An unmanned aerial low-disturbance water sampling device and method for coastal wetlands

Abstract

The application discloses a kind of unmanned aerial vehicle low disturbance water sample sampling device and method for coastal wetland, device includes unmanned aerial vehicle aircraft, sampling unit and recovery unit;Surface sampler is the container bottle of top opening, two sides are connected first float ball and metal ball respectively, after entering water, rely on buoyancy and gravity coupling to keep bottle mouth inclination posture, surface water is naturally flowed into with hydrostatic pressure difference mode;Bottom sampler is the container bottle of airtight, top is equipped with exhaust hole, bottom side is equipped with water inlet, water inlet is hinged with the sealing baffle of with counterweight and guide stress plate, when entering water, water pressure moment overcomes counterweight damping moment to make baffle open smoothly, water enters in laminar flow mode;When rising, counterweight gravity makes baffle automatic reset seal.The application realizes the low physical disturbance of sampling link, can collect surface and bottom water sample once, to obtain water sample for testing dissolved oxygen, solubility greenhouse gas concentration, dissolved organic carbon, particulate carbon, nutrient salt, dissolved organic matter molecular composition.

Description

Technical Field

[0001] This invention belongs to the technical field of environmental monitoring and water sampling technology for ecologically fragile water areas, specifically relating to an unmanned aerial vehicle (UAV)-borne low-disturbance water sampling device and method for coastal wetlands. Background Technology

[0002] Mangrove forests, salt marshes, peat wetlands, and shallow coral reef areas are ecologically fragile water bodies, among the most active ecosystems in the world in terms of biogeochemical cycles and carbon sequestration. Accurate and convenient acquisition of water quality parameters such as dissolved oxygen, dissolved greenhouse gas concentrations, dissolved organic carbon, particulate carbon, nutrients, and the molecular composition of dissolved organic matter in these water bodies is a core foundation for assessing their ecological health, carbon sequestration capacity, and biodiversity.

[0003] However, these waters are generally very shallow, typically 0.3m to 2m deep, and have soft bottoms, complex root systems, and uneven terrain, posing fundamental challenges to conventional manual sampling methods. (1) Manual wading sampling When sampling personnel step into mangrove mudflats or salt marsh mudflats, the surface mud has extremely low bearing capacity, making it easy to sink into the knee-deep or even waist-deep soft mud, posing multiple safety risks such as drowning, tripping over roots, and encountering toxic organisms. More importantly, the trampling action directly stirs up bottom sediments and interstitial water into the overlying water body, causing the collected water samples to be mixed with a large amount of aged organic matter and reducing substances (e.g., Fe) from the interstitial water of the sediments. 2+ Mn 2+ The samples obtained from sampling methods involving pollutants such as H2S are no longer the original water column samples, but rather mixtures contaminated by benthic disturbances. Samples obtained using this method are completely unrepresentative of the original water body.

[0004] (2) Ship sampling Conventional survey vessels or inflatable boats are highly susceptible to running aground in extremely shallow waters, especially in narrow, winding tidal channels that are often only a few meters to a dozen meters wide and lack sufficient depth, making it impossible for vessels to enter. Even if they manage to enter at high tide, the agitation by propellers or outboard motors will suspend bottom sediments into the water, causing drastic changes in key parameters such as suspended particulate matter, dissolved oxygen, and turbidity around the sampling point within minutes. Furthermore, the material costs and time required for vessel transportation, personnel deployment, and on-site operations are extremely high, particularly in remote wetland areas. Moreover, operations are limited to only a few days per month due to tidal windows, and daily tidal variations also contribute to low sampling efficiency.

[0005] In recent years, the rapid development of drone technology has provided new possibilities for addressing the aforementioned challenges. Drones possess advantages such as low-altitude flight, vertical take-off and landing, fixed-point hovering, and independence from ground transportation conditions. Theoretically, they can accurately reach any target point in a body of water to collect water samples without the need for personnel to wade through the water or for vessels to enter.

[0006] Currently available drone-based water sampling solutions mainly fall into two categories: (3) Pump-suction UAV sampler By mounting a miniature peristaltic pump and water intake pipe on a drone, the drone flies to the target location, lowers the water intake pipe to a set depth, and starts the pump to draw water into an onboard storage container. However, in practical applications, the suction action of the peristaltic pump or diaphragm pump generates negative pressure, forming a local high-speed water flow at the water intake pipe inlet. This generates strong eddies and shear forces, which not only disrupt the balance of dissolved gases such as CO2, CH4, and N2O in the water, but also cause dissolved oxygen to be rapidly consumed or oversaturated during the pumping process. At the same time, the pump body and water pipe are too heavy, resulting in high energy consumption, and high-payload drones are very expensive.

[0007] (4) Impact-triggered / electrically operated unmanned aerial vehicle sampler The sampler is lowered to the target depth in a sealed state. The sampling chamber cover is opened by impact with a bottom trigger or an electric signal, allowing water to passively flow into the sampling chamber. The cover then closes to complete the sampling. However, in practical applications, the sampler is triggered by free fall or rapid descent into the water. This impact generates a strong water hammer effect and turbulent flow, completely disrupting the physicochemical field of the water around the sampling point. Dissolved oxygen levels change instantly upon triggering, and the disturbance lasts for several minutes to tens of minutes. The electrically operated opening scheme relies on a complex electrical system including an underwater motor, solenoid valve, pressure sensor, and sealed chamber. In turbid, high-salinity water, problems such as seal failure, motor burnout, and sensor malfunction frequently occur, resulting in a high failure rate during field operations.

[0008] It can be seen that both pump-suction and open-top sampling methods can be connected to local power sources for indoor experiments. However, for drones involving remote sampling, circuit connections are difficult, and in-situ circuit installation increases the load, thus drastically increasing drone costs. More seriously, commercially available pump-suction or open-top sampling equipment mainly relies on high-power ground power supplies and cannot be connected to remote devices. Therefore, developing a sampling device based on mechanical and physical principles that does not require electrical power becomes crucial. At the same time, existing solutions can only collect water samples from a single depth at a time. Field monitoring often involves sampling from different water layers. If surface and bottom water samples need to be collected, two separate flights are required, which is time-consuming, energy-intensive, and results in poor sampling consistency. Summary of the Invention

[0009] To overcome the shortcomings of the prior art, the present invention aims to provide an unmanned aerial vehicle (UAV) low-disturbance water sampling device and method for coastal wetlands, which achieves low physical disturbance in the sampling process to obtain high-fidelity water samples that can be used for testing dissolved oxygen, dissolved greenhouse gas concentration, dissolved organic carbon, particulate carbon, nutrients, and the molecular composition of dissolved organic matter; at the same time, it can realize the function of simultaneously collecting surface and bottom water samples.

[0010] The objective of this invention is achieved through the following technical solution: A drone-borne low-disturbance water sampling device for coastal wetlands includes a drone aircraft and a sampling unit connected to the drone aircraft via a suspension cable; the sampling unit includes a surface sampler and a bottom sampler, the bottom sampler being connected to the surface sampler via a suspension cable. The surface sampler is a container bottle with an open top. A first float and a metal ball are connected to both sides of the surface sampler, respectively. When the surface sampler enters the water, one side of the surface sampler is tilted due to the buoyancy of the first float and the other side is tilted due to the sinking effect of the metal ball, so that the surface sampler and the bottle mouth are in an inclined position to collect surface water samples. The bottom sampler is a sealed container bottle. The top of the bottom sampler has an exhaust vent, and the side of the bottom of the bottom sampler has a water inlet. A sealing baffle is hinged to the top of the water inlet. A counterweight is located at the end of the sealing baffle away from the hinge point, and a guide plate is located on the side of the counterweight away from the bottom sampler. After the bottom sampler enters the water at a constant speed, the guide plate experiences an upward water pressure torque, which overcomes the weight of the counterweight and causes the sealing baffle to flip outward to open the water inlet and collect bottom water samples. When the bottom sampler rises and leaves the water surface, the weight of the counterweight causes the sealing baffle to reset and seal the water inlet.

[0011] Furthermore, a second float is connected between the surface sampler and the bottom sampler via a suspension cable. When the surface sampler is tilted, the second float assists in supporting the surface sampler.

[0012] Furthermore, a one-way flexible membrane is provided inside the bottle opening of the surface sampler. The one-way flexible membrane has a cross-shaped cut. After the surface water enters the bottle opening of the surface sampler, the water flows inward to push open the cross-shaped cut of the one-way flexible membrane and flows into the surface sampler. When the surface sampler is lifted off the water surface, the one-way flexible membrane closes the cross-shaped cut under its own elasticity. Alternatively, when the liquid level in the surface sampler rises, the cross-shaped cut gradually returns to its original position until it is coplanar with the one-way flexible membrane, thus closing the cross-shaped cut.

[0013] Furthermore, the guide plate and the sealing baffle are arranged at a downward angle of 30° to 80°, and the guide plate is made of buoyancy material or has a hollow structure so that the guide plate has buoyancy in water.

[0014] Furthermore, multiple hanging points are provided at intervals on the suspension cable between the surface sampler and the bottom sampler, and the distance between the two can be adjusted by selecting different hanging points to fix the surface sampler or the bottom sampler.

[0015] Furthermore, it also includes a recycling unit installed at a designated recycling point. The recycling unit includes a support frame and an inverted conical support cylinder mounted on the support frame. A limiter is connected between the UAV and the surface sampler via a suspension cable. The outer diameters of both the surface sampler and the bottom sampler are smaller than the diameter of the bottom opening of the inverted conical support cylinder, while the outer diameter of the limiter is larger than the diameter of the bottom opening of the inverted conical support cylinder. After the UAV drives the surface sampler and the bottom sampler through the bottom opening of the inverted conical support cylinder, the limiter restricts them within the neck of the inverted conical support cylinder, so that the surface sampler and the bottom sampler are in a suspended state.

[0016] Furthermore, a latching component is provided in the neck of the inverted conical support cylinder, the latching component including a spring and a limiting ball; a groove is formed on the inner wall of the inverted conical support cylinder, the spring is disposed in the groove, the limiting ball is disposed at the end of the spring, and an annular groove is formed on the outer circumference of the limiter corresponding to the groove. When the limiter falls and moves to the position where the annular groove corresponds to the groove, the limiting ball is reset and inserted into the annular groove by the spring.

[0017] Furthermore, the top surface of the support frame is provided with an aircraft parking position, and the side of the support frame is provided with an access door.

[0018] A method for low-disturbance water sampling using an unmanned aerial vehicle (UAV) in coastal wetlands, employing the aforementioned low-disturbance water sampling device for coastal wetlands, supports the following sampling modes: Mode 1: Only surface samplers are mounted to collect surface water samples; Mode 2: Only attach the bottom sampler to collect bottom water samples; Mode 3: Simultaneously mount surface samplers and bottom samplers to collect surface and bottom water samples at the same time.

[0019] When the UAV-borne low-disturbance water sampling method for coastal wetlands adopts the sampling mode of Mode 3, the following steps are included: S10: Connect the bottom sampler, surface sampler, and limiter to the bottom of the UAV aircraft via a suspension cable. At the same time, adjust the distance between the surface sampler and the bottom sampler by selecting a preset hanging point on the suspension cable according to the depth of the target water area to be sampled. S20: Control the drone to the corresponding sampling position in the target water area, then place the bottom sampler and the surface sampler into the water until the surface sampler is just submerged below the surface of the target water area, and then control the drone to hover. S30: After the surface sampler enters the water, it is tilted under the relative action of the first float and the metal ball, so that the surface water sample of the target water area enters the opening at the top of the surface sampler to collect the surface water sample; after the bottom sampler enters the water, the guide plate is subjected to the upward water pressure torque, which overcomes the weight of the counterweight block, so as to drive the sealing baffle to flip outward to open the water inlet to collect the bottom water sample. S40: After the bottom water sample and surface water sample are collected, the drone is controlled to take off upwards to move the surface sampler and bottom sampler out of the water surface; when it is moved out of the water surface, the counterweight moves the sealing baffle to reset due to gravity and seals the water inlet; S50: The drone is controlled to carry the surface sampler and the bottom sampler into the inverted conical support cylinder of the recovery unit, so that the surface sampler and the bottom sampler pass through the opening at the bottom of the inverted conical support cylinder. The limiter restricts the neck inside the inverted conical support cylinder, so that the surface sampler and the bottom sampler are in a suspended state, which facilitates the subsequent manual recovery of the surface sampler and the bottom sampler.

[0020] The present invention has the following beneficial effects: 1. This invention, by setting up a surface sampler and its two sides with first floats and metal balls, allows the surface sampler to passively maintain a stable tilt of 5° to 15° upwards at the bottle opening after entering the water, relying on the coupling of buoyancy and gravity. By setting up a counterweight, sealing baffle, and guide plate in the bottom sampler, the inlet opens smoothly by the water pressure torque overcoming the counterweight damping torque; during ascent, the weight of the counterweight automatically resets and seals the baffle. A locking mechanism consisting of a spring and a limit ball in the recovery unit automatically locks the limiter when it is engaged. All actuation mechanisms are passive mechanical, without motors, solenoid valves, batteries, sensors, or other electrical components. In harsh outdoor environments such as mangroves and salt marshes with high turbidity, high salinity, and high humidity, this invention completely solves the problem of easy failure of electrical control equipment, significantly improving reliability.

[0021] 2. This invention limits the water inlet velocity of the bottom sampler to ≤0.15m / s and the opening angular velocity of the sealing baffle to ≤30° / s, so that the water pressure torque overcomes the counterweight damping torque in a smooth manner, ensuring that the water inlet is driven by the hydrostatic pressure difference to form laminar flow, avoiding eddies and gas entrainment, achieving low-disturbance sampling, and the collected water samples can be used for accurate analysis of sensitive indicators such as dissolved greenhouse gases, dissolved oxygen, and dissolved organic matter.

[0022] 3. By setting multiple attachment points on the main hoisting cable, the vertical distance between the surface sampler and the bottom sampler can be flexibly adjusted according to the target water depth. Two layers of water samples can be collected simultaneously in one flight, avoiding the problem of inconsistent sampling points caused by two operations. At the same time, only a single sampler can be attached according to the mission requirements, making it flexible in use and adaptable to various complex underwater terrains such as tidal channels, shallow corals, and peat wetlands.

[0023] 4. This invention, by setting an inverted conical support cylinder for the recovery unit, and combining the size matching of the sampler's outer diameter being smaller than the cylinder's opening diameter and the limiter's outer diameter being larger than the cylinder's opening diameter, allows the sampling unit to be lowered after the drone hovers. The limiter is locked in the neck of the inverted conical support cylinder, and the sampler is suspended below the cylinder. Subsequently, the drone releases the hoisting cable for an unloaded descent, completely eliminating the risk of the hoisting cable getting tangled in the rotor when landing with a load. The inverted conical structure can still automatically center itself when the drone is horizontally deviated, without the need for personnel to approach the water area, which helps to improve the recovery success rate. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0025] Figure 2 This is a schematic diagram of the surface sampler of the present invention.

[0026] Figure 3 This is a schematic diagram of the underlying sampler of the present invention.

[0027] Figure 4 This is a state diagram of the sampler recovery process of the present invention.

[0028] Figure 5 This is a state diagram and a partial cross-sectional view of the sampler at the end of the retrieval process according to the present invention.

[0029] Figure 6 for Figure 5 A magnified view of a portion of point A in the middle.

[0030] In the diagram: 1. Unmanned aerial vehicle (UAV); 11. Quick release device; 12. Suspension cable; 121. Hanging point; 2. Limiter; 21. Annular groove; 3. Surface sampler; 31. First float; 32. Metal ball; 33. Second float; 34. One-way flexible film; 341. Cross-shaped cut; 4. Bottom sampler; 41. Water inlet; 42. Vent; 43. Sealing baffle; 44. Counterweight; 45. Guide plate; 5. Recovery unit; 51. Support frame; 511. UAV parking position; 52. Inverted cone-shaped support cylinder; 521. Groove; 53. Spring; 54. Limiter ball. Detailed Implementation

[0031] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Terms such as “upper,” “inner,” “middle,” “left,” “right,” and “one” used in this specification are merely for clarity of description and are not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0032] Example 1 A drone-borne low-disturbance water sampling device for coastal wetlands, such as Figures 1 to 6 As shown, the system includes an unmanned aerial vehicle (UAV) 1, a sampling unit, and a recovery unit 5; the sampling unit includes a surface sampler 3 and a bottom sampler 4. A lifting cable 12 is connected to the bottom of the UAV 1 via a quick-release device 11. The quick-release device 11 is a conventional mechanical release device, which can be triggered by pulling a rope or a mechanical linkage mechanism; the lifting cable 12 is connected from top to bottom to a limiter 2, the surface sampler 3, and the bottom sampler 4. The limiter 2 is fixed to the upper part of the lifting cable 12, the surface sampler 3 is connected to the middle part of the lifting cable 12, and the bottom sampler 4 is connected to the lower end of the lifting cable 12.

[0033] like Figure 1 and Figure 2 As shown, the surface sampler 3 of this invention uses a wide-mouthed container bottle with an open top. A first float 31 and a metal ball 32 are connected to both sides of the surface sampler 3 via connecting ropes. The first float 31 is a lightweight, sealed, hollow sphere that provides buoyancy; the metal ball 32 is made of stainless steel and provides gravity. Before entering the water, the bottle opening of the surface sampler 3 is positioned horizontally upwards at an angle of 5° to 15°. After entering the water, the metal ball 32 pulls down one side of the bottle opening due to gravity, while the first float 31 lifts the other side of the bottle opening due to buoyancy. Together, they maintain a stable tilt of the surface sampler 3 with the bottle opening horizontally upwards at an angle of 5° to 15°. Therefore, when the surface sampler 3 is just submerged in the target water area and close to the water surface, the surface water of the target water area can flow smoothly and naturally into the bottle opening of the surface sampler 3, while air inside the bottle can be smoothly discharged from the same opening in the form of bubbles.

[0034] The surface sampler 3 has a fixedly installed unidirectional flexible membrane 34 covering its opening. This unidirectional flexible membrane 34 is an elastic sheet with a cross-shaped cut 341 in the middle. After surface water enters the opening of the surface sampler 3, the external water pressure generated by the water flow pushes open the cross-shaped cut 341 of the unidirectional flexible membrane, allowing the surface water sample to flow into the surface sampler 3. As the liquid level rises inside the surface sampler 3, the cross-shaped cut 341 gradually returns to its original position until it is coplanar with the unidirectional flexible membrane 34, thus closing the cross-shaped cut 341 and reducing water sample outflow; or, when the surface sampler 3 is lifted away from the water surface, the unidirectional flexible membrane 34 closes the cross-shaped cut 341 under its own elasticity, thus reducing water sample outflow.

[0035] A second float 33 is connected between the surface sampler 3 and the bottom sampler 4 via a suspension cable 12. When the second float 33 is submerged in water, it generates additional buoyancy and applies upward tension to the suspension cable 12, thereby assisting in supporting and maintaining the tilted posture of the surface sampler 3 to reduce excessive swaying of the surface sampler 3 in the water.

[0036] like Figure 1 and Figure 3 As shown, the bottom sampler 4 of the present invention is a sealed container bottle. A vent 42 is provided at the top of the bottom sampler 4, with a diameter of 1 mm to 2 mm. A water inlet 41 is provided on the side of the bottom of the bottom sampler 4, and a sealing baffle 43 is hinged to the top of the water inlet 41. A counterweight 44 is provided at the end of the sealing baffle 43 away from the hinge point, and a guide plate 45 is fixedly connected to the side of the counterweight 44 away from the bottom sampler 4. The guide plate 45 forms a downward angle of 30° to 80° with the sealing baffle 43. The guide plate 45 is made of a buoyancy material such as wood, or it may be made into a hollow structure to provide buoyancy in water.

[0037] When the bottom sampler 4 is not submerged in water, the sealing baffle 43 is pressed against the inlet 41 by the gravity of the counterweight 44, keeping the inlet 41 sealed and preventing external debris from entering the container. When the bottom sampler 4 enters the water at a constant speed of ≤0.15m / s, the guide plate 45 is subjected to an upward water pressure torque. Simultaneously, the guide plate 45 also has its own buoyancy, increasing the effect of the water pressure torque. This water pressure torque overcomes the gravitational damping torque of the counterweight 44, causing the sealing baffle 43 to smoothly flip outward at an angular velocity of ≤30° / s, thus opening the inlet 41. At this time, the water sample from the bottom of the target water area can be driven by the hydrostatic pressure difference to enter the bottom sampler 4 through the inlet 41 in a laminar flow manner, and the air inside the bottom sampler 4 is discharged from the top vent 42.

[0038] This shows that if the water inlet velocity is too high, the water pressure torque on the guide plate 45 will increase sharply, causing the sealing baffle 43 to open suddenly at a high angular velocity. This generates eddies and turbulence near the inlet 41, significantly disturbing the water body. Therefore, limiting the water inlet velocity to ≤0.15m / s ensures that the sealing baffle 43 opens smoothly at an angular velocity of ≤30° / s, maintaining laminar flow during the water inlet process and effectively avoiding physical disturbance to the water body. When the bottom sampler 4 rises and leaves the water surface, the external water pressure torque disappears, and the counterweight 44, under the action of gravity, drives the sealing baffle 43 to return to its original position, re-pressing the sealing inlet 41 to prevent leakage of the collected water sample during the lifting process.

[0039] In this embodiment, multiple hanging points 121 are spaced apart on the suspension cable 12 between the surface sampler 3 and the bottom sampler 4. By selecting different hanging points 121 to hang and fix the surface sampler and / or the bottom sampler 4, the distance between the surface sampler 3 and the bottom sampler 4 can be adjusted so that they reach the preset surface sampling depth and bottom sampling depth respectively, thereby adapting to the sampling requirements of different water depths. Depending on the task requirements, only the surface sampler 3, only the bottom sampler 4, or both samplers can be hung simultaneously.

[0040] like Figures 1 to 6 As shown, the recovery unit 5 of the present invention is installed at a designated recovery point, which is usually selected as the shore of the target sampling water area. The recovery unit 5 is used to achieve safe recovery after sampling. The recovery unit 5 includes a support frame 51 and an inverted conical support cylinder 52 disposed on the support frame 51. The inverted conical support cylinder 52 has its larger opening facing upwards and its smaller opening facing downwards. The top surface of the support frame 51 is provided with an aircraft parking position 511, and the side of the support frame 51 is provided with an access door for entering the support frame 51 to retrieve the surface sampler 3 and / or the bottom sampler 4.

[0041] The outer diameters of both the surface sampler 3 and the bottom sampler 4 are smaller than the diameter of the bottom opening of the inverted conical support cylinder 52, while the outer diameter of the limiter 2 is larger than the diameter of the bottom opening of the inverted conical support cylinder 52. The UAV 1 hovers above the inverted conical support cylinder 52 and lowers the sampling unit. The bottom sampler 4 and the surface sampler 3 pass through the opening of the inverted conical support cylinder 52 in sequence. When the limiter 2 descends to the neck of the inverted conical support cylinder 52, it is stopped because its outer dimensions are larger than the neck opening, thus suspending the sampler below the inverted conical support cylinder 52. This facilitates the manual removal of the surface sampler 3 and / or the bottom sampler 4 from the access door.

[0042] The neck of the inverted conical support cylinder 52 is also equipped with a locking device, which includes a spring 53 and a limiting ball 54. A groove 521 is formed on the inner wall of the inverted conical support cylinder 52, the spring 53 is disposed within the groove 521, and the limiting ball 54 is disposed at the end of the spring 53. An annular groove 21 is formed on the outer circumference of the limiter 2 corresponding to the groove 521. When the limiter 2 falls to the point where the annular groove 21 aligns with the groove 521, the limiting ball 54 automatically springs into the annular groove 21 under the reset action of the spring 53, achieving mechanical locking. After the operator confirms the lock, the lifting cable 12 is released via the quick release device 11, and the UAV 1 ascends and lands unloaded to the parking position. Subsequently, the operator opens the access door and retrieves the suspended sampler from below the inverted conical support cylinder 52 to collect water samples.

[0043] In summary, the UAV-borne low-disturbance water sampling device for coastal wetlands of the present invention abandons the active disturbance and electronic control schemes of the prior art and adopts a passive mechanical structure. Specifically, the surface sampler 3 maintains its attitude through the buoyancy and gravity coupling of the first float 31 and the metal ball 32, allowing surface water to flow in naturally due to hydrostatic pressure difference; the surface sampler 3 also works with a unidirectional flexible membrane 34 to prevent water sample leakage, and a second float 33 assists in maintaining attitude stability. The bottom sampler 4 relies on the damping cooperation between the counterweight 44 and the guide plate 45 to achieve the smooth opening and automatic reset of the sealing baffle 43, allowing water to passively flow in in a laminar flow manner, without applying any additional mechanical work or negative pressure suction force to the water body throughout the process, fundamentally avoiding the generation of eddies, shear forces, and water hammer effects. The recovery unit 5 uses an inverted conical guide structure and a locking mechanism to achieve aerial locking of the sampler and manual sampling.

[0044] Based on the structural description of the UAV-borne low-disturbance water sampling device for coastal wetlands of the present invention in Example 1, the sampling method of the UAV-borne low-disturbance water sampling device for coastal wetlands of the present invention will be further described in detail below: Example 2

[0045] A method for low-disturbance water sampling using unmanned aerial vehicles (UAVs) in coastal wetlands, employing the low-disturbance water sampling device for coastal wetlands described in Example 1 (e.g., Figures 1 to 6 It supports the following sampling modes: Mode 1: Only surface sampler 3 is mounted to collect surface water samples. This mode is suitable for scenarios where only parameters such as dissolved organic matter in surface water need to be analyzed, such as surface water quality monitoring in open water areas. Mode 2: Only the bottom sampler 4 is mounted to collect bottom water samples. This mode is suitable for scenarios where parameters such as dissolved oxygen and benthic environment at the bottom are of interest, such as bottom water quality surveys in shallow wetlands. Mode 3: Simultaneously mount surface sampler 3 and bottom sampler 4 to collect surface and bottom water samples at the same time. This mode is suitable for scenarios that require comprehensive evaluation of water column stratification parameters, such as profile water quality analysis of mangrove tidal channels.

[0046] The sampling methods for the above three modes are described below through three examples: Example 3

[0047] In the open target water area, where the water depth is only 0.3m, only surface water samples are needed for dissolved organic matter analysis. Therefore: A method for low-disturbance water sampling using unmanned aerial vehicles (UAVs) in coastal wetlands, employing the low-disturbance water sampling device for coastal wetlands described in Example 1 (e.g., Figures 1 to 6 The sampling mode of Mode 1 in Example 2 is supported, including the following steps: S10: According to the task requirements, only the surface sampler 3 and the second float 33 are installed in the middle of the suspension cable 12, and the bottom sampler 4 is not installed. Select the corresponding attachment point 121 to make the surface sampler 3 reach the preset surface depth, such as 0.1 to 0.3m below the water surface.

[0048] S20: Control the drone 1 to place the surface sampler 3 into the water until the surface sampler 3 reaches the preset surface depth, and control the drone 1 to hover.

[0049] S30: After the surface sampler 3 enters the water, it maintains a tilted posture with the bottle mouth facing upward at 5° to 15° under the coupling of buoyancy and gravity of the first float 31 and the metal ball 32. The surface water naturally enters from the bottle mouth, and the air inside the bottle is discharged from the same bottle mouth in the form of bubbles. The one-way flexible membrane 34 opens under water pressure, and the surface water sample enters the bottle.

[0050] S40: After sampling is completed, the drone 1 is controlled to take off upwards, bringing the surface sampler 3 out of the water. After being lifted out of the water, the membrane closes under its own elasticity to prevent water sample loss.

[0051] S50: After returning to base, the UAV 1, carrying the surface sampler 3, flies above the recovery unit 5, hovers, and lowers the surface sampler 3 through the inverted conical support cylinder 52. The limiter 2 is caught by the neck of the inverted conical support cylinder 52, and the locking device automatically locks the limiter 2. The lifting cable 12 is released through the quick release device 11, and the UAV 1 rises and lands unloaded to the parking position. The operator opens the access door, removes the surface sampler 3 from under the inverted conical support cylinder 52, collects water samples, and seals the cap for subsequent mass spectrometry analysis of dissolved organic matter.

[0052] Example 4 In the target shallow wetland area, where the water depth is only about 0.3m, it is only necessary to collect water samples from about 0.2m above the bottom water for dissolved oxygen measurement. Therefore: A method for low-disturbance water sampling using unmanned aerial vehicles (UAVs) in coastal wetlands, employing the low-disturbance water sampling device for coastal wetlands described in Example 1 (e.g., Figures 1 to 6 The sampling mode supporting Mode 2 of Example 2 includes the following steps: S10: Install only the bottom sampler 4 at the lower end of the suspension cable 12, and select the corresponding hanging point 121 to make the bottom sampler 4 reach the preset bottom depth, such as 0.05 to 0.2m above the bottom.

[0053] S20: The bottom sampler 4 enters the water and reaches the target depth. The water pressure torque overcomes the gravitational damping torque of the counterweight 44, causing the sealing baffle 43 to open smoothly. Water enters the bottom sampler 4 in a laminar flow manner through the inlet 41. The air inside the bottom sampler 4 is discharged from the top exhaust hole 42, completing the bottom water sample collection.

[0054] S30: After sampling is completed, the drone 1 is controlled to take off upwards, which will move the bottom sampler 4 out of the water. When it is moved out of the water, the counterweight 44 will move the sealing baffle 43 to reset under the action of gravity and seal the water inlet 41.

[0055] S40: After returning to port, the platform handover and recovery were completed according to the aforementioned recovery process. The operator removed the bottom sampler 4, collected water samples, and measured the dissolved oxygen on-site. The measured dissolved oxygen value was highly consistent with the data from the profiler.

[0056] This embodiment demonstrates that the bottom sampler 4 can reliably complete low-disturbance sampling under shallow water conditions, and is suitable for monitoring scenarios in complex shallow water environments such as mangroves and salt marshes where only bottom water samples need to be collected.

[0057] Example 5 In a tidal creek within a mangrove reserve, surface water samples (approximately 0.2m below the surface) and bottom water samples (approximately 0.8m below the surface) can be collected simultaneously during low tide to comprehensively assess water quality parameters at different water column depths. Therefore: A method for low-disturbance water sampling using unmanned aerial vehicles (UAVs) in coastal wetlands, employing the low-disturbance water sampling device for coastal wetlands described in Example 1 (e.g., Figures 1 to 6 The sampling mode supporting Mode 3 of Example 2 includes the following steps: S10: Connect the bottom sampler 4, surface sampler 3, second float 33, and limiter 2 to the bottom of the UAV 1 via the suspension cable 12. Based on the target water depth, adjust the vertical distance between the surface sampler 3 and the bottom sampler 4 by selecting a preset hanging point 121 on the suspension cable 12, so that the two samplers reach the preset surface depth and the preset bottom depth respectively. The bottom sampler 4 is approximately 0.1m from the mangrove bottom mud to avoid collisions.

[0058] S20: Control the drone 1 to the corresponding sampling position in the target water area, vertically place the bottom sampler 4 and the surface sampler 3 into the water until the surface sampler 3 reaches the preset depth of the surface, and control the drone 1 to hover.

[0059] S30: After the surface sampler 3 enters the water, it maintains a tilted posture with the bottle opening horizontally upward at 5° to 15° under the coupling action of buoyancy and gravity of the first float 31 and the metal ball 32. The surface water sample enters the bottle through the opening at the top of the surface sampler 3. The unidirectional flexible membrane 34 opens under water pressure, and at the same time, the air in the bottle is discharged from the same bottle opening in the form of bubbles, completing the surface water sample collection. After the bottom sampler 4 enters the water at a constant speed, the guide plate 45 is subjected to an upward water pressure torque, which overcomes the gravitational damping torque of the counterweight 44, causing the sealing baffle 43 to flip outward smoothly, opening the water inlet 41. Water enters the bottom sampler 4 in a laminar flow manner, and the air in the cylinder is discharged from the top exhaust hole 42, completing the bottom water sample collection.

[0060] S40: After the data collection is completed, the drone 1 is controlled to take off upwards, which will move the surface sampler 3 and the bottom sampler 4 out of the water. When it is moved out of the water, the counterweight 44 will move the sealing baffle 43 to reset and seal the water inlet 41 under the action of gravity; the unidirectional flexible film 34 of the surface sampler 3 will close under its own elasticity to prevent water sample loss.

[0061] S50: The unmanned aerial vehicle 1, carrying the sampling unit, flies to a height of approximately 2 meters above the recovery unit 5 and hovers there. The sampling unit is then slowly lowered. The sampler passes through the inverted conical support cylinder 52 in sequence. Even if the unmanned aerial vehicle deviates horizontally, the sampler accurately slides into the cylinder opening due to the conical guiding effect of the inverted conical support cylinder 52. When the limiter 2 descends to the neck of the inverted conical support cylinder 52, it is stopped. The limiting ball 54 of the locking component automatically springs into the annular groove 21 of the limiter 2 under the action of the spring 53, completing the mechanical locking.

[0062] S60: After visually confirming the lock, the operator releases the hoisting cable 12 via the quick release device 11, and the UAV 1 ascends and lands unloaded to the parking position. The operator opens the access door and takes out the bottom sampler 4 and the surface sampler 3 sequentially from under the inverted conical support cylinder 52 to collect water samples, seal the caps, mark the depth, and measure parameters such as dissolved oxygen on site.

[0063] As can be seen, this embodiment can achieve simultaneous collection of surface and bottom water samples in one go, and complete safe retrieval through mechanical handover at aerial checkpoints. The entire process does not require manual wading and there is no risk of rope entanglement. It is suitable for stratified water quality monitoring in various complex water areas such as tidal channels, shallow coral reefs, and peat wetlands.

[0064] The embodiments of the present invention are not limited thereto. Based on the above description of the present invention, and using common technical knowledge and conventional means in the field, the present invention can be modified, replaced or combined in various other forms without departing from the basic technical idea of ​​the present invention, and all such modifications, replacements or combinations fall within the scope of protection of the present invention.

Claims

1. A drone-borne low-disturbance water sampling device for coastal wetlands, characterized in that, The system includes an unmanned aerial vehicle (UAV) and a sampling unit connected to the UAV via a suspension cable. The sampling unit includes a surface sampler and a bottom sampler, with the bottom sampler connected to the surface sampler via a suspension cable. The surface sampler is a container bottle with a bottle opening at the top. A first float and a metal ball are connected to the two sides of the surface sampler, respectively. When the surface sampler enters the water, one side of the surface sampler is buoyed by the first float, and the other side is tilted by the sinking action of the metal ball, so that the surface sampler and the bottle opening are in an inclined posture to collect surface water samples. The bottom sampler is a sealed container bottle. The top of the bottom sampler has an exhaust vent, and the side of the bottom of the bottom sampler has a water inlet. A sealing baffle is hinged to the top of the water inlet. A counterweight is located at the end of the sealing baffle away from the hinge point, and a guide plate is located on the side of the counterweight away from the bottom sampler. After the bottom sampler enters the water at a constant speed, the guide plate experiences an upward water pressure torque, which overcomes the weight of the counterweight and causes the sealing baffle to flip outward to open the water inlet and collect bottom water samples. When the bottom sampler rises and leaves the water surface, the weight of the counterweight causes the sealing baffle to reset and seal the water inlet.

2. The unmanned aerial vehicle-borne low-disturbance water sampling device for coastal wetlands as described in claim 1, characterized in that, A second float is connected between the surface sampler and the bottom sampler via a cable. When the surface sampler is tilted, the second float assists in supporting the surface sampler.

3. The unmanned aerial vehicle-borne low-disturbance water sampling device for coastal wetlands as described in claim 1, characterized in that, The surface sampler has a unidirectional flexible membrane inside its opening, with a cross-shaped cut. When surface water enters the opening, the water flows inward, pushing open the cross-shaped cut of the unidirectional flexible membrane and flowing into the surface sampler. When the surface sampler is lifted off the water surface, the unidirectional flexible membrane closes the cross-shaped cut due to its own elasticity; alternatively, as the liquid level rises within the surface sampler, the cross-shaped cut gradually returns to its original position until it is coplanar with the unidirectional flexible membrane, thus closing the cross-shaped cut.

4. The unmanned aerial vehicle-borne low-disturbance water sampling device for coastal wetlands as described in claim 1, characterized in that, The guide plate and the sealing baffle are arranged at a downward angle of 30° to 80°. The guide plate is made of buoyancy material or has a hollow structure so that the guide plate has buoyancy in water.

5. The unmanned aerial vehicle-borne low-disturbance water sampling device for coastal wetlands as described in claim 1, characterized in that, The cable between the surface sampler and the bottom sampler has multiple hanging points at intervals. The distance between the two can be adjusted by selecting different hanging points to fix the surface sampler or the bottom sampler.

6. The unmanned aerial vehicle-borne low-disturbance water sampling device for coastal wetlands as described in claim 1, characterized in that, It also includes a recycling unit installed at a designated recycling point. The recycling unit includes a support frame and an inverted conical support cylinder mounted on the support frame. A limiter is connected between the UAV and the surface sampler via a suspension cable. The outer diameters of the surface sampler and the bottom sampler are both smaller than the diameter of the bottom opening of the inverted conical support cylinder, and the outer diameter of the limiter is larger than the diameter of the bottom opening of the inverted conical support cylinder. After the UAV drives the surface sampler and the bottom sampler through the bottom opening of the inverted conical support cylinder, the limiter restricts them within the neck of the inverted conical support cylinder, so that the surface sampler and the bottom sampler are in a suspended state.

7. The unmanned aerial vehicle-borne low-disturbance water sampling device for coastal wetlands as described in claim 6, characterized in that, The neck of the inverted conical support cylinder is provided with a fastening element, which includes a spring and a limiting ball. The inner wall of the inverted conical support cylinder is provided with a groove, the spring is disposed in the groove, the limiting ball is disposed at the end of the spring, and the outer circumference of the limiter is provided with an annular groove corresponding to the groove. When the limiter falls and moves to the position where the annular groove corresponds to the groove, the limiting ball is reset and inserted into the annular groove by the spring.

8. The unmanned aerial vehicle-borne low-disturbance water sampling device for coastal wetlands as described in claim 6, characterized in that, The top surface of the support frame is provided with an aircraft parking position, and the side of the support frame is provided with an access door.

9. A method for unmanned aerial vehicle (UAV)-borne low-disturbance water sampling for coastal wetlands, employing the unmanned aerial vehicle (UAV)-borne low-disturbance water sampling device for coastal wetlands as described in any one of claims 1 to 8, characterized in that, The following sampling modes are supported: Mode 1: Only surface samplers are mounted to collect surface water samples; Mode 2: Only attach the bottom sampler to collect bottom water samples; Mode 3: Simultaneously mount surface samplers and bottom samplers to collect surface and bottom water samples at the same time.

10. The method for low-disturbance water sampling by unmanned aerial vehicle (UAV) for coastal wetlands as described in claim 9, characterized in that, When using the sampling mode of mode three, the following steps are included: S10: Connect the bottom sampler, surface sampler, and limiter to the bottom of the UAV aircraft via a suspension cable. At the same time, adjust the distance between the surface sampler and the bottom sampler by selecting a preset hanging point on the suspension cable according to the depth of the target water area to be sampled. S20: Control the drone to the corresponding sampling position in the target water area, and then place the bottom sampler and the surface sampler into the water at a speed of ≤0.15m / s until the surface sampler is just submerged below the water surface of the target water area, and then control the drone to hover. S30: After the surface sampler enters the water, it is tilted under the relative action of the first float and the metal ball, so that the surface water sample of the target water area enters the opening at the top of the surface sampler to collect the surface water sample; after the bottom sampler enters the water, the guide plate is subjected to the upward water pressure torque, which overcomes the weight of the counterweight block, so as to drive the sealing baffle to flip outward to open the water inlet to collect the bottom water sample. S40: After the bottom water sample and surface water sample are collected, the drone is controlled to take off upwards to move the surface sampler and bottom sampler out of the water surface; when it is moved out of the water surface, the counterweight moves the sealing baffle to reset due to gravity and seals the water inlet; S50: The drone is controlled to carry the surface sampler and the bottom sampler into the inverted conical support cylinder of the recovery unit, so that the surface sampler and the bottom sampler pass through the opening at the bottom of the inverted conical support cylinder. The limiter restricts the neck inside the inverted conical support cylinder, so that the surface sampler and the bottom sampler are in a suspended state, which facilitates the subsequent manual recovery of the surface sampler and the bottom sampler.

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