Plant protection unmanned aerial vehicle for precision sowing

Abstract

This invention discloses a plant protection drone for precision seeding, belonging to the field of agricultural drone technology. It includes a central body and four arc-shaped arms that can move relative to the central body. Each arm is equipped with a power unit and rotors. Driven by a deformation drive mechanism, the arms can switch between a cruising state (forming a circular shape) and an operational state (arching inward to form a three-dimensional structure). In the cruising state, the rotor planes are coplanar, resulting in high aerodynamic efficiency; in the operational state, the rotor planes are raised and moved away from the seeding device, effectively isolating the downwash airflow from interfering with the seeded material, significantly improving seeding accuracy and uniformity. This invention solves the technical problem of seeding drift caused by rotor wind fields in existing plant protection drones.

Description

Technical Field

[0001] This invention belongs to the field of agricultural drone technology, specifically relating to a plant protection drone for precision seeding. Background Technology

[0002] Currently, most agricultural drones have rigid, fixed structures. The downwash airflow generated by the rotors directly affects the sprayed pesticides or granules, leading to material drift and uneven distribution in the field. Existing technologies mainly mitigate this by lowering the flight altitude and adjusting nozzle parameters, but the effects are limited, and flying too low increases the risk of hitting crops, posing a safety hazard. Therefore, how to fundamentally isolate the interference of the rotor airflow on the spraying path has become a pressing technical problem that needs to be solved to achieve precision agriculture. Summary of the Invention

[0003] This invention discloses an agricultural drone for precision seeding and its operating method. The agricultural drone includes a power unit, a frame, landing gear, and a seeding device. The frame includes a central body and four arms capable of moving relative to the central body, designed in a quarter-circle shape. The arms have a cruise mode and an operating mode. In the cruise mode, the four arms are connected end-to-end to form a ring shape; in the operating mode, the four arms arch upwards or to the side of the central body, forming a three-dimensional arched structure.

[0004] The power unit includes a motor and a rotor. The rotor is mounted on the output shaft of the motor, and the power unit is located at the midpoint of the arc length of the arm. The arm is connected to the central body via a hinge shaft and includes a deformation drive mechanism. This mechanism drives the arm to rotate around the hinge shaft, enabling switching between cruise and operational states. The deformation drive mechanism can optionally be an electric actuator, with one end hinged to the central body and the other end hinged to the arm; or it can be a shape memory alloy-based actuator located at the connection between the arm and the central body, which induces a phase change through electrical heating to drive the arm's rotation.

[0005] In the cruise state, the rotation planes of all the rotors are coplanar; in the operation state, the rotation planes of all the rotors are higher than the plane of the spreading device.

[0006] The spreading device includes a material hopper, a stirring assembly, and an opening and closing mechanism. The stirring assembly includes a stirring motor mounted on the upper part of the material hopper and a stirring shaft extending into the hopper, with stirring blades mounted on the stirring shaft. The opening and closing mechanism is located at the bottom of the material hopper and includes a second panel fixedly connected to the open bottom of the hopper and a first panel capable of engaging or disengaging with the second panel. The upper surface of the second panel has two symmetrical wedge-shaped surfaces, with two discharge ports located at the lowest points of the two wedge-shaped surfaces. The upper part of the first panel has a meshing structure adapted to the wedge-shaped surfaces. The opening and closing mechanism also includes a first one-way bearing and a second one-way bearing located at the center of the first panel, arranged vertically with opposite locking directions. The inner ring of the first one-way bearing has a first locking slot, and the inner ring of the second one-way bearing has a second locking slot. A key is fixedly mounted on the outer wall of the stirring shaft, located axially between the first and second one-way bearings. The outer rings of both the first and second one-way bearings are fixedly connected to the inner wall of the first panel. Optionally, the opening and closing mechanism further includes a scraper, which is fixedly sleeved on the outer wall of the stirring shaft, and when the first panel is raised, the lower surface of the scraper is in contact with the upper surface of the first panel.

[0007] The agricultural drone also includes a control module, which is used to receive instructions and control the deformation drive mechanism to achieve automatic or manual switching of the arm state according to the flight stage.

[0008] An operational method for an agricultural drone, applied to the aforementioned agricultural drone, includes the following steps:

[0009] Step 1: Control the drone to take off in cruise mode and fly to the work area;

[0010] Step 2: Hover over the work area and control the deformation drive mechanism to switch the arm from cruise mode to work mode;

[0011] Step 3: Start the spreading device in working condition to carry out plant protection operations;

[0012] Step 4: After the operation is completed, control the arm to return to cruise mode and control the drone to return to home.

[0013] Compared with the prior art, the beneficial effects of the present invention are:

[0014] 1) Precise seeding: By physically isolating the rotor wind field from the seeding path, reagent drift is fundamentally reduced, significantly improving deposition uniformity.

[0015] 2) Dual-purpose: High aerodynamic efficiency, long flight time, and fast relocation in cruise mode; high spraying accuracy in operation mode, adapting to the precision application requirements of modern agriculture.

[0016] 3) Structural innovation: The circular and arched structure formed by the arc-shaped arm has good mechanical properties and torsional stiffness. The arched structure can also play a certain role in buffering and protection during operation.

[0017] 4) Integrated and efficient: The spreading device adopts a mechanical opening and closing mechanism that is linked to the mixing. The control logic is simple and reliable, avoiding the complexity and failure points of setting up an additional discharge valve. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the agricultural drone of the present invention in cruise mode.

[0020] Figure 2 This is a schematic diagram of the structure of the agricultural drone of the present invention in operation.

[0021] Figure 3 This is a schematic diagram of the spreading device of the present invention.

[0022] Figure 4 This is a schematic diagram of the opening and closing mechanism of the present invention (closed state).

[0023] Figure 5 This is a schematic diagram of the opening and closing mechanism of the present invention (open state).

[0024] Figure 6 This is a schematic diagram of the internal structure of the opening and closing mechanism of the present invention.

[0025] Explanation of reference numerals in the attached figures:

[0026] 11. Central body; 12. Arm; 13. Power unit; 14. Rotor; 15. Electric push rod; 16. Spreading device; 161. Material bin; 162. Mixing assembly; 1621. Mixing motor; 1622. Mixing shaft; 1622a. Key; 1623. Mixing blades; 163. Opening and closing mechanism; 1631. Second panel; 1631a. Discharge port; 1632. First panel; 1633. First one-way bearing; 1633a. First bayonet; 1634. Second one-way bearing; 1634a. Second bayonet; 1635. Scraper; 17. Landing gear. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only a part of the present invention, and not all of the 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.

[0028] Example 1:

[0029] like Figures 1 to 3 As shown, this embodiment provides an agricultural drone for precision seeding. The frame includes a central body 11 and four quarter-circular arms 12. The inner ends of the arms 12 are connected to the central body 11 via hinge shafts. A power unit 13, including a motor and a rotor 14, is installed at the midpoint of the arc length of each arm 12. A seeding device 16 and landing gear 17 are installed below the central body 11.

[0030] The morphing drive mechanism uses four electric push rods 15, which are connected to the central body 11 and the corresponding arms 12, respectively. The control module is integrated into the flight control system.

[0031] Cruise status Figure 1 The control module controls the electric push rod 15 to extend, so that the four arms 12 are unfolded and on the same horizontal plane, forming a ring shape. At this time, the rotor planes are coplanar, the aerodynamic efficiency is high, and it is suitable for stable flight and ferry.

[0032] Job status Figure 2 After the drone hovers over the work area, the control module controls the electric push rod 15 to retract synchronously, pulling the four arms 12 to rotate upwards and inwards around the hinge axis, forming a three-dimensional arched structure. At this time, the rotation plane of all rotors is raised, much higher than the outlet plane of the dispersing device 16. The rotor downwash airflow mainly diffuses laterally and upwards, greatly weakening the direct impact on the dispersible material below, thereby significantly reducing drift and improving deposition uniformity.

[0033] After the operation is completed, the control module controls the electric push rod 15 to extend, so that the arm 12 returns to the cruise state, and then returns to base.

[0034] Example 2:

[0035] The difference between this embodiment and Embodiment 1 lies in the deformation drive mechanism. This embodiment uses a shape memory alloy actuator (not shown in the figure). The shape memory alloy actuator is located at the connection between the arm and the center body. When switching to the working state, the control module energizes and heats the shape memory alloy, causing it to undergo an austenitic phase transformation, generating a restoring force to drive the hinge shaft to rotate, thereby arching the arm. After power is cut off and cooling occurs, the arm returns to its original position under the action of an auxiliary spring.

[0036] Example of a spreading device:

[0037] like Figure 4-6 As shown, the spreading device 16 includes a material hopper 161, a stirring assembly 162, and an opening and closing mechanism 163. The stirring assembly 162 is used to mix the materials, and the bottom end of its stirring shaft 1622 extends into the opening and closing mechanism 163. The stirring assembly 162 includes a stirring motor 1621 disposed on the upper part of the material hopper 161 and a stirring shaft 1622 extending into the material hopper 161, with stirring blades 1623 disposed on the stirring shaft 1622. The opening and closing mechanism 163 is disposed at the bottom of the material hopper 161 and includes a second panel 1631 fixedly connected to the open bottom of the material hopper 161 and a first panel 1632 that can be engaged or disengaged from the second panel 1631. The upper surface of the second panel 1631 is machined with two symmetrical wedge-shaped surfaces, and two discharge ports 1631a are respectively opened at the lowest point of the two wedge-shaped surfaces. The upper part of the first panel 1632 is provided with an engagement structure adapted to the wedge-shaped surfaces. The opening and closing mechanism 163 also includes a first one-way bearing 1633 and a second one-way bearing 1634 disposed at the center of the interior of the first panel 1632. The first one-way bearing 1633 and the second one-way bearing 1634 are arranged vertically and their locking directions are opposite. The inner ring of the first one-way bearing 1633 has a first latch 1633a, and the inner ring of the second one-way bearing 1634 has a second latch 1634a. A key 1622a is fixedly disposed on the outer wall of the stirring shaft 1622, and the key 1622a is located axially between the first one-way bearing 1633 and the second one-way bearing 1634. The outer rings of both the first one-way bearing 1633 and the second one-way bearing 1634 are fixedly connected to the inner wall of the first panel 1632. Optionally, the opening and closing mechanism 163 further includes a scraper 1635, which is fixedly sleeved on the outer wall of the stirring shaft 1622, and when the first panel 1632 is raised, the lower surface of the scraper 1635 is in contact with the upper surface of the first panel 1632.

[0038] The working principle of the opening and closing mechanism 163 is as follows:

[0039] In the off state, corresponding to stirring or non-operation: The stirring motor 1621 rotates forward, driving the stirring shaft 1622 to rotate forward. At this time, the key 1622a is located in the first slot 1633a of the first one-way bearing 1633, the first one-way bearing 1633 rotates freely, the first panel 1632 is engaged with the second panel 1631, and the discharge port 1631a is closed.

[0040] Switching from opening to discharge: When discharge is required, the stirring motor 1621 is controlled to rotate in reverse. At this time, the first one-way bearing 1633 is locked, and the reverse torque of the stirring shaft 1622 is transmitted to the first panel 1632 through the key 1622a and the locked bearing, driving it to reverse. Since the upper structure of the first panel 1632 engages with the wedge-shaped surface of the second panel 1631, the reversal causes it to rise along the wedge-shaped surface, separating it from the second panel 1631, and the discharge port 1631a opens. During the lifting process, the key 1622a disengages from the first latch 1633a and engages with the second latch 1634a of the second one-way bearing 1634 when the first panel 1632 reaches the predetermined height. At this time, the second one-way bearing 1634 is free to rotate in the reverse direction, and the first panel 1632 remains in the open position. The scraper 1635 rotates with the stirring shaft 1622, scraping off the residual material on the surface of the first panel 1632.

[0041] The closing process stops the discharge: When closing is required, the control stirring motor 1621 resumes forward rotation. At this time, the second one-way bearing 1634 locks, and the torque drives the first panel 1632 to rotate forward. Under the action of gravity, the first panel 1632 slides down along the wedge-shaped surface and re-engages with the second panel 1631, closing the discharge port 1631a. Key 1622a disengages from the second latch 1634a and re-inserts into the first latch 1633a, resetting the system.

[0042] Example of the control logic of this invention:

[0043] The control module is integrated into or communicates with the flight controller. It can receive manual switching commands from the remote controller and can also execute commands automatically according to a preset program. A preferred automatic control logic is as follows: After the UAV flies to the work area via GNSS navigation and hovers stably at a preset working altitude (e.g., 3 meters above the canopy), the control module automatically triggers a transformation program, driving the mechanism to work and smoothly switching the arm to the working state within 2-3 seconds. Subsequently, the flight controller unlocks the seeding device motors, and the operation begins. After the working route is completed, seeding stops, the control module controls the arm to return to the cruise state, the UAV raises its altitude, and returns to base. This process ensures the safety and stability of the state switching process.

[0044] The above description is merely a preferred embodiment of the present invention. It should be understood that the preferred embodiments disclosed in this application are illustrative of the principles of the implementation scheme of the present invention and are not intended to limit the present invention. Any equivalent structural transformations made based on the inventive concept of the present invention and the description and drawings of the present invention, or direct / indirect applications in other related technical fields, are included within the scope of patent protection of the present invention.

Claims

1. A plant protection drone for precision seeding, comprising a power unit (13), a frame, landing gear (17), and a seeding device (16), characterized in that: The frame includes a central body (11) and four arms (12) that can move relative to the central body (11). The arms (12) are designed in a quarter-circular arc shape. The arms (12) have a cruising state and an operating state. When in the cruising state, the four arms (12) are connected end to end to form a ring shape. When in the operating state, the four arms (12) arch upwards or to the side of the central body (11) to form a three-dimensional arch structure. The spreading device (16) includes a material box (161) and a mixing assembly (162). 62) and opening and closing mechanism (163); the stirring assembly (162) includes a stirring motor (1621) disposed on the upper part of the material box (161) and a stirring shaft (1622) extending into the material box (161), and stirring blades (1623) are disposed on the stirring shaft (1622); the opening and closing mechanism (163) is disposed at the bottom of the material box (161) and includes a second panel (1631) fixedly connected to the bottom opening of the material box (161) and a first panel (1632) that can be fitted or separated from the second panel (1631).

2. The agricultural drone for precision seeding according to claim 1, characterized in that: The power unit (13) includes a motor and a rotor (14), the rotor being mounted on the output shaft of the motor; the power unit (13) is located at the midpoint of the arc length of the arm (12).

3. The agricultural drone for precision seeding according to claim 2, characterized in that: The arm (12) is connected to the center body (11) via a hinge shaft and includes a deformation drive mechanism; the deformation drive mechanism is used to drive the arm (12) to rotate around the hinge shaft to realize the switching between cruise state and operation state.

4. The agricultural drone for precision seeding according to claim 3, characterized in that: The deformation drive mechanism is an electric push rod (15), one end of which is hinged to the central body (11) and the other end is hinged to the machine arm (12); by controlling the extension and retraction of the electric push rod (15), the machine arm (12) is driven to rotate.

5. The agricultural drone for precision seeding according to claim 4, characterized in that: The deformation drive mechanism is a driver based on shape memory alloy. The driver is located at the connection between the arm and the center body. By heating the shape memory alloy with electricity, it undergoes a phase change and generates deformation force, thereby driving the arm (12) to rotate.

6. The agricultural drone for precision seeding according to claim 5, characterized in that: In the cruise state, the rotation planes of all the rotors are coplanar; in the operation state, the rotation planes of all the rotors are higher than the plane of the spreading device (16).

7. A plant protection drone for precision seeding according to claim 6, characterized in that: The upper surface of the second panel (1631) is machined with two symmetrical wedge-shaped surfaces, and two discharge ports (1631a) are respectively opened at the lowest point of the two wedge-shaped surfaces; the upper part of the first panel (1632) is provided with a meshing structure adapted to the wedge-shaped surfaces, and the opening and closing mechanism (163) further includes a first one-way bearing (1633) and a second one-way bearing (1634) disposed at the center inside the first panel (1632), the first one-way bearing (1633) and the second one-way bearing (1634) are arranged vertically and their locking directions are opposite; the first The inner ring of a one-way bearing (1633) has a first bayonet (1633a), and the inner ring of a second one-way bearing (1634) has a second bayonet (1634a); a key (1622a) is fixedly provided on the outer wall of the stirring shaft (1622), and the key (1622a) is located at an axial position between the first one-way bearing (1633) and the second one-way bearing (1634); the outer rings of the first one-way bearing (1633) and the second one-way bearing (1634) are both fixedly connected to the inner wall of the first panel (1632).

8. A plant protection drone for precision seeding according to claim 7, characterized in that: The opening and closing mechanism (163) further includes a scraper (1635), which is fixedly sleeved on the outer wall of the stirring shaft (1622), and when the first panel (1632) is raised, the lower surface of the scraper (1635) is in contact with the upper surface of the first panel (1632).

9. A plant protection drone for precision seeding according to claim 8, characterized in that: The plant protection drone also includes a control module, which is used to receive instructions and control the action of the deformation drive mechanism to achieve automatic or manual switching of the arm (12) state according to the flight stage.

10. A method for operating a plant protection drone, applied to the plant protection drone of claim 9, characterized in that, Includes the following steps: S1: Control the drone to take off in cruise mode and fly to the work area; S2: Hover in the work area and control the deformation drive mechanism to switch the arm (12) from the cruise state to the work state; S3: Start the spreading device (16) in the working state to carry out plant protection operations; S4: After the operation is completed, control the arm (12) to return to the cruise state and control the drone to return to home.

Images