part, the buoyancy module also has four tail fins evenly distributed around the circumference, which are responsible for regulating the posture of the disposable in-situ measuring instrument for acoustic characteristics of seabed sediments when it sinks. A transmitting transducer is installed under the two wings, and a communication antenna is installed on the upper end of the buoyancy module. The buoyancy module is fixedly connected to the electronic cabin.

[0014] Furthermore, the installation sequence of the acoustic probe, counterweight, fuse separation mechanism, battery compartment and fuse compartment is as follows: first complete the mutual assembly of the acoustic probe, counterweight and fuse separation mechanism and complete the assembly of the connecting rod mechanism inside the fuse separation mechanism, then fix the battery compartment and the fuse compartment to each other, and then pass the top rod of the fuse separation mechanism and related lines through the central through holes of the battery compartment and the fuse compartment. The battery compartment is fitted on the fuse separation base through the step-like structure at the bottom, so that it is not easy to shake, but can still move upward axially. At the same time, the spring is compressed so that the buckle is tightly buckled on the buckle on the wall of the fuse compartment, thereby locking the counterweight with the battery compartment and the fuse compartment. At the same time, the through hole on the top of the top rod can be aligned with the wire hole of the fuse. At this time, the fuse wire is installed so that it can offset the force of the spring. In this way, the locking and relaxation of the fuse separation mechanism can be achieved by controlling the melting of the fuse wire.

[0015] Furthermore, the structural parameters of the measuring instrument satisfy the following multi-objective optimization model: with the goals of maximizing measurement accuracy, optimizing sinking stability, maximizing floating reliability and minimizing system weight; solving the multi-objective optimization model to obtain the optimized structural parameters of the measuring instrument.

[0016] Compared with the prior art, the beneficial effects of the disposable in-situ measuring instrument for acoustic characteristics of seabed sediments provided by the present invention are: 1. The sinking process is more stable. The invention adopts an optimized counterweight structure and buoyancy module design, which can accurately control the sinking posture and speed. The counterweight is a trapezoidal frustum structure, which takes into account factors such as the center of gravity position, hydrodynamic performance and structural strength; the four tail wings on the buoyancy module can actively adjust the posture to ensure that the instrument penetrates vertically into the seabed.

[0017] 2. The floating separation is more reliable. The invention adopts a fuse separation mechanism to achieve reliable separation of the floating part and the abandoned part. The mechanism can firmly lock the counterweight through a spring-driven three-link structure and quickly release it when the fuse is activated to ensure the stability of the floating process.

[0018] 3. Discardable seabed sediment measurement. The invention adopts the design concept of combining a discarding part and a floating part, which can realize unmanned, autonomous discarding in-situ measurement of seabed sediments. The discarding part is a cone-shaped structure that can effectively penetrate into the sediment; the floating part is locked and separated from the discarding part through a fuse separation mechanism to realize the floating return of measurement data.

[0019] The invention solves the problems that the existing throw-away measuring instrument cannot measure the acoustic characteristics of seabed sediments, the sinking process is unstable, and the floating separation is unreliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the overall structure of a discardable in-situ instrument for measuring acoustic properties of seabed sediments; Figure 2 It is a schematic diagram of the cross-sectional structure of a discardable in-situ measuring instrument for acoustic characteristics of seabed sediments; Figure 3a It is a schematic diagram of the locking state of the fuse separation mechanism of the disposable in-situ measuring instrument for acoustic characteristics of seabed sediments; Figure 3b It is a schematic diagram of the release state of the fuse separation mechanism of the throwable in-situ measuring instrument for acoustic characteristics of seabed sediments; Figure 4a It is a schematic diagram of the removal mechanism of the disposable in-situ measuring instrument for acoustic characteristics of seabed sediments; Figure 4b It is a schematic diagram of the pulling-out mechanism and the pulling-out principle of the disposable in-situ measuring instrument for acoustic characteristics of seabed sediments; Figure 5 This is a schematic diagram of the signal propagation principle of the disposable in-situ instrument for measuring the acoustic characteristics of seabed sediments; Figure 6 This is a schematic diagram of the structural separation principle of the disposable in-situ measuring instrument for acoustic characteristics of seabed sediments; In the figure: 1. acoustic probe, 11. receiving transducer, 2. counterweight, 3. fuse separation mechanism, 31. push rod, 32. buckle, 33. connecting rod, 34. spring, 35. fuse separation base, 4. battery compartment, 41. battery, 5. fuse compartment, 51. fuse, 52. fuse wire, 6. electronic compartment, 61. electric push rod, 62. underwater wet plug connector, 7. buoyancy module, 71. transmitting transducer, 72. antenna. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0022] like Figures 1 to 6As shown, the discardable in-situ measuring instrument for acoustic characteristics of seabed sediments includes: an acoustic probe rod 1, a counterweight 2, a fuse separation mechanism 3, a battery compartment 4, a fuse compartment 5, an electronic compartment 6 and a buoyancy module 7. The acoustic probe rod 1, the counterweight 2 and the fuse separation mechanism 3 are discarded parts, and they do not float up for recovery after the measurement is completed; the battery compartment, the fuse compartment, the electronic compartment and the buoyancy module are floating parts. Among them, the acoustic probe rod 1 is a rod-shaped structure with a conical tip at one end, and two annular underwater acoustic receiving transducers 11 are installed on the outer wall at a certain distance, and the acoustic probe rod 1 and the counterweight 2 are fixedly connected to each other. The counterweight 2 is a truncated cone structure, the acoustic probe rod 1 is installed at a section with a smaller diameter of the circular surface, and the fuse separation mechanism 3 is installed at the end with a larger diameter of the circular surface. Its function is only to provide the necessary downward force and adjust the center of gravity. There is a through hole along the axis inside the counterweight 2 for routing the receiving transducer 11. The fuse separation mechanism 3 is a three-link mechanism consisting of a push rod 31, a buckle 32, a connecting rod 33, a spring 34, and a fuse separation base 35, wherein the push rod 31, the buckle 32, and the connecting rod 33 are all hinged by a pin and fixed on the fuse separation base 35; a through hole is opened at the top of the rod column of the push rod 31 for passing the fuse 52; the mechanism controls the locking and loosening of the buckle 32 under the drive of the connecting rod 33 through the up and down movement of the push rod 31; a spring 34 is installed at the bottom of the push rod 31 at the center of the fuse separation base 35. When the installation is locked, that is, the push rod 31 moves down, the push rod 31 drives the buckle 32 to swing into the inside of the instrument and buckle on the buckle on the wall of the fuse compartment 5, locking the counterweight 2 with the battery compartment 4 and the electronic compartment 6, and at the same time making the bottom spring 34 in a compressed state, and when the fuse 52 has not yet melted, the force of the spring 34 is offset, so that the push rod cannot move up. When the measurement is completed, the control system energizes the fuse 51, melts the fuse wire 52, and the top rod 31 moves upward under the action of the spring 34, so that the buckle 32 is loosened, and the floating part is separated from the bottom acoustic probe 1 and the counterweight 2 under the action of the spring force. The battery compartment 4 is a cylindrical sealed pressure-resistant structure with an axial through hole in the center. It is installed at the upper end of the fuse separation mechanism 3, but is not fixed to the fuse separation mechanism 3. It can be separated from the fuse separation mechanism 3 under the action of external force; the purpose of the through hole in the center of the battery compartment 4 is to leave space for the top rod 31 and the wires in the fuse separation mechanism 3. The battery compartment 4 is sealed with a battery 41 inside, which is responsible for providing energy for the entire instrument.The fuse compartment 5 is an open structure, and seawater can flow in freely. The fuse compartment 5 is fixedly connected to the battery compartment 4. An opening with the same diameter as the battery compartment 4 is opened in the center of the bottom surface of the fuse compartment 5, which is used for the wires and the top rod 31 of the fuse separation mechanism 3 to pass through; four axially evenly distributed bayonet holes are opened on the wall of the fuse compartment 5, and the buckles 32 of the fuse separation mechanism 3 can be buckled into their corresponding bayonet holes when locked; the fuse compartment 5 is fixedly connected to the battery compartment 4 and the electronic compartment 6; two symmetrically distributed fuses 51 are installed inside the fuse compartment 5, and the fuse wire 52 is installed in the fuse 51, and can pass through the hole at the upper end of the top rod 31 when the top rod 31 in the fuse separation mechanism 3 compresses the spring 34, and offsets the force of the spring 34 so that the top rod 31 cannot move up. The electronic cabin 6 is a cylindrical pressure-resistant sealed structure, with necessary control modules and data communication modules installed inside, and is fixedly connected to the fuse cabin 6. In addition, an electric push rod 61 is also installed inside the electronic cabin 6; the telescopic rod of the electric push rod 61 is sealed and passes through from the bottom of the electronic cabin and extends into the fuse cabin 5, and the telescopic rod of the electric push rod 61 and the top rod 31 of the fuse separation mechanism 3 are respectively installed with underwater wet plug connectors 62; the electric push rod 61 is initially in an extended state. After the measurement of the disposable seabed sediment acoustic characteristics in-situ measuring instrument is completed, the telescopic rod of the electric push rod 61 is retracted to drive the underwater wet plug connector 62, thereby realizing the line separation of the floating part and the discarded part. The buoyancy module 7 is responsible for providing the buoyancy required for the floating part of the structure. At the same time, the buoyancy module 7 also has four wing-shaped structures evenly distributed circumferentially, which are responsible for regulating the posture of the disposable seabed sediment acoustic characteristics in-situ measuring instrument when it sinks. A transmitting transducer 71 is installed under the two wings, and a communication antenna 72 is installed on the upper end of the buoyancy module 7. The buoyancy module 7 also needs to be fixedly connected to the electronic cabin 6.

[0023] Since the fuse separation mechanism 3 of the present invention requires sufficient space during installation, it is necessary to first complete the installation of the acoustic probe 1, the counterweight 2, the fuse separation mechanism 3, the battery compartment 4 and the fuse compartment 5, and reserve sufficient wire length. Only after these five parts are completely installed can the electronic compartment 6 and the buoyancy module 7 be loaded on the fuse compartment 5. Specifically, after the acoustic probe 1, the counterweight 2, and the fuse separation mechanism 3 are assembled with each other and the connecting rod mechanism inside the fuse separation mechanism is assembled, the battery compartment 4 and the fuse compartment 5 are fixed to each other first, and then the top rod 31 of the fuse separation mechanism 3 and the related circuits are passed through the central through holes of the battery compartment 4 and the fuse compartment 5. The battery compartment 4 is fitted on the fuse separation base 35 through the step-like structure at the bottom, so that it is not easy to shake, but can still move upward in the axial direction. At the same time, the spring 34 is compressed to make the buckle 32 tightly buckle on the buckle on the wall of the fuse compartment 5, so as to achieve the locking of the counterweight 2 with the battery compartment 4 and the fuse compartment 5. At the same time, the through hole at the top of the top rod 31 can be aligned with (or close to) the wire hole of the fuse 51. At this time, the fuse wire 52 is installed so that it can offset the force of the spring 34, so that the locking and loosening of the fuse separation mechanism 3 can be achieved by controlling the melting of the fuse wire 52. After that, it only needs to be assembled normally.

[0024] The structural parameters of the measuring instrument meet the following multi-objective optimization model: the objectives are to maximize the measurement accuracy, optimize the sinking stability, maximize the floating reliability and minimize the system weight; solve the multi-objective optimization model to obtain the optimized structural parameters of the measuring instrument; specifically, the structural parameters include the distance L between the transmitting transducer and the receiving transducer, the weight of the counterweight , buoyancy of the floating part , counterweight cone structure taper angle , Wing structure span length , Total system length , Battery compartment capacity , System power consumption , measurement time , Spring preload , locking force , Acoustic probe cone tip angle , Center of gravity , Wall thickness of each sealed compartment , the contact area between buckle and bayonet .

[0025] The multi-objective optimization model is specifically expressed as follows: Objective function 1-maximize measurement accuracy: ; In the formula, For the Theoretical value of each measuring point; is the measured value; is the inclination angle of the acoustic probe; The interference degree of the receiving transducer signal; is the weight coefficient, and its value range is ; is the number of measuring points; Objective function 2-optimal sinking stability: ; In the formula, is the lateral and longitudinal angular velocity; is the vertical speed; is the attitude angle; is the weight coefficient, and its value range is ; for the sinking time; Objective function 3-maximum floating reliability: ; In the formula, is the probability of successful separation; is the failure rate; is the running time; Objective function 4-minimum system weight: ; In the formula, For the The density of the components; is the corresponding volume; is the total number of parts; The constraints include at least: 1. The distance L between the transmitting transducer and the receiving transducer is greater than 3 to 4 sound wave wavelengths; 2. Buoyancy ratio constraint: ; 3. Dynamic stability constraints: ; In the formula, is the damping coefficient; is the allowable error; 4. Structural strength constraints: ; In the formula, is the maximum stress; is the allowable stress; The solution method of the multi-objective optimization model adopts the improved NSGA-III algorithm, and the specific solution steps are as follows: Step 1: Initial population generation: ; In the formula, For the Individuals represent a set of structural parameters; is the population size; Step 2: Fitness calculation: ; In the formula, For the The weight of each target; is the objective function value; Step 3: Non-dominated sorting: ; In the formula, is the indicator function; express Dominate ; Step 4: Crowding calculation: ; Step 5: Select an action: ; In the formula, is the offspring population; is a selection operator based on non-dominated sorting; Step 6: Crossover operation: ; In the formula, is the cross coefficient, subject to Even distribution; Step 7: Mutation operation: ; In the formula, is a normally distributed random number; Step 8: Termination judgment: When the number of iterations reaches the maximum value or the population converges, the calculation stops and the Pareto optimal solution set is output; Parameter acquisition method: 1. Through finite element simulation, we can obtain: ; In the formula, is the sound field potential; is the wave number; 2. Measured by water tank test: Experimental steps: (1) Arrange the photoelectric tracking system in the pool; (2) Install reflective markers on the measuring instrument; (3) Launch the measuring instrument and record the motion trajectory; (4) Obtain the angular velocity time history through data processing; 3. Obtained through reliability test: Test steps: (1) Conduct Separation test; (2) record the number of successes ;(3) Calculation ; 4. Through stress analysis, we can obtain: ; In the formula, is the radial stress; is the hoop stress; is the shear stress.

[0026] The optional optimization model can also include the following constraints: (1) The distance L between the transmitting transducer and the receiving transducer is greater than 3 to 4 sound wave wavelengths; (2) The ratio of the mass M of the counterweight to the buoyancy F of the floating part should satisfy the following constraint: 1.2≤M / F≤1.5. This constraint ensures the rationality of the sinking speed. (3) The taper angle θ of the counterweight cone structure should satisfy the following constraint: 10°≤θ≤25°. This constraint is used to optimize the hydrodynamic performance. (4) The ratio of the span length S of the four wing-shaped structures of the buoyancy module to the total length H of the instrument should satisfy the following constraint: 0.15≤S / H≤0.25. This constraint is used to ensure attitude stability. (5) The relationship between the volume V of the battery compartment, the total power consumption P of the system and the measurement time T should satisfy: V ≥ αPT, where α is the safety factor and 1.2 ≤ α ≤ 1.5; (6) The ratio of the spring preload force F1 to the locking force F2 of the fuse separation mechanism should satisfy: 2≤F1 / F2≤3. This constraint ensures the separation reliability; (7) The cone tip angle β of the acoustic probe should satisfy the following constraint: 30°≤β≤45°. This constraint is used to optimize the penetration resistance. (8) The center of gravity of the whole machine should be located at a distance d below the upper surface of the counterweight, which should satisfy the following conditions: 0.2H≤d≤0.3H, where H is the total length of the instrument. This constraint ensures the sinking stability. (9) The wall thickness t of each sealed compartment is to satisfy the following requirement: t ≥ kP0h / σs, where k is the safety factor and is between 1.5 and 2.0, P0 is the design water depth pressure, h is the compartment diameter, and σs is the allowable material stress; (10) The contact area A between the clip of the fuse separation mechanism and the clip of the fuse compartment should satisfy: A ≥ βF2, where β is the surface pressure coefficient and is in the range of 0.8-1.2, and F2 is the locking force.

[0027] Step S1: Initial population generation.

[0028] First, we need to generate the initial population The population consists of Individual Composition, each individual Represents a set of structural parameters. Specifically, a uniform distribution method can be used to randomly generate feasible solutions as the initial population .

[0029] Step S2: Fitness calculation.

[0030] For each individual , its fitness needs to be calculated The fitness function is a weighted sum of four objective functions, namely: ; in, For the The weight coefficient of the objective function, For the The objective function is in the individual The value at .

[0031] Step S3: non-dominated sorting.

[0032] The population is sorted by non-dominated sorting method. Specifically, define the indicator function ,like Dominate Then its value is 1, otherwise it is 0. Then calculate each individual Non-dominated level .

[0033] Step S4: Calculation of congestion degree.

[0034] For each individual , calculate its congestion , which indicates the sparseness of the individual in the target space. The calculation formula for crowding is: ; in, and Respectively The maximum and minimum values ​​of the objective function.

[0035] Step S5: Select an operation.

[0036] Based on the aforementioned non-dominated sorting and crowding information, the selection strategy of the NSGA-III algorithm can be used to select the current population. and progeny population Select and get the next generation population .

[0037] Step S6: Crossover operation.

[0038] For the selected individual pairs , we can use convex combination to perform crossover operation and get new individuals : ; in, is the cross coefficient, subject to of uniform distribution.

[0039] Step S7: mutation operation.

[0040] For newly generated individuals , we can use Gaussian mutation to perform mutation operation and get the mutated individuals: ; in, It means that the mean is 0 and the variance is A normally distributed random number.

[0041] Step S8: Terminate the judgment.

[0042] Repeat steps S2 to S7 until the number of iterations reaches the maximum or the population converges, and then output the current Pareto optimal solution set.

[0043] Parameter acquisition method: 1. Measurement point value Obtaining: Solving the acoustic field equations through finite element simulation Obtain, among which is the sound field potential, is the wave number.

[0044] 2. Angular velocity and Obtaining: Obtained through water pool test measurement. The specific steps are: (1) Arrange the photoelectric tracking system in the water pool; (2) Install reflective markers on the measuring instrument; (3) Launch the measuring instrument and record the motion trajectory; (4) Obtain the angular velocity time history through data processing.

[0045] 3. Separation success probability Obtaining: Obtained through reliability testing. The specific steps are: (1) Separation test; (2) record the number of successes ; (3) Calculation .

[0046] 4. Maximum stress Obtaining: Obtained through stress analysis. The calculation formula is: ; in, is the radial stress, is the hoop stress, is the shear stress.

[0047] In addition, the following constraints can be considered: (1) The distance L between the transmitting transducer and the receiving transducer is greater than 3 to 4 sound wave wavelengths.

[0048] (2) Counterweight quality With buoyancy The ratio should satisfy: .

[0049] (3) Taper angle of the counterweight cone structure Should meet: .

[0050] (4) Span length of the buoyancy module wing structure Total length of the instrument The ratio should satisfy: .

[0051] (5) Battery compartment capacity Should meet: ,in is the safety factor and , is the system power consumption, To measure time.

[0052] (6) Spring preload of fuse separation mechanism And locking force The ratio should satisfy: .

[0053] (7) Angle of the conical tip of the acoustic probe Should meet: .

[0054] (8) Center of gravity of the whole machine Should meet: ,in is the total length of the instrument.

[0055] (9) Wall thickness of each sealed compartment Should meet: ,in is the safety factor and , is the design water depth pressure, is the cabin diameter, is the allowable stress of the material.

[0056] (10) The contact area between the clip of the fuse separation mechanism and the clip of the fuse compartment Should meet: ,in is the surface pressure coefficient and , For the locking force.

[0057] By solving this multi-objective optimization problem, the optimal size ratio of each component can be obtained, thereby achieving comprehensive optimization of measurement accuracy, sinking stability, floating reliability and system weight.

[0058] When the present invention is used, after completing the assembly of the structure and ensuring that the fuse separation mechanism 3 can be locked normally, it can be directly put into the seawater. Due to the structure and mass distribution of the present invention with a heavy and small lower part and a light and large upper part, it can gradually adjust its posture like a "tumbler" when sinking so that the angle between the instrument axis and the vertical direction is stable in a very small range. At the same time, the structure of the tail wing can also assist the overall posture of the instrument to return to a vertical state, so that after quickly sinking to the seabed, the vertical penetration of the instrument can be basically guaranteed. After the instrument is penetrated, the control system can detect that the instrument is stable (for example, through an accelerometer) and start measuring the sediment. After the measurement is completed, the control system energizes the fuse 52 through the fuse 51. After the fuse 52 is blown, it can no longer resist the force of the spring 34 in the fuse separation mechanism 3, so that the top rod 31 moves upward under the action of the spring 34, and the buckle 32 is released. The battery compartment 4 and the module above it are separated from the fuse separation mechanism 3 and the counterweight 2 below under the action of the spring 34 and its own buoyancy, thereby carrying the measured data to the sea surface and transmitting the data back through the antenna 72.

[0059] Specifically, the principle of the present invention is: 1. The acoustic probe is the core component of the instrument, equipped with two hydroacoustic receiving transducers set at intervals. During the sinking process, the acoustic probe can vertically penetrate the seabed to measure the propagation time difference and amplitude attenuation of the sound wave, thereby obtaining parameters such as the sound velocity and attenuation coefficient. In order to optimize the performance of entering the soil, the acoustic probe adopts a special conical tip design, which can minimize the resistance to entering the soil and improve the measurement accuracy.

[0060] 2. The counterweight is a key component required to achieve the sinking of the instrument. In order to balance the sinking stability and structural strength, the counterweight adopts a trapezoidal frustum structure, in which the short side corresponds to the small diameter section and the long side corresponds to the large diameter section. This structure can not only control the center of gravity within a reasonable range, but the inclination angle on the frustum surface is also conducive to optimizing the hydrodynamic characteristics and ensuring the stability of the sinking process.

[0061] 3. The fuse separation mechanism is the key to separating the floating part from the abandoned part. The mechanism is composed of components such as a push rod, a connecting rod, and a buckle, and is locked and released by a spring. After the measurement is completed, the action of the fuse moves the push rod upward, driving the connecting rod and the buckle to separate, thereby achieving the autonomous release of the floating part. In order to ensure the reliability of separation, the design of the fuse separation mechanism fully considers factors such as preload, locking force, and contact area, ensuring a separation success rate of up to 98%.

[0062] 4. The battery compartment, fuse compartment and electronic compartment constitute the core structure of the floating part. The battery compartment is sealed with batteries to provide energy for the entire instrument; the fuse compartment is equipped with fuses to work with the fuse separation mechanism; the electronic compartment is equipped with electronic equipment such as control modules, data communication modules and electric push rods to achieve line separation between the floating part and the jettison part.

[0063] 5. The buoyancy module is the key to achieving stable sinking and reliable floating. The module has four wing-shaped structures evenly distributed around the circumference, which can actively adjust the posture during the sinking process to ensure vertical entry into the sea. A communication antenna is also installed on the top of the module for data transmission. By reasonably designing the buoyancy size, it can achieve smooth floating without excessive floating affecting the measurement stability.

[0064] 6. The working principle of the present invention is as follows: the measuring instrument of the present invention is directly dropped into the seawater from a mobile platform (such as a scientific research vessel), and the measuring instrument relies on its own gravity and realizes rapid and stable sinking in a vertical posture under the regulation of its own appearance characteristics, the position of the center of gravity and buoyancy, and the tail wing; after sinking to the seabed, the measuring instrument relies on its own kinetic energy to penetrate into the sediment, and autonomously performs in-situ measurement of the sediment through the transmitting transducer on the tail wing and the receiving transducer on the acoustic probe, and stores the results in the electronic cabin; after the measurement is completed, the fuse wire is blown by the fuse in the fuse cabin, and the fuse separation mechanism releases the floating part, and at the same time, the electric push rod in the electronic cabin disconnects the underwater wet plug connector, and the floating part floats to the sea surface under the action of its own buoyancy, and the measurement data is recovered through the antenna on the buoyancy module.

[0065] In summary, the present invention realizes the disposable in-situ measurement of the acoustic characteristics of seabed sediments, and through the optimized design of components such as the acoustic probe rod, counterweight, fuse separation mechanism, and electronic cabin, it achieves the improvement of measurement accuracy, the stability of the sinking process, the reliability of floating separation, and the reduction of the weight of the whole machine. It is a disposable in-situ measuring instrument for the acoustic characteristics of seabed sediments with excellent performance.

[0066] An embodiment of a specific application scenario of the present invention is provided below: The disposable in-situ measuring instrument for acoustic characteristics of seabed sediments of the present invention is mainly composed of acoustic probe, counterweight, fuse separation mechanism, battery compartment, fuse compartment, electronic compartment and buoyancy module, etc. The working principle and structural design thereof are described below with a specific embodiment.

[0067] The main parameters of the measuring instrument are shown in Table 1. The diameter of the acoustic probe rod D is 60 mm, and the distance between the transmitting transducer and the receiving transducer L is 700 mm. The mass of the counterweight M is 6 kg, and the buoyancy F of the floating part is 45 N. The cone angle of the counterweight is The span length S of the four wing-shaped structures of the buoyancy module is 220 mm, and the total length H of the system is 1 m. The volume V of the battery compartment is 800 cm , the system power consumption P is 100W, and the measurement time T is 5min. The spring preload of the fuse separation mechanism The locking force is 200N. 500N. Acoustic probe cone tip angle The angle is 40°, and the center of gravity position d is 0.3m. The wall thickness t of each sealed compartment is 5mm, and the contact area A between the buckle and the bayonet is 160mm. .

[0068] Table 1 Main parameters of measuring instrument

[0069] The working process of the measuring instrument is as follows:

[0070] 1. The acoustic probe is installed at the lower end of the instrument and is equipped with two hydroacoustic receiving transducers spaced 100 mm apart. When penetrating into the seabed sediment and starting measurement, the sound wave signal will reach the two transducers in succession. By measuring the propagation time difference and amplitude attenuation of the sound wave, parameters such as the sound velocity and attenuation coefficient can be obtained, thereby realizing in-situ measurement of the acoustic characteristics of the seabed sediment.

[0071] 2. The counterweight adopts a trapezoidal frustum structure, with a short side diameter of 60mm, a long side diameter of 120mm, and a height of about 310mm. This structure can control the center of gravity at 0.3m, which is conducive to the stability of the sinking process. At the same time, the 12° inclination angle of the frustum can also optimize the hydrodynamic performance and reduce the resistance to entering the soil.

[0072] 3. The fuse separation mechanism consists of a push rod, a connecting rod and a buckle, and is locked with the battery compartment and the fuse compartment through a 200N spring preload. After the measurement is completed, the push rod moves upward through the action of two symmetrically arranged fuses, driving the connecting rod and the buckle to separate, thereby achieving the autonomous release of the floating part. The locking force F of this mechanism is The load is 500N, which can reliably keep the counterweight fixed.

[0073] 4. The battery compartment is sealed with a volume of 800cm The fuse compartment is equipped with two fuses, which work in conjunction with the fuse separation mechanism. The electronic compartment is equipped with electronic equipment such as control modules, data communication modules and electric push rods to achieve line separation between the floating part and the jettison part.

[0074] 5. The buoyancy module has four wing-shaped structures evenly distributed around the circumference, with a length of 220mm, which can adjust the posture during the sinking process to ensure vertical entry into the sea. The buoyancy of the floating part is 45N, which forms a buoyancy ratio of 1.2-1.5 with the 6kg counterweight mass, which can achieve smooth floating without excessive floating affecting the measurement stability. A communication antenna is installed on the top of the module for real-time transmission of measurement data.

[0075] Through the above design, the discarded in-situ measuring instrument for acoustic characteristics of seabed sediments can achieve the following performances: 1. The measurement accuracy is improved by more than 20%. The acoustic probe adopts a special conical tip design, which can minimize the resistance to soil penetration. At the same time, the interval measurement method of the two hydroacoustic receiving transducers greatly improves the measurement accuracy of sound velocity and attenuation coefficient.

[0076] 2. Excellent stability during the sinking process. The counterweighted trapezoidal cone structure and the four tail fins of the buoyancy module can accurately control the sinking posture and speed of the instrument. The water tank test shows that the trajectory deviation is only 3%.

[0077] 3. High reliability of floating separation. The fuse separation mechanism firmly fixes the counterweight with a locking force of 500N, and can be quickly released when the fuse is actuated. Reliability tests show that the separation success rate is 98%.

[0078] 4. The weight of the whole machine is significantly reduced. Through optimized design, the total weight of the measuring instrument is only about 15kg, which greatly improves the convenience of deployment and recovery.

[0079] In summary, the disposable in-situ measuring instrument for the acoustic properties of seabed sediments, through the systematic optimization design of components such as acoustic probes, counterweights, and fuse separation mechanisms, is superior to existing technologies in key indicators such as measurement accuracy, sinking stability, floating reliability, and overall weight, providing a new high-performance solution for the in-situ measurement of the acoustic properties of seabed sediments.

[0080] Example 2 Optimization of measuring instrument structure parameters based on multi-objective optimization The disposable in-situ measuring instrument for acoustic characteristics of seabed sediments of the present invention involves multiple key structural parameters, such as the distance L between the transmitting transducer and the receiving transducer, the weight mass M, the buoyancy F, the taper angle of the counterweight truncated cone structure, and the relative position of the truncated cone. , buoyancy module wing length S, etc. The reasonable values ​​of these parameters have an important impact on the instrument's measurement accuracy, sinking stability, floating reliability, and overall weight. In order to comprehensively optimize these performance indicators, a multi-objective optimization model was established and solved using the improved NSGA-III algorithm.

[0081] The specific expression of the multi-objective optimization model is as follows: Objective function 1-maximize measurement accuracy: ; Objective function 2-optimal sinking stability: ; Objective function 3-maximum floating reliability: ; Objective function 4-minimum system weight: ; in, For the Theoretical value of the measuring point, is the measured value, is the inclination angle of the acoustic probe, is the interference degree of the receiving transducer signal, and is the weight coefficient, is the number of measuring points; and are the lateral and longitudinal angular velocities, is the vertical velocity, is the attitude angle, and is the weight coefficient, for the sinking time; is the probability of successful separation, is the failure rate, is the running time; For the Component density, is the corresponding volume, is the total number of parts.

[0082] The optimization solution process is as follows: Step 1. Initial population generation. Randomly generate in the feasible domain of each parameter individuals as the initial population .

[0083] Step 2. Fitness calculation. According to the above objective function formula, calculate each individual Fitness .

[0084] Step 3. Non-dominated sorting. Use the non-dominated sorting strategy of the NSGA-III algorithm to calculate the non-dominated level of each individual. .

[0085] Step 4. Crowding calculation. According to the sparsity in the target space, calculate the crowding degree of each individual .

[0086] Step 5. Select an operation. Based on the non-dominated sorting and congestion information, the selection strategy of the NSGA-III algorithm is adopted. and Select the next generation of population .

[0087] Step 6. Crossover operation. , crossover is performed by convex combination to obtain new individuals .

[0088] Step 7. Mutation operation. , using Gaussian mutation to obtain the new individual after mutation .

[0089] Step 8. Termination judgment. Repeat steps 2-7 until the number of iterations reaches the maximum value or the population converges, then output the Pareto optimal solution set.

[0090] By solving the multi-objective optimization model, the optimal values ​​of the structural parameters of the measuring instrument are obtained, as shown in Table 2. Among them, the distance L between the transmitting transducer and the receiving transducer is 700mm, and the weight mass is 6kg, buoyancy The counterweight cone structure has a taper angle of 45N. 12°, buoyancy module wing length 220mm, total system length For 1m, the battery compartment volume 800cm ,System power consumption 100W, measurement time For 5min, spring preload The locking force is 200N. 500N, probe tip angle is 40°, the center of gravity 0.36m, the cabin wall thickness 5mm, buckle contact area 160mm .

[0091] Table 2 Optimized measuring instrument structural parameters

[0092] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A disposable in-situ measuring instrument for acoustic properties of seabed sediments, comprising: Acoustic probe, counterweight, fuse separation mechanism, battery compartment, fuse compartment, electronic compartment and buoyancy module; the acoustic probe, counterweight and fuse separation mechanism are the discarded part, and the battery compartment, fuse compartment, electronic compartment and buoyancy module are the floating part; the acoustic probe is installed at the lower end of the instrument and is equipped with two receiving transducers arranged at intervals; the counterweight is a whole piece of material, which is used to provide the gravity required for the sinking of the discardable in-situ measuring instrument for acoustic characteristics of seabed sediments; the fuse separation mechanism is a three-link mechanism composed of a push rod, a connecting rod and a buckle driven by a spring, which drives the movement of the internal push rod through the spring to drive the connecting rod and the buckle to achieve locking and loosening; the battery compartment, fuse compartment, electronic compartment and buoyancy module are arranged in the manner described in the sequential manner. The components are installed in sequence and are fixedly connected to each other, with the battery compartment at the bottom, connected to the fuse separation mechanism, but not fixedly connected to each other; a battery for providing energy is placed inside the battery compartment; the fuse compartment is used to cooperate with the fuse separation mechanism to achieve the locking and loosening of the buckle in the fuse separation mechanism, and a fuse is installed inside it; the electronic compartment is installed with electronic devices, an underwater wet plug connector and an electric push rod, and the two ports of the underwater wet plug connector are respectively installed on the top rod of the fuse separation mechanism and the electric push rod, and the connection and disconnection of the underwater wet plug connector are achieved through the action of the electric push rod; the buoyancy module provides the buoyancy required for the battery compartment, the fuse compartment, and the electronic compartment to float, and its structure is designed with a tail wing for adjusting the falling posture and an antenna for sending data.

2. The disposable in-situ measuring instrument for acoustic properties of seabed sediments according to claim 1, characterized in that: The acoustic probe rod is a rod-shaped structure with a conical tip at one end, and two annular underwater acoustic receiving transducers spaced a certain distance apart are installed on the outer wall. The acoustic probe rod and the counterweight are fixedly connected to each other.

3. The disposable in-situ measuring instrument for acoustic properties of seabed sediments according to claim 2, characterized in that: The counterweight is a truncated cone structure, and the longitudinal cross-section of the truncated cone structure is a trapezoid, including a short side and a long side. The short side corresponds to a section of the truncated cone structure with a smaller diameter, and the long side corresponds to a section of the truncated cone structure with a larger diameter. The acoustic probe rod is installed at the section with a smaller diameter of the circular surface, and the fuse separation mechanism is installed at the end with a larger diameter of the circular surface. There is a through hole along the axis inside the counterweight for routing the receiving transducer.

4. The disposable in-situ measuring instrument for acoustic properties of seabed sediments according to claim 3, characterized in that: The fuse separation mechanism includes a push rod, a buckle, a connecting rod, a spring, and a fuse separation base, wherein the push rod, the buckle, and the connecting rod are hinged by a pin shaft and fixed on the fuse separation base; a through hole is opened at the top of the push rod column for passing the fuse wire; the mechanism controls the locking and loosening of the buckle through the up and down movement of the push rod driven by the connecting rod; a spring is installed at the bottom of the push rod at the center of the fuse separation base, and when the installation is locked, the push rod drives the buckle to swing toward the inside of the instrument and buckle on the buckle on the wall of the fuse compartment, locking the counterweight with the battery compartment and the electronic compartment, while making the bottom spring in a compressed state.

5. The disposable in-situ measuring instrument for acoustic properties of seabed sediments according to claim 4, characterized in that: The battery compartment is a cylindrical sealed pressure-resistant structure with an axial through hole at the center. It is installed at the upper end of the fuse separation mechanism but is not fixedly connected to the fuse separation mechanism, so that it can be separated from the fuse separation mechanism under the action of external force. The purpose of providing a through hole in the center of the battery compartment is to leave space for the top rod and wires in the fuse separation mechanism. A battery is sealed inside the battery compartment, which is responsible for providing energy for the entire instrument.

6. The disposable in-situ measuring instrument for acoustic properties of seabed sediments according to claim 5, characterized in that: The fuse compartment is an open structure, and seawater can flow in freely. The fuse compartment is fixedly connected to the battery compartment. An opening with the same diameter as the battery compartment is opened in the center of the bottom surface of the fuse compartment, which is used for the wires and the top rod of the fuse separation mechanism to pass through; four axially evenly distributed bayonet slots are opened on the wall surface of the fuse compartment, and the buckles of the fuse separation mechanism can just buckle on their corresponding bayonet slots when locked; the fuse compartment is fixedly connected to the battery compartment and the electronic compartment; two symmetrically distributed fuses are installed inside the fuse compartment, and the fuse wire is installed on the fuse, and can pass through the hole at the upper end of the top rod when the top rod in the fuse separation mechanism compresses the spring, and offset the force of the spring so that the top rod cannot move up.

7. The disposable in-situ measuring instrument for acoustic properties of seabed sediments according to claim 6, characterized in that: The electronic cabin is a cylindrical pressure-resistant sealed structure, with a control module and a data communication module installed inside, and fixedly connected to the fuse cabin. In addition, an electric push rod is also installed inside the electronic cabin; the telescopic rod of the electric push rod is sealed and passes through from the bottom of the electronic cabin and extends into the fuse cabin, and underwater wet plug connectors are respectively installed on the telescopic rod of the electric push rod and the top rod of the fuse separation mechanism; the electric push rod is initially in an extended state, and after the measurement of the disposable seabed sediment acoustic characteristics in situ measuring instrument is completed, the telescopic rod of the electric push rod is retracted to drive the underwater wet plug connector, thereby realizing the line separation of the floating part and the discarded part.

8. The disposable in-situ measuring instrument for acoustic properties of seabed sediments according to claim 7, characterized in that: The buoyancy module has four wing-shaped structures evenly distributed around it, which are responsible for regulating the posture of the disposable in-situ measuring instrument for acoustic characteristics of seabed sediments when it sinks. Transmitting transducers are installed under two wings, and a communication antenna is installed on the upper end of the buoyancy module. The buoyancy module is fixedly connected to the electronic cabin.

9. The disposable in-situ measuring instrument for acoustic properties of seabed sediments according to claim 8, characterized in that: The installation sequence of the acoustic probe, counterweight, fuse separation mechanism, battery compartment and fuse compartment is as follows: first complete the mutual assembly of the acoustic probe, counterweight and fuse separation mechanism and the assembly of the connecting rod mechanism inside the fuse separation mechanism, then fix the battery compartment and the fuse compartment to each other, and then pass the top rod of the fuse separation mechanism and related lines through the central through holes of the battery compartment and the fuse compartment. The battery compartment is fitted on the fuse separation base through the step-like structure at the bottom, so that it is not easy to shake, but can still move upward axially. At the same time, the spring is compressed so that the buckle is tightly buckled on the buckle on the wall of the fuse compartment, so as to achieve the locking of the counterweight with the battery compartment and the fuse compartment. At the same time, the through hole on the top of the top rod can be aligned with the wire hole of the fuse. At this time, the fuse wire is installed so that it can offset the force of the spring. In this way, the locking and relaxation of the fuse separation mechanism can be achieved by controlling the melting of the fuse wire.

10. A disposable in-situ measuring instrument for acoustic properties of seabed sediments according to any one of claims 1 to 9, characterized in that: The structural parameters of the measuring instrument satisfy the following multi-objective optimization model: taking maximization of measurement accuracy, optimization of sinking stability, maximum buoyancy reliability and minimum system weight as the objectives; solving the multi-objective optimization model to obtain the optimized structural parameters of the measuring instrument.

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