A simulation experiment system for pesticide behavior on crop surface under unmanned aerial vehicle pesticide application

Abstract

The utility model relates to unmanned plane pesticide spraying experimental technical field discloses a kind of simulation experiment system of crop surface pesticide behavior under unmanned plane pesticide application condition. The system is mainly composed of wind tunnel, multiple droplet generating device, simulation blade, high-speed observation and synchronous control etc. system. Wind tunnel system is composed of rectifier grid and fan, for simulating unmanned plane rotor airflow;Multiple droplet generating system generates multiple equal-diameter liquid droplets through micropore and high-frequency oscillation;Simulation blade system is equipped with spring leaf and simulation surface, simulation blade shakes;High-speed observation system captures the transient behavior of pesticide droplets;Synchronous control system (pull-type electromagnet, signal delay device, photoelectric switch etc.) coordinates and controls each system component. The present application can simulate unmanned plane rotor airflow, control pesticide droplet composition, speed and diameter, adjust blade surface characteristics and vibration law, provide experimental conditions for pesticide droplet behavior observation under unmanned plane pesticide application condition, and provide strong support for the development of unmanned plane pesticide application technology.

Description

Technical Field

[0001] This utility model relates to the field of drone pesticide spraying simulation technology, specifically a simulation experimental system for pesticide behavior on crop surface under drone spraying conditions. Background Technology

[0002] Traditional spraying methods rely primarily on manual labor and land-based machinery. Manual labor can spray approximately 10-20 acres per day, while machinery, although more efficient, is easily limited by terrain, leading to insufficient spraying precision and excess pesticides flowing into the soil or groundwater, causing environmental pollution. Furthermore, manual operation suffers from issues of overspraying and missed areas. Traditional spreading not only incurs high labor costs but also relatively high maintenance costs for the machinery. For operators, exposure to pesticides also poses a significant risk of poisoning. Overall, traditional spreading methods have many limitations, are mainly suitable for flat fields, and are not conducive to promoting agricultural modernization.

[0003] Small agricultural drones offer numerous advantages for spraying, including low operating altitude, hovering capability, no need for dedicated take-off and landing airports, downward airflow generated by the rotors increasing the penetration of the mist into crops for high control efficacy, remote control operation, and reduced pesticide exposure for spraying personnel, thus improving spraying safety. Furthermore, electric drone spraying technology can save at least 50% of pesticide usage and 90% of water consumption, significantly reducing resource costs. Drone spraying also greatly reduces the risk of contact with personnel gathered together.

[0004] The process and research of pesticide spraying by agricultural drones essentially involves applying fundamental theories such as multiphase flow dynamics, interface science, and impact mechanics to agricultural engineering practice. The pesticide droplets (typically 50-400 micrometers in diameter) sprayed by drones impact complex plant surfaces (hydrophobic, hairy, or waxy) at a certain speed, and their spreading, rebounding, or splashing behavior directly affects the pesticide deposition rate.

[0005] Studies have found that when agricultural drones are operating, the vibration of leaves due to external factors causes the sprayed droplets to act on an unstable wall surface. This results in the droplets breaking apart and being unable to be detected, and they cannot be maintained at a stable level, leading to a high drift rate during application, wasting pesticides, and severely hindering the study of their mechanisms. The main reason for these problems is that the downdraft velocity of the drone can reach 3-8 m / s, which couples with the initial velocity of the droplets (1-5 m / s), changing the impact angle and kinetic energy. The vertical shaking and horizontal swaying of the leaves caused by the airflow also exacerbate the uncertainty of droplet impact. Furthermore, the surface properties of the leaves change in real time due to humidity, temperature, or chemical stimuli (such as the opening and closing of stomata affecting wettability). Different areas of the same leaf may exhibit a coexistence of hydrophilic (near stomata) and hydrophobic (waxy layer) properties (contact angle differences can reach more than 60°). Under high temperature and low humidity conditions, droplets may shrink in volume by more than 20% before impact, resulting in a significant decrease in the Weber number.

[0006] Limited by experimental observation systems, existing research mainly focuses on the adhesion and splashing phenomena of single droplets impacting a fixed wall in a non-airflow environment. Existing experimental systems do not clearly explain the mechanisms underlying the actual spreading, rebounding, or splashing behavior of droplets. Furthermore, in practice, the fixed wall cannot realistically simulate the swaying of leaves under external forces, making it difficult to study the drift and penetration of pesticides during application. This is because there is a lack of a wind tunnel system to simulate the airflow-droplet-leaf interaction during agricultural drone flight. Therefore, a wind tunnel system consisting of a rectifier grid and a fan was designed to simulate the downwash airflow generated by the drone. A wall structure equipped with spring plates simulates the dynamic effect of the leaf's up-and-down swaying. By changing the incident angle of the droplet generator and the wall position, high-speed photography and fluorescent labeling were used to observe the interaction between droplets and the leaf surface. This aims to optimize spraying efficiency, reduce pesticide waste, and lower environmental pollution. Utility Model Content

[0007] To address the shortcomings of existing technologies, this invention provides a simulation experimental system for pesticide behavior on crop surfaces under unmanned aerial vehicle (UAV) application conditions, which has advantages such as accurate simulation and solves the aforementioned technical problems.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a simulation experimental system for pesticide behavior on crop surface under drone spraying conditions, including an external light source and a wind tunnel system simulating the downwash airflow of the drone, and also including a multi-droplet generator, a baffle, a second laser photoelectric switch, a simulated blade, a pull electromagnet, a high-speed camera, a first signal delay unit, etc. arranged in sequence; The multi-droplet generator generates incident droplets through a liquid supply pipeline; The second laser photoelectric switch is located below the multi-droplet generator and is used to determine whether the incident droplets generated by the multi-droplet generator are stable. It is also electrically connected to the second signal delay unit, which is electrically connected to a motor. The motor drives the baffle to rotate, and the incident droplets fall to the first laser photoelectric switch after the baffle rotates. The first laser photoelectric switch is electrically connected to the first signal delay unit, which is electrically connected to a pull electromagnet. The high-speed camera is positioned above the simulated blade, below the first laser photoelectric switch, and corresponding to the external light source. A spring plate is provided at the output end of the pull electromagnet. The end of the spring plate away from the pull electromagnet is fixedly set, and a simulated blade is installed at the top of the spring plate.

[0009] As a preferred embodiment of the present invention, the liquid supply pipeline consists of a vibration driver, a second accumulator, a pressure gauge, a pressure stabilizing mechanism, and a droplet generator; High-pressure air is drawn in by the pressure stabilizing mechanism and fed into the first and second accumulators respectively. The water stored in the first and second accumulators is then output to two symmetrically arranged droplet generators. The droplet generators generate incident droplets through a vibration driver. A pressure gauge is installed at the gas passage between the pressure stabilizing mechanism and the first and second accumulators.

[0010] As a preferred embodiment of the present invention, a drainage groove is provided on the top surface of the baffle, and an inclined blade is provided on one side of the drainage groove on the top surface of the baffle. The droplets collected at the tail end of the drainage groove are fed into a water tank.

[0011] Compared with existing technologies, this invention provides a simulation experimental system for pesticide behavior on crop surfaces under unmanned aerial vehicle (UAV) application conditions, which has the following beneficial effects: This invention simulates the airflow generated during drone flight by establishing a wind tunnel experiment. It adds a multi-droplet generator with an adjustable incident angle and an adjustable wall with springs to simulate the vibration of real blades. A high-speed camera captures the initial splashing moment when droplets contact the wall. The incident angle and height are adjusted according to the splashing, spreading, and breaking of the droplets. Based on the data obtained from the simulation, the Ohnesorge number of the droplets is adjusted in practice to suppress splashing. The flight altitude is then adjusted in real time according to the database to optimize spraying efficiency, reduce pesticide waste, and reduce environmental pollution. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the liquid supply pipeline structure of the present invention; Figure 2 This is a schematic diagram of the system framework of the present invention; Figure 3 This is a schematic diagram of the baffle of the present invention; Figure 4A schematic diagram illustrating how a baffle cuts through an irregular droplet. 1. Multi-droplet generator; 2. Baffle; 3. First laser photoelectric switch; 4. Simulated blade; 5. Spring plate; 6. Pull electromagnet; 7. Fan; 8. High-speed camera; 9. First signal delay unit; 901. Drainage trough; 902. Inclined blade; 10. External light source; 11. Rectifying grid; 12. Second laser photoelectric switch; 13. Second signal delay unit; 14. Motor; 15. Water tank; 16. Vibration actuator; 17. Pressure gauge; 18. Voltage stabilizing mechanism; 19. First accumulator; 20. Second accumulator. Detailed Implementation

[0013] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0014] Please see Figures 1-4 A simulation experimental system for pesticide behavior on crop surface under drone spraying conditions includes an external light source 10, a rectifier grid 11 for uniform flow velocity distribution and to eliminate airflow unevenness through collision integration, a multi-droplet generator 1, a baffle 2, a second laser photoelectric switch 12, a simulated blade 4, a pull electromagnet 6, a high-speed camera 8, a first signal delay unit 9, and a fan 7. The fan 7 and the rectifier grid together form a wind tunnel system to simulate the downwash airflow of the drone. The multi-droplet generator 1 generates incident droplets through a liquid supply pipeline; The second laser photoelectric switch 12 is located below the multi-droplet generator 1 and is used to determine whether the incident droplets generated by the multi-droplet generator 1 are stable. It is electrically connected to the second signal delay unit 13, which is electrically connected to the motor 14. The motor 14 drives the baffle 2 to rotate. After the baffle 2 rotates, the incident droplets fall to the first laser photoelectric switch 3. The first laser photoelectric switch 3 is electrically connected to the first signal delay unit 9, which is electrically connected to the pull electromagnet 6. The high-speed camera 8 is positioned above the simulated blade 4, below the first laser photoelectric switch 3, and corresponds to the external light source 10. The output end of the pull electromagnet 6 is provided with a spring plate 5. The end of the spring plate 5 away from the pull electromagnet 6 is fixedly set, and the simulated blade 4 is installed on the top of the spring plate 5.

[0015] The liquid supply pipeline consists of a vibration driver 16, a first accumulator 19, a second accumulator 20, a pressure gauge 17, a pressure stabilizing mechanism 18, and a droplet generator. High-pressure air is drawn in by the pressure stabilizing mechanism 18 and input into the first accumulator 19 and the second accumulator 20 respectively. The water stored in the first accumulator 19 and the second accumulator 20 is output to two symmetrically arranged droplet generators. The incident droplets are generated by the vibration driver 16 in conjunction with the droplet generators. A pressure gauge 17 is installed at the gas passage between the pressure stabilizing mechanism 18 and the first accumulator 19 and the second accumulator 20.

[0016] A drainage groove 901 is provided on the top surface of the baffle 2. An inclined blade 902 is provided on one side of the drainage groove 901 on the top surface of the baffle 2. The drips collected at the tail end of the drainage groove 901 are fed into the water tank 15. The first laser photoelectric switch 3 is located directly below the multi-droplet generator 1 in the center of the wind tunnel. One end of the first signal delay unit 9 is connected to the fast-pull electromagnet 6, and the other end is connected to the first laser photoelectric switch 3. The multi-droplet generator 1 and the movable baffle 2 with blades on one side are installed sequentially in the simulated wind tunnel system according to the gas flow direction. Above the movable baffle 2 with blades on one side, a second laser photoelectric switch 12 is installed. At the rear end of the movable baffle 2, a drain pipe for discharging irregularly sized droplets from the multi-droplet generator 1 and a motor 14 are installed. The second signal delay unit 13 connects the second laser photoelectric switch 12 and the motor 14. A fast-pull electromagnet is installed on the simulated blade 4, and a fan 7 simulating the airflow generated by the drone is installed at the bottom.

[0017] The main functions of the first signal delay unit 9 are: ① to collect the electrical signal generated when the droplet passes through, detected by the first laser photoelectric switch 3; ② to transmit the received electrical signal to the pull electromagnet 6 to release the simulated blade 4.

[0018] The main functions of the second signal delay unit 13 are: ① to collect the passage of irregularly sized droplets detected by the second laser photoelectric switch 12; ② to control the motor 14 to rotate at a certain speed to remove the baffle 2 after the multi-droplet generator 1 generates stable, regularly sized droplets. Please see Figure 4When observing the interaction of multiple droplets during the collision with a wall, two droplet generators are needed to produce two identical droplet streams. To this end, a dual-droplet generator liquid supply pipeline was constructed. When the multi-droplet generator 1 is working, the liquid supply pipeline remains open. The liquid in the supply pipeline, through a vibration actuator 16, alters the vibration frequency of the jet, changing the diameter and velocity of the ejected droplets to stabilize them. Small droplets of the same frequency, incident through the pipeline, reach the droplet generator, which ejects droplets at the same frequency. However, because the upstream valve is open and the jet has not yet reached a stable state, the droplet generator cannot produce stable, dispersed droplets. The unstable droplets are irregular and difficult to observe. Therefore, when unstable droplets fall, a movable baffle 2 with an inclined blade 902 on one side is used to block the initial droplets. The inclined blade 902 is installed on one side of the baffle. After the jet stabilizes, the baffle is moved away at a certain speed so that the blade cuts the droplet bundle, causing the subsequent stable droplets to hit the wall. A drainage channel 901 is provided at the bottom of the baffle 2 to discharge the liquid generated by the breakup of irregular droplets, which flows out to the water tank 15 through the pipeline. The main function of the movable baffle 2 is to block unstable irregular droplets. If only a baffle is set, when the baffle moves quickly from the side to below the droplet generator, the initial droplets falling on the baffle are very likely to seep out from the side. The inclined blade 902 is provided on the side of the baffle so that when it moves quickly to below the droplet generator, the inclined wall surface of the blade blocks the waste liquid to prevent it from flowing to the outside, and the sharp blade can quickly cut and separate regular and irregular droplets. Irregular droplets are discharged into the water tank 15 through the drainage channel 901. The second laser photoelectric switch 12 determines whether the incident droplet is a stable jet conforming to the specified size and shape based on its size and shape. Once a stable droplet is formed, it transmits an electrical signal to the second signal delay unit 13. The signal delay unit controls the motor 14 to retract the baffle 2 at a certain speed, allowing the subsequent stable droplet beam to impact the simulated blade 4. A first laser photoelectric switch 3 is located under the baffle and is connected to the first signal delay unit 9. When the droplet beam falls past the first laser photoelectric switch 3, the first signal delay unit 9 receives the transmitted electrical signal, which controls the fast-pull electromagnet 6 connected to the other end to release the spring plate 5 fastened at the front end. The simulated blade 4 on the spring plate, influenced by inertia and the bottom fan 7, swings irregularly up and down, simulating the blade's swaying under the influence of the drone's airflow. While the simulated blade 4 swings up and down, the external light source 10 is turned on, and the high-speed camera 8 is activated to capture the droplet's breaking, spreading, and splashing states at different wall positions. This droplet generator uses microporous sheets (pinhole diameters ranging from 25 μm to 100 μm) to obtain ultra-fine diameter jets. A piezoelectric block surrounds the main pipe, and a high-frequency, periodically fluctuating current is input to the piezoelectric block to induce periodic vibrations. The laminar jet at the outlet generates periodic surface waves under the periodic vibration of the pipe. These surface waves cause the jet to break into a stream of discrete droplets as it develops, with each droplet having a volume equal to the volume of a liquid column equal to the wavelength of one surface wave. In the experiment, the droplet size and velocity can be altered by changing the microporous sheet diameter, the upstream water pressure, and the jet's vibration frequency.

[0019] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A simulation experimental system for pesticide behavior on crop surfaces under unmanned aerial vehicle (UAV) application conditions, characterized in that: The system includes a rectifier grid (11), a multi-droplet generator (1), a baffle (2), a second laser photoelectric switch (12), a simulated blade (4), a pull electromagnet (6), a high-speed camera (8), an external light source (10), a first signal delay unit (9), and a fan (7), which together with the rectifier grid (11) form a wind tunnel system. The multi-droplet generator (1) generates incident droplets through a liquid supply pipeline; The second laser photoelectric switch (12) is located below the multi-droplet generator (1) and is used to determine whether the incident droplets generated by the multi-droplet generator (1) are stable. It is also electrically connected to the second signal delay unit (13). The second signal delay unit (13) is electrically connected to the motor (14). The motor (14) drives the baffle (2) to rotate. After the baffle (2) rotates, the incident droplets fall to the first laser photoelectric switch (3). The first laser photoelectric switch (3) is electrically connected to the first signal delay unit (9). The first signal delay unit is electrically connected to the pull electromagnet (6). The high-speed camera (8) is positioned above the simulated blade (4), below the first laser photoelectric switch (3), and corresponds to the external light source (10). The output end of the pull electromagnet (6) is provided with a spring plate (5). The end of the spring plate (5) away from the pull electromagnet (6) is fixedly set. The top of the spring plate (5) is equipped with a simulated blade (4).

2. The simulation experimental system for pesticide behavior on crop surface under unmanned aerial vehicle (UAV) application conditions according to claim 1, characterized in that: The liquid supply pipe route consists of a vibration driver (16), a second accumulator (20), a pressure gauge (17), a pressure stabilizing mechanism (18), and a droplet generator; High-pressure air is drawn in by the pressure stabilizing mechanism (18) and input into the first accumulator (19) and the second accumulator (20) respectively. The water stored in the first accumulator (19) and the second accumulator (20) is output to two symmetrically arranged droplet generators. The incident droplets are generated by the vibration driver (16) in conjunction with the droplet generators. A pressure gauge (17) is installed at the gas passage between the pressure stabilizing mechanism (18) and the first accumulator (19) and the second accumulator (20).

3. The simulation experimental system for pesticide behavior on crop surface under unmanned aerial vehicle (UAV) application conditions according to claim 1, characterized in that: The top surface of the baffle (2) has a drainage groove (901), and an inclined blade (902) is provided on one side of the drainage groove (901) on the top surface of the baffle (2). The drips collected at the end of the drainage groove (901) are fed into the water tank (15).

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