An underwater inspection sampling system and method based on negative pressure replacement and visual obstacle avoidance

Abstract

The application provides an underwater inspection sampling system and method based on negative pressure replacement and visual obstacle avoidance, which comprises a suspension ring, a buoyancy adjusting cabin, a main function cabin and a bottom cabin arranged in sequence below the suspension ring; the suspension ring is used for connecting a unmanned aerial vehicle; the bottom cabin is connected with a main camera and a wide-angle camera, and a plurality of electromagnetic devices are arranged below the bottom cabin; a plurality of main control circuit boards are arranged in the main function cabin, and a plurality of first sensors are arranged on the outer periphery of the main function cabin; a plurality of sampling bottles are arranged in the main function cabin, a water inlet pipe is arranged in the bottom cabin, one end of the water inlet pipe is located outside the bottom cabin, and the other end of the water inlet pipe is connected with the sampling bottles; an inner capsule is arranged in the sampling bottle. The application adopts a negative pressure replacement sampling principle, and water sample collection is passively completed by relying on water pressure difference in the sampling process, so that water body disturbance caused by pump stirring in traditional pump suction sampling is avoided, and bubbles are reduced, the demand of high-precision pollution tracing and ecological monitoring can be met, and the accuracy of sample detection results is obviously improved compared with traditional sampling modes.

Description

Technical Field

[0001] This invention relates to the field of underwater inspection and sampling technology, specifically to an underwater inspection and sampling system and sampling method based on negative pressure displacement and visual obstacle avoidance. Background Technology

[0002] Water environment monitoring is a core and fundamental link in water resource protection, pollution control, and ecological restoration. Underwater fixed-point sampling and in-situ parameter detection are key means to obtain real environmental data of water bodies. Traditional underwater sampling operations mainly rely on manual diving, sampling vessels towing samplers, or remotely operated underwater vehicles (ROVs) carrying sampling equipment.

[0003] However, existing technologies have many limitations:

[0004] First, manual diving operations are limited by conditions such as water depth, water flow, and water toxicity, resulting in high operational risks, low efficiency, and difficulty in achieving large-scale, multi-depth batch sampling. Sampling vessel operations, on the other hand, suffer from high deployment costs and poor adaptability to shallow water areas and narrow waterways. Furthermore, the traditional pump-suction sampling method causes water disturbance during sampling due to the agitation of the pump, leading to the resuspension of bottom sediments and mixing of water from different layers, which severely compromises the in-situ authenticity of the samples and fails to meet the needs of high-precision pollution source tracing and ecological monitoring.

[0005] Secondly, most existing underwater sampling equipment is deployed independently, requiring specialized deployment and retrieval equipment. This leads to complex deployment processes, slow response times, and an inability to meet the rapid sampling needs of sudden water pollution incidents. In recent years, the solution of using drones to carry sampling equipment has gradually gained attention; however, most existing solutions can only collect surface water samples, cannot perform sampling at a fixed depth, and lack underwater environmental perception and obstacle avoidance capabilities. They are prone to collision damage in complex underwater environments and cannot achieve batch sampling of multiple bottles.

[0006] In addition, traditional samplers often require active water pumping to complete the sampling process. This process not only disturbs the water body but also easily leads to residual pollution in the pipeline. Samples from different sampling points are prone to cross-contamination, affecting the accuracy of the test results. Summary of the Invention

[0007] The main objective of this invention is to provide an underwater inspection and sampling system and method based on negative pressure displacement and visual obstacle avoidance, which solves the problems of large disturbance, slow deployment, inability to sample in batches, and lack of underwater obstacle avoidance capability in traditional sampling methods.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: An underwater inspection and sampling system based on negative pressure displacement and visual obstacle avoidance includes a suspension ring, with a buoyancy adjustment chamber, a main functional chamber and a bottom chamber arranged sequentially below the suspension ring; the suspension ring is used to connect to a drone to realize the system's mounting, deployment and recovery.

[0009] The bottom compartment is connected to a main camera and a wide-angle camera. Several electromagnetic devices are located below the bottom compartment. Several main control circuit boards are located inside the main functional compartment, and several first sensors are located on the outer periphery. Several sampling bottles are located inside the main functional compartment. A water inlet pipe is located in the bottom compartment. One end of the water inlet pipe is located outside the bottom compartment, and the other end is connected to the sampling bottle. An inner bladder is located inside the sampling bottle.

[0010] In the preferred embodiment, the suspension ring is connected to the buoyancy adjustment chamber via a universal joint, and the buoyancy adjustment chamber contains buoyancy material. The suspension ring and the buoyancy adjustment chamber form at least two rotational degrees of freedom through the universal joint, which is used to achieve adaptive deflection of the system at any angle and ensure that the system maintains a vertical attitude during the descent. The overall shape of the system is streamlined to reduce underwater motion resistance. The suspension ring is connected to the UAV via a cable, and the UAV is equipped with a cable retraction and deployment structure. The cable is wrapped with a wire and / or coaxially connected to a cable to achieve synchronous transmission of power supply and data.

[0011] In the preferred embodiment, the main camera and the wide-angle camera are symmetrically arranged on both sides of the bottom hull. The main camera is equipped with an LED light strip to adapt to low-light underwater environments. The wide-angle camera has a 360° rotation structure to work with the main camera to achieve underwater panoramic inspection, target recognition, and visual obstacle avoidance. The LED light strip is electrically connected to the main control circuit board and adjusts its brightness via a PWM signal. It has four modes: standby, inspection, sampling, and strobe, to meet the supplementary lighting needs of different operating scenarios. The electromagnetic device is an electromagnet that electromagnetically attracts a counterweight assembly. The counterweight assembly includes a counterweight magnet and a counterweight block, which are fixedly connected. Different weights of counterweights can be quickly replaced according to the operating water depth to adjust the system's sinking speed.

[0012] In a preferred embodiment, the first sensor includes a temperature sensor, a pressure sensor, a turbidity sensor, a conductivity sensor, a dissolved oxygen sensor, and a pH sensor. Multiple mounting holes are arranged in a circular array on the exterior of the main functional compartment. The first sensor is fixedly installed through these mounting holes, and its signal lines are connected to the sensor interface on the main control circuit board. The temperature sensor detects water temperature to determine thermal pollution and stratification, and assists in recording sampling depth. The pressure sensor detects water depth to record the precise depth of the sampling point, assisting in depth-controlled sampling and buoyancy adjustment. The turbidity sensor detects suspended solids concentration to identify areas with high suspended solids, trigger sampling, and determine silt, algae, or pollution plumes. The conductivity sensor detects water conductivity to determine salinity changes, industrial wastewater, or agricultural runoff pollution. The dissolved oxygen sensor detects dissolved oxygen content in the water to identify eutrophic areas with organic pollution. The pH sensor detects water acidity / alkalinity to determine acid / alkaline pollution.

[0013] In the preferred embodiment, the main control circuit board is equipped with a battery and a controller, and is externally connected to the UAV control unit via a cable; a partition is provided inside the main functional compartment, with the main control circuit board and sampling bottles located on both sides of the partition; the main control circuit board and the partition are connected by fixed copper pillars to achieve physical isolation between the circuit part and the sampling part, preventing water leakage from damaging the circuit.

[0014] In the preferred embodiment, the bottom chamber is equipped with a rotating chassis and a motor. The motor drives multiple sampling bottles connected to the rotating chassis to rotate. The rotating chassis is circular. The multiple sampling bottles are connected to the rotating chassis and arranged in a ring. A water inlet pipe is connected to one of the sampling bottles. The sampling bottle completes the switching of the water inlet pipe connection by rotating, realizing sequential sampling of multiple bottles. The sampling bottle is equipped with an inner bladder, and the inner bladder is equipped with a second valve. Before sampling, the inner bladder and the sampling bottle are in a negative pressure state. The inner bladder is an elastic bladder made of food-grade silicone material to avoid contaminating the sample.

[0015] In a preferred embodiment, the rotating chassis includes a fixed disk fixed to the bottom chamber, with a motor fixed in the middle of the fixed disk; a rotating ring is rotatably connected to the top of the fixed disk, with the motor located inside the rotating ring; an internal gear ring is provided on the inner wall of the rotating ring; a first gear and a second gear are rotatably connected inside the fixed disk, with the first gear connected to the output shaft of the motor; the second gear meshes with the first gear and with the internal gear ring, forming a two-stage reduction mechanism to ensure stable rotational speed and accurate positioning of the rotating ring; several insertion posts are provided at the top of the rotating ring, which are inserted into the sampling bottle, and a second sealing ring is provided between the insertion post and the sampling bottle to achieve a sealed connection; several through holes are provided inside the rotating ring, which communicate with the sampling bottle and the water inlet pipe; a first valve is provided inside the through holes to control the opening and closing of the sampling pipeline.

[0016] In the preferred embodiment, the bottom of the rotating ring is provided with several positioning holes located at the bottom of the through hole; a second sensor is provided on the side of the positioning hole to detect the positioning position of the rotating ring and ensure accurate docking of the sampling bottle and the water inlet pipe; the water inlet pipe is provided with a third valve, and a first sealing ring is provided between the water inlet pipe and the bottom chamber; a pump is provided in the bottom chamber, which is a bidirectional pump, one end of which is connected to the water inlet pipe, and the other end is connected to a movable pipe through a connecting pipe, which is a flexible tube; the movable pipe is slidably connected to the fixed plate, and a sealing ring is provided at the connection; the movable pipe is adapted to the positioning hole, and the top end of the movable pipe is inserted into the positioning hole to complete the connection with the through hole, and a sealing gasket is provided; the movable pipe is provided with a connecting plate, and several push rods are provided between the connecting plate and the fixed plate to drive the movable pipe to complete the docking action.

[0017] A method for using an underwater inspection and sampling system based on negative pressure displacement and visual obstacle avoidance includes the following steps: S1. Connect the system to the drone, complete the power-on self-test and first sensor calibration, and pre-evacuate the sampling bottle and its inner bladder under negative pressure. Establish two-way communication between the drone control terminal and the main control circuit board; S2. The drone carrying the system flies over the target sampling water area and slowly lowers the system. The sensor transmits water depth data, and the control unit lowers the system to the specified sampling depth based on the water depth data; S3. After the system reaches the designated depth, the dual cameras work together to complete underwater obstacle avoidance and sampling point benchmark positioning, and the sensors synchronously collect water environment parameters and transmit them back in real time. S4. Samples are collected using the sampling bottle; S5, Proceed to the next location; S6. Repeat S4-S5 until the sampling task is completed or all sampling bottles have been sampled. S7. The drone slowly recovers the system and returns it to its initial position. S8. Recover the sampling bottle and conduct sample testing; In S4, the system completes undisturbed sampling by displacing negative pressure within the sampling bottle.

[0018] This invention provides an underwater inspection and sampling system and method based on negative pressure displacement and visual obstacle avoidance. By adopting the above scheme, the following beneficial effects are achieved: Employing the principle of negative pressure displacement sampling, negative pressure is pre-extracted from the ground, and water samples are passively collected by relying on the water pressure difference during the sampling process. This not only avoids water disturbance caused by pump agitation in traditional pump-suction sampling, but also solves the problems of resuspension of bottom sediments and mixing of water from different water layers, maximizing the preservation of the in-situ authenticity of the water sample, but also reduces air bubbles. It can meet the needs of high-precision pollution source tracing and ecological monitoring, and the accuracy of sample detection results is significantly improved compared with traditional sampling methods.

[0019] The deployment method using drones eliminates the need for dedicated sampling vessels or ROV delivery equipment, enabling rapid deployment within minutes and quick access to target water areas. This is particularly suitable for emergency sampling needs in the event of sudden water pollution incidents. At the same time, the system is small in size and lightweight, allowing it to easily enter shallow water areas, narrow channels, and other areas inaccessible to traditional sampling equipment, significantly expanding the coverage of sampling operations.

[0020] The rotating multi-sampling bottle structure allows for the carrying of multiple independently sealed sampling bottles in a single task, enabling batch sampling at multiple different sampling points. Each sampling bottle is independently sealed and automatically switches during the sampling process, completely avoiding cross-contamination between samples from different sampling points. This significantly improves operational efficiency compared to traditional single-sampling methods and greatly reduces the time cost of multi-sampling point operations.

[0021] Equipped with a dual-camera visual perception system, it can achieve 360° underwater environmental scanning, automatically identify obstacles such as aquatic plants, reefs, and fishing nets, and complete obstacle avoidance path planning, solving the problem of traditional underwater sampling equipment being easily damaged by collisions in complex environments; at the same time, the system can simultaneously collect multi-parameter water environment data and transmit it back to the control terminal in real time, automatically identify pollution plume areas and trigger sampling, with a high degree of intelligence, and can be adapted to various complex underwater operation scenarios.

[0022] The counterweight components can be quickly replaced according to the operating water depth to adapt to different operating needs; the sampling bottles can be quickly disassembled and replaced for convenient subsequent sample transportation and testing; the whole system can be adapted to conventional multi-rotor drones without the need for special customized equipment, resulting in low deployment costs and easy promotion and application. At the same time, it has reserved function expansion interfaces to expand more sensors or sampling functions as needed. Attached Figure Description

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the universal joint structure of the present invention; Figure 3 This is a cross-sectional view of the sampling bottle of the present invention; Figure 4 This is a schematic diagram of the combined structure of the sampling bottle and the rotatable chassis of the present invention; Figure 5 This is a top view schematic diagram of the rotatable chassis structure of the present invention; Figure 6 This is a bottom view of the lower compartment of the present invention; Figure 7 This is a top view of the overall structure of the present invention; Figure 8 This is a cross-sectional view of the buoyancy regulating chamber of the present invention; Figure 9 This is a schematic diagram of the sensor assembly structure of the present invention; Figure 10 This is a cross-sectional view of the rotatable chassis and bottom compartment of the present invention; In the picture: 1. Suspension ring; 2. Universal joint; 3. Buoyancy adjustment chamber; 4. Main functional chamber; 5. Main control circuit board; 6. Rotating chassis; 61. Fixed plate; 62. Rotating ring; 63. Internal gear ring; 64. First gear; 65. Second gear; 66. Insertion post; 67. Through hole; 68. First valve; 7. Motor; 8. Sampling bottle; 9. First sealing ring; 10. Water inlet pipe; 11. Central circular hole; 12. Bottom chamber; 13. Main camera; 14. Wide-angle camera; 15. Electromagnetic device; 16. Buoyancy material; 17. Fixed copper column; 18. Cable; 19. Second sealing ring; 20. LED light strip; 21. First sensor; 22. Partition; 23. Second valve; 24. Inner bladder; 25. Third valve; 26. Pump; 27. Movable pipe; 28. Connecting pipe; 29. ​​Connecting plate; 30. Push rod; 31. Second sensor. Detailed Implementation

[0024] Example 1: like Figure 1-10 As shown, this embodiment provides an underwater inspection and sampling system based on negative pressure displacement and visual obstacle avoidance. The overall shape is preferably a streamlined cylinder with a diameter of 120mm and a height of 300mm, which reduces underwater movement resistance and can be adapted to be mounted on multi-rotor UAVs.

[0025] Specifically, the system is equipped with a suspension ring 1, which is made of stainless steel and is used to connect to the pull rope of the drone. The pull rope is preferably a Kevlar braided rope, which is wrapped with an optoelectronic composite cable 18. The cable 18 is preferably a 4-core shielded cable, which can simultaneously realize 12V power supply and communication transmission.

[0026] The suspension ring 1 and the buoyancy adjustment chamber 3 are connected by a universal joint 2, which can form multiple rotational degrees of freedom. When the pull rope tilts during the lowering process, the buoyancy adjustment chamber 3 and the structure below it can automatically remain vertical under the action of gravity, ensuring the stability of the system's attitude.

[0027] The buoyancy adjustment chamber 3 is filled with buoyancy material 16, which is preferably epoxy resin composite glass microsphere solid buoyancy material with a density of 0.4 g / cm³. It can provide 0.8 N of buoyancy to offset part of the system weight. Together with the counterweight component below, it can achieve neutral buoyancy adjustment of the system and ensure the stability of the descent process.

[0028] The main functional compartment 4 is a sealed aluminum alloy body with an IP68 waterproof rating, meeting the operational requirements at different water depths. The interior of the main functional compartment 4 is divided into upper and lower chambers by a partition 22. The upper chamber houses the main control circuit board 5, and the lower chamber houses the sampling mechanism. The partition 22 and the main control circuit board 5 are connected by a fixed copper pillar 17, which is 5-10mm high, providing space for heat dissipation and physically isolating the circuitry from the sampling mechanism to prevent water leakage from damaging the circuitry.

[0029] The main control circuit board 5 is preferably an STM32F103 as the main controller, which integrates a power management module, a communication module, and a motor drive module. It has an onboard 2000mAh lithium battery, which can support the system to operate continuously for 2 hours. At the same time, it is connected to the control unit of the UAV through cable 18 to realize remote control and data transmission.

[0030] Six first sensors 21 are installed in a circular array around the outer periphery of the main functional compartment 4, namely: Temperature sensor: Preferably a DS18B20 waterproof temperature sensor with a detection range of -20℃ to 80℃ and an accuracy of 0.1℃, used to detect water temperature and determine thermal pollution and water stratification; Pressure sensor: Preferably an MS5837 waterproof pressure sensor with a detection range of 0~1.2MPa and an accuracy of 0.01MPa, used to detect water depth and achieve constant depth sampling; Turbidity sensor: Preferably a TS-300B turbidity sensor, with a detection range of 0~1000 NTU and an accuracy of 1%FS, used to detect suspended solids concentration and identify pollutant plumes; Conductivity sensor: preferably EC-5 conductivity sensor, detection range 0~100mS / cm, accuracy 2%FS, used for detecting salinity and polluted runoff; Dissolved oxygen sensor: preferably a DO-100 dissolved oxygen sensor, with a detection range of 0~20 mg / L and an accuracy of 0.1 mg / L, used for detecting organic pollution; pH sensor: Preferably a PH-014 waterproof pH sensor with a detection range of 0~14pH and an accuracy of 0.01pH, used to detect acid and alkaline contamination.

[0031] All sensor signal lines converge at the sensor interface on the main control circuit board 5 to achieve synchronous data acquisition.

[0032] The lower compartment 12 is an aluminum alloy body, which is detachably and sealed to the main functional compartment 4. The specific connection method can use existing technology, such as snap-fit ​​or threaded connection. A sealing gasket is provided at the connection point. The main camera 13 and the wide-angle camera 14 are symmetrically installed on both sides of the lower compartment 12. The main camera 13 is preferably an 8-megapixel underwater CMOS camera with a focal length of 2.8mm and a field of view of 90°. It is surrounded by an LED light strip 20 composed of 12 2835 LED beads. The brightness of the LED light strip 20 is adjusted by a PWM signal. Preferably, it has four modes: standby mode with 10% brightness and low power consumption; inspection mode with 50% brightness and normal supplemental lighting; sampling mode with 100% brightness and high-definition supplemental lighting; and strobe mode as an alarm mode, in which the LED flashes to alert when an obstacle is detected. The wide-angle camera 14 is preferably a 5-megapixel panoramic camera, equipped with a miniature gimbal, which can achieve 360° horizontal rotation. Together with the main camera 13, it can realize underwater panoramic environmental perception and achieve target recognition and visual obstacle avoidance through the YOLOv8 algorithm.

[0033] Four electromagnetic devices 15 are evenly installed below the bottom of the hull 12. These devices are preferably ELE-20 DC chuck electromagnets, powered by DC 12V, with a suction force of 10kg. They are used to attract the counterweight assembly, which includes a magnetic counterweight and a lead counterweight. These components can be replaced according to the operating water depth; for example, a 500g counterweight is used when operating in 100-meter water to ensure the system can sink smoothly. When necessary, the electromagnetic devices 15 are de-energized or their magnetic poles are adjusted, causing the counterweight assembly to detach, allowing the entire system to quickly rise using buoyancy to respond to emergencies.

[0034] The bottom compartment 12 is equipped with a rotating chassis 6, which includes a fixed plate 61. The fixed plate 61 is fixed to the bottom compartment 12. A motor 7 is installed in the middle of the fixed plate 61. The motor 7 is preferably a 28BYJ-48 waterproof stepper motor, powered by DC12V, with a reduction ratio of 1:64, a step angle of 0.0879°, and high positioning accuracy. It is controlled by existing methods.

[0035] The output shaft of motor 7 is connected to the first gear 64, which meshes with the second gear 65. The second gear 65 meshes with the internal gear ring 63 on the inner wall of the rotating ring 62, forming a two-stage reduction mechanism. This reduces the speed of the motor while increasing the torque, ensuring that the rotating ring 62 can rotate smoothly. Five to eight insertion posts 66 are evenly installed on the top of the rotating ring 62. Each insertion post 66 is equipped with a second sealing ring 19, preferably made of nitrile rubber, for inserting the sampling bottle 8 to achieve a seal.

[0036] Inside the rotating ring 62, each plug post 66 is provided with a through hole 67, and a first valve 68 is installed in the through hole 67. The first valve 68 is preferably a miniature electromagnetic ball valve, powered by DC12V, with a response time of 100ms, and is used to control the opening and closing of the pipeline.

[0037] At the bottom of the rotating ring 62, each through hole 67 is provided with a positioning hole. A second sensor 31 is installed on the side of the positioning hole. The second sensor 31 is preferably a Hall sensor, which is used to detect the position of the rotating ring to ensure that the sampling bottle 8 can be accurately aligned with the position where the water inlet pipe 10 is connected.

[0038] Inside the bottom compartment 12, above the water inlet pipe 10, a pump 26 is installed. The pump 26 is preferably a Hailin Technology S15 series miniature liquid-gas dual-purpose diaphragm pump, IP68 waterproof, DC12V powered, capable of bidirectional transmission. It can be used to create a vacuum during the pre-evacuation stage or to transfer liquid when needed. Other pumps capable of achieving the functions described in this application can also be selected according to requirements and usage. One end of the pump 26 is connected to the water inlet pipe 10, which is preferably a 304 stainless steel pipe. The water inlet pipe 10 is externally sealed to the bottom compartment 12 by a first sealing ring 9. A third valve 25, preferably a miniature electromagnetic ball valve, is installed on the water inlet pipe 10.

[0039] The other end of pump 26 is connected to movable tube 27 via flexible hose connecting pipe 28. Movable tube 27 is slidably connected to fixed plate 61. A nitrile rubber sealing ring is provided at the connection point. A sealing gasket is provided at the top of movable tube 27, which can be inserted into the positioning hole of rotating ring to achieve a sealed connection. A connecting plate 29 is connected to the outer periphery of movable tube 27. Two to four push rods 30 are provided between connecting plate 29 and fixed plate 61. The push rods 30 are preferably FY02 miniature waterproof electric push rods, used to push movable tube 27 up and down to complete the connection action.

[0040] The sampling bottle 8 is preferably a rigid bottle made of PET material, with an inner bladder 24 inside. The inner bladder 24 is made of food-grade elastic silicone material, which is elastic, non-toxic and non-polluting. The inner bladder 24 has its own elastic expansion capability. A second valve 23 is provided at the top of the inner bladder 24, which is also preferably a miniature electromagnetic ball valve. Before sampling, the cavity inside the inner bladder 24 and the sampling bottle 8 is pre-evacuated to a negative pressure state, and the inner bladder 24 contracts at the top of the sampling bottle. During sampling, the valve is opened, and external water enters the inner bladder 24 under the action of negative pressure and water pressure. At the same time, through the elasticity of the inner bladder 24 itself, the inner bladder 24 expands, and the water fully enters the inner bladder 24 to complete the sampling. The whole process does not require the operation of a pump and will not disturb the water body. After sampling, the second valve 23 is closed to seal the inner bladder 24.

[0041] Example 2: A method for using the above-mentioned underwater inspection and sampling system based on negative pressure displacement and visual obstacle avoidance includes the following steps: S1. Connect the system to the drone, complete the power-on self-test and calibration of the first sensor 21, and perform negative pressure pre-evacuation on all sampling bottles 8 and their inner bladders 24; establish bidirectional communication between the drone control terminal and the main control circuit board 5.

[0042] Specifically, in this step, during the ground operation phase or on the sampling vessel, the cavity between the hard shell and the inner bladder 24 of each sampling bottle 8 is first evacuated using an external vacuum pump to complete the negative pressure pre-evacuation. Then, all valves are closed to ensure the negative pressure state of the sampling bottles. Alternatively, the vacuuming process of each sampling bottle 8 can be completed one by one using pump 26. The first sensor 21 is then calibrated, including zero-point calibration of the temperature sensor and atmospheric pressure calibration of the pressure sensor, to ensure detection accuracy. After that, the suspension ring 1 is connected to the pull rope of the drone, and the cable 18 is connected to the control unit of the drone to complete the system mounting. After powering on, the main control circuit board 5 completes a self-test to confirm that all components are working properly.

[0043] S2. The drone carrying the system flies to the target sampling area and slowly lowers the system; the sensors transmit water depth data back, and the control terminal lowers the system to the designated sampling depth based on the water depth data.

[0044] Specifically, in this step, the drone carrying the system flies directly above the target sampling point. After hovering and stabilizing, the drone's electric winch is activated to slowly lower the system at a speed of 0.1 m / s. During the descent, the pressure sensor transmits water depth data in real time. When the system reaches the preset sampling depth, i.e., when the pressure sensor detects the preset value, the winch is controlled to stop lowering. At this time, the universal joint 2 can adaptively adjust the tilt angle of the rope to ensure that the underwater system always maintains a vertical attitude and is not affected by the drone's swaying or water flow.

[0045] S3. After the system reaches the designated depth, the dual cameras work together to complete underwater obstacle avoidance and sampling point benchmark positioning, and the sensors synchronously collect water environment parameters and transmit them back in real time.

[0046] Specifically, in this step, after the system reaches the designated depth, the main camera 13 and the wide-angle camera 14 are activated, the LED light strip 20 switches to inspection mode, and the brightness is adjusted to 50% to provide supplementary lighting for the underwater environment; the wide-angle camera 14 starts a 360° rotating scan, and together with the high-definition image of the main camera 13, it uses the YOLOv8 target detection algorithm to identify surrounding obstacles, such as aquatic plants, reefs, fishing nets, etc., and at the same time completes environmental modeling and obstacle avoidance path planning; at the same time, the first sensor 21 synchronously collects water environment parameters such as water temperature, pressure, turbidity, conductivity, dissolved oxygen, and pH at a frequency of 1Hz, and transmits them back to the ground control terminal in real time through the cable 18. The control terminal can identify the polluted area based on the transmitted data and trigger the sampling action.

[0047] S4. After aligning with the target sampling bottle, complete the pipeline connection and valve opening, and complete the undisturbed sampling by replacing the negative pressure in the sampling bottle 8.

[0048] Specifically, in this step, the main control circuit board 5 first controls the motor 7 to start, driving the first gear 64 to rotate. After being decelerated by the second gear 65, it drives the inner gear ring 63 to rotate, which in turn drives the rotating ring 62 to rotate, rotating the empty sampling bottle 8 directly above the water inlet pipe 10. When the second sensor 31 detects that the positioning hole of the rotating ring 62 is aligned with the position of the movable tube 27, the motor 7 stops rotating, completing the positioning of the sampling bottle 8. Subsequently, the push rod 30 retracts, pulling the connecting plate 29 upward, inserting the movable tube 27 into the positioning hole of the rotating ring 62, and completing the sealing docking through the sealing gasket. After docking, the first valve 68, the second valve 23, and the third valve 25 are opened in sequence. At this time, the pre-extraction negative pressure inside the sampling bottle 8 forms a pressure difference with the external water pressure. Under the action of pressure, the external water sample automatically flows into the inner bladder 24 through the water inlet pipe 10, the connecting pipe 28, the movable tube 27, and the through hole 67. The elastic inner bladder 24 gradually expands due to its own elasticity, and water enters the inner bladder 24 until the internal and external pressures are balanced, and the sampling is completed.

[0049] Negative pressure does not cause water disturbance and there are no air bubbles in the sample, thus achieving interference-free sampling. After sampling is completed, all second valves 23 are closed, pump 26 is started, and the liquid between sampling bottle 8 and inner bladder 24, through hole 67, movable tube 27, connecting tube 28 and water inlet tube 10 are discharged. Then, first valve 68 and third valve 25 are closed in sequence. Finally, push rod 30 extends and movable tube 27 is reset, completing the sampling of a single sampling bottle 8.

[0050] S5, Location Switching: Control the drone to move the system to the next sampling location.

[0051] Specifically, in this step, after completing the sampling at the current sampling point, the drone moves horizontally to directly above the next sampling point according to the path planned for the mission, repeats the lowering and positioning process, and prepares for the next sampling.

[0052] S6. Batch sampling loop: Repeat S4-S5 until the sampling task is completed or all sampling bottles 8 have been sampled.

[0053] Specifically, in this step, the system samples multiple sampling points sequentially, switching to a new sampling bottle for each sampling to avoid cross-contamination between samples from different sampling points. It can complete batch sampling of up to 5-8 different sampling points.

[0054] S7. System Recovery: The drone slowly recovers the system and returns it to its initial position.

[0055] Specifically, once all sampling tasks are completed, the drone starts its electric winch and slowly retrieves the system to its mounting position at a speed of 0.15 m / s. The drone then carries the system back to the ground work site.

[0056] S8. Sample processing: Recycle sampling bottle 8 and perform sample testing.

[0057] Specifically, after returning to the ground, the sampling bottle 8 is removed from the rotating base plate 6, and then the inner capsule 24 is taken out, sealed and stored, and sent to the laboratory for subsequent water quality testing and analysis.

[0058] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. An underwater inspection and sampling system based on negative pressure displacement and visual obstacle avoidance, characterized in that: Includes a suspension ring (1), and below the suspension ring (1) are arranged a buoyancy adjustment chamber (3), a main functional chamber (4) and a bottom chamber (12); the suspension ring (1) is used to connect the UAV; The bottom compartment (12) is connected to a main camera (13) and a wide-angle camera (14), and several electromagnetic devices (15) are installed below the bottom compartment (12). The main functional compartment (4) is equipped with several main control circuit boards (5) and several first sensors (21) are provided on the outer periphery. The main functional compartment (4) is equipped with several sampling bottles (8), and the bottom compartment (12) is equipped with a water inlet pipe (10). One end of the water inlet pipe (10) is located outside the bottom compartment (12), and the other end is connected to the sampling bottle (8). The sampling bottle (8) is equipped with an inner bladder (24).

2. The underwater inspection and sampling system based on negative pressure displacement and visual obstacle avoidance according to claim 1, characterized in that: The suspension ring (1) is connected to the buoyancy adjustment chamber (3) through the universal joint (2), and the buoyancy adjustment chamber (3) is equipped with buoyancy material (16). The suspension ring (1) and the buoyancy adjustment chamber (3) form at least two rotational degrees of freedom through the universal joint (2) to achieve adaptive deflection of the system at any angle; The system has a streamlined overall shape to reduce underwater drag. The suspension ring (1) is connected to the drone via a pull rope. The drone is equipped with a pull rope retraction structure. The pull rope is wrapped with a cable (18) and / or has a cable (18) coaxially connected to it.

3. The underwater inspection and sampling system based on negative pressure displacement and visual obstacle avoidance according to claim 1, characterized in that: The main camera (13) and the wide-angle camera (14) are symmetrically arranged on both sides of the lower compartment (12); The main camera (13) is equipped with an LED light strip (20) to adapt to low-light underwater environments; The wide-angle camera (14) has a 360° rotating structure, which is used to cooperate with the main camera (13) to realize underwater panoramic inspection, target recognition and visual obstacle avoidance; The LED light strip (20) is electrically connected to the main control circuit board (5) and its brightness is adjusted by PWM signal. It has four modes: standby, inspection, sampling and strobe. The electromagnetic device (15) is an electromagnet, and the electromagnetic device (15) electromagnetically attracts a counterweight assembly. The counterweight assembly includes a counterweight magnet and a counterweight block, which are fixedly connected.

4. The underwater inspection and sampling system based on negative pressure displacement and visual obstacle avoidance according to claim 1, characterized in that: The first sensor (21) includes a temperature sensor, a pressure sensor, a turbidity sensor, a conductivity sensor, a dissolved oxygen sensor, and a pH sensor. The main functional compartment (4) has multiple mounting holes arranged in a circular array on the outside. The first sensor (21) is fixedly installed through the mounting holes. The signal lines of the first sensor (21) are connected to the sensor interface of the main control circuit board (5). Temperature sensors detect water temperature to identify thermal pollution and stratification, and assist in recording sampling depth; pressure sensors detect water depth to record the precise depth of sampling points, assisting in depth-controlled sampling and buoyancy adjustment; turbidity sensors detect suspended solids concentration to identify areas with high suspended solids, trigger sampling, and identify silt, algae, or pollution plumes; conductivity sensors detect water conductivity to identify salinity changes, industrial wastewater, or agricultural runoff pollution; dissolved oxygen sensors detect dissolved oxygen content in water to identify eutrophic areas with organic pollution; and pH sensors detect water acidity or alkalinity to identify acidic or alkaline pollution.

5. The underwater inspection and sampling system based on negative pressure displacement and visual obstacle avoidance according to claim 1, characterized in that: The main control circuit board (5) is equipped with a battery and a controller, and is connected to the UAV control unit via a cable (18); The main functional compartment (4) is equipped with a partition (22), and the main control circuit board (5) and sampling bottle (8) are located on both sides of the partition (22); The main control circuit board (5) and the partition (22) are connected by a fixed copper pillar (17).

6. The underwater inspection and sampling system based on negative pressure displacement and visual obstacle avoidance according to claim 1, characterized in that: The bottom chamber (12) is equipped with a rotating chassis (6) and a motor (7) on top. The motor (7) is used to drive the rotation of multiple sampling bottles (8) connected to the rotating chassis (6). The rotating chassis (6) is circular. Multiple sampling bottles (8) are connected to a rotating base (6) and arranged in a ring; The inlet pipe (10) is connected to one of the sampling bottles (8); The sampling bottle (8) completes the connection and conversion of the water inlet pipe (10) by rotating.

7. The underwater inspection and sampling system based on negative pressure displacement and visual obstacle avoidance according to claim 6, characterized in that: The sampling bottle (8) is equipped with an inner bladder (24), and the inner bladder (24) is equipped with a second valve (23); before sampling, the inner bladder (24) and the sampling bottle (8) are under negative pressure. The internal capsule (24) is an elastic internal capsule.

8. The underwater inspection and sampling system based on negative pressure displacement and visual obstacle avoidance according to claim 7, characterized in that: The rotating chassis (6) includes a fixed plate (61) fixed to the bottom compartment (12), and a motor (7) fixed to the middle of the fixed plate (61); A rotating ring (62) is rotatably connected to the top of the fixed disk (61), and the motor (7) is located inside the rotating ring (62); the inner wall of the rotating ring (62) is provided with an internal toothed ring (63). The fixed disk (61) is rotatably connected to a first gear (64) and a second gear (65). The first gear (64) is connected to the output shaft of the motor (7). The second gear (65) meshes with the first gear (64) and with the internal gear ring (63). The top of the rotating ring (62) is provided with several plug-in posts (66), which are inserted into the sampling bottle (8). A second sealing ring (19) is provided between the plug-in post (66) and the sampling bottle (8). The rotating ring (62) is provided with several through holes (67), which are connected to the sampling bottle (8) and the water inlet pipe (10); A first valve (68) is provided inside the through hole (67).

9. The underwater inspection and sampling system based on negative pressure displacement and visual obstacle avoidance according to claim 8, characterized in that: The bottom of the rotating ring (62) is provided with several positioning holes located at the bottom of the through hole (67); a second sensor (31) is provided on the side of the positioning hole. The inlet pipe (10) is equipped with a third valve (25), and a first sealing ring (9) is provided between the inlet pipe (10) and the bottom tank (12). A pump (26) is installed in the bottom compartment (12). The pump (26) is a two-way pump. One end of the pump (26) is connected to the water inlet pipe (10), and the other end is connected to the movable pipe (27) through the connecting pipe (28). The connecting pipe (28) is a flexible hose. The movable tube (27) is slidably connected to the fixed plate (61), and a sealing ring is provided at the connection point; The movable tube (27) is adapted to the positioning hole. The top end of the movable tube (27) is inserted into the positioning hole to complete the connection with the through hole (67), and a sealing gasket is provided. The movable tube (27) is provided with a connecting plate (29), and several push rods (30) are provided between the connecting plate (29) and the fixed plate (61).

10. A method of using the underwater inspection and sampling system based on negative pressure displacement and visual obstacle avoidance as described in any one of claims 1-9, characterized in that: Includes the following steps: S1. Connect the system to the drone, complete the power-on self-test and calibration of the first sensor (21), and pre-evacuate the sampling bottle (8) and its inner bladder (24) under negative pressure. Two-way communication is established between the UAV control terminal and the main control circuit board (5); S2. The drone carrying the system flies over the target sampling water area and slowly lowers the system. The sensor transmits water depth data, and the control unit lowers the system to the specified sampling depth based on the water depth data; S3. After the system reaches the designated depth, the dual cameras work together to complete underwater obstacle avoidance and sampling point benchmark positioning, and the sensors synchronously collect water environment parameters and transmit them back in real time. S4. Sampling is carried out using sampling bottles (8); S5, Proceed to the next location; S6. Repeat S4-S5 until the sampling task is completed or all sampling bottles (8) have been sampled. S7. The drone slowly recovers the system and returns it to its initial position. S8. Collect the sampling bottle (8) and perform sample testing; In S4, the system completes undisturbed sampling by negative pressure displacement within the sampling bottle (8).

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