A soil heavy metal on-site sampling device

Abstract

The application relates to a soil heavy metal on-site sampling device which comprises a drone, an auxiliary counterweight and a sampling cylinder, the bottom of the drone is provided with landing gears, the bottom of the drone is also provided with a camera, the bottom of the landing gears is installed with a bottom frame, and at least three groups of flexible connecting pieces are installed between the bottom frame and the side wall of the sampling cylinder; the central part of the auxiliary counterweight is provided with a guide hole used for guiding the sampling cylinder. The soil heavy metal on-site sampling device adopts the drone, the sampling cylinder and other accessories, can remotely sample some dangerous soil heavy metals on site, is high in safety, free of risks, small in sampling limitation, large in optional sampling area, capable of sampling the area with hard soil, good in sampling effect, low in control difficulty of the drone, easy to recycle other equipment in the sampling area after sampling is completed, high in practicality and high in popularization value.

Description

Technical Field

[0001] This invention relates to a soil heavy metal field sampling device, belonging to the field of soil remote sampling technology. Background Technology

[0002] In the field of environmental protection, soil sampling is indispensable, especially for detecting heavy metals in soil, obtaining topographic information, and analyzing soil type information. After sampling the soil using sampling tools and instruments, the topographic information of the sampled soil is first analyzed, followed by analysis of heavy metal elements and organic matter in the soil. These processes provide data support for monitoring technologies before and after soil remediation.

[0003] Therefore, soil sampling is the foundation of everything mentioned above. Existing soil sampling methods are usually quite simple, using mechanical equipment (such as the "soil sampler" in publication number CN101592563B and the "a soil sampler" in publication number CN105388040B), which are all collected manually on-site.

[0004] However, for some high-risk areas (such as soil contaminated with heavy metals, which are generally remote and difficult to sample), manual sampling carries significant risks. While existing drone technology is very mature and theoretically allows for remote sampling, experiments have revealed the following problems:

[0005] While it's easy for drones to transport samplers to designated locations, the challenge lies in applying a downward force to the sampler for sampling. If the sampler is dropped into the sampling area using free fall, the soil column inside the sampler is too small to meet sampling requirements. In this case, if a drone is used to apply a downward impact or thrust to the sampler, the drone's level is difficult to adjust, making it impossible to maintain perfect horizontality at all times. The deviation angle between the drone and the horizontal plane can reach over 5°, which can easily cause the sampler to tip over due to the impact, resulting in sampling failure.

[0006] If the sampler is fixed below the drone, and the drone is used to generate downward thrust for sampling, it is theoretically feasible. However, because the drone's level is difficult to adjust and cannot be kept perfectly level at all times, messy expansion pits easily appear around the sampler, and the soil column inside the sampler is broken or even contains a large amount of broken soil, resulting in a near 100% sampling failure rate.

[0007] Based on this, the present invention is proposed. Summary of the Invention

[0008] This invention addresses the shortcomings of existing technologies by providing a soil heavy metal on-site sampling device, the specific technical solution of which is as follows:

[0009] A soil heavy metal on-site sampling device includes a drone, an auxiliary counterweight, and a cylindrical sampling tube. The drone has a landing gear at its bottom and a camera at its bottom. The sampling tube is located below the landing gear, and a base frame is installed at the bottom of the landing gear. At least three sets of flexible connectors are installed between the base frame and the side wall of the sampling tube. The auxiliary counterweight has a guide hole in its center for guiding the sampling tube.

[0010] In a further improvement, the flexible connector includes a V-shaped rod, a ball string component, a conical spring, and an inclined pad fixed to the outside of the sampling cylinder. The V-shaped rod includes a connecting rod one and a connecting rod two. The first end of the connecting rod one and the tail end of the connecting rod two are connected by an arc transition. The tail end of the connecting rod one is fixedly connected to the lower part of the base frame. The included angle between the connecting rod one and the base frame is γ, where γ is an obtuse angle; the included angle between the connecting rod one and the connecting rod two is α, where α is an acute angle. An inclined surface is provided on the outside of the inclined pad. The included angle between the inclined surface and the axis of the sampling cylinder is β, where β is an acute angle. The large end of the conical spring is fixedly connected to the inclined surface. The ball string component includes a hemispherical sphere two, multiple sets of ball groups, and a connecting rope. The ball groups include a spherical sphere one. The first sphere has a larger diameter than the third sphere. The second connecting rod is perpendicular to and fixedly connected to the bottom surface of the second sphere. The first end of the connecting rope is fixedly connected to the spherical surface of the second sphere. The first sphere has a threaded hole 1 at its axis for the connecting rope to pass through. The first sphere also has grooves on both sides that are adapted to the third sphere. The grooves are spherical notches. The grooves on both sides of the first sphere are connected through the threaded hole 1. The third sphere has a threaded hole 2 at its axis for the connecting rope to pass through. The tail end of the connecting rope passes through all the threaded holes 1 of the first sphere, all the threaded holes 2 of the third sphere, and the conical spring before being fixedly connected to the inclined plane. The inner diameter of the small end of the conical spring is smaller than the diameter of the third sphere.

[0011] In a further improvement, the diameter of sphere one is equal to the diameter of sphere two, and the ratio of the diameter of sphere one to the diameter of sphere three is x, where 1.6 ≤ x ≤ 2.2.

[0012] A further improvement is made, wherein α = 75°, β = 24°, and γ = 135°.

[0013] In a further improvement, four n-shaped hangers are fixedly installed on the upper edge of the auxiliary counterweight, and a hoisting rope is connected to the upper part of the hanger. An electric release device is installed between the hoisting rope and the landing gear.

[0014] In a further improvement, the guide hole includes a conical hole and a circular hole adapted to the sampling cylinder, wherein the small end of the conical hole is connected to the upper end of the circular hole, and the circular hole and the sampling cylinder are in clearance fit.

[0015] In a further improvement, the bottom frame includes an outer frame and a circular fixing ring disposed in the center of the outer frame. A connecting plate connects the fixing ring to the outer frame, and the surface of the fixing ring is provided with mounting holes that correspond one-to-one with the landing gear.

[0016] In a further improvement, the inner diameter of the fixing ring is R, the outer diameter of the sampling tube is r, and 0.01≤(Rr) / r≤0.2.

[0017] A further improvement is made to the on-site sampling method:

[0018] Step S1: The auxiliary counterweight is hoisted to the sampling area by a drone and then placed in the sampling area.

[0019] Step S2: Install the bottom frame at the bottom of the landing gear. The bottom frame and the sampling tube are connected by a flexible connector. The sampling tube is inserted into the guide hole by the drone until the lower end of the sampling tube contacts the ground in the area to be sampled.

[0020] Step S3: A level sensor is installed on the upper surface of the bottom frame. The level sensor is used to measure the horizontal deviation angle of the bottom frame, and its value is δ.

[0021] The drone hovers directly above the area to be sampled, and the drone's attitude is adjusted. When δ≤y, y is the first set value, and all the drone's propellers stop rotating.

[0022] Step S4: When the drone stops falling, reverse all the drone's propellers to make the drone continue to move downwards.

[0023] Step S5: When the drone stops moving downwards, all the drone's propellers stop rotating. Then, by adjusting all the drone's propellers to reverse, the drone continues to move downwards.

[0024] Step S6: Repeat step S5 until the sampling tube completes the sampling operation;

[0025] Step S7: By adjusting all the drone's propellers to rotate clockwise, the drone moves upward and transports the sampling tube that has completed sampling to the designated area.

[0026] A further improvement is made: y = 5.3°.

[0027] The soil heavy metal field sampling device described in this invention uses a drone, sampling tube, and other accessories to remotely sample heavy metals in some hazardous soil sites. It is highly safe and risk-free. Sampling is minimally restricted, allowing for a large selectable sampling area, including areas with hard soil. The sampling effect is good, and the drone is easy to control. After sampling, other equipment in the sampling area is easily retrieved, making it highly practical and valuable for widespread application. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the soil heavy metal field sampling device described in this invention;

[0029] Figure 2 This is a schematic diagram showing the connection of the bottom frame, flexible connector, and sampling cylinder described in this invention;

[0030] Figure 3 This is a schematic diagram of the structure of the flexible connector described in this invention;

[0031] Figure 4 This is a schematic diagram of the structure of the ball assembly described in this invention;

[0032] Figure 5 This is a schematic diagram showing the connection between the inclined pad and the sampling cylinder described in this invention;

[0033] Figure 6 This is a schematic diagram of the structure of the sphere one described in this invention;

[0034] Figure 7 This is a schematic diagram of the auxiliary counterweight described in this invention;

[0035] Figure 8 This is a schematic diagram of the structure of the bottom frame described in this invention;

[0036] Figure 9 This is a schematic diagram of the horizontal deviation angle described in this invention;

[0037] Figure 10 This is a graph showing the relationship between the x-value and the dumping rate. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0039] In the description of this invention, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0040] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0041] Example 1

[0042] like Figure 1 As shown, the soil heavy metal on-site sampling device includes a drone 10, an auxiliary counterweight 30, and a cylindrical sampling tube 40. The drone 10 is equipped with a landing gear 11 at its bottom and a camera 12 at its bottom. The sampling tube 40 is located below the landing gear 11, and a bottom frame 13 is installed at the bottom of the landing gear 11. At least three sets of flexible connectors 20 are installed between the bottom frame 13 and the side wall of the sampling tube 40. The auxiliary counterweight 30 has a guide hole 31 in the center for guiding the sampling tube 40.

[0043] The drone 10 is preferably a modified DJI heavy-duty drone (with a maximum payload of 50kg), for example, by adding landing gear 11 and a camera 12. The camera 12 is positioned to facilitate observation, especially of the real-time situation of the sampling tube 40 below it.

[0044] The sampling process of the soil heavy metal on-site sampling device is as follows:

[0045] Step S1) The auxiliary counterweight 30 is hoisted to the sampling area by the drone 10 and the auxiliary counterweight 30 is placed in the sampling area.

[0046] Step S2) Install the bottom frame 13 at the bottom of the landing gear 11. The bottom frame 13 is connected to the sampling tube 40 through the flexible connector 20. The sampling tube 40 is inserted into the guide hole 31 by the drone 10 until the lower end of the sampling tube 40 contacts the ground in the sampling area.

[0047] Step S3) A level sensor is installed on the upper surface of the bottom frame 13. The level sensor is used to measure the horizontal deviation angle of the bottom frame 13, and its value is δ.

[0048] The drone 10 hovers directly above the area to be sampled. The attitude of the drone 10 is adjusted. When δ≤y, y is the first set value, and all the propellers of the drone 10 stop rotating.

[0049] (Step S4) When the drone 10 stops falling, the propellers of the drone 10 are reversed to make the drone 10 continue to move downward. At this time, the reversal generates a downward thrust, which, based on the gravity of the drone 10, can apply another thrust to make the sampling tube 40, which can no longer move forward, move downward again to continue sampling.

[0050] (Step S5) When the drone 10 stops moving downwards, all the propellers of the drone 10 stop rotating. Then, by adjusting all the propellers of the drone 10 to reverse, the drone 10 continues to move downwards. Since the thrust applied by the drone 10 to continue moving downwards has a peak value, after reaching the limit, as the resistance increases as it goes deeper, the drone 10 will stop moving downwards again. At this time, step S4 needs to be repeated.

[0051] Step S6) Repeat step S5) until the sampling tube 40 completes the sampling operation.

[0052] Step S7) By adjusting all the propellers of the drone 10 to rotate forward, the drone 10 moves upward and transports the sampling tube 40, which has completed sampling, to the designated area.

[0053] Among them, the horizontal deviation angle, such as Figure 9 As shown. The levelness sensor typically provides a levelness value directly, measured in mm / m; for example, a levelness of 3 mm / m means a height difference of 3 mm over a length of one meter. Therefore, the δ value can be obtained using trigonometric functions based on the length of the base frame 13.

[0054] As a supplement to existing technology: Taking a quadcopter drone as an example, the drone 10 has four propellers, each driven by a motor. When the motor drives the propellers downwards, due to the principle of action and reaction, the air generates upward lift on the propellers. The direction of rotation of all propellers at this time is marked as clockwise rotation. The faster the propeller speed, the greater the lift. When the lift is greater than the drone's weight, the drone rises; conversely, the slower the propeller speed, the less the lift. When the lift is less than the drone's weight, the drone descends. Therefore, if a greater downward thrust is needed, the rotation direction of all propellers can be adjusted to counter-clockwise (opposite to clockwise rotation). In this case, the propellers will blow upwards, and due to the principle of action and reaction, the air will generate downward thrust on the propellers. Combined with the drone's own weight, the drone can accelerate downwards.

[0055] Compared with the prior art, since the present invention uses three specially designed flexible connectors 20, and since the flexible connectors 20 themselves have a certain buffering effect and also have a certain downward force transmission effect, as long as the horizontal deviation angle is less than or equal to 5.3°, the sampling pass rate exceeds 91%, which is a high pass rate.

[0056] The sampling tube 40 is less likely to have messy expansion pits around its perimeter, and the soil columns inside the sampling tube 40 are all complete soil columns, which can preserve the original soil conditions to the greatest extent.

[0057] In this embodiment, since the maximum payload of the UAV 10 is 50 kg, the maximum mass of the auxiliary counterweight 30 is typically no more than 40 kg. Therefore, the horizontal thrust generated by the tilting of the UAV 10 has a limit, and the horizontal deviation angle cannot exceed 5.3°. In this context, the horizontal thrust is eliminated to the maximum extent by using three sets of flexible connectors 20, while effectively maintaining the stability between the sampling cylinder 40 and the UAV 10, thereby improving the sampling pass rate.

[0058] Example 2

[0059] Based on Example 1, such as Figures 2-6 As shown, the flexible connector 20 includes a V-shaped rod 21, a ball joint, a conical spring 24, and an inclined pad 27 fixed to the outside of the sampling cylinder 40. The V-shaped rod 21 includes a first connecting rod 211 and a second connecting rod 212. The first end of the first connecting rod 211 and the tail end of the second connecting rod 212 are connected by an arc transition. The tail end of the first connecting rod 211 is fixedly connected to the lower part of the bottom frame 13. The included angle between the first connecting rod 211 and the bottom frame 13 is γ, where γ is obtuse. Angle; the included angle between the first connecting rod 211 and the second connecting rod 212 is α, where α is an acute angle; an inclined surface 271 is provided on the outer side of the inclined pad 27, and the included angle between the inclined surface 271 and the axis of the sampling cylinder 40 is β, where β is an acute angle; the large end of the cone spring 24 is fixedly connected to the inclined surface 271; the ball string component includes a hemispherical sphere 25, multiple sets of ball groups, and a connecting rope 26; the ball group includes a spherical sphere 22 and a spherical sphere... Sphere 22 has a larger diameter than sphere 23. Connecting rod 212 is perpendicular to and fixedly connected to the bottom surface of sphere 25. The first end of connecting rope 26 is fixedly connected to the spherical surface of sphere 25. A rope hole 221 for the connecting rope 26 to pass through is provided at the axis of sphere 22. Grooves 222, which are adapted to sphere 23, are also provided on both sides of sphere 22. The structure is spherical, with the grooves 222 on both sides of the sphere 1 22 connected by the rope hole 221; the axis of the sphere 3 23 is provided with the rope hole 231 for the connecting rope 26 to pass through, and the tail end of the connecting rope 26 passes through the rope holes 221 of all the spheres 1 22, the rope holes 231 of all the spheres 3 23, and the conical spring 24 and is then fixedly connected to the inclined surface 271; the inner diameter of the small end of the conical spring 24 is smaller than the diameter of the sphere 3 23.

[0060] The force on the bottom frame 13 can be decomposed and accurately transmitted to the ball string component through the V-shaped rod 21. On the one hand, the ball string component itself can transmit force through the "hard contact" between the first ball 22 and the third ball 23. On the other hand, the relative displacement between the first ball 22 and the third ball 23 can be free and flexible to adapt to the flexible deformation of the three sets of flexible connectors 20 caused by the offset of the bottom frame 13. The sampling cylinder 40 can be restrained by the auxiliary counterweight 30 (as long as the thrust does not exceed the maximum static friction). The force of the bottom frame 13 on the sampling cylinder 40 can be decomposed to the maximum extent and force the sampling cylinder 40 to move downward.

[0061] Because the bottom frame 13 is affected by the drone 10, the horizontal deviation angle changes constantly. The cooperation between the conical spring 24 and the ball joint significantly improves stability, so that even if the drone 10 starts or stops immediately in a short time, the sampling cylinder 40 can be prevented from tipping over.

[0062] Example 3

[0063] Based on Example 2, such as Figure 7 As shown, the guide hole 31 includes a conical hole 311 and a circular hole 312 adapted to the sampling cylinder 40. The small end of the conical hole 311 is connected to the upper end of the circular hole 312, and the circular hole 312 and the sampling cylinder 40 are in clearance fit.

[0064] The conical hole 311 is mainly for guiding the sampling cylinder 40, and the round hole 312 is a limiting hole.

[0065] Example 4

[0066] Based on Example 2, such as Figure 7 As shown, four n-shaped hangers 32 are fixedly installed on the upper edge of the auxiliary counterweight 30. The upper part of the hangers 32 is connected to the hoisting rope 33, and an electric unhooking device is installed between the hoisting rope 33 and the landing gear 11.

[0067] In step S1), the auxiliary counterweight 30 is first hoisted to the sampling area by installing the electric release device and the lifting rope 33, and then the auxiliary counterweight 30 is placed in the sampling area. Afterwards, the electric release device and the lifting rope 33 are removed. Then, proceed to step S2).

[0068] During the subsequent recovery process, the four n-shaped lifting frames 32 can be hooked by reinstalling the electric release device, lifting rope 33 and lifting hook, so that the auxiliary counterweight 30 can be transported back.

[0069] Example 5

[0070] Based on Example 2, such as Figure 8As shown, the bottom frame 13 includes an outer frame 131 and an annular fixing ring 132 disposed in the center of the outer frame 131. A connecting plate 133 connects the fixing ring 132 and the outer frame 131. The surface of the fixing ring 132 is provided with mounting holes 134 corresponding to the landing gear 11.

[0071] The fixing ring 132 is designed so that, on the one hand, it does not affect the field of view of the camera 12 on the sampling tube 40, and on the other hand, the fixing ring 132 can be fitted on the outside of the sampling tube 40, thereby effectively preventing large tilting or displacement between the bottom frame 13 and the sampling tube 40.

[0072] Example 6

[0073] Based on embodiment 5, the diameter of sphere 1 22 is equal to the diameter of sphere 25, and the ratio of the diameter of sphere 1 22 to the diameter of sphere 3 23 is x, where 1.6 ≤ x ≤ 2.2.

[0074] When the x-value is changed, the spillage rate is calculated according to the "Throwing Rate Test" (the height of the sampling cylinder is 1m for a 40mm diameter sample), and the result is as follows. Figure 10 As shown, the preferred value of x is 1.9.

[0075] Example 7

[0076] Based on Example 6, α = 75°, β = 24°, and γ = 135°. According to the pentagonal structure, β should be equal to 30°. However, practical experience has shown that when β = 30°, the spillage rate calculated according to the "Spillage Rate Test" is as follows: 12% when the height of sampling cylinder 40 is 1m; 55% when the height of sampling cylinder 40 is 2m; and 91% when the height of sampling cylinder 40 is 3m. Therefore, β cannot be equal to 30°.

[0077] The value of α mainly affects the effect of downward force transmission. When α = 90°, it will affect the number of times step S6 is repeated, which will be 20 to 30% more than when α = 75°.

[0078] Example 8

[0079] Based on embodiment 7, the inner diameter of the fixing ring 132 is R, the outer diameter of the sampling cylinder 40 is r, and 0.01≤(Rr) / r≤0.2.

[0080] When the value of (Rr) / r varies from 0 to 0.3, the spillage rate is calculated according to the "Throwing Rate Test" (the height of the sampling cylinder 40 is 1m). The results are shown in Table 2. The preferred value of (Rr) / r is 0.11.

[0081] Experimental Example 1

[0082] Compared with Example 8, this example uses a cylindrical helical spring to replace the ball joint, while keeping the other conditions unchanged; the tipping rate and sampling pass rate are calculated according to the "Tilting Rate Test" and "Sampling Pass Rate Test", and the results are shown in Table 1.

[0083] Experimental Example 2

[0084] Compared with Example 8, this example uses a cylindrical helical spring to replace the conical spring 24, while keeping the other conditions unchanged; the spillage rate and sampling pass rate are calculated according to the "Tilting Rate Test" and "Sampling Pass Rate Test", and the results are shown in Table 1.

[0085] Experimental Example 3

[0086] Compared with Example 8, this example uses a straight rod to connect the second connecting rod 212 to the inclined plane 271, while the other conditions remain unchanged; the tipping rate and sampling pass rate are calculated according to the "Tilting Rate Test" and "Sampling Pass Rate Test", and the results are shown in Table 1.

[0087] Test Example 4

[0088] Compared with Example 8, in this example, connecting rod 212 is directly connected to the bottom frame 13 and β = 90°, while other conditions remain unchanged; the tipping rate and sampling pass rate are calculated according to the "Tilting Rate Test" and "Sampling Pass Rate Test", and the results are shown in Table 1.

[0089] Table 1

[0090]

[0091] Table 2

[0092]

[0093]

[0094] In the above embodiments, for the conical structure, the large end is the end with the largest diameter in the cone, and the small end is the end with the smallest diameter in the cone; and so on for the others.

[0095] Tilting Rate Test

[0096] The heights of the sampling cylinder 40 are 1m, 2m, and 3m respectively. 100 samples are taken, and the number of times the sampling cylinder 40 tilts is recorded. The tilt rate is calculated as follows: Tilting rate = Number of times tilting occurs / 100 * 100%.

[0097] Sampling Pass Rate Test

[0098] Sampling was performed 100 times. The soil column inside the sampling tube 40 was desampled, and the samples were judged to be qualified and counted. The pass rate was calculated. The sampling pass rate = number of qualified samplings / 100 * 100%.

[0099] The soil heavy metal field sampling device described in this invention has a sampling qualification rate of over 91% as long as the horizontal deviation angle is less than or equal to 5.3°, which is a high qualification rate; even if the height of the sampling tube 40 reaches 3m, the tipping rate is less than 5%.

[0100] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A soil heavy metal on-site sampling device, characterized in that: The system includes a drone (10), an auxiliary counterweight (30), and a cylindrical sampling tube (40). The drone (10) has a landing gear (11) at its bottom and a camera (12) at its bottom. The sampling tube (40) is located below the landing gear (11). A bottom frame (13) is installed at the bottom of the landing gear (11). At least three sets of flexible connectors (20) are installed between the bottom frame (13) and the side wall of the sampling tube (40). The auxiliary counterweight (30) has a guide hole (31) in the center to guide the sampling tube (40). The flexible connector (20) includes a V-shaped rod (21), a ball joint, a conical spring (24), and an inclined pad (27) fixed to the outside of the sampling cylinder (40). The V-shaped rod (21) includes a connecting rod one (211) and a connecting rod two (212). The head end of the connecting rod one (211) and the tail end of the connecting rod two (212) are connected by an arc transition. The tail end of the connecting rod one (211) is fixedly connected to the lower part of the bottom frame (13). The included angle between the connecting rod one (211) and the bottom frame (13) is γ, where γ is an obtuse angle. The included angle between the first connecting rod (211) and the second connecting rod (212) is α, where α is an acute angle; the outer side of the inclined pad (27) is provided with an inclined surface (271), and the included angle between the inclined surface (271) and the axis of the sampling cylinder (40) is β, where β is an acute angle; the large end of the cone spring (24) is fixedly connected to the inclined surface (271); the ball string component includes a hemispherical sphere two (25), multiple sets of ball groups, and a connecting rope (26); the ball group includes a spherical sphere one (22) and a spherical sphere three (23). The diameter of sphere one (22) is larger than that of sphere three (23). The connecting rod two (212) is perpendicular to the bottom surface of sphere two (25) and fixedly connected. The first end of the connecting rope (26) is fixedly connected to the spherical surface of sphere two (25). A rope hole one (221) for the connecting rope (26) to pass through is provided at the axis of sphere one (22). Grooves (222) that are adapted to sphere three (23) are also provided on both sides of sphere one (22). The grooves (222) are spherical notches. The structure is such that the grooves (222) on both sides of the first sphere (22) are connected by the first rope hole (221); the axis of the third sphere (23) is provided with the second rope hole (231) for the connecting rope (26) to pass through, and the tail end of the connecting rope (26) passes through the first rope hole (221) of all the first spheres (22), the second rope hole (231) of all the third spheres (23) and the conical spring (24) and is fixedly connected to the inclined surface (271); the inner diameter of the small end of the conical spring (24) is smaller than the diameter of the third sphere (23).

2. The soil heavy metal field sampling device according to claim 1, characterized in that: The diameter of sphere one (22) is equal to the diameter of sphere two (25), and the ratio of the diameter of sphere one (22) to the diameter of sphere three (23) is x, 1.6≤x≤2.

2.

3. The soil heavy metal field sampling device according to claim 1, characterized in that: The α=75°, β=24°, and γ=135°.

4. The soil heavy metal field sampling device according to claim 1, characterized in that: Four n-shaped hangers (32) are fixedly installed on the upper edge of the auxiliary counterweight (30). The upper part of the hangers (32) is connected to the hoisting rope (33), and an electric unhooking device is installed between the hoisting rope (33) and the landing gear (11).

5. The soil heavy metal field sampling device according to claim 1, characterized in that: The guide hole (31) includes a conical hole (311) and a circular hole (312) adapted to the sampling cylinder (40). The small end of the conical hole (311) is connected to the upper end of the circular hole (312), and the circular hole (312) and the sampling cylinder (40) are in clearance fit.

6. The soil heavy metal field sampling device according to claim 1, characterized in that: The bottom frame (13) includes an outer frame (131) and a circular fixing ring (132) located in the center of the outer frame (131). A connecting plate (133) connects the fixing ring (132) and the outer frame (131). The surface of the fixing ring (132) is provided with mounting holes (134) that correspond one-to-one with the landing gear (11).

7. A soil heavy metal field sampling device according to claim 6, characterized in that: The inner diameter of the fixing ring (132) is R, and the outer diameter of the sampling tube (40) is r, where 0.01 ≤ (Rr) / r ≤ 0.

2.

8. A soil heavy metal field sampling device according to claim 7, characterized in that, The on-site sampling method is as follows: Step S1: The auxiliary counterweight (30) is hoisted to the sampling area by the drone (10), and the auxiliary counterweight (30) is placed in the sampling area; Step S2: Install the bottom frame (13) at the bottom of the landing gear (11). The bottom frame (13) and the sampling tube (40) are connected by a flexible connector (20). The sampling tube (40) is inserted into the guide hole (31) by the drone (10) until the lower end of the sampling tube (40) contacts the ground in the sampling area. Step S3: A level sensor is installed on the upper surface of the bottom frame (13). The level sensor is used to measure the horizontal deviation angle of the bottom frame (13), and its value is δ. The drone (10) hovers directly above the area to be sampled. The attitude of the drone (10) is adjusted. When δ≤y, y is the first set value. All propellers of the drone (10) stop rotating. Step S4: When the drone (10) stops falling, adjust all the propellers of the drone (10) to reverse so that the drone (10) continues to move downward. Step S5: When the drone (10) stops moving downwards, all the propellers of the drone (10) stop rotating. Then, by adjusting all the propellers of the drone (10) to reverse, the drone (10) continues to move downwards. Step S6: Repeat step S5 until the sampling tube (40) completes the sampling operation; Step S7: By adjusting all the propellers of the drone (10) to rotate forward, the drone (10) moves upward and transports the sampling tube (40) that has completed sampling to the designated area.

9. A soil heavy metal field sampling device according to claim 8, characterized in that: y=5.3°。

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