Multi-platform acoustic-optical coordinated underwater target search and transmission device and method

Abstract

This invention belongs to the field of underwater target search technology, specifically involving a multi-platform acoustic-optical coordinated underwater target search and transmission device and method. It includes the following steps: S1, multi-ship cooperative wide-area sonar search; S2, near-field approximation and position correction; S3, acoustic-optical coordinated data transmission: when the distance between the underwater vehicle and the target is less than the optical communication ranging threshold, the underwater optical communication module located in the search and transmission device is activated. The underwater acoustic communication module tracks the target's bearing, and the underwater optical communication module achieves accurate ranging and data transmission. During transmission, the underwater acoustic communication module continuously measures the relative position with the target, and performs closed-loop control of the underwater vehicle's attitude and navigation direction to maintain the stability of the optical communication link until data transmission is complete. This invention solves the technical problems existing in current underwater target search and transmission methods regarding the platform, search range, search accuracy, and data transmission performance.

Description

Technical Field

[0001] This invention belongs to the field of underwater target search technology, specifically involving a multi-platform acoustic-optical coordinated underwater target search and transmission device and method. Background Technology

[0002] In the field of marine Internet of Things (IoT) technology, underwater target search and transmission devices are key equipment for underwater data collection, marine environmental monitoring, and resource exploration and development. Existing devices have several shortcomings: insufficient platform adaptability, making it difficult to adapt to various operational modes; limitations in search technology across different scenarios; and insufficient data transmission capabilities to meet demand. Specifically: First, existing devices mostly rely on single-ship or single-machine operation, which cannot be applied to multiple platforms, limiting the search range and lacking a multi-platform information sharing mechanism. This results in large blind spots when searching in vast sea areas, and it is difficult to continuously lock onto moving underwater targets, failing to meet the actual needs of rapid search in large sea areas.

[0003] II. Existing search devices primarily rely on sonar technology, optical detection, and underwater cameras for their search capabilities. However, these technologies have numerous limitations. Sonar technology is susceptible to environmental factors such as salinity, temperature, and water flow, leading to decreased detection accuracy and insufficient ability to identify details of close-range targets. Optical detection has a limited propagation distance, making it impossible to achieve large-scale searches. Underwater cameras are limited by underwater visibility, making it difficult to obtain clear images in turbid water and effectively identify targets. Existing technologies have attempted to simply integrate acoustic and optical detection devices, but they lack environmentally adaptive parameter switching logic, making them unsuitable for complex aquatic environments with varying turbidity levels.

[0004] Third, underwater acoustic communication typically has a transmission rate below 100kbps and a latency of several seconds, making it difficult to meet the backhaul requirements of large-scale data such as high-definition video and real-time monitoring data in marine IoT. While optical communication has a higher transmission rate, its transmission distance is short, making it only suitable for short-distance data transmission. It cannot transmit the detected target data back in real time and accurately, resulting in severe real-time lag. Existing acoustic and optical detection systems are independent of each other, lacking a guiding and connecting logic from far to near, and it is difficult to maintain high-precision optical communication alignment in dynamic environments. This makes it easy for large-capacity data backhaul to be interrupted, failing to meet the real-time and accuracy requirements of scenarios such as marine resource development and emergency rescue. Summary of the Invention

[0005] This invention provides a multi-platform-mounted acoustic-optical coordinated underwater target search and transmission device and method, which has the capabilities of multi-platform mounting, acoustic-optical coordinated detection, and dynamic closed-loop high-speed data transmission, thereby solving the above-mentioned technical problems.

[0006] The technical solution adopted by this invention to solve its technical problem is as follows: a multi-platform acoustic-optical coordinated underwater target search and transmission method, comprising the following steps: S1. Multi-ship cooperative wide-area sonar search: Deploy no fewer than 4 working vessels equipped with acoustic-optical cooperative underwater target search and transmission devices via electromagnetic connection modules to the target sea area. Each vessel transmits low-frequency sonar signals through the underwater acoustic communication module located in the search and transmission device to search for underwater targets. When a target is found, data sharing is achieved through multi-ship cooperative communication, and the initial position of the underwater target is obtained based on multilateral positioning calculation. S2. Near-field approach and position correction: The search and transmission device on the ship closest to the target is transferred and attached to the underwater vehicle via an electromagnetic connection module. The underwater vehicle is controlled to approach the target's initial position. During the navigation, the target position is continuously corrected by the cooperative detection data of the surface ships. When the distance between the underwater vehicle and the target meets the preset switching conditions, the autonomous guidance mode is entered. The underwater vehicle is guided to approach the target by the high-frequency ranging function of the underwater acoustic communication module. S3. Acoustic-optical coordinated data backhaul: When the distance between the underwater vehicle and the target is less than the optical communication ranging threshold, the underwater optical communication module located in the search and backhaul device is activated. The underwater acoustic communication module tracks the target's orientation, and the underwater optical communication module achieves accurate ranging and data transmission. During the transmission process, the underwater acoustic communication module continuously measures the relative position with the target, and controls the attitude and navigation direction of the underwater vehicle in a closed loop to maintain the stability of the optical communication link until the data backhaul is completed.

[0007] Preferably, the specific method for the multilateral positioning calculation in step S1 is as follows: when the number of ships that detect the target in the network is ≥4, the three-dimensional spatial coordinates of each ship and the corresponding sonar ranging results are collected. A nonlinear equation system is established based on the distance equation between the coordinates of each ship and the coordinates of the target. The initial position of the underwater target is obtained by iterative calculation using the Taylor series expansion method combined with the least squares method.

[0008] Preferably, the preset switching condition in step S2 is: the ratio of the real-time distance between the underwater vehicle and the target to the distance between the surface vessel and the vessel furthest from the target is less than a predetermined threshold. , .

[0009] Preferably, the specific method of closed-loop control in step S3 is as follows: during the optical communication data transmission process, the ranging results of the underwater acoustic communication module, the target azimuth angle data and the attitude data of the underwater vehicle are collected at a preset frequency. The navigation attitude of the underwater vehicle and the angle of the servo alignment mechanism of the optical communication module are adjusted by an adaptive control algorithm so that the distance between the search and return device and the target is always kept within the effective transmission threshold range of optical communication, and the laser beam is aligned with the target optical communication terminal.

[0010] The multi-platform acoustic-optical coordinated underwater target search and transmission device enables the implementation of the multi-platform acoustic-optical coordinated underwater target search and transmission method described in this application, including: The main control cabin on the surface integrates a surface communication module, a control module, and a power module. The underwater exploration cabin integrates an underwater communication module; A retractable connector, with its two ends rigidly and sealed to the surface main control cabin and the underwater detection cabin respectively, has built-in power supply cables, data transmission cables and control cables to realize mechanical connection, electrical connection and data interaction between the surface main control cabin and the underwater detection cabin; The electromagnetic connection module has a fixed end that is rigidly connected to the main control cabin on the water surface, and an adsorption end that is adapted to the mounting base of a ship or underwater vehicle to enable the device to be switched between multiple platforms. The underwater communication module includes an underwater acoustic communication module and an underwater optical communication module. The underwater acoustic communication module is used for long-range underwater target detection, ranging, and underwater acoustic communication, while the underwater optical communication module is used for short-range underwater target detection, ranging, and data transmission.

[0011] Preferably, the underwater acoustic communication module includes a sonar transducer capable of switching between a low-frequency wide-area detection mode and a high-frequency near-field ranging mode, and the underwater optical communication module uses a blue-green laser source and includes an optical receiving unit, a signal encoding and decoding unit, and a servo alignment mechanism for laser beam alignment.

[0012] Preferably, the surface communication module supports both wireless and wired communication. Wireless communication connects to the shipborne wireless information receiving device via an antenna that transmits and receives wireless signals. Wired communication connects to the shipborne wired information receiving device via an interface with a waterproof and sealed design, enabling multi-ship collaborative search data sharing and high-speed data export after device recovery.

[0013] Preferably, the electromagnetic connection module includes a seawater corrosion-resistant electromagnet assembly, a mechanical guiding structure, and a mechanical locking structure. The electromagnet assembly is controlled by an electrical signal output by a control module to control the adsorption and release states of the electromagnet assembly, thereby achieving automated rigid connection and disconnection under high pressure environments on the sea surface or in deep water. The mechanical locking structure is used to form redundant locking after electromagnetic adsorption is completed.

[0014] Preferably, the retractable connector adopts an armored spiral telescopic structure, the length of which can be adjusted according to the requirements of the mounting platform. It has built-in gigabit shielded data cable, control cable and power supply cable, which can realize high-speed data interaction between the underwater communication module and the control module and provide a stable power supply connection.

[0015] Preferably, the power supply module supplies power to the surface communication module, the underwater communication module, the control module, and the electromagnetic connection module; the control module establishes signal connections with the surface communication module, the underwater communication module, and the electromagnetic connection module respectively; the control module includes a processor module and a storage module for data processing and analysis; the processor module is used for target position calculation, mode switching, attitude closed-loop control, and data integrity verification; the storage module is used to store target positioning results and underwater target feedback data.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. By collaborating with multiple vessels, underwater vehicles, and other platforms, information sharing can be achieved, enabling rapid searches of large sea areas and solving the problem of limited search range for single-platform underwater target search and transmission devices.

[0017] 2. By combining underwater acoustic communication with optical communication, a large-scale coarse-grained search for underwater targets can be performed based on sonar technology. After approaching the underwater target, optical detection can be used to achieve a high-precision search at close range, thus solving the problems of low accuracy of underwater acoustic communication and limited distance of optical communication.

[0018] 3. Utilize the high transmission rate of optical communication to transmit data back, and use acoustic communication to maintain continuous search and tracking of underwater targets, thus maintaining the effective transmission distance of optical communication and solving the problem of poor coordination between underwater target search and data transmission devices.

[0019] In summary, this invention provides an underwater target search and transmission device with multi-platform capability, acoustic-optical coordinated detection, and dynamic closed-loop high-speed data transmission capability. It solves the technical problems of existing underwater target search and transmission devices in terms of platform, search range, search accuracy, and data transmission performance, and has important practical significance and broad application prospects. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the underwater target search device in this invention.

[0021] Figure 2 This is a schematic diagram illustrating the target search principle of multi-ship cooperation in this invention.

[0022] Figure 3 This is a schematic diagram illustrating the underwater target search principle based on position correction of the present invention.

[0023] Figure 4 This is a schematic diagram illustrating the principle of underwater target search using the acoustic-optical synergy of the present invention.

[0024] In the diagram: 1. Surface communication module; 2. Underwater communication module; 3. Control module; 4. Retractable connector; 5. Electromagnetic connection module; 6. Power supply module; 7. Antenna; 8. Interface; 9. Underwater acoustic communication module; 10. Underwater optical communication module; 11. Processor module; 12. Storage module; N is the underwater target; A, B, C, and D are the vessels carrying the device described in this invention; A1 is the underwater vehicle carrying the device described in this invention, released by vessel A. Detailed Implementation

[0025] To facilitate understanding of the present invention, it will be described in more detail below with reference to the accompanying drawings and specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described in this specification. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention.

[0026] Example 1: A multi-platform acoustic-optical coordinated underwater target search and transmission device, including a surface communication module 1, an underwater communication module 2, a control module 3, a retractable connector 4, an electromagnetic connection module 5, a power supply module 6, an antenna 7, an interface 8, an underwater acoustic communication module 9, an underwater optical communication module 10, a processor module 11, and a storage module 12.

[0027] The surface communication module 1, control module 3, and power module 6 are integrated into the surface main control cabin, while the underwater communication module 2 is integrated into the underwater detection cabin. The retractable connector 4 is connected to both the surface main control cabin and the underwater detection cabin via a dynamic sealing structure. The internal cables are connected to corresponding watertight terminals, enabling mechanical, electrical, and data communication between the surface main control cabin and the underwater detection cabin. The electromagnetic connection module 5 is rigidly connected to the surface main control cabin at its fixed end, and its adsorption end can be adapted to the mounting base of platforms such as ships and underwater vehicles, enabling rapid multi-platform mounting of the device. The antenna 7 is electrically connected to the radio frequency end of the surface communication module 1, and the waterproof sealing interface 8 is connected to the wired ends of the surface communication module 1 and control module 3. The underwater acoustic communication module 9 and underwater optical communication module 10 are both electrically connected to the signal processing unit of the underwater communication module 2. The processor module 11 and storage module 12 are both electrically connected to the main control PCB board of the control module 3. The power module 6 is physically connected to each functional module via industrial-grade power distribution cables.

[0028] The surface communication module 1 is mainly used for communication with ships and underwater vehicles. It has both wireless and wired communication modes. When using wireless communication, it connects to the shipborne wireless information receiving equipment through the antenna 7 to transmit and receive wireless signals. When using wired communication, it connects to the shipborne wired information receiving equipment through the interface 8 with a waterproof and sealed design, so as to realize multi-ship collaborative search data sharing and high-speed data export after the device is recovered.

[0029] The underwater communication module 2 is mainly used for underwater information interaction and detection, including an underwater acoustic communication module 9 and an underwater optical communication module 10. Both are connected to the control module 3 via a retractable connector 4, and possess detection, ranging, and communication capabilities. The underwater acoustic communication module 9 includes a sonar transducer capable of switching between a low-frequency wide-area detection mode and a high-frequency near-field ranging mode. It operates in low-frequency mode during the wide-area search phase and in high-frequency ranging mode during the near-field approach phase. The underwater optical communication module 10 uses a high-penetration blue-green laser source to adapt to high-speed data transmission at close range. The underwater optical communication module 10 includes an optical receiving unit, a signal encoding / decoding unit, and a servo alignment mechanism for laser beam alignment. Both are connected to the control module 3 via the retractable connector 4 and achieve acoustic-optical coordination under the control of the control module 3.

[0030] The control module 3 serves as the computation and control center of the device, comprising a processor module 11 and a storage module 12. Both are soldered to the main control PCB board via onboard pads and electrically connected and enabling high-speed data exchange through internal PCB traces. The processor module 11 is connected to the control terminals of the surface communication module 1, underwater communication module 2, and electromagnetic connection module 5 via an industrial bus. It is mainly used to process and analyze the collected data, calculate the position of underwater targets, switch modes, perform attitude closed-loop control, and verify data integrity. The storage module 12 is electrically connected to the processor module 11 and is mainly used to store the calculation results of the processor module and the data transmitted back from the underwater targets.

[0031] The retractable connector 4 adopts an armored spiral telescopic structure, with built-in dedicated power supply cables, gigabit shielded data cables, and control cables. Both ends of the internal cables are sealed and connected to corresponding terminals on the surface main control compartment and the underwater detection compartment, respectively, connecting the underwater communication module 2 and the control module 3. Its length can be adjusted according to the platform requirements. When operating onboard, the underwater communication module 2 is located underwater, while other modules are located on the ship. Data collected by the underwater communication module 2 is transmitted to the control module via the data transmission cable in the retractable connector. Simultaneously, a stable power supply is provided to the underwater communication module 2 via the power supply cable in the retractable connector.

[0032] The electromagnetic connection module 5 is used to connect this device to various platforms such as ships and underwater vehicles. The electromagnetic connection module 5 includes a seawater-resistant electromagnet assembly, a mechanical guiding structure, and a mechanical locking structure. The electromagnet assembly is used to quickly connect or release between platforms. The control module 3 outputs electrical signals to control the adsorption and release states of the electromagnet assembly, achieving automated rigid connection and disconnection in high-pressure environments at sea surface or deep water. The mechanical guiding structure ensures adsorption and positioning accuracy. The mechanical locking structure forms redundant locking after electromagnetic adsorption is completed, preventing the device from detaching due to sudden power outages.

[0033] Power module 6, serving as the core energy supply center of the system, is physically connected to each functional module via industrial-grade power distribution cables. Power module 6 directly provides operating power to the surface communication module 1, control module 3, and electromagnetic connection module 5 through its internal power distribution branches. For the underwater detection unit, the electrical energy output from power module 6 is transmitted down via a dedicated power supply cable encapsulated within the retractable connector 4, ensuring stable power support for the underwater communication module 2 in deep-water environments.

[0034] The underwater target search and data transmission device is divided into three working stages: the multi-ship cooperative target search stage, the position-corrected underwater target search stage, and the acoustic-optical coordinated underwater target search and data transmission stage.

[0035] During the target search phase involving multiple vessels, this device is installed on the vessel via electromagnetic connection module 5. While navigating, the vessel uses underwater acoustic communication module 9 in underwater communication module 2 to emit underwater acoustic signals to search for underwater targets. Upon target detection, the vessel notifies itself via surface communication module 1. This vessel then transmits its position information to other vessels through its onboard communication equipment. Other vessels approach the vessel that detected the target and continue searching for it. When the number of vessels detecting the underwater target within the network is ≥4, multilateral positioning calculation is initiated. The initial position of the underwater target is calculated via control module 3. Due to errors in ranging and calculation, as well as the movement of the underwater target with the current, the initial position has a relatively large error and requires further searching to refine the target position.

[0036] After obtaining the initial position, the underwater target search phase based on position correction begins. The transfer mechanism for the device initiated by the closest ship to the target is as follows: First, the device is retrieved from its working position on the ship using a ship-mounted hoisting winch or robotic arm. The power supply to the electromagnetic connection module 5 is then disconnected by the control module, releasing it from its attachment to the ship. Subsequently, with manual assistance or robotic arm guidance, the device is transferred horizontally to the predetermined mounting surface of the ship-mounted underwater vehicle. The electromagnetic connection module 5 is then reconnected and its magnetic closure is controlled, ensuring it is firmly attached and locked to the underwater vehicle. After mounting, the underwater vehicle carrying the device is released into the sea. Once in the sea, the underwater vehicle moves towards the initial position of the underwater target, while continuously communicating with surface vessels using the underwater communication module 2, constantly receiving data to correct the target position. The error in the multi-directional positioning increases as the underwater vehicle approaches the target. When the ratio of the distance between the underwater vehicle and the target to the distance to the farthest ship from the target is less than a predetermined threshold... Subsequently, the control module stops receiving cooperative positioning data from surface vessels and ceases updating its position based on surface vessel information. At this point, the device switches to autonomous guidance mode, utilizing the high-frequency local ranging function of the underwater acoustic communication module 9 to move in the direction where the ranging value decreases.

[0037] When the distance between the device and the underwater target is less than the optical communication ranging threshold, the device enters the acoustic-optical coordinated underwater target search phase. The device activates the underwater optical communication module 10 and uses the ranging capabilities of the underwater acoustic communication module 9 and the underwater optical communication module 10 to measure the distance to the target, continuously moving in the direction where the ranging distance is decreasing. When the distance between the device and the underwater target is less than the optical communication transmission threshold, the device uses the underwater optical communication module 10 to receive data from the underwater target and stores it in the storage module 12. Although the underwater optical communication module 10 has a higher data transmission speed, its transmission distance is shorter. To ensure that the data return process is not interrupted, the underwater acoustic communication module 9 continues to measure the distance and guide the underwater vehicle to follow the underwater target, ensuring that it remains within the effective range of the optical communication until data transmission is complete. The underwater vehicle then surfaces, completing the underwater target search mission.

[0038] This device transmits the data in the storage module 12 to the ship via the surface communication module 1, and then the shipborne communication equipment transmits it to the server to complete the data return task.

[0039] Example 2: A multi-platform acoustic-optical coordinated underwater target search and data transmission device, with the same structure as Example 1, has a complete workflow divided into three core stages: a multi-ship cooperative target search stage, a position-corrected underwater target search stage, and an acoustic-optical coordinated underwater target search and data transmission stage. The specific implementation steps of each stage are described in detail below with reference to the accompanying drawings: Phase 1: Target search phase involving multi-ship cooperation, combined with... Figure 2 understand.

[0040] (1) Preparation and parameter setting before operation: Before executing the search mission, at least four vessels equipped with this device will be deployed to the target search area, with each vessel dispersed to ensure full coverage of the search area. Mission parameters will be preset for each device, including: search area range, sonar detection parameters, multi-vessel collaborative communication parameters, multilateral positioning calculation threshold, target feature template, and switching threshold for subsequent stages. , , Once the parameters are preset, the device enters standby mode.

[0041] In this embodiment, the threshold is preset to be: mode switching threshold. Optical communication ranging threshold Optical communication transmission threshold ;in, The value is determined based on the accuracy degradation characteristics of the polygonal positioning geometric accuracy factor. To find the optimal value that balances positioning accuracy and approximation efficiency; The maximum effective detection range of the underwater acoustic communication module 9 in high-frequency mode; This represents the maximum effective transmission distance of the underwater optical communication module 10. The target feature template includes the target's sonar echo characteristics, spectral characteristics, dimensions, and optical communication response code, used for target identification and matching.

[0042] Meanwhile, the devices on each vessel are networked with the onboard vessels through the surface communication module 1, establishing a multi-vessel collaborative communication link to achieve time synchronization, position synchronization, and data sharing among the vessels. The time synchronization accuracy is ≤1ms, providing a benchmark for subsequent multilateral positioning calculations.

[0043] (2) Wide-area sonar search and initial target discovery: Each vessel synchronously activates its device, which enters a wide-area search mode. Control module 3 controls underwater communication module 2's underwater acoustic communication module 9 to switch to low-frequency operating mode. According to preset detection parameters, it periodically transmits low-frequency sonar detection signals underwater and simultaneously receives echo signals. The signal processing unit of underwater acoustic communication module 9 filters, amplifies, and performs correlation operations on the echo signals to extract target echo features. These features are then matched with preset target feature templates. When the matching degree exceeds a preset threshold, a suspected underwater target is detected.

[0044] In this embodiment, the low-frequency detection period of the underwater acoustic communication module 9 is set to 1 second, and the horizontal beamwidth of a single detection is... Pitch beamwidth With a maximum detection range of 10km, it can achieve omnidirectional wide-area search during ship navigation. The ship's speed is set to 8~12 knots, and it navigates along a gridded route within the preset search area to ensure no search blind spots.

[0045] When a certain ship (corresponding appendix) Figure 2 After the device on ship A detects a suspected underwater target N, the processor module 11 immediately acquires the BeiDou positioning coordinates of ship A at that moment. , , Ship attitude data, sonar ranging results The target azimuth data is broadcast to all other ships in the network via the multi-ship collaborative communication link of the surface communication module 1. The message contains the coordinates of ship A, the ranging result, the target azimuth, and the timestamp information.

[0046] (3) Multi-ship collaborative convergence and continuous detection: Other vessels within the network (corresponding to the attached list) Figure 2After receiving the target detection message, ships B, C, and D immediately converge towards the coordinates of ship A according to the preset route planning strategy. Simultaneously, they continuously transmit sonar detection signals, aligning their underwater acoustic communication modules 9 with the target's azimuth direction, to continuously detect the underwater target N. Once ships B, C, and D have successively detected the echo signal of underwater target N, they each collect their own BeiDou positioning coordinates. , , and the corresponding sonar ranging results It broadcasts in real time to all ships in the network through a multi-ship collaborative communication link.

[0047] In this embodiment, when the number of ships detecting the target within the network is ≥4, the multilateral positioning calculation process is automatically initiated. The device on each ship can synchronously receive the coordinates and ranging data of other ships. The multilateral positioning calculation is completed by the processor module 11 of the control module 3 to obtain the initial position coordinates of the underwater target N. The solution formula is as follows: ; in, These are the straight-line distances between ships A, B, C, and D and underwater target N, measured by underwater acoustic communication module 9, respectively. , , , These are the three-dimensional spatial coordinates of the corresponding ships, where the X and Y planes are the sea level projection coordinates, and the Z axis is the water depth coordinate.

[0048] (4) Initial position calculation and error correction For the nonlinear equation system of the solution formula, processor module 11 uses Taylor series expansion combined with least squares method for iterative solution. The specific solution steps are as follows: ① Set the initial position of the underwater target and the initial iteration value as follows: The solution formula is expanded by first-order Taylor at the initial value to obtain a linearized system of equations. ② Solve the linearized system of equations using the least squares method to obtain the position correction. ; ③ Update target location coordinates: , , ; ④ Repeat steps ① to ③ until the magnitude of the position correction is less than the preset convergence threshold, which is set to 0.5m in this embodiment. Complete the iterative calculation and obtain the initial position coordinates of the underwater target N. .

[0049] Meanwhile, the processor module 11 calculates the positioning error circle of the initial position based on the ranging error, positioning error, and time synchronization error of each ship. When the radius of the positioning error circle is ≤50m, the initial position calculation is deemed valid, the multi-ship collaborative target search stage is completed, and the next stage is entered. If the radius of the positioning error circle exceeds 50m, more ships will continue to participate in the detection, the number of positioning base stations will be increased, and the positioning error will be reduced until the valid calculation condition is met.

[0050] In this embodiment, by using multilateral positioning with four or more ships, the initial positioning error of underwater targets can be controlled within 50m. Compared with single-ship detection, the search range is increased by more than 20 times and the search efficiency is increased by more than 10 times, effectively solving the problem of large-scale search in vast sea areas.

[0051] Due to errors in ranging and calculation, as well as the movement of underwater targets with the water flow, the initial position has a large error and requires further searching to refine the target position.

[0052] Phase Two: Underwater Target Search Phase Based on Position Correction, combined with... Figure 3 understand.

[0053] The core objective of this phase is to achieve near-field approximation of underwater targets by transferring the device from the ship to the underwater vehicle. Simultaneously, it aims to continuously correct the target position using collaborative positioning data from multiple surface vessels, addressing issues such as large initial positioning errors and positional shifts caused by underwater target movement. The specific implementation steps are as follows: (1) Platform switching and mounting deployment of the device: After completing the initial position calculation of the underwater target, control module 3 calculates the straight-line distance between each vessel and the initial position of the underwater target through the multi-vessel cooperative communication link, and selects the vessel closest to the target (corresponding to the attached...). Figure 3 Vessel A) serving as the mission execution vessel, the platform switching operation of the execution device follows these steps: ① Ship A uses its onboard hoisting winch to retract the underwater detection cabin from the water to the deck, and controls the retractable connector 4 to retract to its shortest length, so that the entire device can be retracted to the working position on the ship.

[0054] ② The processor module 11 sends a disconnect command to the electromagnetic connection module 5 to cut off the power supply to the electromagnet assembly, release the device from the adsorption state of the ship mounting base, and unlock the mechanical locking structure.

[0055] ③ The device is transferred as a whole to the predetermined mounting surface of the shipborne autonomous underwater vehicle or remotely controlled underwater vehicle by the shipborne robotic arm. In this embodiment, a large-load underwater vehicle is preferred, with a maximum operating water depth ≥1000m, a maximum endurance time ≥24h, and autonomous navigation and attitude control capabilities.

[0056] ④ The processor module 11 sends an adsorption command to the electromagnetic connection module 5, which connects the power supply to the electromagnet assembly, so that the device is firmly adsorbed on the mounting surface of the underwater vehicle. At the same time, the mechanical locking structure automatically engages to complete the rigid connection. The control module 3 connects to the shipborne control system of the underwater vehicle through the docking interface of the interface 8, so as to realize the command interaction and data sharing between the device and the underwater vehicle. The underwater vehicle can receive the target position data of the device and adjust its own navigation route and attitude.

[0057] (2) Deployment and close-range approach navigation of underwater vehicles: After the device is mounted, ship A releases the underwater vehicle A1, which carries the device, into the sea through the shipboard deployment system. After entering the water, underwater vehicle A1 starts autonomous navigation mode according to the initial position coordinates of the underwater target issued by the device and approaches the target position. During the navigation, the maximum diving depth of underwater vehicle A1 is matched with the target water depth, and the navigation speed is set to 2 to 4 knots to avoid excessive noise caused by high-speed navigation, which would affect the sonar detection accuracy.

[0058] During navigation, the underwater communication module 2 of the device continuously communicates with surface vessels B, C, and D through the underwater acoustic communication module 9, receiving the position coordinates of each vessel and the sonar ranging results of the underwater target in real time. The processor module 11 continuously iteratively calculates the real-time position of the underwater target according to the calculation formula, constantly corrects the target coordinates, and sends the corrected target coordinates to the navigation control system of the underwater vehicle A1. The underwater vehicle A1 dynamically adjusts the navigation route based on the real-time corrected target position to ensure that it always approaches the real-time position of the target, thus solving the problem of position deviation caused by the movement of the underwater target with the water flow.

[0059] Simultaneously, the underwater acoustic communication module 9 of the device periodically transmits high-frequency sonar signals towards the target direction to measure the real-time distance between the underwater vehicle A1 and the underwater target. The ranging results are fused with the multi-ship positioning calculation results to further improve the accuracy of target position correction.

[0060] (3) Switching to autonomous guidance mode: As the underwater vehicle A1 approaches the underwater target, the error of multi-ship multilateral positioning gradually increases as the distance between underwater vehicle A1 and the underwater target N decreases. This is because the geometrical precision factor (GDOP) of multilateral positioning deteriorates as the distance difference between the base station and the target increases, leading to a decrease in positioning accuracy. Therefore, this invention sets a mode switching threshold. When the preset switching conditions are met, the device automatically switches to autonomous guidance mode. The specific implementation steps are as follows: Processor module 11 calculates in real time the distance between the underwater vehicle A1 and the target, and the distance between the surface vessel farthest from the target. When the distance between the underwater vehicle A1 and the target Distance from the target ship The ratio is less than the predetermined threshold After that, ; Location updates will no longer be based on information about surface vessels. It can be modified according to the actual situation, and is usually set as follows: After the trigger mode switch, the processor module 11 automatically disconnects the external coupling of the multi-ship collaborative search, no longer updating the target position through the detection data of surface vessels, and the device enters the autonomous guidance mode. In the autonomous guidance mode, the device relies on the high-frequency ranging function of the underwater acoustic communication module 9 to measure the distance and azimuth of the underwater target in real time. The processor module 11 uses the gradient descent method to control the underwater vehicle A1 to move in the direction where the ranging value continuously decreases, while adjusting the navigation attitude of the underwater vehicle A1 in real time to ensure that the sonar detection beam is always aligned with the target direction, thereby achieving precise approach to the underwater target.

[0061] The above parameters are preferred embodiments. Those skilled in the art can adjust the thresholds and parameter settings according to the actual marine environment and target type, all of which fall within the protection scope of this invention.

[0062] Phase Three: Acoustic-optical coordinated underwater target search phase, combined with... Figure 4 understand.

[0063] The core objective of this phase is to achieve precise targeting of underwater targets through an acoustic-optical coordinated detection and tracking mechanism, while simultaneously establishing a stable high-speed optical communication link to complete high-speed data transmission from underwater targets. This addresses the issues of significant disconnect between mobile search and high-speed data transmission, as well as the susceptibility to optical communication link interruptions in existing technologies. The specific implementation steps are as follows: (1) Precise search and locking using a combination of sound and light: Processor module 11 acquires high-frequency ranging results from underwater acoustic communication module 9 in real time. ,when Less than the preset optical communication ranging threshold At this time, the device enters the acoustic-optical coordinated target search mode. The processor module 11 starts the underwater optical communication module 10, turns on the blue-green laser, and starts the laser ranging function to perform ranging and target detection synchronously with the underwater acoustic communication module 9. The underwater acoustic communication module 9 is responsible for wide-beam range target orientation tracking, measuring the approximate orientation and distance of the underwater target, and providing guidance for the servo alignment mechanism of the underwater optical communication module 10. The underwater optical communication module 10 is responsible for narrow-beam high-precision ranging and orientation identification to achieve precise target locking.

[0064] After target lock, processor module 11 employs an acoustic-optical coordinated Kalman filter algorithm to predict the target's position, speed, and direction of motion in real time. This allows for pre-control of the underwater vehicle A1's attitude and the angle of the servo alignment mechanism, enabling continuous tracking of the moving target. This ensures the target remains within the wide beam coverage of the sonar and the narrow beam alignment range of the laser, with a tracking error ≤1m. For extreme conditions such as turbid water, when turbidity >10 NTU, processor module 11 automatically adjusts the laser emission power by 30%, increases the sonar detection frequency, and narrows the search beam angle, enhancing the anti-interference capability of target identification.

[0065] (2) Establishment of high-speed optical communication links and data backhaul: Processor module 11 acquires the results of acoustic-optical coordinated ranging in real time. ,when Less than the preset optical communication transmission threshold When the device initiates the underwater optical communication link establishment process and enters the data return mode, the processor module 11 controls the laser emitting unit of the underwater optical communication module 10 to transmit a link establishment handshake signal to the underwater target's optical communication terminal according to the preset modulation method and communication protocol. After receiving the handshake signal, the underwater target's optical communication terminal returns a response signal, completing the establishment of the two-way optical communication link. After the link is established, the underwater target sends large amounts of data, such as collected monitoring data, high-definition video, and equipment status data, to the device through the optical communication link. After receiving the data, the optical receiving unit of the underwater optical communication module 10 performs decoding and error correction processing through the signal encoding and decoding unit, and transmits the processed data in real time to the storage module 12 of the control module 3 for local storage through the data cable of the retractable connector 4.

[0066] (3) Closed-loop stability control of sonar-following link: Throughout the entire optical communication data transmission process, the underwater acoustic communication module 9 operates continuously, constantly measuring the distance, azimuth, and relative speed to the underwater target in real time. Based on the real-time data collected by the sonar, the processor module 11 performs closed-loop control of the underwater vehicle's attitude, speed, and direction, while simultaneously adjusting the angle of the servo alignment mechanism to ensure that the distance between the device and the underwater target remains within the effective transmission threshold for optical communication. Within this range, the laser beam is always precisely aimed at the target optical communication terminal, maintaining the continuous stability of the optical communication link.

[0067] The specific closed-loop control logic is as follows: ① The processor module 11 acquires the ranging results of the underwater acoustic communication module 9 in real time at a frequency of 10Hz. Target azimuth data, as well as the attitude and speed data of the underwater vehicle; ②Real-time ranging results With the preset optimal transmission distance (In this embodiment) Compare and calculate the distance deviation. The target azimuth angle is compared with the current angle of the optical antenna to calculate the angle deviation. ; ③ Using a PID control algorithm, the thruster control quantity and the rotation control quantity of the servo alignment mechanism of the underwater vehicle A1 are calculated respectively. The underwater vehicle A1 is controlled to move in the direction of reducing the distance deviation, while the servo alignment mechanism is controlled to compensate for the angle deviation.

[0068] ④ Repeat steps ① to ③ to achieve real-time closed-loop control of the entire transmission process and ensure that the optical communication link is not interrupted.

[0069] (4) Return and data transmission: To address the data backhaul delay issue mentioned in the background art, this embodiment adopts a "synchronous return and dynamic backhaul" strategy. After all data transmissions of the underwater target are completed, the underwater target sends a transmission completion message to this device; after confirming that the data has been completely received and stored in the storage module 12, the processor module 11 controls the shutdown of the laser emission unit of the underwater optical communication module 10 and immediately issues a surface return command to the underwater vehicle A1.

[0070] When underwater vehicle A1 executes the return command, and after it surfaces with this device, processor module 11 activates surface communication module 1. Surface communication module 1 can establish a connection with the ship or shore-based equipment via high-bandwidth wireless links, including but not limited to WiFi 6 or satellite relay signals, or it can transmit data via a wired connection on the ship. The high-definition video and monitoring data stored in storage module 12 are transmitted in real time to the shipboard server or shore-based data center, realizing "instant data search and transmission" without waiting for the device storing the data to return to shore, effectively solving the data lag problem caused by the time spent on equipment recovery.

[0071] After the underwater vehicle A1 returns to the ship's recovery area, it is retrieved onto the deck using the ship's onboard robotic arm. Utilizing the automated switching function of the electromagnetic connection module 5, the device is remounted from the underwater vehicle to the ship's mounting base, enabling rapid cyclical deployment and preparing it for the next search mission.

[0072] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A multi-platform acoustic-optical coordinated underwater target search and transmission method, characterized in that, Includes the following steps: S1. Multi-ship cooperative wide-area sonar search: Deploy no fewer than 4 working vessels equipped with acoustic-optical cooperative underwater target search and transmission devices via electromagnetic connection modules to the target sea area. Each vessel transmits low-frequency sonar signals through the underwater acoustic communication module located in the search and transmission device to search for underwater targets. When a target is found, data sharing is achieved through multi-ship cooperative communication, and the initial position of the underwater target is obtained based on multilateral positioning calculation. S2. Near-field approach and position correction: The search and transmission device on the ship closest to the target is transferred and attached to the underwater vehicle via an electromagnetic connection module. The underwater vehicle is controlled to approach the target's initial position. During the navigation, the target position is continuously corrected by the cooperative detection data of the surface ships. When the distance between the underwater vehicle and the target meets the preset switching conditions, the autonomous guidance mode is entered. The underwater vehicle is guided to approach the target by the high-frequency ranging function of the underwater acoustic communication module. S3. Acoustic-optical coordinated data backhaul: When the distance between the underwater vehicle and the target is less than the optical communication ranging threshold, the underwater optical communication module located in the search and backhaul device is activated. The underwater acoustic communication module tracks the target's orientation, and the underwater optical communication module achieves accurate ranging and data transmission. During the transmission process, the underwater acoustic communication module continuously measures the relative position with the target, and controls the attitude and navigation direction of the underwater vehicle in a closed loop to maintain the stability of the optical communication link until the data backhaul is completed.

2. The multi-platform acoustic-optical coordinated underwater target search and transmission method according to claim 1, characterized in that, The specific method for the multilateral positioning solution in step S1 is as follows: when the number of ships that detect the target in the network is ≥4, the three-dimensional spatial coordinates of each ship and the corresponding sonar ranging results are collected. A nonlinear equation system is established based on the distance equation between the coordinates of each ship and the coordinates of the target. The initial position of the underwater target is obtained by iterative solution using the Taylor series expansion method combined with the least squares method.

3. The multi-platform acoustic-optical coordinated underwater target search and transmission method according to claim 1, characterized in that, The preset switching condition in step S2 is: the ratio of the real-time distance between the underwater vehicle and the target to the distance between the surface vessel and the vessel furthest from the target is less than a predetermined threshold. , .

4. The multi-platform acoustic-optical coordinated underwater target search and transmission method according to claim 1, characterized in that, The specific method of closed-loop control in step S3 is as follows: During the optical communication data transmission process, the ranging results of the underwater acoustic communication module (9), the target azimuth angle data and the attitude data of the underwater vehicle are collected at a preset frequency. The navigation attitude of the underwater vehicle and the angle of the optical communication module servo alignment mechanism are adjusted by an adaptive control algorithm so that the distance between the search and return device and the target is always kept within the effective transmission threshold range of optical communication, and the laser beam is aligned with the target optical communication terminal.

5. A multi-platform acoustic-optical coordinated underwater target search and transmission device, capable of realizing the multi-platform acoustic-optical coordinated underwater target search and transmission method as described in any one of claims 1-4, characterized in that, include: The main control room on the surface integrates a surface communication module (1), a control module (3) and a power supply module (6). The underwater exploration cabin integrates an underwater communication module (2). The retractable connector (4) has rigidly sealed connections at both ends to the surface main control cabin and the underwater detection cabin, respectively. The retractable connector (4) has built-in power supply cables, data transmission cables and control cables to realize mechanical connection, electrical connection and data interaction between the surface main control cabin and the underwater detection cabin. The electromagnetic connection module (5) has a fixed end that is rigidly connected to the main control cabin on the water surface, and an adsorption end that is adapted to the mounting base of a ship or underwater vehicle to realize the device's mounting and switching between multiple platforms. The underwater communication module (2) includes an underwater acoustic communication module (9) and an underwater optical communication module (10). The underwater acoustic communication module (9) is used for long-distance underwater target detection, ranging and underwater acoustic communication, and the underwater optical communication module (10) is used for short-distance underwater target detection, ranging and data transmission.

6. The multi-platform acoustic-optical coordinated underwater target search and transmission device according to claim 5, characterized in that, The underwater acoustic communication module (9) includes a sonar transducer that can switch between low-frequency wide-area detection mode and high-frequency near-area ranging mode. The underwater optical communication module (10) uses a blue-green laser source and includes an optical receiving unit, a signal encoding and decoding unit, and a servo alignment mechanism for laser beam alignment.

7. The multi-platform acoustic-optical coordinated underwater target search and transmission device according to claim 5, characterized in that, The surface communication module (1) supports wireless and wired communication. Wireless communication is connected to the shipborne wireless information receiving device by transmitting and receiving wireless signals through the antenna (7). Wired communication is connected to the shipborne wired information receiving device through the interface (8) with waterproof sealing design, so as to realize multi-ship collaborative search data sharing and high-speed data export after device recovery.

8. The multi-platform acoustic-optical coordinated underwater target search and transmission device according to claim 5, characterized in that, The electromagnetic connection module (5) includes a seawater corrosion resistant electromagnet assembly, a mechanical guiding structure and a mechanical locking structure. The electromagnet assembly controls the adsorption and release state of the electromagnet assembly by outputting an electrical signal through the control module (3), thereby realizing automated rigid connection and disconnection release under high pressure environment on the sea surface or in deep water. The mechanical locking structure is used to form redundant locking after the electromagnetic adsorption is completed.

9. The multi-platform acoustic-optical coordinated underwater target search and transmission device according to claim 5, characterized in that, The retractable connector (4) adopts an armored spiral telescopic structure, and its length can be adjusted according to the requirements of the mounting platform. It has built-in gigabit shielded data cable, control cable and power supply cable, which can realize high-speed data interaction between the underwater communication module and the control module and provide a stable power supply connection.

10. The multi-platform acoustic-optical coordinated underwater target search and transmission device according to claim 5, characterized in that, The power module (6) supplies power to the surface communication module (1), the underwater communication module (2), the control module (3) and the electromagnetic connection module (5); the control module (3) establishes signal connections with the surface communication module (1), the underwater communication module (2) and the electromagnetic connection module (5) respectively. The control module (3) includes a processor module (11) and a storage module (12) for data processing and analysis. The processor module (11) is used for target position calculation, mode switching, attitude closed-loop control and data integrity verification. The storage module (12) is used to store target positioning results and underwater target feedback data.

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