A bottom-mounted acoustic in-situ measurement device for seabed sediments based on an autonomous underwater vehicle

Abstract

The present invention provides a bottom-mounted seabed sediment acoustic in-situ measuring device based on an autonomous underwater vehicle, belonging to the technical field of underwater measurement. The bottom-mounted seabed sediment acoustic in-situ measuring device based on the autonomous underwater vehicle comprises a mounting frame and a pressure-resistant cabin, an electric cylinder and a transmitting transducer. The top of the mounting frame is used to mount the autonomous underwater vehicle, and the bottom is used to mount the measuring device. The pressure-resistant cabin is fixedly mounted on the bottom of the mounting frame and is used to supply power to the measuring device and communicate with the outside. The electric cylinder is fixedly connected to the bottom of the mounting frame and is located on both sides of the pressure-resistant cabin. It is used to receive signals from the pressure cabin and penetrate deep into the sediment to detect sediments to be detected when the autonomous underwater vehicle is idle. The transmitting transducer is located at the bottom of the mounting frame and is fixedly connected to the mounting frame for transmitting signals. The present invention can combine the seabed sediment acoustic in-situ measuring device with the autonomous underwater vehicle, has a small size, and is flexible and convenient to use.

Description

Technical Field

[0001] The present invention belongs to the technical field of underwater measurement, and in particular relates to a bottom-mounted acoustic in-situ measurement device for seabed sediments based on an autonomous underwater vehicle. Background Art

[0002] The acoustic properties of seabed sediments are crucial for the study of seabed geological structure, sediment physical properties, ocean sound propagation, etc., and play an important role in the exploration of oil and gas resources, the development of deep-sea resources, and the evaluation of geological engineering.

[0003] Currently, there are two main methods for measuring the acoustic properties of seabed sediments: laboratory measurement and in-situ measurement. Laboratory measurement involves taking samples from the seabed and bringing them back to the laboratory for measurement. This process may damage the original structure of the sediment, resulting in large errors in the actual measurement data. In-situ measurement is performed directly on the seabed without the need for sampling, completely preserving the natural state of the sediment, and resulting in smaller errors in the measurement results. Existing in-situ measurement instruments usually require a winch or use their own gravity for deployment. The instruments are usually large, heavy, and labor-intensive, and may be interfered with and unable to complete when measuring sensitive sea area information.

[0004] The bottom-mounted acoustic in-situ measurement device for seabed sediments, based on autonomous underwater vehicles (AUVs), can be flexibly mounted on various types of AUVs. This allows for the measurement of seabed sediments during their free time, without affecting their normal operations. It is flexible to use and easy to install. However, the main application of this technology is the combination of acoustic in-situ measurement of seabed sediments with autonomous underwater vehicles (AUVs), which remains relatively limited. Summary of the Invention

[0005] In view of this, the present invention provides a bottom-mounted seabed sediment acoustic in-situ measurement device based on an autonomous underwater vehicle, which can combine the seabed sediment acoustic in-situ measurement device with the autonomous underwater vehicle, has a small size, and is flexible and convenient to use.

[0006] The present invention is achieved in that:

[0007] The present invention provides a bottom-mounted acoustic in-situ measurement device for seabed sediments based on an autonomous underwater vehicle. The device comprises a mounting frame, a pressure-resistant cabin, an electric cylinder, and a transmitting transducer. The top of the mounting frame is used to mount the autonomous underwater vehicle, and the bottom is used to mount the measuring device. The pressure-resistant cabin is fixedly mounted on the bottom of the mounting frame and is used to supply power to the measuring device and communicate with the outside. The electric cylinder is fixedly connected to the bottom of the mounting frame and is located on both sides of the pressure-resistant cabin. The electric cylinder is used to receive signals from the pressure-resistant cabin and penetrate deep into the sediment to detect sediments to be detected when the autonomous underwater vehicle is idle. The transmitting transducer is located at the bottom of the mounting frame and is fixedly connected to the mounting frame for transmitting signals.

[0008] On the basis of the above technical solution, the present invention's bottom-mounted seabed sediment acoustic in-situ measurement device based on an autonomous underwater vehicle can also be improved as follows:

[0009] Among them, the mounting frame includes a bottom bracket, a mounting base and a clamp ring. The bottom bracket is two circular ring structures arranged in front and back, which are used to provide a support structure for the entire body structure of the measuring device. The mounting base is a flat structure, located above the inside of the bottom bracket, and is used to install the pressure cabin, electric cylinder and transmitting transducer. Two clamp rings are provided on the top of the bottom bracket for installing and fixing the autonomous underwater vehicle.

[0010] Furthermore, the electric cylinder includes two groups, which are respectively installed on the front and rear sides of the mounting base. Each electric cylinder consists of two parts, including a motor, a multi-stage telescopic mechanism and a probe. The electric cylinder base at the bottom of the multi-stage telescopic mechanism is installed on the mounting base and is fixedly connected to the mounting base. One side of the bottom of the electric cylinder base is fixedly connected to the multi-stage telescopic mechanism, and the other side is fixedly connected to the motor. The motor is used to control the extension and retraction of the multi-stage telescopic mechanism; the probe is located at the top of the multi-stage telescopic mechanism and is fixedly connected to the multi-stage telescopic mechanism.

[0011] Furthermore, the multi-stage telescopic mechanism includes a multi-stage sleeve and a transmission screw. The multi-stage sleeve includes a first-stage sleeve and a second-stage sleeve. The first-stage sleeve is fixedly installed on the base of the electric cylinder, and a second-stage sleeve is provided inside. The outer wall of the second-stage sleeve is movably connected to the first-stage sleeve through a slide rail. The inner wall of the second-stage sleeve is provided with a threaded structure. A transmission screw is provided inside the second-stage sleeve. The transmission screw includes an active screw and a driven screw. The active screw is a solid cylindrical structure, and the top is installed on the base of the electric cylinder and is rotatably connected to the base of the electric cylinder. The active screw is engaged with the gear of the motor output shaft through the gear on the top of the outer wall. The driven screw is a hollow cylindrical structure, and the inner and outer walls of the driven screw are provided with threads. The threads on the inner wall of the driven screw match the threads on the outer wall of the active screw, and the threads on the outer wall match the threads on the inner wall of the second-stage sleeve.

[0012] Furthermore, the probe is located at the bottom of the secondary sleeve and is fixedly connected to the secondary sleeve for detecting seabed sediments; a receiving transducer is provided at the bottom of the probe for receiving signals.

[0013] Furthermore, the pressure cabin is a capsule-shaped structure, installed at the bottom of the mounting base, and includes two power supply batteries and an electronic group. The pressure cabin is used to power the acoustic in-situ measurement device. The electronic group is equipped with a control module and a communication module for receiving instructions and controlling the rotation of the motor.

[0014] Furthermore, two floating modules are provided inside the base support. The two floating modules are arranged on both sides of the base support and are fixedly connected to the base support to balance the overall gravity and buoyancy and reduce the impact on the normal operation of the autonomous underwater vehicle.

[0015] Furthermore, the pressure cabin is fixedly connected to the mounting base via a circular connecting component, the center of the pressure cabin is welded to the circular connecting component, and the circular connecting component is connected to the mounting base via bolts.

[0016] Furthermore, the bottom of the electric cylinder is welded to one end of the right-angle connecting plate, and the other end is fixedly connected to the mounting base by bolts.

[0017] Furthermore, the surface of the probe has a tree-like structure.

[0018] Compared with the existing technology, the beneficial effects of the bottom-sitting seabed sediment acoustic in-situ measurement device based on an autonomous underwater vehicle provided by the present invention are: before the start of work, the bottom-sitting seabed sediment acoustic in-situ measurement device based on an autonomous underwater vehicle (AUV) needs to be installed on the bottom of the autonomous underwater vehicle (AUV) through a clamp ring. During the idle time of its main task, the device dives to the seabed with the autonomous underwater vehicle (AUV) and sits on the seabed under the support of the bottom support. At the start of the operation, the data communication module receives a command from the autonomous underwater vehicle (AUV). Upon receiving the command, the control module issues a command to the motor on the side of the electric cylinder, which activates the motor. The forward rotation of the gears causes the active screw to rotate, pushing the driven screw downward. The secondary sleeve, through threads, moves synchronously with the driven screw, and the probe, through threads, moves synchronously with the secondary sleeve, thus penetrating the probe into the seabed sediment. Similarly, after the measurement is completed, the control module issues another command to the motor on the side of the electric cylinder. The motor activates the motor again, which activates the reverse rotation of the gears, causing the active screw to rotate, pushing the driven screw upward. The secondary sleeve, through threads, moves synchronously with the driven screw, and the probe, through threads, moves synchronously with the secondary sleeve, thus retracting the probe from the seabed sediment. The data communication module performs temporary data processing, and the measurement is concluded. After receiving the command from the data communication module that the measurement is complete, the autonomous underwater vehicle (AUV) ends its landing and resumes its journey to other tasks. This bottom-mounted acoustic in-situ measurement device for seabed sediments based on an autonomous underwater vehicle (AUV) can combine in-situ measurement with the autonomous underwater vehicle (AUV) to achieve rapid and convenient measurement of seabed sediment characteristics. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0020] Figure 2 It is a bottom view of the overall structure of the present invention;

[0021] Figure 3 This is a schematic diagram of the pressure cabin structure of the present invention;

[0022] Figure 4 This is a schematic diagram of the structure of the electric cylinder of the present invention;

[0023] Figure 5 It is a schematic diagram of the overall operation of the present invention;

[0024] In the accompanying drawings, the components represented by the reference numerals are as follows:

[0025] 1. Bottom support; 2. Mounting base; 3. Clamping ring; 4. Pressure cabin; 41. Power supply battery; 42. Electronics group; 5. Electric cylinder; 51. Electric cylinder base; 52. Motor; 53. First-stage sleeve; 54. Second-stage sleeve; 55. Probe; 56. Receiving transducer; 6. Transmitting transducer; 7. Floating body module; 8. Autonomous underwater vehicle. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0027] like Figure 1-Figure 5 As shown, a first embodiment of a bottom-mounted seabed sediment acoustic in-situ measurement device based on an autonomous underwater vehicle provided by the present invention is shown. In this embodiment, it includes a mounting frame and a pressure cabin 4, an electric cylinder 5 and a transmitting transducer 6. The top of the mounting frame is used to install the autonomous underwater vehicle 8, and the bottom is used to install the measuring device. The pressure cabin 4 is fixedly installed at the bottom of the mounting frame and is used to power the measuring device and communicate with the outside. The electric cylinder 5 is fixedly connected to the bottom of the mounting frame and is located on both sides of the pressure cabin 4. It is used to receive signals from the pressure cabin 4 and penetrate deep into the sediment to detect the sediment to be detected when the autonomous underwater vehicle 8 is idle. The transmitting transducer 6 is located at the bottom of the mounting frame and is fixedly connected to the mounting frame for transmitting signals.

[0028] Among them, in the above technical scheme, the mounting frame includes a bottom bracket 1, a mounting base 2 and a clamp ring 3. The bottom bracket 1 is two circular ring structures arranged in front and back, which are used to provide a support structure for the entire body structure of the measuring device. The mounting base 2 is a flat plate structure, located above the inside of the bottom bracket 1, and is used to install the pressure cabin 4, the electric cylinder 5 and the transmitting transducer 6. Two clamp rings 3 are provided on the top of the bottom bracket 1 for installing and fixing the autonomous underwater vehicle 8.

[0029] Furthermore, in the above technical solution, the electric cylinder 5 includes two groups, which are respectively installed on the front and rear sides of the mounting base 2. Each electric cylinder 5 consists of two parts, including a motor 52, a multi-stage telescopic mechanism and a probe 55. The electric cylinder base 51 at the bottom of the multi-stage telescopic mechanism is installed on the mounting base 2 and is fixedly connected to the mounting base 2. One side of the bottom of the electric cylinder base 51 is fixedly connected to the multi-stage telescopic mechanism, and the other side is fixedly connected to the motor 52. The motor 52 is used for measurement; the probe 55 is located at the top of the multi-stage telescopic mechanism and is connected to the multi-stage telescopic mechanism to control the extension and contraction of the multi-stage telescopic mechanism. The multi-stage telescopic mechanism is fixedly connected to the seabed deposit when used for exploration.

[0030] Furthermore, in the above technical solution, the multi-stage telescopic mechanism includes a multi-stage sleeve and a transmission screw. The multi-stage sleeve includes a primary sleeve 53 and a secondary sleeve 54. The primary sleeve 53 is fixedly mounted on the electric cylinder base 51, and a secondary sleeve 54 is provided inside. The outer wall of the secondary sleeve 54 is movably connected to the primary sleeve 53 through a slide rail, and the inner wall of the secondary sleeve 54 is provided with a threaded structure. A transmission screw is provided inside the secondary sleeve 54. The transmission screw includes an active screw and a driven screw. The active screw is a solid cylindrical structure, and the top is mounted on the electric cylinder base 51 and is rotatably connected to the electric cylinder base 51. The active screw is engaged with the gear of the output shaft of the motor 52 through the gear at the top of the outer wall. The driven screw is a hollow cylindrical structure, and the inner and outer walls of the driven screw are provided with threads. The threads on the inner wall of the driven screw match the threads on the outer wall of the active screw, and the threads on the outer wall match the threads on the inner wall of the secondary sleeve 54.

[0031] Furthermore, in the above technical solution, the probe 55 is located at the bottom of the secondary sleeve 54 and is fixedly connected to the secondary sleeve 54 for detecting seabed sediments; a receiving transducer 56 is provided at the bottom of the probe 55 for receiving signals.

[0032] Furthermore, in the above technical solution, the pressure cabin 4 is a capsule-shaped structure, installed at the bottom of the mounting base 2, and includes two power supply batteries 41 and an electronic group 42. The two power supply batteries 41 in the pressure cabin 4 are used to power the acoustic in-situ measurement device. The electronic group 42 is internally provided with a control module and a communication module for receiving instructions and controlling the rotation of the motor 52.

[0033] Furthermore, in the above technical solution, two float modules 7 are provided inside the base support 1. The two float modules 7 are arranged on both sides of the base support 1 and are fixedly connected to the base support 1 to balance the overall gravity and buoyancy and reduce the impact on the normal operation of the autonomous underwater vehicle 8.

[0034] Furthermore, in the above technical solution, the pressure cabin 4 is fixedly connected to the mounting base 2 via a circular connecting component, the center of the pressure cabin 4 is welded to the circular connecting component, and the circular connecting component is connected to the mounting base 2 via bolts.

[0035] Furthermore, in the above technical solution, the bottom of the electric cylinder 5 is welded to one end of the right-angled connecting plate, and the other end is fixedly connected to the mounting base 2 by bolts.

[0036] Furthermore, in the above technical solution, the surface of the probe 55 is a tree-shaped structure.

[0037] like Figure 1-Figure 5As shown, the present invention proposes a second embodiment of a bottom-mounted in-situ seabed sediment measurement device based on an autonomous underwater vehicle (AUV). The device comprises: a bottom support 1, a mounting base 2, a clamping ring 3, a pressure chamber 4, an electric cylinder 5, a transmitting transducer 6, and a float module 7. For ease of description, the bottom support 1, mounting base 2, clamping ring 3, pressure chamber 4, electric cylinder 5, transmitting transducer 6, and float module 7 are collectively referred to as the bottom-mounted in-situ seabed sediment measurement device. The bottom support 1 provides support for the entire device. The mounting base 2 is fixed to the bottom support 1, facilitating the installation of various instruments and equipment. The clamping ring 3 has a double semicircular structure and is used to secure the entire bottom-mounted in-situ seabed sediment measurement device to the AUV 8 before operation begins. The pressure chamber 4 is a cylindrical "capsule" structure that accommodates two power batteries 41 and an electronics module 42. The electronics module 42 houses a control module, a data communication module, and other components. There are two groups of electric cylinders 5, distributed on both sides of the mounting base. The main body consists of two parts, namely the motor 52 and the multi-stage telescopic structure. The multi-stage telescopic structure consists of an electric cylinder base 51, a primary sleeve 53, a secondary sleeve 54, a probe 55 and a spiral transmission structure. The primary sleeve 53 is fixed on the electric cylinder base 51, and a slide rail is installed on the inner wall. The secondary sleeve 54 is not fixed, and the inner wall is a threaded structure. The outer wall is equipped with a slide rail, and a telescopic structure is formed with the primary sleeve 53 through the slide rail. A probe 55 is installed at the end of the telescopic structure, and the probe 55 forms a telescopic structure with the secondary sleeve 54 through the slide rail; a transmission screw is installed at the innermost part of the multi-stage telescopic structure, which consists of an active screw and a driven screw. The active screw is a solid cylindrical structure, which is connected to the motor inside the motor 52 through gears. The driven screw is a cylindrical structure with a hollow center. The inner wall thread matches the thread of the active screw, and the outer wall thread matches the thread of the inner wall of the secondary sleeve 54. There are two transmitting transducers 6 for transmitting signals.

[0038] Among them, the bottom bracket 1 is connected to the autonomous underwater vehicle 8 through the clamp ring 3; the bottom bracket 1 is connected to the mounting base 2 through the reserved holes using specific screws; the electric cylinder 5 is connected to the mounting base 2 through a right-angle connecting plate, and the specific connection method is that one side of the right-angle connecting plate is welded to the electric cylinder 5, and the other side has a connecting hole, which is fixed to the mounting base 2 by specific screws; the pressure cabin 4 is connected to the mounting base 2 through a circular connecting component, and the specific connection method is that the circular connecting component is welded to the middle of the outer shell of the pressure cabin 4, and there is a cylindrical protrusion at the bottom of the circular connecting component, and it is designed with a thread, which is convenient for connection with the reserved hole on the mounting base 2. At the same time, a watertight joint is left on the pressure cabin 4, which is convenient for leading out cables to communicate with the autonomous underwater vehicle 8; the transmitting transducer 6 is connected to the mounting base 2 through the threaded structure at its bottom.

[0039] Before use, the present invention needs to install the entire seabed sediment in-situ measurement device to the bottom of the autonomous underwater vehicle 8 through the clamp ring 3. Before measurement, it dives to the seabed with the autonomous underwater vehicle 8 and sits on the seabed under the support of the bottom support 1. When the operation starts, the data communication module of the electronic group 42 receives a command sent by the autonomous underwater vehicle 8. After receiving the command, the control module of the electronic group 42 sends a command to the motor 52 on the side wall of the electric cylinder 5. The motor 52 drives the motor to start working. The positive rotation of the gear causes the active screw to start rotating, which drives the driven screw to rotate and move downward. The secondary sleeve 54 moves synchronously with the driven screw through the thread. The primary sleeve 53 and the probe 55 also move downward synchronously under the action of the slide rail, thereby penetrating the probe 55 into the seabed sediment. Similarly, after the measurement is completed, the control module of the electronic group 42 again sends a command to the motor 52 on the side wall of the electric cylinder 5. The motor 52 starts working. The reverse rotation of the gear causes the active screw to start rotating, which drives the driven screw to rotate and move upward. The secondary sleeve 54 moves synchronously with the driven screw through the thread. The primary sleeve 53 and the probe 55 also move upward synchronously under the action of the slide rail, thereby retracting the probe 55 that has penetrated the seabed sediment. Temporary data processing is performed by the data communication module of the electronic group 42, and the measurement is completed. After receiving the instruction of completing the measurement task from the data communication module of the electronic group 42, the autonomous underwater vehicle 8 stops sitting on the bottom, starts sailing, and continues other operation tasks.

[0040] A specific application scenario of the present invention is provided below:

[0041] After the research vessel completes its positioning in the target area, it smoothly lowers the AUV 8, equipped with a sediment measurement device, to the surface via a deck-mounted hoisting system. The drop location is typically chosen at the inflection point of the continental slope or the top of a submarine canyon, with the operating water depth controlled between 200 and 3,000 meters. Upon entering the water, the AUV 8 immediately activates its autonomous navigation system and proceeds toward the seabed along a pre-set descent path at an inclination angle of 30 to 45 degrees. During the descent, the AUV 8 uses a multibeam echo sounder to monitor changes in the seabed topography in real time, automatically adjusting its trajectory to avoid obstacles.

[0042] When AUV 8 approaches approximately 10 meters from the seabed, the deceleration system activates, reducing its speed from 1.5 knots to 0.3 knots. Once the pressure sensor on the bottom of the support frame contacts the seabed, AUV 8 automatically shuts off its thrusters, leveraging the support frame's triangular support structure to achieve stable landing. The anti-slip teeth on the bottom of the support frame dig approximately 3 to 5 centimeters into the surface sediment, ensuring stability on slopes up to 25 degrees. During this time, AUV 8's attitude sensor continuously monitors the device's tilt and immediately initiates a balancing procedure if it detects a tilt exceeding 5 degrees.

[0043] After stabilizing on the bottom, the AUV's main control system sends a start command to the electronics group in the pressure chamber via a watertight connector. The electronics group first performs a self-check to confirm the normal function of all sensors before sending a start command to the electric cylinders on both sides. The servo motors in the electric cylinders begin rotating the active screw at 200 rpm. This speed is then reduced to 20 rpm by a precision gear train and transmitted to the driven screw.

[0044] As the driven screw rotates, its outer threads engage with the inner threads of the secondary sleeve, pushing the sleeve downward at a constant speed of 8 cm / s. A linear guide within the primary sleeve ensures a vertical deviation of less than 0.5 degrees. The probe head features a conical design with a 60-degree taper angle, allowing real-time monitoring of axial pressure and lateral friction during penetration.

[0045] The measurement system records penetration resistance data at a sampling rate of 100 Hz, covering a range of 5 kPa to 250 kPa with a resolution of 0.1 kPa. Simultaneously collected compression displacement data is measured with a laser displacement sensor, with an accuracy of 0.01 mm. The data processing unit within the electronics suite calculates shear strength and compression modulus in real time, generating a mechanical parameter data package every 10 cm depth.

[0046] In a typical continental slope region, measured data show a stable penetration resistance of 50 to 70 kPa within the surface layer from 0 to 20 cm, corresponding to unconsolidated silty sediments. As the probe penetrates to a depth of 20 to 50 cm, the resistance value decreases significantly, reaching a minimum of 15 kPa and remaining stable within this range. This change in mechanical properties indicates the presence of a weak clay layer approximately 30 cm thick.

[0047] Three repeated penetration measurements at the same station confirmed the spatial continuity of the weak layer. Combined with multibeam topographic data from the Autonomous Underwater Vehicle 8, a three-dimensional map of sediment intensity was constructed for the survey area. Data analysis revealed that in areas with slopes between 18 and 22 degrees, the weak layer was generally over 25 centimeters thick and formed a distinct interface with the underlying sandy layer.

[0048] Based on these parameters, the risk assessment model calculated a safety factor of 1.1 to 1.3 for the area under a magnitude 7 earthquake load, placing it near critical stability. Specifically, at the intersection of two submarine canyons, the model predicted the possibility of a localized landslide, with a volume of approximately 5,000 to 8,000 cubic meters. These results were transmitted in real time to a surface support vessel via hydroacoustic communication, providing a basis for subsequent engineering decisions.

[0049] After completing the on-site measurement, the AUV 8 automatically retracts the probe device and continues operations at the next measurement station according to a pre-set procedure. All raw data is stored in the solid-state memory in the pressure chamber and then uploaded in batches via the underwater acoustic communication module after being processed using a compression algorithm. On the research vessel, specialized software processes the data as follows:

[0050] Deep correction of mechanical parameters to eliminate errors caused by equipment tilt during measurement; screening and elimination of outliers to ensure data quality; comparative analysis with historical measurement data; generation of charts and reports for geological interpretation.

[0051] The resulting results include sediment strength contour maps, potential slip surface distribution maps, and slope stability classification maps. These findings are directly applicable to marine engineering projects such as submarine pipeline routing optimization and platform pile foundation design, and also provide basic data for subsequent scientific research.

[0052] This device demonstrates significant technological progress compared to traditional bottom-mounted measurement equipment. In terms of operational maneuverability, traditional devices require the ship to be repositioned and hoisted for each measurement, while this system uses an autonomous underwater vehicle 8 to achieve single-time deployment and multi-station continuous measurement. Actual tests have shown that within a 3000×3000 meter survey area, the traditional method requires 15-20 deployment operations, while this system only requires 3-5 operations to complete the same workload. The ability to adapt to terrain has been significantly improved. Traditional equipment is prone to failure at slopes exceeding 15 degrees. This device uses a tripod with an anti-slip tooth structure, and can maintain a stable working state at a slope of 25 degrees. Actual measurement data in the South China Sea in 2023 showed that the operation success rate in the 18-22 degree continental slope area increased from 63% of traditional equipment to 92%.

[0053] Measurement efficiency has achieved a significant improvement. Traditionally, single-point measurements require a complete 40-minute process. This system, leveraging the autonomous capabilities of the AUV8, reduces this time to 12-15 minutes. The number of measurement points that can be completed within the same operating timeframe has increased by 2-3 times. Regarding data quality, the penetration rate of traditional equipment fluctuates between 3 and 15 cm / s. This system, through precise control using electric cylinders, achieves a stable penetration rate of 8 ± 0.5 cm / s. Comparative tests have confirmed that the deviation between repeated measurements at the same point has been reduced from 12% to within 5%, significantly improving data reliability.

[0054] This device offers significant advantages in terms of operating costs. Traditional operations require the full cooperation of a survey vessel, with an average daily cost of 80,000 to 120,000 yuan. This system, however, utilizes the autonomous underwater vehicle 8 to conduct measurements during breaks between operations, reducing the marginal cost of a single measurement to 30-40% of the traditional method. Based on a 30-day voyage, this can save 1.5 to 2 million yuan in operating expenses. Safety performance has been significantly improved. Conventional equipment has a 25% recovery failure rate in 1.5-meter wave heights. This system, through the autonomous underwater vehicle 8's autonomous obstacle avoidance and emergency surfacing capabilities, can ensure safe recovery even in 2-meter wave heights, significantly reducing the risk of equipment loss.

[0055] This system achieves a breakthrough in data acquisition. While conventional equipment is equipped with only a single probe, this system utilizes a dual-probe, synchronized measurement architecture, enabling simultaneous acquisition of shear strength and compression modulus parameters. Test results from the 2024 East China Sea show that dual-parameter measurement increased formation identification accuracy from 78% to 93%. The system also demonstrates exceptional adaptability in extreme environments. While conventional equipment is limited by cables in waters deeper than 3,000 meters, this system, powered by autonomous underwater vehicles (AUVs), extends its operating depth to 6,000 meters and has been successfully deployed in scientific research missions in the Mariana Trench.

[0056] Specifically, the principle of the present invention is as follows: the seabed sediment in-situ measurement device is pre-installed on an AUV 8 via a clamp ring 3 and then loaded onto a mother ship (such as a research vessel). When the mother ship reaches the designated working area, the AUV 8, equipped with the seabed sediment in-situ measurement device, is lowered into the seawater using the mother ship's crane arm to perform operations. During breaks in operation, the AUV 8 rests on the seabed. At this time, the autonomous underwater vehicle 8 will release a working signal to the pressure-resistant cabin 4 of the seabed in-situ measurement device. The control module of the electronic group 42 in the pressure-resistant cabin 4 receives the signal and controls the electric cylinder 5 to start working. The active screw starts to rotate through the positive rotation of the gear, pushing the driven screw to rotate and move downward. The secondary sleeve 54 moves synchronously with the driven screw through the thread. The primary sleeve 53 and the probe 55 move downward synchronously under the action of the slide rail, and then the probe 55 is penetrated into the seabed sediment for in-situ measurement. After the measurement is completed, the control module of the electronic group 42 sends an instruction to the electric cylinder 5 again, and the motor 52 drives the motor to drive the gear to rotate in the opposite direction to make the active screw start to rotate, pushing the driven screw to rotate and move upward. The secondary sleeve 54 moves synchronously with the driven screw through the thread. The primary sleeve 53 and the probe 55 also move upward synchronously under the action of the slide rail, thereby retracting the probe 55 that has penetrated the seabed sediment. Temporary data processing and data storage are performed through the data communication module of the electronic group 42, and the measurement is completed. After receiving the instruction of completing the measurement task from the data communication module of the electronic group 42, the autonomous underwater vehicle 8 stops sitting on the bottom and continues to carry out other operation tasks.

[0057] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed by the present invention, which should be covered by the scope of protection of the present invention.

Claims

1. A bottom-mounted acoustic in-situ measurement device for seabed sediments based on an autonomous underwater vehicle, characterized in that: The system comprises a mounting frame, a pressure-resistant cabin, an electric cylinder and a transmitting transducer. The top of the mounting frame is used to mount the autonomous underwater vehicle, and the bottom is used to mount the measuring device. The pressure-resistant cabin is fixedly mounted on the bottom of the mounting frame and is used to power the measuring device and communicate with the outside. The electric cylinder is fixedly connected to the bottom of the mounting frame and is located on both sides of the pressure-resistant cabin. It is used to receive signals from the pressure-resistant cabin and penetrate deep into the sediment to detect the sediment when the autonomous underwater vehicle is idle. The transmitting transducer is located at the bottom of the mounting frame and is fixedly connected to the mounting frame for transmitting signals. The mounting frame includes a bottom bracket, a mounting base, and a clamp ring. The bottom bracket is a two-ring structure arranged in a front-to-back manner, which is used to provide support for the overall structure of the measuring device. The mounting base is a flat plate structure located above the bottom bracket and is used to install the pressure cabin, electric cylinder, and transmitting transducer. The top of the bottom bracket is provided with two clamp rings for installing and fixing the autonomous underwater vehicle. The electric cylinder consists of two groups, which are installed on the front and rear sides of the mounting base respectively. Each electric cylinder consists of two parts, including a motor, a multi-stage telescopic mechanism and a probe. The electric cylinder base at the bottom of the multi-stage telescopic mechanism is installed on the mounting base and fixedly connected to the mounting base. One side of the bottom of the electric cylinder base is fixedly connected to the multi-stage telescopic mechanism and the probe, and the other side is fixedly connected to the motor, which is used to control the extension and retraction of the multi-stage telescopic mechanism; the probe is located at the top of the multi-stage telescopic mechanism and is fixedly connected to the multi-stage telescopic mechanism through threads; There are also two floating modules inside the base support. The two floating modules are arranged on both sides of the base support and are fixedly connected to the base support. They are used to balance the overall gravity and buoyancy and reduce the impact on the normal operation of the autonomous underwater vehicle.

2. The bottom-mounted acoustic in-situ measurement device for seabed sediments based on an autonomous underwater vehicle according to claim 1, characterized in that: The multi-stage telescopic mechanism includes a multi-stage sleeve and a transmission screw. The multi-stage sleeve includes a primary sleeve and a secondary sleeve. The primary sleeve is fixedly mounted on the base of the electric cylinder, and a secondary sleeve is provided inside. The outer wall of the secondary sleeve is movably connected to the primary sleeve through a slide rail. The inner wall of the secondary sleeve is provided with a threaded structure. A transmission screw is provided inside the secondary sleeve. The transmission screw includes an active screw and a driven screw. The active screw is a solid cylindrical structure, and the top is mounted on the base of the electric cylinder and is rotatably connected to the base of the electric cylinder. The active screw meshes with the gear of the motor output shaft through the gear at the top of the outer wall. The driven screw is a hollow cylindrical structure, and the inner and outer walls of the driven screw are provided with threads. The threads on the inner wall of the driven screw match the threads on the outer wall of the active screw, and the threads on the outer wall match the threads on the inner wall of the secondary sleeve.

3. The bottom-mounted acoustic in-situ measurement device for seabed sediments based on an autonomous underwater vehicle according to claim 2, characterized in that: The probe is located at the bottom of the secondary sleeve and is fixedly connected to the secondary sleeve for detecting seabed sediments. A receiving transducer is provided at the bottom of the probe for receiving signals.

4. The bottom-mounted acoustic in-situ measurement device for seabed sediments based on an autonomous underwater vehicle according to claim 3, characterized in that: The pressure cabin is a capsule-shaped structure installed at the bottom of the mounting base. It includes two power supply batteries and an electronic group. The pressure cabin is used to power the acoustic in-situ measurement device. The electronic group is equipped with a control module and a communication module for receiving instructions and controlling the rotation of the motor.

5. The bottom-mounted acoustic in-situ measurement device for seabed sediments based on an autonomous underwater vehicle according to claim 4, characterized in that: The pressure cabin is fixedly connected to the mounting base through a circular connecting component, the center of the pressure cabin is welded to the circular connecting component, and the circular connecting component is connected to the mounting base through bolts.

6. The bottom-mounted acoustic in-situ measurement device for seabed sediments based on an autonomous underwater vehicle according to claim 5, characterized in that: The bottom of the electric cylinder is welded to one end of the right-angle connecting plate, and the other end is fixedly connected to the mounting base by bolts.

7. The bottom-mounted acoustic in-situ measurement device for seabed sediments based on an autonomous underwater vehicle according to claim 6, characterized in that: The surface of the probe has a tree-like structure.

Images