A drone-based low-altitude rice transplanting system

Abstract

This invention discloses a low-altitude rice seedling throwing system based on unmanned aerial vehicles (UAVs), comprising a large-wheelbase multi-rotor flight platform and a working platform. The latter includes a frame, a seedling-carrying module, and a seedling-collecting module. In addition to providing sufficient lift, the large-wheelbase multi-rotor flight platform ensures that the projection of the sweeping space during rotor rotation is separate from the sweeping space of the seedling-carrying module's lateral movement, with a distance of no less than 10 cm, enabling stable flight with its inherent load. Two sets of seedling-collecting modules are symmetrically arranged left and right, utilizing drive motors connected via drive shafts to multiple sets of coaxial reversing seedling-collecting mechanisms for non-interference, compressible seedling collection in both forward and reverse directions, thus offsetting torque and reducing vibration. The two sets of seedling-carrying modules are arranged symmetrically in a V-shape on the frame, performing lateral seedling-feeding movements in opposite directions during operation. The overall center of gravity does not change drastically with the lateral movement of the seedling tray, further enhancing the overall flight stability. This invention features a compact structure and ingenious design, enabling efficient and highly maneuverable rice seedling throwing operations.

Description

Technical Field

[0001] This invention relates to the field of agricultural aviation technology, specifically to a low-altitude rice seedling throwing system based on unmanned aerial vehicles (UAVs). Background Technology

[0002] Multi-rotor drones, flying without contact with the ground, possess the potential to serve as the power platform for rice transplanting systems due to their high speed, high efficiency, and high maneuverability. Currently, published patents related to drone-based rice transplanting mainly fall into two categories: those concerning potted seedlings and those concerning matted seedlings. While some progress has been made in these technologies, existing technologies generally suffer from drawbacks such as complex working principles, redundant structures, insufficient lightweighting, and low seedling-collecting efficiency. This results in insufficient seedling capacity and low operational efficiency per drone flight, hindering practical implementation. For potted seedling tray transplanting drones, common transplanting methods include clamping and ejection. These two methods are complex in their working principles and redundant in their structures, resulting in heavy weight, insufficient lightweighting, and low seedling-collecting efficiency. The significant inertial forces generated during high-speed movement severely impact the drone's flight stability, placing high demands on its payload capacity and flight performance, and severely limiting the seedling capacity and operational efficiency per drone flight. While patents for matted seedling tray transplanting drones are also emerging, they similarly suffer from numerous shortcomings. For example, patent CN220545457U discloses a drone rice-throwing device, which uses a combination of a drive unit, a cam, and a rotating cutter head. The device uses a ejector and a seedling-collecting needle on the rotating cutter head to achieve the seedling-collecting and throwing actions. This device has a complex structure, a cumbersome working principle, insufficient lightweight design, and high requirements for the drone's payload capacity. Furthermore, the rice-throwing system overlaps with the drone's wind field, significantly impacting the drone's flight stability. Patent CN221082009U proposes a rice-throwing mechanism and system that combines a load module, a seedling delivery module, and a seedling-collecting module through modular design. However, this rice-throwing system is relatively heavy, making it difficult to meet the drone's payload requirements. The problem of interference between the rice-throwing system and the drone's wind field is not effectively solved, and the numerous drive units and complex overall structure increase the system's failure risk and maintenance costs.

[0003] In summary, existing technologies generally suffer from drawbacks such as complex working principles, redundant structures, insufficient weight and susceptibility to lightweighting, and low seedling-collecting efficiency. These drawbacks result in insufficient seedling capacity and low operational efficiency per drone flight, making practical implementation impossible. Therefore, a novel drone-based seedling-throwing system that can effectively solve these problems is urgently needed. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a drone rice transplanting system in response to the above problems and requirements.

[0005] To solve the above technical problems, the present invention adopts the following technical solution:

[0006] A low-altitude rice-throwing system based on unmanned aerial vehicles (UAVs) includes a long-wheelbase multi-rotor flight platform and a working platform. The working platform includes a frame, two sets of rice-carrying modules, and two sets of rice-receiving modules. The two sets of rice-carrying modules are symmetrically arranged in a V-shape on the front and rear sides of the frame. The two sets of rice-receiving modules are designated as a first rice-receiving module and a second rice-receiving module. The first and second rice-receiving modules are arranged side-by-side on the left and right sides of the frame, located at the angle between the two sets of rice-carrying modules. Each set of rice-receiving modules includes multiple coaxial, counter-rotating rice-receiving modules. The group is driven by a motor, and the motors corresponding to the two seedling picking modules rotate in opposite directions. The two motors are symmetrically located on the left and right sides of the working platform. Each coaxial reverse seedling picking module includes at least one forward-rotating seedling picking turntable mechanism and one reverse-rotating seedling picking turntable mechanism. Both the forward-rotating and reverse-rotating seedling picking turntable mechanisms are connected to the motor shaft. The reverse-rotating seedling picking turntable mechanism includes a reverse-rotating seedling picking turntable device and a coaxial reverse mechanism. The coaxial reverse mechanism uses gear transmission to make the rotation of the reverse-rotating seedling picking turntable device opposite to the rotation of the forward-rotating seedling picking turntable mechanism.

[0007] The seedling-carrying module is used to drive the seedlings to reciprocate and translate on the crossbeam of the seedling box to achieve lateral seedling delivery. Multiple seedling gate notches are evenly arranged at the front end of the crossbeam. The two sets of seedling-carrying modules are a forward seedling-carrying module and a reverse seedling-carrying module, and their lateral seedling delivery movements are either in opposite directions. The position of the seedling gate notches on the forward seedling-carrying module corresponds to the forward rotation seedling-taking turntable mechanism of the first seedling-taking module and the reverse rotation seedling-taking turntable mechanism of the second seedling-taking module. The position of the seedling gate notches on the reverse seedling-carrying module... The first seedling-picking module has a reversing seedling-picking turntable mechanism and the second seedling-picking module have a forward-rotating seedling-picking turntable mechanism. The forward-rotating seedling-picking turntable mechanism in the first seedling-picking module and the reversing seedling-picking turntable mechanism in the second seedling-picking module have the same rotation direction. They are used to cut off and throw out the seedlings at the notch of the seedling box crossbeam in the forward seedling loading module. The reversing seedling-picking turntable mechanism in the first seedling-picking module and the forward-rotating seedling-picking turntable mechanism in the second seedling loading module have the same rotation direction. They are used to cut off and throw out the seedlings at the notch of the seedling box crossbeam in the reverse seedling loading module.

[0008] Furthermore, the large wheelbase multi-rotor flight platform consists of 4-8 rotor shafts, each rotor shaft is equipped with 1-2 sets of propellers, and the projection of the sweep space when the rotor rotates is separate from the sweep space when the seedling-carrying module moves laterally to deliver seedlings, with a distance of not less than 10cm.

[0009] Furthermore, both the forward and reverse seedling loading modules include a movable seedling box, a seedling box crossbeam, and a transverse seedling feeding assembly. The movable seedling box is used to place seedlings, and the transverse seedling feeding drive assembly is used to drive the movable seedling box to move horizontally back and forth on the seedling box crossbeam. The movable seedling box includes a seedling box frame, a longitudinal seedling feeding conveyor belt, and a seedling pressing frame. Multiple longitudinal seedling feeding conveyor belts are arranged side by side on the rear side of the seedling box frame, and a seedling pressing frame is arranged on the front side of the seedling box frame. Seedlings are placed on the longitudinal seedling feeding conveyor belt, and the seedling pressing frame is used to press the seedlings onto the longitudinal seedling feeding conveyor belt. As the seedling throwing process proceeds, the number of seedlings on the seedling box crossbeam gradually decreases, and the seedlings above can descend under the action of gravity and drive the longitudinal seedling feeding conveyor belt to rotate.

[0010] Multiple constraint devices are evenly arranged on the crossbeam of the seedling box. The inner side of the constraint device is arc-shaped. Each seedling picking module has a forward-rotating seedling picking turntable mechanism or a reverse-rotating seedling picking turntable mechanism corresponding to a constraint device. The distance between the constraint device and the seedling gate is the same as the distance between the forward-rotating seedling picking turntable mechanism and the reverse-rotating seedling picking turntable device.

[0011] Furthermore, the seedling pressing frame includes a crossbar and a seedling pressing rod assembly. The seedling pressing rod assembly is evenly arranged along the axial direction of the crossbar. Each seedling pressing rod assembly corresponds to a longitudinal seedling conveyor belt. Each seedling pressing rod assembly includes a long rod and a short rod. The seedling pressing frame is fixed to both sides of the seedling box frame by bolts, and the distance between the seedling pressing frame and the longitudinal seedling conveyor belt is adjusted by adjusting the position of the bolts to accommodate seedlings of different heights so that the seedlings can descend smoothly under the action of gravity to complete the longitudinal seedling delivery.

[0012] Furthermore, both the reversible seedling-picking turntable device and the forward-rotating seedling-picking turntable mechanism include multiple compressible seedling-picking mechanisms evenly distributed along the circumference of the turntable. The motor shaft is connected to the turntable and is used to drive the turntable and the compressible seedling-picking mechanisms to rotate in a vertical plane. The compressible seedling-picking mechanism includes a seedling needle, a first spring base, a bushing, a push rod, a first connecting rod, a second connecting rod, a first spring, a second spring, and a second spring base. The middle part of the first connecting rod is hinged to the turntable via a rotating shaft, the lower end of the first connecting rod contacts the outer surface of the cam, and the upper end of the first connecting rod is hinged to the second connecting rod. Next, the other end of the second connecting rod is hinged to the push rod. A bushing is fitted on the outside of the push rod. A seedling needle is fixed above the bushing. A first spring base is set below the bushing. The lower end of the first spring base is fixed on the turntable. Straight slots are opened on both sides of the first spring base. A short shaft is set in the straight slot. The bushing is fixed to the short shaft. The upper end of the first spring is connected to the bushing, and the lower end is connected to the inner side of the bottom of the fixing part. The second spring base is set on the outside of the upper end of the first connecting rod. A second spring is set between one end of the second spring base and the upper end of the first connecting rod. The other end of the second spring base is fixed to the short shaft.

[0013] When the turntable rotates, it can drive the connecting rod to move along the cam. When the seedling needle is in front of the seedling gate, the contact point between the lower end of the connecting rod and the double cams changes from the highest point to the lowest point. The second spring is released from the compressed state, pushing the first connecting rod, which in turn drives the second connecting rod to push the push rod forward relative to the seedling needle, quickly popping the seedlings at the seedling gate and completing the seedling throwing.

[0014] When the seedling needle rotates into the constraint mechanism, the bushing moves backward to compress the first spring, causing the short shaft and the seedling needle to move downward and inward along the straight groove of the first spring base, thus avoiding interference with the crossbeam on the opposite side during rotation. When the second connecting rod and the seedling needle are both disengaged from the constraint mechanism, the first spring returns to its original state and completes the compression.

[0015] Furthermore, the coaxial reversing mechanism includes a gearbox, a first gear, a second gear, and a third gear. The drive shaft drives the first gear to rotate, and the first gear drives the third gear to rotate in the opposite direction through the second gear. The third gear is connected to the turntable of the reversing seedling picking turntable device, thereby realizing the coaxial reversing motion of the forward-rotating seedling picking turntable mechanism and the reverse-rotating seedling picking turntable mechanism.

[0016] The beneficial effects of the invention are as follows: The UAV-based low-altitude rice seedling throwing system includes a large-wheelbase multi-rotor flight platform and an operating platform. The latter includes a frame, two sets of seedling-carrying modules, and two sets of seedling-retrieving modules, presenting an overall V-shaped structure. Seedlings are thrown out from the middle of the front and rear seedling-carrying platforms, which can effectively avoid the influence of the dispersed wind field of the UAV rotor on the seedling-carrying modules and improve the flight stability of the UAV. The frame is mainly composed of carbon fiber rods, which can effectively reduce the overall weight. The number of seedling trays that the seedling-carrying modules can carry and the number of seedling-retrieving modules can be adjusted according to the UAV's payload. The seedling-retrieving modules adopt a compressible seedling-retrieving mechanism, which can effectively avoid interference between the seedling-retrieving modules and the opposite crossbeams during rotation, ensuring smooth seedling retrieval. This design can greatly reduce the weight of the seedling-retrieving mechanism and improve the UAV's operational capability and flight stability. The seedling-carrying modules move towards or away from each other, and the forward and reverse seedling-retrieving modules in the two sets of seedling-retrieving modules move in opposite directions, which can cancel out the torque generated by each seedling-retrieving module and ensure the flight stability of the UAV. The present invention has a light overall weight, simple structure, meets the requirements of lightweighting, and has high seedling harvesting efficiency.

[0017] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of a low-altitude rice seedling throwing system based on unmanned aerial vehicles (UAVs).

[0019] Figure 2 A top view of the structure of a low-altitude rice-throwing system based on unmanned aerial vehicles (UAVs);

[0020] Figure 3 This is a schematic diagram of the working platform.

[0021] Figure 4 This is a schematic diagram of the frame structure;

[0022] Figure 5 This is a schematic diagram of the seedling-carrying module;

[0023] Figure 6 This is a front view of the seedling-carrying module;

[0024] Figure 7 This is a schematic diagram of the seedling pressing frame;

[0025] Figure 8 This is a schematic diagram of the seedling-harvesting module.

[0026] Figure 9 This is a schematic diagram of the coaxial reversing mechanism;

[0027] Figure 10 This is a schematic diagram of the seedling-harvesting turntable mechanism;

[0028] Figure 11 This is a schematic diagram illustrating the structure and workflow of the compressible seedling harvesting mechanism;

[0029] Figure 12 This is a schematic diagram of a double-sided cam.

[0030] Figure 13 This is a schematic diagram of the first link;

[0031] Figure 14 This is a schematic diagram of the constraint mechanism;

[0032] Figure 15 This is a schematic diagram of the structure of the first gear;

[0033] Figure 16 This is a schematic diagram of the second gear.

[0034] The following is a list of components represented by the numbers in the attached diagram:

[0035] 1. Large wheelbase multi-rotor flight platform; 2. Working platform; 2-1. Frame; 2-2. First seedling loading module; 2-3. Second seedling loading module; 2-3-1. Movable seedling box assembly; 2-3-1-1. Roller trough; 2-3-1-2. Conveyor belt; 2-3-1-3. Seedling box frame; 2-3-1-4. Seedling pressing frame; 2-3-2. Seedling box crossbeam assembly; 2-3-2-1. Seedling box crossbeam; 2-3-2-2. Crossbeam fixing component; 2-3-2-3. Restraint mechanism; 2-3-2-4. Seedling gate; 2-3-3. Lateral... Seedling delivery drive assembly, 2-3-3-1, roller, 2-3-3-2, crossbar, 2-3-3-3, screw pair, 2-3-3-4, reciprocating screw, 2-3-3-5, first drive motor; 2-4, first seedling picking module, 2-4-1, third drive motor, 2-4-2, first coaxial reverse seedling picking module, 2-4-21, coaxial reverse mechanism, 2-4-21-1, third gear, 2-4-21-2, gearbox, 2-4-21-3, second gear, 2-4-21-4, first gear, 2-4-2 1-5, Bearing 1; 2-4-21-6, Bearing 2; 2-4-21-7, Central Shaft; 2-4-21-8, Bearing 3; 2-4-22, Forward Rotating Seedling Picking Turntable Mechanism; 2-4-23, Reverse Rotating Seedling Picking Turntable Mechanism; 2-4-23-1, First Compressible Seedling Picking Mechanism; 2-4-23-11, Seedling Needle; 2-4-23-12, First Spring Base; 2-4-23-13, Bushing; 2-4-23-14, Push Rod; 2-4-23-15, Connecting Rod 2; 2-4-23-16, Second Spring; 2- 4-23-17, Second spring base; 2-4-23-18, Connecting rod one; 2-4-23-19, Double-sided cam; 2-4-23-110, Turntable; 2-4-23-111, First spring; 2-4-23-112, First and second spring bases; 2-4-23-2, Second compressible seedling picking mechanism; 2-4-23-3, Third compressible seedling picking mechanism; 2-4-3, Drive shaft; 2-4-4, Second coaxial reverse seedling picking module; 2-5, Second seedling picking module; 2-5-1, Fourth drive motor. Detailed Implementation

[0036] The following explanation uses a quadcopter drone with a large payload carrying eight seedling boxes as an example.

[0037] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0038] like Figure 1 , Figure 2The diagram shows the overall layout of the UAV rice-throwing system. The system is fixed to the lower part of the large-wheelbase multi-rotor flight platform 1. The projection of the sweep space when the rotors of the flight platform rotate is separated from the sweep space when the first rice-carrying module 2-2 and the second rice-carrying module 2-3 move laterally to deliver rice seedlings, with a distance of not less than 10cm. The first rice-carrying module 2-2 and the second rice-carrying module 2-3 are arranged in a V-shape and mounted on the frame 2-1. During operation, the lateral rice-delivering movements of the first rice-carrying module 2-2 and the second rice-carrying module 2-3 are either opposite or in the opposite direction. The first rice-picking module 2-4 and the second rice-picking module 2-5 are arranged symmetrically on the frame 2-1. Each rice-picking module includes two sets of coaxial reversible rice-picking modules, which are driven by the third drive motor 2-4-1 and the fourth drive motor 2-5-1 arranged on the left and right sides, realizing non-interference compressible rice-picking and throwing actions at the seedling gates on the crossbeams of the first rice-carrying module 2-2 and the second rice-carrying module 2-3.

[0039] like Figure 3 As shown, the operating platform 2 is V-shaped overall. The first seedling-carrying module 2-2 and the second seedling-carrying module 2-3 move towards or in opposite directions, while the first seedling-retrieving module 2-4 and the second seedling-retrieving module 2-5 rotate in opposite directions. The V-shaped structure and the movement patterns of the first seedling-carrying module 2-2, the second seedling-carrying module 2-3, the first seedling-retrieving module 2-4, and the second seedling-retrieving module 2-5 can effectively avoid the impact of torque generated by the seedling throwing system and the interaction between the UAV wind field and the seedling throwing system on the stability of the UAV.

[0040] like Figure 4 As shown, the frame 2-1 is used to carry the first seedling loading module 2-2, the second seedling loading module 2-3, the first seedling picking module 2-4, and the second seedling picking module 2-5 and connects to the flight platform. The whole is constructed of carbon fiber rods and buckles.

[0041] like Figure 5 , Figure 6The seedling loading module 2-3 includes a movable seedling box 2-3-1, a seedling box crossbeam assembly 2-3-2, and a transverse seedling feeding drive assembly 2-3-3. The movable seedling box 2-3-1 is used to hold seedlings. The transverse seedling feeding drive assembly 2-3-3 uses a first drive motor 2-3-3-5 to drive a reciprocating screw 2-3-3-4 to rotate. The screw pair 2-3-3-3 is fixedly connected to the seedling box frame 2-3-1-4, and is used to drive the movable seedling box 2-3-1 to move horizontally back and forth on the seedling box crossbeam 2-3-2-1. At the same time, five rollers 2-3-3-1 are fixed on the frame 2-1, and the roller grooves 2-3-1 slide back and forth on the rollers 2-3-3-1 to realize transverse seedling feeding. The movable seedling box 2-3-2 includes roller grooves 2- 3-1-1, longitudinal seedling conveyor belt 2-3-1-2, seedling box frame 2-3-1-3, and seedling pressing frame 2-3-1-4. Four sets of longitudinal seedling conveyor belts 2-3-1-2 are arranged side by side on the rear side of the seedling box frame 2-3-1-3, and the seedling pressing frame 2-3-1-4 is arranged on the front side of the seedling box frame 2-3-1-3. Four trays of seedlings are stacked on the longitudinal seedling conveyor belts 2-3-1-2. The seedling pressing frame 2-3-1-4 is used to press the seedlings onto the longitudinal seedling conveyor belts 2-3-1-2. As the seedling feeding process proceeds, the number of seedlings on the seedling box crossbeam 2-3-2-1 gradually decreases. The seedlings above fall down under the action of gravity and drive the longitudinal seedling conveyor belts 2-3-1-2 to rotate, thus realizing longitudinal seedling feeding.

[0042] like Figure 7 As shown, the ends of the seedling pressing frame 2-3-1-3 are curled to facilitate the placement of seedlings into the conveyor belt. The front end is higher than the pressing part, which makes it easier to compress the tips of the seedlings and avoid damage to the seedlings during the seedling picking process. It can also prevent the seedlings from piling up and blocking at the seedling gate 2-3-1-7, ensuring the smooth progress of the seedling throwing operation.

[0043] like Figure 8 As shown, the first seedling picking module 2-4 is arranged between the first seedling loading module 2-2 and the second seedling loading module 2-3. The first seedling picking module 2-4 drives the first coaxial reverse seedling picking module 2-4-2 and the second coaxial reverse seedling picking module 2-4-4 to rotate through the third drive motor 2-4-1 driving the transmission shaft 2-4-3. The forward-rotating seedling picking turntable mechanism 2-4-22 achieves forward seedling picking by being fixedly connected to the third gear 2-4-21-1 under the action of the coaxial reverse mechanism 2-4-21. The reverse seedling picking turntable mechanism 2-4-23 achieves reverse seedling picking by being fixedly connected to the transmission shaft 2-4-3.

[0044] like Figure 9As shown, the coaxial reversing mechanism 2-4-21 is used to realize that the rotation direction of the forward-rotating seedling-harvesting turntable mechanism 2-4-22 is opposite to the rotation direction of the transmission shaft 2-4-3. The coaxial reversing mechanism 2-4-21 includes a third gear 2-4-21-1, a gearbox 2-4-21-2, a second gear 2-4-21-3, a first gear 2-4-21-4, a bearing 1 2-4-21-5, a bearing 2 2-4-21-6, a central shaft 2-4-21-7, and a bearing 3 2-4-21-8. The transmission shaft is connected to... Figure 16 The first gear 2-4-21-4 is fixedly connected and passes through the turntable 2-4-23-110 via the bearing 2-4-21-8, driving the first gear 2-4-21-4 to rotate. The first gear 2-4-21-4 drives the second gear 2-4-21-3 to rotate around the central axis 2-4-21-7. The second gear 2-4-21-3 drives the third gear 2-4-21-1 to rotate. The third gear 2-4-21-1 is fixedly connected to the turntable 2-4-23-110, driving the forward-rotating seedling-picking turntable mechanism 2-4-22 to rotate in the forward direction. The transmission shaft 2-4-3 is fixedly connected to the reverse-rotating seedling-picking turntable mechanism 2-4-23, driving it to rotate in the reverse direction.

[0045] like Figure 10 As shown, the reverse seedling picking turntable mechanism 2-4-23 includes a first compressible seedling picking mechanism 2-4-23-1, a second compressible seedling picking mechanism 2-4-23-2, and a third compressible seedling picking mechanism 2-4-23-3.

[0046] like Figure 11As shown, the reversible seedling-picking turntable mechanism 2-4-23 includes three sets of compressible seedling-picking mechanisms evenly distributed along the circumference of the seedling-picking turntable. The compressible seedling-picking mechanism 2-4-23-1 includes a seedling needle 2-4-23-11, a first spring base 2-4-23-12, a bushing 2-4-23-13, a push rod 2-4-23-14, a second connecting rod 2-4-23-15, a second spring 2-4-23-16, a second spring base 2-4-23-17, and a first connecting rod 2-4-23-1. 8. Double-sided cam 2-4-23-19, turntable 2-4-23-110, first spring 2-4-23-111, first and second spring bases 2-4-23-112; the middle part of the first connecting rod 2-4-23-18 is hinged to the turntable 2-4-23-110, the lower end of the first connecting rod 2-4-23-18 contacts the outer surface of one side of the double-sided cam 2-4-23-19, the upper end of the first connecting rod 2-4-23-18 is hinged to the second connecting rod 2-4-23-15, the second connecting rod 2... The other end of -4-23-15 is hinged to push rod 2-4-23-14. Push rod 2-4-23-14 is fitted with bushing 2-4-23-13. Seedling needle 2-4-23-11 is fixed above bushing 2-4-23-13. Bushing 2-4-23-13 is fixed by first spring base 2-4-23-12. The lower end of first spring base 2-4-23-12 is connected to first spring 2-4-23-111. The lower end of first spring 2-4-23-111 is fixed to first and second springs. Inside the base 2-4-23-112, one end of the second spring 2-4-23-16 contacts the first connecting rod 2-4-23-18, and the other end is fixed inside the second spring base 2-4-23-17. The second spring base 2-4-23-17 is fixedly connected to the first spring base 2-4-23-12. The first spring base 2-4-23-12 can move back and forth in the slot on the first spring base 2-4-23-112 by compressing the first spring 2-4-23-111.

[0047] The reverse seedling-picking turntable mechanism 2-4-23 has three steps in operation: seedling picking state A, seedling throwing state B, and compression state C.

[0048] The seedling picking process is as follows: During the rotation of the reverse seedling picking turntable mechanism 2-4-23, the three seedling needles pass through the seedling gate in sequence. As the transverse and longitudinal seedling feeding continues, the seedlings at the seedling gate 2-3-2-4 are continuously picked up. At this time, the first spring 2-4-23-111 is in its original state, the end of the first connecting rod 2-4-23-18 contacts the highest point on one side of the double-sided cam 2-4-23-19, and the second spring 2-4-23-16 is in a compressed state. Under the action of the second connecting rod 2-4-23-15, the push rod 2-4-23-14 is positioned relative to the seedling needle as follows: Figure 11As shown in state A, this avoids the push rods 2-4-23-14 from affecting the seedling picking and prepares for subsequent seedling throwing;

[0049] The seedling throwing process is as follows: When the turntable 2-4-23-110 rotates, it drives the connecting rod 2-4-23-18 to move along the cam 2-4-23-19. After the seedling needle 2-4-23-11 picks up the seedling, the contact point between the lower end of the first connecting rod 2-4-23-18 and the double-sided cam 2-4-23-19 changes from the highest point to the lowest point. The second spring 2-4-23-16 is released from the compressed state, pushing the first connecting rod 2-4-23-18, which in turn drives the second connecting rod 2-4-23-15 to push the push rod 2-4-23-14 forward relative to the seedling needle 2-4-23-11, quickly ejecting the seedlings cut by the seedling needle 2-4-23-11, thus completing the seedling throwing.

[0050] The compression process is as follows: when the seedling needle 2-4-23-11 rotates to contact the constraint mechanism 2-3-2-3, the first spring base 2-4-23-12 compresses the first spring 2-4-23-111, causing the seedling needle 2-4-23-11 to move downwards along the straight groove of the first and second spring bases 2-4-23-112, avoiding interference with the opposite crossbeam during rotation. When the second connecting rod 2-4-23-15 and the seedling needle 2-4-23-11 both disengage from the constraint mechanism 2-3-2-3, the first spring 2-4-23-111 returns to its original state, completing the compression.

[0051] The working principle of the forward-rotating seedling-picking turntable mechanism 2-4-22 is basically the same as that of the reverse-rotating seedling-picking turntable mechanism 2-4-23. The difference is that it is driven by the coaxial reverse mechanism 2-4-21.

[0052] like Figure 12 As shown, the double-sided cam 2-4-23-19 can be fixed to the frame 2-1 by bolts and kept fixed by the transmission shaft bearing installed in the center hole. It can simultaneously switch the forward-rotating seedling picker turntable mechanism 2-4-22 and the reverse-rotating seedling picker turntable mechanism 2-4-23 between seedling pickering and seedling throwing states.

[0053] like Figure 13 As shown, hole a of the first connecting rod 2-4-23-18 is connected to the second connecting rod 2-4-23-15. Protrusion b is used to fix the second spring 2-4-23-16. The arc d of the first connecting rod 2-4-23-18 is tangent to one side of the outer surface of the double-sided cam 2-4-23-19. Hole c is used to fix it on the turntable 2-4-23-110. The first connecting rod 2-4-23-18 can rotate around hole c.

[0054] like Figure 14As shown, the constraint mechanism 2-3-2-3 is installed at the bottom of the crossbeam 2-3-2-1 through three holes at the top. When the seedling needle 2-4-23-11 contacts the constraint mechanism 2-3-2-3, the spring 2-4-23-111 is compressed. The seedling needle 2-4-23-11 and the first spring base 2-4-23-12 move obliquely downward in the straight groove of the first and second spring bases 2-4-23-112 to reach the compression state C.

[0055] like Figure 15 As shown, the first gear 2-4-21-4 has a hexagonal hole in the middle, which cooperates with the transmission shaft 2-4-3 and rotates synchronously with the transmission shaft 2-4-3.

[0056] like Figure 16 As shown, the second gear 2-4-21-3 has a raised step in the middle, and the central shaft 2-4-21-7 is installed in the middle.

[0057] The above description provides examples of the preferred embodiments of the present invention. Parts not detailed herein are common knowledge to those skilled in the art. The scope of protection of the present invention is determined by the claims. Any equivalent modifications based on the technical teachings of the present invention are also within the scope of protection of the present invention.

Claims

1. A low-altitude rice transplanting system based on unmanned aerial vehicles (UAVs), characterized in that, The system includes a long-wheelbase multi-rotor flight platform and a work platform. The work platform includes a frame, two sets of seedling-carrying modules, and two sets of seedling-receiving modules. The two sets of seedling-carrying modules are symmetrically arranged in a V-shape on the front and rear sides of the frame. The two sets of seedling-receiving modules are designated as a first seedling-receiving module and a second seedling-receiving module. The first and second seedling-receiving modules are arranged side-by-side on the left and right sides of the frame, located at the angle between the two sets of seedling-carrying modules. Each set of seedling-receiving modules includes multiple coaxial reversing seedling-receiving modules. Each set of seedling-receiving modules is driven by a motor, and the motors corresponding to the two seedling-receiving modules rotate in opposite directions. The two motors are symmetrically located on the left and right sides of the work platform. Each coaxial reversing seedling-receiving module includes at least one forward-rotating seedling-receiving turntable mechanism and one reverse-rotating seedling-receiving turntable mechanism. Both the forward-rotating and reverse-rotating seedling-receiving turntable mechanisms are connected to the motor shaft. The reverse-rotating seedling-receiving turntable mechanism includes a reverse-rotating seedling-receiving turntable device and a coaxial reversing mechanism. The coaxial reversing mechanism uses gear transmission to make the rotation of the reverse-rotating seedling-receiving turntable device opposite to the rotation of the forward-rotating seedling-receiving turntable mechanism. The seedling-carrying module is used to drive the seedlings to reciprocate and translate on the crossbeam of the seedling box to achieve lateral seedling delivery. Multiple seedling gate notches are evenly distributed at the front end of the crossbeam. The two sets of seedling-carrying modules are a forward seedling-carrying module and a reverse seedling-carrying module, and their lateral seedling delivery movements are either opposite or in opposite directions. The position of the seedling gate notches on the forward seedling-carrying module corresponds to the forward rotation seedling-taking turntable mechanism of the first seedling-taking module and the reverse rotation seedling-taking turntable mechanism of the second seedling-taking module. The position of the seedling gate notches on the reverse seedling-carrying module... The first seedling-picking module has a reversing seedling-picking turntable mechanism and the second seedling-picking module have a forward-rotating seedling-picking turntable mechanism. The forward-rotating seedling-picking turntable mechanism in the first seedling-picking module and the reversing seedling-picking turntable mechanism in the second seedling-picking module have the same rotation direction. They are used to cut off and throw out the seedlings at the notch of the seedling box crossbeam in the forward seedling loading module. The reversing seedling-picking turntable mechanism in the first seedling-picking module and the forward-rotating seedling-picking turntable mechanism in the second seedling loading module have the same rotation direction. They are used to cut off and throw out the seedlings at the notch of the seedling box crossbeam in the reverse seedling loading module.

2. The low-altitude rice seedling throwing system based on UAV according to claim 1, characterized in that the large wheelbase multi-rotor flight platform consists of 4-8 rotor shafts, each rotor shaft is equipped with 1-2 sets of propellers, and the projection of the sweep space when the rotor rotates is separate from the sweep space when the rice seedling carrying module moves laterally to deliver the rice seedlings, and the distance between them is not less than 10cm.

3. The low-altitude rice transplanting system based on unmanned aerial vehicles according to claim 1, characterized in that, Both the forward and reverse seedling loading modules include a movable seedling box, a seedling box crossbeam, and a transverse seedling conveying assembly. The movable seedling box is used to place seedlings, and the transverse seedling conveying drive assembly is used to drive the movable seedling box to move horizontally back and forth on the seedling box crossbeam. The movable seedling box includes a seedling box frame, a longitudinal seedling conveyor belt, and a seedling pressing frame. Multiple longitudinal seedling conveyor belts are arranged side by side on the rear side of the seedling box frame, and a seedling pressing frame is arranged on the front side of the seedling box frame. Seedlings are placed on the longitudinal seedling conveyor belt, and the seedling pressing frame is used to press the seedlings onto the longitudinal seedling conveyor belt. As the seedling throwing process proceeds, the number of seedlings on the seedling box crossbeam gradually decreases, and the seedlings above can descend under the action of gravity and drive the longitudinal seedling conveyor belt to rotate. Multiple constraint devices are evenly arranged on the crossbeam of the seedling box. The inner side of the constraint device is arc-shaped. Each seedling picking module has a forward-rotating seedling picking turntable mechanism or a reverse-rotating seedling picking turntable mechanism corresponding to a constraint device. The distance between the constraint device and the seedling gate is the same as the distance between the forward-rotating seedling picking turntable mechanism and the reverse-rotating seedling picking turntable device.

4. The low-altitude rice transplanting system based on unmanned aerial vehicles according to claim 3, characterized in that, The seedling pressing frame includes a crossbar and a pressing rod assembly. The pressing rod assemblies are evenly arranged along the axial direction of the crossbar. Each pressing rod assembly corresponds to a longitudinal seedling conveyor belt. Each pressing rod assembly includes a long rod and a short rod. The pressing frame is fixed to both sides of the seedling box frame by bolts. The distance between the pressing frame and the longitudinal seedling conveyor belt can be adjusted by adjusting the position of the bolts to accommodate seedlings of different heights so that the seedlings can descend smoothly under the action of gravity to complete the longitudinal seedling delivery.

5. The low-altitude rice transplanting system based on unmanned aerial vehicles according to claim 1, characterized in that, Both the reversible seedling-picking turntable device and the forward-rotating seedling-picking turntable mechanism include multiple compressible seedling-picking mechanisms evenly distributed along the circumference of the turntable. The motor shaft is connected to the turntable and is used to drive the turntable and the compressible seedling-picking mechanisms to rotate in a vertical plane. The compressible seedling-picking mechanism includes a seedling needle, a first spring base, a bushing, a push rod, a first connecting rod, a second connecting rod, a first spring, a second spring, and a second spring base. The middle part of the first connecting rod is hinged to the turntable via a rotating shaft, the lower end of the first connecting rod contacts the outer surface of the cam, and the upper end of the first connecting rod is hinged to the second connecting rod. The other end of the two connecting rods is hinged to the push rod. A bushing is fitted on the outside of the push rod. A seedling needle is fixed above the bushing. A first spring base is set below the bushing. The lower end of the first spring base is fixed on the turntable. Straight slots are opened on both sides of the first spring base. A short shaft is set in the straight slot. The bushing is fixed to the short shaft. The upper end of the first spring is connected to the bushing, and the lower end is connected to the inner side of the bottom of the fixing part. The second spring base is set on the outside of the upper end of the first connecting rod. A second spring is set between one end of the second spring base and the upper end of the first connecting rod. The other end of the second spring base is fixed to the short shaft. When the turntable rotates, it can drive the connecting rod to move along the cam. When the seedling needle is in front of the seedling gate, the contact point between the lower end of the connecting rod and the double cams changes from the highest point to the lowest point. The second spring is released from the compressed state, pushing the first connecting rod, which in turn drives the second connecting rod to push the push rod forward relative to the seedling needle, quickly popping the seedlings at the seedling gate and completing the seedling throwing. When the seedling needle rotates into the constraint mechanism, the bushing moves backward to compress the first spring, causing the short shaft and the seedling needle to move downward and inward along the straight groove of the first spring base, thus avoiding interference with the crossbeam on the opposite side during rotation. When the second connecting rod and the seedling needle are both disengaged from the constraint mechanism, the first spring returns to its original state and completes the compression.

6. The low-altitude rice transplanting system based on unmanned aerial vehicles according to claim 1, characterized in that, The coaxial reversing mechanism in the coaxial reversing seedling picking module includes a gearbox, a first gear, a second gear, and a third gear. The drive shaft drives the first gear to rotate, and the first gear drives the third gear to rotate in the opposite direction through the second gear. The third gear is connected to the turntable of the reversing seedling picking turntable device, so as to realize the coaxial reversing motion of the forward rotating seedling picking turntable mechanism and the reverse rotating seedling picking turntable mechanism.

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