Low-cost transportable system for UUV path planning and control experiment

Abstract

The invention discloses a low-cost transportable system for UUV path planning and control experiments. The low-cost transportable system comprises a shore-based unit, a buoy unit, an underwater vehicle unit, a zero-buoyancy cable and a software stack, the UWB tag, the router, the GNSS and the rocker receiver are integrated in the buoy, a sealing waterproof design is adopted, and the buoy can stably float on the water surface and is in wired connection with the underwater vehicle through the zero-buoyancy cable; the three-dimensional position of the underwater vehicle is obtained, the upper computer and the UWB base station are deployed on a shore base, the upper computer interacts the calculated position with the router in the buoy through wireless communication, and a stable and efficient communication link is constructed. The system can be quickly arranged in indoor and outdoor environments, supports closed-loop path planning and control experiments, can effectively replace expensive USBL or indoor dynamic capturing and positioning systems, remarkably reduces experiment cost, and improves experiment flexibility and portability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of underwater robots, and particularly relates to a low-cost movable system for UUV path planning and control experiment. BACKGROUND

[0002] As an important technical equipment for deep-sea exploration and operation, the unmanned underwater vehicle (UUV) has shown great application potential in the fields of marine resource exploration, environmental monitoring, engineering inspection, scientific investigation and national defense security. The UUV can play a unique advantage in replacing human beings to perform boring, harsh or even dangerous underwater tasks, and the advantages and disadvantages of its autonomous navigation, path planning and control capability directly determine the operation efficiency and task success rate. Therefore, in the process of UUV research and application, the design, verification and optimization of control algorithm and path planning strategy are the core links to promote the progress of the technology.

[0003] However, under the existing technical conditions, the experimental verification of the UUV path planning and control algorithm often faces high infrastructure cost and complex deployment process. In order to obtain high-precision underwater position and attitude information, the traditional scheme depends on ultra short baseline (USBL), long baseline (LBL), acoustic Doppler velocity log (DVL) or indoor dynamic capture system (such as Vicon, OptiTrack, etc.).

[0004] Although such systems perform excellently in precision and stability, they have the following outstanding problems:

[0005] Firstly, the equipment cost is extremely high, and the price is tens of thousands or even hundreds of thousands of yuan, which is not suitable for teaching and general scientific research experiment popularization and use;

[0006] Secondly, the system is large in size and weight, and has high requirements for installation environment. The deployment process is time-consuming and laborious when used outdoors, and has high restrictions on water conditions;

[0007] Thirdly, the indoor dynamic capture system is subject to optical sensors and marker point arrangement, and can only be used in limited enclosed spaces, and cannot directly adapt to outdoor water experiment requirements;

[0008] Finally, the acoustic positioning scheme such as USBL is easily disturbed in shallow water or multi-path reflection environment, and the positioning precision is significantly reduced, which limits its availability in different scenes.

[0009] In addition, due to the high cost and complexity of high-precision positioning systems, many research teams have to rely on simplified open-loop experiments or use low-precision water surface GNSS for approximate verification, which not only reduces the accuracy of algorithm evaluation, but also affects the transferability of research results in real tasks.

[0010] Especially in the scene of combining teaching and scientific research, there is a lack of a low-cost, rapid deployment, and indoor and outdoor universal closed-loop experimental platform, which leads students and researchers to invest a lot of effort in equipment debugging and environment preparation during the algorithm design and verification process, which seriously hinders the efficiency of technological innovation.

[0011] Therefore, there is an urgent need for a compact, easy-to-move, low-cost UUV path planning and control experimental system that can be quickly deployed in various experimental environments, which can not only efficiently operate in indoor experimental pools, outdoor lakes or ports and other environments, but also provide stable and reliable positioning and communication capabilities, thereby significantly reducing the experimental threshold and improving the flexibility and efficiency of scientific research and teaching activities. SUMMARY

[0012] Therefore, the present application provides a low-cost portable system for UUV path planning and control experiments.

[0013] To solve the above technical problems, the present application adopts the following technical solutions:

[0014] A low-cost portable system for UUV path planning and control experiments, comprising a shore-based unit, a floating unit, a submersible unit, a zero-float cable and a software stack;

[0015] The shore-based unit is composed of an upper computer, a UWB base station and a human-computer interaction device, and is used for task planning, experiment monitoring, data processing and indoor positioning calculation;

[0016] The shore-based unit and the floating unit transmit control instructions and sensing data through a wireless network, and the floating unit and the submersible unit use a zero-float cable for wired communication;

[0017] The floating unit is used for transmitting high-bandwidth, low-latency data streams and receiving motion control instructions and task parameters issued by the shore-based unit; the submersible and the shore-based unit are connected through the floating unit;

[0018] The submersible unit collects real-time attitude information, state information, environmental information and video streams collected by the front-end camera through onboard sensors, and sends them to the floating unit router through a network cable, and then transmits them to the shore-based unit through a wireless network to realize real-time monitoring; the submersible system receives GNSS data and joystick control signals from the floating unit, and combines with its own depth gauge data to calculate the current three-dimensional position coordinates through the ROS system, providing accurate feedback for closed-loop control.

[0019] Preferably, the host computer adopts an industrial or commercial computer running Windows system, with built-in task management, state visualization and data recording modules, and maintains real-time communication with other units through wired or wireless means.

[0020] Preferably, the human-computer interaction device mainly uses a dual-joystick remote controller for manual control of the attitude and movement speed of the underwater vehicle; its signals are transmitted to the host computer through a USB interface or a 2.4 GHz wireless link, and are analyzed and protocol-encapsulated by the host computer software module, then sent to the floating unit router, and then transmitted to the underwater vehicle control system through the zero-buoyancy cable; in the indoor positioning mode, the UWB base station obtains relative distance information by bidirectional ranging with the UWB tag of the floating unit; the host computer positioning algorithm module calculates the two-dimensional position of the floating tag based on the ranging data of the three base stations, and generates three-dimensional position information in combination with the depth gauge information of the underwater vehicle.

[0021] Preferably, the core module of the shore-based unit includes: ① task planning module: supporting route setting, depth curve planning and task parameter configuration; ② state monitoring module: real-time display of power, depth, attitude, video screen and communication quality indicators of the underwater vehicle and the floating unit; ③ data recording module: synchronous saving of sensor data, video stream and control instructions with time stamp, facilitating later analysis and experimental reproduction; ④ positioning and fusion module: calling UWB or GNSS data according to the experimental mode, and matching and fusing with depth information to provide a unified pose data source for path planning and control.

[0022] Preferably, the data stream with high bandwidth and low delay includes real-time video, attitude information, depth, power and other state parameters.

[0023] The attitude information includes acceleration, angular velocity and heading angle, the state information includes power, internal temperature and propeller speed, and the environmental information includes water depth and external pressure.

[0024] Preferably, the floating unit adopts a sealed waterproof shell design, and the key hardware integrated inside includes: (i) multi-protocol router: responsible for protocol conversion and data forwarding of wired and wireless links; (ii) UWB tag: as a ranging terminal in indoor positioning mode, working in cooperation with the shore-based UWB base station; (iii) GNSS module: providing real-time geographic coordinates in outdoor mode; (iv) STM32 microcontroller: used to calculate the position of the floating unit from the data obtained from the GNSS module, which can be omitted if the GNSS module has a built-in calculation module; (v) battery system: providing independent power supply for all core modules to ensure continuous operation for several hours without external power supply.

[0025] Preferably, the submersible combines its depth gauge reading to complete three-dimensional position estimation, providing absolute position information for path planning and attitude control; in environments where indoor or GNSS signals are not available, the system switches to UWB mode: the shore-based UWB base station and the UWB tag of the floating unit perform bidirectional ranging, obtaining two-dimensional position data; the upper computer fuses it with the submersible depth gauge information to generate complete three-dimensional position information, and transmits it back to the float through a wireless link, and then to the submersible through a wired link, realizing positioning feedback and closed-loop control.

[0026] Preferably, the submersible can also receive path planning and control instructions issued by the shore-based upper computer, analyze the instruction content through the motion control node of ROS, and drive the propeller to adjust the speed, attitude and position to complete the intended task.

[0027] Preferably, the system further comprises a floating unit and submersible connecting device, which is composed of a universal joint, a zero buoyancy cable, a float ball and a floating body.

[0028] Preferably, the zero buoyancy cable is made of hard material and is used to fix the floating body at the water surface position directly above the submersible; the lower end of the cable is connected to the submersible body through the universal joint, and the float ball is sleeved on the hard rod, with the internal structure designed as lightweight at the upper part and heavy at the lower part.

[0029] The present application has the following technical effects compared with the prior art:

[0030] (1) The present application highly integrates core components such as UWB tags, GNSS, routers, joystick receivers, etc. in a sealed and waterproof float, and connects them to the underwater submersible through a zero buoyancy cable, so that the entire positioning and communication module can float directly on the water surface, avoiding the burden of arranging complex communication and positioning equipment underwater, and ensuring the waterproof reliability and long-term stable operation ability of the equipment in various environments;

[0031] (2) The present application uses GNSS and UWB positioning methods to realize the universality of indoor and outdoor environments. In an indoor experimental pool or other satellite signal-free environment, ranging and positioning are performed between the UWB base station and the UWB tag in the float, and three-dimensional position is obtained by fusing with the depth gauge on the submersible; in outdoor waters, GNSS can be directly used for two-dimensional positioning, and three-dimensional position calculation can also be realized by combining depth gauge data, thereby effectively bypassing expensive indoor dynamic capture systems and outdoor systems (such as USBL), significantly reducing system construction and use costs;

[0032] (3) The application adopts a distributed architecture of a shore base-float-submarine vehicle, the host computer on the shore base and the UWB base station perform data interaction with the router in the float through a wireless link, so that the control instructions and sensing data can be stably transmitted, the bandwidth, delay and interference limitations of the traditional all-underwater communication scheme are reduced, and the real-time performance and reliability of the control closed loop are improved; at the same time, the float as a water relay node can be quickly deployed in different test sites without complex site modification, and the portability and experimental layout efficiency of the system are greatly improved;

[0033] (4) The closed-loop path planning and control experimental platform constructed by the application can be compatible with various control algorithms and path planning strategies, support rapid replacement and iteration of algorithms, and is suitable for high-precision experimental requirements of scientific research institutions in algorithm verification and performance evaluation, and is also suitable for intuitive demonstration and practical operation of UUV principles, navigation and control methods in teaching;

[0034] (5) The system of the application not only shortens the period from algorithm design to experimental verification, but also improves the repeatability and scalability of the experiment, and provides a low-cost, high-flexibility and generalizable experimental condition for UUV technology research and development;

[0035] (6) The application realizes an indoor and outdoor fast deployment, low-cost, high-reliability UUV path planning and control experimental platform through structural simplification, module integration, multi-environment adaptation and rapid layout, supports closed-loop algorithm verification and manual remote control operation, has the characteristics of compact structure, simple deployment, wide application scenarios and strong scalability, and can be widely applied in scientific research, teaching and UUV technology verification fields; the system deployment process is simple, the float and the submarine vehicle can be quickly put into use in different test sites without large fixed infrastructure, which significantly reduces the layout time and cost, and can flexibly support algorithm research and development, teaching demonstration, system debugging and function verification and other application scenarios. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is the overall system architecture of the application;

[0037] Figure 2 is the connection device diagram of the float unit and the submarine vehicle of the application;

[0038] Figure 3 is an indoor pool experimental system based on the application. DETAILED DESCRIPTION

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Example 1:

[0041] like Figure 1 As shown, the low-cost portable UUV path planning and control experimental system of the present invention includes five core components: shore-based unit, buoy unit, submersible unit, zero-buoyancy cable and software stack.

[0042] The system adopts a distributed architecture design that combines wired and wireless technologies, and modularizes functions such as positioning, communication, command generation and execution to achieve rapid deployment and closed-loop control algorithm verification in indoor and outdoor environments, significantly reducing experimental costs and improving portability and flexibility.

[0043] The shore-based unit mainly consists of three parts: a host computer, a UWB base station, and human-computer interaction equipment. It undertakes core functions such as mission planning, experimental monitoring, data processing, and indoor positioning calculation.

[0044] The host computer uses an industrial or commercial computer running Windows, with built-in task management, status visualization and data recording modules, and maintains real-time communication with other units via wired or wireless means.

[0045] The human-machine interface primarily uses a dual-joystick remote controller for manual control of the submersible's attitude and speed. Signals are transmitted to a host computer via a USB interface or a 2.4GHz wireless link. The host computer software module parses and encapsulates the signals before sending them to the float unit router, and then transmits them to the submersible's control system via a zero-buoyancy cable. In indoor positioning mode, UWB base stations perform bidirectional ranging with the UWB tags on the float unit to obtain relative distance information. The host computer's positioning algorithm module calculates the two-dimensional position of the float tag based on ranging data from at least three base stations and combines this with the submersible's depth gauge information to generate three-dimensional position information, achieving high-precision positioning and path tracking in indoor environments.

[0046] This location information is not only used for real-time navigation display, but also serves as feedback input for closed-loop control algorithms, supporting online control accuracy evaluation and performance analysis.

[0047] The software layer of the shore-based unit adopts a modular architecture, and the core modules include: ① task planning module: support for route setting, depth curve planning and task parameter configuration; ② state monitoring module: real-time display of power, depth, attitude, video screen and communication quality indicators of the underwater vehicle and the float; ③ data recording module: synchronized saving of sensor data, video stream and control instructions with time stamp, facilitating post-analysis and experimental reproduction; ④ positioning and fusion module: call UWB or GNSS data according to the experimental mode, and match and fuse with depth information to provide a unified pose data source for path planning and control.

[0048] Through the cooperation of the above hardware and software, the shore-based unit not only realizes real-time monitoring and control of the underwater vehicle, but also provides high flexibility and operability for subsequent algorithm verification, data analysis and system expansion.

[0049] The design concept emphasizes portability and rapid deployment: in outdoor experiments, UWB base stations can not be used, and only GNSS positioning and depth meters of the float can be used to complete the task; in indoor experiments, only UWB base stations and depth meters can be used to complete precise positioning and control without satellite signals.

[0050] The float unit plays a dual role of communication relay and surface positioning node in the overall system architecture, directly connecting the underwater vehicle and the shore-based unit to realize bidirectional information transmission and multi-mode positioning support.

[0051] In terms of communication link, the float unit and the underwater vehicle unit establish a wired high-speed connection through a zero-buoyancy cable for transmitting high-bandwidth, low-latency data streams, including real-time video, attitude information, depth, power and other state parameters; at the same time, it receives motion control instructions and task parameters issued by the shore-based unit.

[0052] The float unit and the shore-based unit establish a stable data link through a wireless network (2.4GHz or 5GHz), so that the system still has good communication stability and flexibility in deployment scenarios with long shore distance or limited terrain.

[0053] To adapt to the environmental requirements of long-time operation on the sea surface, the float unit adopts a sealed waterproof housing design and has the ability to prevent surge, corrosion and water intrusion.

[0054] The key hardware integrated inside includes: (i) a multi-protocol router: responsible for protocol conversion and data forwarding of wired and wireless links; (ii) a UWB tag: as a ranging terminal in indoor positioning mode, working with the shore-based UWB base station; (iii) a GNSS module: providing real-time geographic coordinates in outdoor mode; (iv) an STM32 microcontroller: used to calculate the position of the float from the data obtained from the GNSS module, which can be omitted if the GNSS module has a built-in calculation module; (v) a battery system: providing independent power supply for all core modules, ensuring continuous operation for several hours without external power supply.

[0055] In the positioning mode, the float unit supports both outdoor GNSS + depth gauge and indoor UWB + depth gauge strategies. In outdoor mode, the position data collected by the GNSS module is processed by the STM32, then transmitted to the underwater vehicle through the router and zero buoyancy cable; the underwater vehicle combines its depth gauge readings to complete the three-dimensional position estimation, providing absolute position information for path planning and attitude control. In indoor or GNSS signal unavailable environments, the system switches to UWB mode: the shore-based UWB base station performs bidirectional ranging with the UWB tag of the float unit to obtain two-dimensional position data; the host computer fuses it with the underwater vehicle depth gauge information to generate complete three-dimensional position information, and transmits it back to the float through the wireless link, and then to the underwater vehicle through the wired link, realizing positioning feedback and closed-loop control.

[0056] Based on the Linux system combined with the ROS (Robot Operating System) software architecture, the application constructs a highly modular and extensible task execution and data management platform. The underwater vehicle collects real-time attitude information (such as acceleration, angular velocity, heading angle), state information (such as power, internal temperature, thruster speed), environmental information (such as water depth, external pressure), and video stream collected by the front-end camera through onboard sensors, and sends them to the float unit router through the network cable, and then transmits them to the shore unit through the wireless network, realizing real-time monitoring.

[0057] The underwater vehicle system receives GNSS data and joystick control signals from the float unit, and combines its depth gauge data to calculate the current three-dimensional position coordinates through the ROS system, providing accurate feedback for closed-loop control. The underwater vehicle can also receive path planning and control instructions from the shore host computer, analyze the instruction content through the motion control node of ROS, and drive the thruster to adjust the speed, attitude and position to complete the specified task.

[0058] The entire underwater vehicle control system supports algorithm replacement and function extension, allowing different control strategies and path planning algorithms to be quickly deployed on the same hardware platform.

[0059] A dual-mode positioning solution is provided for different experimental environments: in outdoor water areas, the system adopts a fusion positioning method of GNSS+depth gauge, uses the GNSS coordinates obtained by the floating unit and the depth gauge measurement value of the underwater vehicle, and obtains high-precision three-dimensional position through fusion calculation; in indoor experimental pools or satellite signal-free environments, the system switches to the UWB positioning mode, and the shore-based UWB base station and the floating unit UWB tag perform distance measurement, and three-dimensional position information is generated in combination with the depth gauge information of the underwater vehicle.

[0060] In terms of communication link, the shore-based unit and the floating unit transmit control instructions and sensing data through a wireless network, ensuring deployment flexibility and portability; the floating unit and the underwater vehicle unit use a zero-buoyancy cable for wired communication, which not only provides a high-bandwidth, low-latency data transmission channel, but also provides power supply or transmission of synchronization signals for the underwater vehicle, improving system stability.

[0061] In application scenarios requiring high-precision positioning, such as using UWB or GNSS positioning results as real trajectories in underwater simultaneous localization and mapping (SLAM) algorithms for algorithm evaluation, the present application proposes a specially designed floating unit and underwater vehicle connection device, as shown in Figure 2 .

[0062] The device is composed of a universal joint, a zero-buoyancy cable (hard rod structure), a floating ball, and a floating body.

[0063] The zero-buoyancy cable is made of hard material and has sufficient longitudinal rigidity and zero-buoyancy characteristics, and is used to fix the floating body at the water surface position directly above the underwater vehicle.

[0064] The lower end of the cable is connected to the underwater vehicle body through a universal joint, which can effectively eliminate the twisting effect of the hard rod caused by the pitch and roll of the underwater vehicle during navigation and turning, thereby reducing the possibility of lateral displacement of the floating body caused by changes in the attitude of the underwater vehicle. The floating ball is sleeved on the hard rod and can slide up and down along the hard rod. Its internal structure is designed with a lightweight upper part and a heavy lower part. When the underwater vehicle dives to different depths, the floating ball automatically adjusts its attitude under the action of buoyancy and gravity and keeps the hard rod vertical, thereby keeping the UWB or GNSS antenna inside the floating body directly above the underwater vehicle on the water surface.

[0065] This structure significantly reduces the lateral positioning error caused by water flow, waves, or underwater vehicle movement, providing a stable geometric reference relationship for high-precision positioning.

[0066] When the positioning accuracy requirement is not high, the present application can replace the above-mentioned hard rod type zero-buoyancy cable with a flexible soft zero-buoyancy cable and remove the floating ball structure. At this time, the floating body relies on its own buoyancy to float on the water surface and is connected to the underwater vehicle through a soft cable.

[0067] The design is more convenient to deploy and retrieve, while reducing the weight and structural complexity of the equipment. In this mode, there is a certain deviation between the positions of the float and the submersible in the horizontal direction, which is directly related to the depth of the submersible. If the length of the zero buoyancy cable is l and the depth of the submersible is d, the theoretical maximum error between the float and the submersible in the water surface direction is:

[0068]

[0069] where E is the horizontal offset distance. This formula provides a theoretical basis for error estimation during system operation, which can be used for evaluation and compensation of positioning accuracy in task planning. By flexibly selecting the structure of the connecting device in different modes, the invention can balance between deployment convenience and positioning accuracy, and adapt to various operation and experimental needs.

[0070] As shown in Figure 3 , UWB positioning systems are arranged around the pool, with multiple UWB base stations fixedly installed on adjustable height and angle tripods, distributed in a closed manner around the pool to ensure high coverage of positioning signal collection in the entire experimental area. Each UWB base station communicates with the shore-based control system to measure the spatial coordinates of the submersible or related tags in real time. The interior of the pool can be arranged with different shapes and positions of obstacles according to experimental needs to simulate underwater obstacle environments.

[0071] In addition, local flow generating devices can be installed in specific areas of the pool to simulate the fluid disturbance environment existing in natural water areas by changing the flow speed and direction, to evaluate the motion control and positioning accuracy of the submersible in dynamic flow conditions. The submersible can freely navigate during the experiment, interact with the positioning system through the UWB tag carried by the submersible to obtain position data, and combine with attitude sensor information for navigation and obstacle avoidance.

[0072] This experimental platform can flexibly adjust the base station layout, obstacle shape, and flow field parameters, providing repeatable and controllable experimental conditions for performance evaluation of different algorithms such as SLAM, path planning, and positioning fusion.

[0073] The experimental environment of the outdoor system is relatively simple, mainly relying on natural water areas (such as lakes, rivers, or bays) to carry out submersible navigation and control verification.

[0074] In this system, the submersible directly uses the GNSS module to obtain its real-time position information in the geographic coordinate system, and combines with attitude sensors, depth meters, and other sensing units to realize autonomous positioning and attitude calculation in three-dimensional space. Due to the high quality of GNSS signals in the absence of outdoor water surface obstructions, high positioning accuracy can be provided in the horizontal direction, so there is no need to arrange additional positioning infrastructure such as UWB base stations.

[0075] The underwater vehicle returns the position, attitude, power, video stream and other state information to the shore-based host computer system in real time through a wireless communication link. The host computer generates control instructions according to the task requirements and sends them to the underwater vehicle through the wireless link for execution. During the experiment, temporary buoys, artificial obstacles or natural water flow conditions can be set in the water area as needed to test the path tracking, obstacle avoidance ability and task execution stability of the underwater vehicle in different hydrodynamic environments.

[0076] The outdoor system has simple structure and rapid deployment, and is suitable for large-scale navigation test and verification of robustness and adaptability of the algorithm in a real environment.

[0077] In summary, the present application overcomes the problems of high cost, complex layout and poor portability of existing experimental platforms. By integrating various positioning and communication modules in the float and forming a wired and wireless combined communication link with the underwater vehicle and shore-based equipment, the system can be quickly deployed in indoor and outdoor environments, real-time three-dimensional position of the underwater vehicle can be obtained, and closed-loop path planning and control algorithm verification and optimization can be realized. It can not only meet the diversified needs of research institutions and universities in UUV technology research and development, algorithm testing, teaching training and other aspects, but also can comprehensively verify the system function and performance before actual task deployment. It can be quickly laid out indoors and outdoors, support closed-loop path planning and control experiments, effectively replace expensive USBL or dynamic capture systems, greatly reduce the experimental threshold and cost, improve the flexibility, scalability and portability of the experiment, and provide an efficient, economical and applicable platform for scientific research, teaching and UUV technology verification.

[0078] The above is only the preferred embodiment of the present application, and does not limit the technical scope of the present application. Any slight modification, equivalent change and modification of the above embodiment according to the technical essence of the present application still belongs to the scope of the technical solution of the present application.

Claims

1. A low-cost, portable system for UUV path planning and control experiments, characterized in that, Includes shore-based units, buoy units, submersible units, zero-buoyancy cables, and software stack; The shore-based unit consists of three parts: a host computer, a UWB base station, and a human-computer interaction device. It is used for task planning, experimental monitoring, data processing, and indoor positioning calculation. The shore-based unit and the buoy unit transmit control commands and sensor data via a wireless network, while the buoy unit and the submersible unit communicate via a zero-buoyancy cable. The float unit is used to transmit high-bandwidth, low-latency data streams and receive motion control commands and mission parameters issued by the shore-based unit; the submersible is connected to the shore-based unit through the float unit. The submersible unit collects attitude, status, and environmental information in real time through onboard sensors, as well as video streams captured by the front-end camera. This information is then transmitted via network cable to the buoy unit router and then via wireless network to the shore-based unit for real-time monitoring. The submersible system receives GNSS data and joystick control signals from the buoy unit and, in conjunction with its own depth gauge data, calculates the current three-dimensional position coordinates through the positioning module within the ROS, providing precise feedback for closed-loop control.

2. The low-cost, portable system for UUV path planning and control experiments according to claim 1, characterized in that, The host computer is an industrial or commercial computer running Windows, with built-in task management, status visualization and data recording modules, and maintains real-time communication with other units via wired or wireless means.

3. The low-cost, portable system for UUV path planning and control experiments according to claim 1, characterized in that, The human-machine interface device is mainly a dual-joystick remote controller, used for manual control of the submersible's attitude and speed. Its signals are transmitted to the host computer via USB interface or 2.4GHz wireless link. After being parsed and encapsulated by the host computer software module, the signals are sent to the float unit router and then transmitted to the submersible control system via a zero-buoyancy cable. In indoor positioning mode, the UWB base station obtains relative distance information by performing bidirectional ranging with the UWB tag of the float unit. The positioning algorithm module on the host computer calculates the two-dimensional position of the float tag based on the ranging data of the three base stations and generates three-dimensional position information by combining it with the submersible depth gauge information.

4. A low-cost, portable system for UUV path planning and control experiments according to claim 1, characterized in that, The core modules of the shore-based unit include: ① Mission planning module: supporting route setting, depth curve planning, and mission parameter configuration; ② Status monitoring module: displaying the battery level, depth, attitude, video footage, and communication quality indicators of the submersible and buoy in real time; ③ Data recording module: synchronously saving sensor data, video streams, and control commands with timestamps for easy analysis and experimental reproduction later; ④ Positioning and fusion module: calling UWB or GNSS data according to the experimental mode and matching and fusing it with depth information to provide a unified location data source for path planning and control.

5. A low-cost, portable system for UUV path planning and control experiments according to claim 1, characterized in that, The transmission of high-bandwidth, low-latency data streams includes real-time video, attitude information, depth, battery level, and other status parameters. The attitude information includes acceleration, angular velocity, and heading angle; the status information includes battery level, internal temperature, and thruster rotation speed; and the environmental information includes water depth and external pressure.

6. A low-cost, portable system for UUV path planning and control experiments according to claim 1, characterized in that, The float unit adopts a sealed waterproof housing design, and its key integrated hardware includes: (i) a multi-protocol router: responsible for protocol conversion and data forwarding between wired and wireless links; (ii) a UWB tag: serving as a ranging terminal in indoor positioning mode, working in conjunction with a shore-based UWB base station; (iii) a GNSS module: providing real-time geographic coordinates in outdoor mode; (iv) an STM32 microcontroller: used to calculate the float's position from the data obtained from the GNSS module. If the GNSS module has its own calculation module, this microcontroller can be omitted; (v) a battery system: providing power to all modules within the float unit, ensuring continuous operation for several hours without external power supply.

7. A low-cost, portable system for UUV path planning and control experiments according to claim 1, characterized in that, The submersible combines its depth gauge readings to complete three-dimensional position estimation, providing absolute position information for path planning and attitude control. In indoor environments or environments where GNSS signals are unavailable, the system switches to UWB mode: the shore-based UWB base station and the UWB tag of the float unit perform bidirectional ranging to obtain two-dimensional position data; the host computer fuses this data with the submersible's depth gauge information to generate complete three-dimensional position information, which is then transmitted back to the float via a wireless link and then transmitted to the submersible via a wired link to achieve positioning feedback and closed-loop control.

8. A low-cost, portable system for UUV path planning and control experiments according to claim 1, characterized in that, The submersible can also receive path planning and control commands from a shore-based host computer. By parsing the command content through the motion control nodes of ROS, it drives the thrusters to adjust speed, attitude and position to complete the predetermined mission.

9. A low-cost, portable system for UUV path planning and control experiments according to claim 1, characterized in that, The system also includes a floating unit and a connection device for the submersible, which consists of a universal joint, a zero-buoyancy cable, a buoy, and a floating body.

10. A low-cost, portable system for UUV path planning and control experiments according to claim 9, characterized in that, The zero-buoyancy cable is made of rigid material and is used to fix the floating body at the water surface position directly above the submersible. The lower end of the cable is connected to the submersible body through the universal joint. The float is sleeved on the rigid rod, and its internal structure is designed to be lightweight at the top and heavy at the bottom.

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