Camellia oil tree fruit period coordination fruit protection method based on unmanned aerial vehicle precision operation

Abstract

The application discloses a camellia flower and fruit period synergic fruit protection method based on unmanned aerial vehicle precise operation, relates to the technical field of agricultural and forestry plant protection, and comprises the following steps: generating an imitation ground flight route by using a multispectral camera to pre-scan, identifying a flower cluster concentration area, a fruit development area and a sparse branch and leaf area in real time through an airborne visual sensor in the operation flight, adopting a weak wind and fine mist mode for the flower cluster area, reducing the rotor speed and generating micro-mist with a size of 50-100 mu, then adopting a strong wind penetration mode for the fruit area, improving the rotor speed and generating coarse mist with a size of 150-250 mu, and automatically closing the spray head for the sparse branch and leaf area, finally keeping a constant distance between the unmanned aerial vehicle and the top of the tree crown of 1.5-2.5 m during the operation process, and adjusting the body pitch angle and the spray head angle when the slope changes to make the mist droplets vertically descend; the application realizes the synergic operation of camellia flower and fruit period flower protection and fruit protection, the flower drop rate is reduced by more than 15%, and the fruit protection rate is increased by more than 22%.

Description

Technical Field

[0001] This invention relates to the field of agricultural and forestry plant protection technology, and in particular to a method for coordinated fruit protection during the flowering and fruiting stages of Camellia oleifera based on precision drone operations. Background Technology

[0002] Camellia oleifera ( Camellia oleifera Camellia oleifera is an important woody oilseed tree species in my country, primarily growing in the hilly and mountainous areas of southern China. It possesses the biological characteristic of "flowering and fruiting simultaneously," meaning that the previous year's fruits gradually mature while the following year's flower buds simultaneously open and pollinate in large numbers. This period is a critical window for determining camellia oleifera yield, placing high demands on nutrient supplementation, pest and disease control, and flower and fruit preservation.

[0003] Existing technologies for fruit preservation during the flowering and fruiting stages of camellia oleifera include the following: (1) Traditional manual backpack spraying technique. This technique involves manually carrying a manual or electric sprayer to spray each tree in the camellia oleifera forest. This method is inefficient and costly, especially in the hilly and mountainous areas of southern China where the terrain is rugged, the slopes are steep, and the labor intensity is high. The length and pressure structure of the sprayer are limited, and the effective range is only 1 to 2 meters. Mature camellia oleifera trees have a high canopy and dense foliage, so the spraying angle from bottom to top means that the pesticide or fertilizer can only adhere to the outer or lower leaves of the canopy, and cannot effectively penetrate the canopy to reach the flowers and young fruits inside. In addition, the flow rate of manual spraying is uncontrollable, which can easily lead to excessively high local concentrations, causing flower burn or dripping, resulting in soil pollution.

[0004] (2) Large-scale mechanized ground spraying technology. This technology uses tracked air-assisted sprayers, which utilize tractors or tracked chassis to carry large-capacity medicine tanks and air-assisted sprayers. They travel along the forest access roads and blow atomized medicine to both sides. This type of machinery has a wide chassis and a large wheelbase, and its mechanical structure requires the orchard to have a flat and wide row spacing. Most existing camellia oleifera forests are planted on terraced fields along the mountain slopes, lacking standardized mechanical access roads, making it impossible for large machinery to enter the site. Forced entry is prone to rollover, and the tracked or tire structure will compact the topsoil of the camellia oleifera forest, damaging the soil's physical and chemical properties and hindering the respiration and nutrient absorption of the shallow roots of the camellia oleifera.

[0005] (3) Traditional plant protection drone large-area spraying technology. This technology uses a multi-rotor plant protection drone equipped with a spraying system to perform top spraying above the camellia oleifera forest at a fixed flight altitude and fixed spray width. Traditional plant protection drones use a single downdraft design. The canopy of camellia oleifera trees has a dense umbrella-like structure. When the drone flies over the top, the downdraft flattens the leaves at the top of the canopy, forming a physical barrier, i.e., the canopy shading effect. This causes most of the fertilizer-carrying droplets to be intercepted on the surface of the canopy and unable to settle onto the flowers and young fruits located in the middle and lower parts of the branches. The existing drone spraying system consists of a deionized water pump and centrifugal or pressure nozzles. The control logic is uniform speed and equal volume spraying. If the pressure of the deionized water pump and the downdraft force of the rotor are increased to ensure penetration, the strong airflow and coarse droplets can easily knock down the pollinating flowers, i.e., mechanical flower drop; if the wind force is reduced, the liquid cannot penetrate the canopy. The existing technology cannot achieve coordinated and precise operation to meet the differentiated needs of flowers and fruits in terms of hardware structure and algorithm. In summary, existing fruit preservation technologies are either limited by mechanical structures that cannot adapt to hilly terrain and dense canopies, or limited by extensive spraying methods that cannot solve the contradiction of penetrating the canopy to preserve fruit while avoiding wind damage to flowers during the "flowering and fruiting on the same tree" period of Camellia oleifera. Therefore, this invention proposes a method for coordinated fruit preservation during the flowering and fruiting period of Camellia oleifera based on precise operation by drones to solve the problems existing in the prior art. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to propose a method for synergistic fruit preservation during the flowering and fruiting stages of Camellia oleifera based on precise drone operations. This invention can simultaneously achieve effective sedimentation of the fruit-preserving solution into the middle and lower target areas and reduce the rate of mechanical flower drop, thereby solving the problems existing in the prior art.

[0007] To achieve the objectives of this invention, the invention is implemented through the following technical solution: a method for coordinated fruit preservation during the flowering and fruiting stages of camellia oleifera based on precision drone operations, comprising the following steps: Step 1: Forest Stand Background Data Modeling and Flight Route Planning Using a multispectral camera mounted on a drone, the target camellia forest is pre-scanned to obtain information on plant distribution, canopy density, and terrain slope. Then, based on the spatial distribution of flower clusters and fruits during the flowering and fruiting period of camellia, key operation areas are delineated, and terrain-following flight routes are generated. Step 2: Real-time identification and classification of target features: During the operation of the UAV along the terrain-following flight route, the airborne visual sensor collects tree canopy information in real time and classifies the tree canopy information into three categories: A-type characteristic flower cluster concentration area, B-type characteristic fruit development area and C-type characteristic sparse branch and leaf area. Step 3: Dynamic decision-making for synergistic spraying parameters: Based on the identified tree canopy information characteristics, the following synergistic spraying decisions are made through the central control system using the prepared synergistic fruit-preserving agent: For the characteristics of type A, a weak wind and fine mist mode is adopted, the rotor speed is reduced, and the deionized water pump pressure is increased to generate micro-mist with a particle size of 50μm to 100μm. The nozzle swing is controlled by the servo motor to make the micro-mist drift and penetrate into the flower cluster. For the characteristics of type B, a strong wind penetration mode is adopted to increase the rotor speed to generate a strong downwash flow. At the same time, the deionized water pump pressure is adjusted to generate coarse mist with a particle size of 150μm to 250μm, so that the coarse mist penetrates the canopy and settles on the fruit surface. For Category C characteristics, the nozzles will automatically shut off to stop spraying; Step 4: Coupling adjustment of operating height and wind field angle During step three, based on the distance between the drone and the top of the tree canopy measured by the ultrasonic radar sensor, the drone is kept at a constant distance of 1.5m to 2.5m from the top of the tree canopy. When encountering changes in slope, the drone's pitch angle and nozzle servo angle are adjusted to ensure that the droplets enter the center of the canopy vertically.

[0008] A further improvement is made in the following step: In step one, the spatial distribution of flower clusters and fruits is specifically determined by using a multispectral camera mounted on an unmanned aerial vehicle to obtain the normalized vegetation index (NDI) value of the camellia oleifera forest, and then identifying the spatial distribution of the flower cluster concentration area and the fruit development area based on the spatial distribution differences of the NDI values.

[0009] A further improvement is made in step two, where the airborne vision sensor includes a high-resolution multispectral camera and an ultrasonic radar ranging sensor. The high-resolution multispectral camera is used to identify the reflected signals of white flowers and the shadows of dark green spherical fruits, while the ultrasonic radar ranging sensor is used to acquire information about the height of the tree canopy.

[0010] A further improvement is made in step three, in the weak wind and fine mist mode, by controlling the nozzle to swing within a range of ±30 degrees using a servo motor.

[0011] A further improvement is made in step three, in the strong wind penetration mode, increasing the rotor speed to generate a strong downwash that causes the leaves on the surface of the tree canopy to flip, allowing the coarse fog to penetrate the closed canopy.

[0012] A further improvement is made in step three, where the synergistic fruit-preserving agent consists of the following components: potassium dihydrogen phosphate at a concentration of 1 g / L to 2 g / L, borax at a concentration of 0.5 g / L to 1 g / L, gibberellin at a concentration of 20 mg / L to 50 mg / L, and the remainder being deionized water.

[0013] A further improvement is that, in step four, maintaining a constant distance between the drone and the top of the tree canopy is achieved by using the drone's altimeter and real-time dynamic positioning module to achieve centimeter-level positioning, and by adjusting the flight altitude in a closed loop based on feedback from the ultrasonic radar sensor.

[0014] Further improvements include: the drone adopts a six-axis multi-rotor structure or a four-axis multi-rotor structure, is equipped with a real-time dynamic positioning module, and the central control system is an onboard edge computing module with a built-in collaborative control algorithm for executing collaborative spraying decisions.

[0015] The beneficial effects of this invention are as follows: This invention establishes a forest stand background data model through pre-scanning with a multispectral camera and generates a terrain-following flight path, enabling the UAV to adapt to the complex terrain of hilly and mountainous areas and avoid inconsistent operating heights due to terrain undulations. Then, the airborne visual sensor identifies areas with concentrated flower clusters, fruit development areas, and sparse branches and leaves in real time, and executes differentiated spraying strategies. At the same time, the operating height and nozzle angle are adjusted synchronously during the operation to maintain the vertical settling of droplets, realizing the coordinated operation of flower protection and fruit preservation. Compared with traditional UAV uniform spraying, this method reduces the flower drop rate of Camellia oleifera by more than 15% and increases the fruit preservation rate of young fruit by more than 22%. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the unmanned aerial vehicle system structure of the present invention.

[0017] Figure 2 This is a schematic diagram comparing the differentiated wind field and droplet settling trajectory between the flower cluster area and the fruit area of ​​the present invention.

[0018] Figure 3 This is a schematic diagram of the method steps of the present invention. Detailed Implementation

[0019] To enhance understanding of the present invention, the present invention will be further described in detail below with reference to embodiments. These embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0020] Example 1 according to Figure 1 - Figure 3 As shown in the figure, this embodiment provides a method for coordinated fruit protection during the flowering and fruiting period of Camellia oleifera based on precise operation by UAV. It is applied to a Camellia oleifera forest in a hilly area in southern China. The Camellia oleifera forest is in the flowering and fruiting period, with a canopy closure of about 0.8, an average tree height of 2.5m, and a terrain slope of 10° to 25°.

[0021] For unmanned aerial vehicle (UAV) systems, as shown in the appendix Figure 1 As shown, it adopts a six-axis multi-rotor structure and is equipped with an altimeter and a real-time dynamic positioning module. Specifically, it includes: Airframe platform: It adopts a six- or four-axis multi-rotor structure and is equipped with an altimeter and RTK positioning module to achieve centimeter-level positioning.

[0022] Sensing system: Located below the body, it integrates a high-resolution multispectral camera and an ultrasonic radar sensor to acquire the NDVI value (vegetation index) of the camellia oleifera canopy and the canopy height in real time.

[0023] The spraying execution system includes a medicine tank, a variable frequency deionized water pump, and a pressure nozzle installed below the rotor. Its feature is that the nozzle angle can be adjusted by ±30 degrees as the servo motor rotates.

[0024] Central control and coordination system: Onboard edge computing module with built-in collaborative control algorithm of the present invention (for executing collaborative spraying decisions), used to receive sensing data and adjust rotor speed (control wind field) and deionized water pump flow rate in real time.

[0025] The method includes the following steps: Step 1: Forest Stand Background Data Modeling and Flight Route Planning The target camellia oleifera forest was pre-scanned using a multispectral camera mounted on a drone to obtain information on plant distribution, canopy closure, and terrain slope. The normalized vegetation index (NVI) value was obtained using the multispectral camera. Based on the spatial distribution differences of the NVI values, the spatial distribution of flower cluster concentration areas (flower cluster area) and fruit development areas (fruit area) was identified, key operation areas were delineated, and terrain-following flight routes were generated.

[0026] Step 2: Real-time identification and classification of target features During the UAV's operation along the terrain-following flight path, high-resolution multispectral cameras and ultrasonic radar ranging sensors are used to collect tree canopy information in real time. The high-resolution multispectral camera identifies the reflected signals of white flowers and the shadows of dark green spherical fruits, while the ultrasonic radar ranging sensor acquires the canopy height information. The central control system classifies the canopy information into three categories: Category A features: concentrated flower clusters (identifying a large number of white flower reflected signals), Category B features: fruit development areas (identifying dark green spherical targets and the shadows of mature fruits), and Category C features: sparse branches and leaves areas (identifying bare ground or weeds).

[0027] Step 3: Dynamic decision-making for synergistic spraying parameters Based on the identified tree canopy information characteristics, the following synergistic spraying decisions are made through the central control system using the prepared synergistic fruit-preserving agent: For Category A characteristics, a weak wind and fine mist mode is adopted. The central control system commands a reduction in rotor speed, lowering the downwash airflow velocity to only slightly disturb the canopy; simultaneously, the pressure of the variable frequency deionized water pump is increased, causing the nozzles to produce micro-mist with a particle size of 50μm to 100μm. The servo motor controls the nozzles to oscillate within a range of ±30 degrees, utilizing the drift property of the micro-mist to allow it to penetrate into the flower clusters, avoiding direct impact of strong winds on the flower stamens.

[0028] For characteristics of type B, a strong wind penetration mode is adopted. The central control system commands to increase the rotor speed, generating a strong downwash, causing the leaves on the surface of the canopy to flip; at the same time, the deionized water pump pressure is adjusted to produce coarse mist with a particle size of 150μm to 250μm from the nozzles. The strong wind field carries the coarse mist directly through the closed canopy and settles on the surface of the young fruit in the middle and lower parts.

[0029] For Category C characteristics, the central control system commands the nozzles to automatically shut off and stop spraying.

[0030] In this embodiment, the preparation method of the synergistic fruit-preserving agent is as follows: weigh potassium dihydrogen phosphate and prepare a deionized water solution with a concentration of 1.5 g / L; weigh borax and prepare a deionized water solution with a concentration of 0.8 g / L; weigh gibberellin and prepare a deionized water solution with a concentration of 30 mg / L; mix the above three solutions, add deionized water to make up to the required volume, and stir evenly to obtain the final product.

[0031] Step 4: Coupling adjustment of operating height and wind field angle During step three, the ultrasonic radar sensor measures the distance between the drone and the top of the tree canopy in real time. The central control system achieves centimeter-level positioning through the altimeter and real-time dynamic positioning module, and adjusts the flight altitude based on the feedback loop of the ultrasonic radar sensor to maintain a constant distance of 1.8m between the drone and the top of the tree canopy. When the drone flies to an area with changing slope, the central control system adjusts the fuselage pitch angle and the nozzle servo angle to ensure that the droplets always enter the center of the canopy vertically. Figure 2 The study shows a comparison of the different wind fields and droplet settling trajectories in the flower cluster area and the fruit area: the flower cluster area shows a gently curved drift trajectory of fine fog, while the fruit area shows a vertically downward penetrating trajectory of coarse fog.

[0032] After this embodiment was completed, the statistical results showed that compared with the traditional uniform spraying operation of plant protection drones, the flower drop rate of camellia was reduced by 16.2% and the fruit retention rate of young fruit was increased by 23.5% after adopting this method.

[0033] Example 2 The difference between this embodiment and Embodiment 1 is that the ratio of the synergistic fruit-preserving agent is as follows: the concentration of potassium dihydrogen phosphate is 1 g / L, the concentration of borax is 0.5 g / L, the concentration of gibberellin is 20 mg / L, and the remainder is deionized water. In step four, maintain a constant distance of 1.5m between the drone and the top of the tree canopy.

[0034] Other parameters and operations are the same as in Example 1. After this example was completed, the statistical results showed that compared with the traditional uniform spraying operation of plant protection drones, the flower drop rate of camellia was reduced by 15.1% and the fruit retention rate of young fruit was increased by 21.8% after adopting this method.

[0035] Example 3 The difference between this embodiment and Embodiment 1 is that the ratio of the synergistic fruit-preserving agent is as follows: the concentration of potassium dihydrogen phosphate is 2 g / L, the concentration of borax is 1 g / L, the concentration of gibberellin is 50 mg / L, and the remainder is deionized water. In step four, maintain a constant distance of 2.5m between the drone and the top of the tree canopy.

[0036] Other parameters and operations are the same as in Example 1. After this example was completed, the statistical results showed that compared with the traditional uniform spraying operation of plant protection drones, the flower drop rate of camellia was reduced by 15.8% and the fruit retention rate of young fruit was increased by 22.9% after adopting this method.

[0037] Comparative Example 1 This comparative example uses traditional agricultural drone spraying methods for uniform application, conducting fruit preservation operations in the same camellia oleifera forest during the same flowering and fruiting period. The drone's flight altitude is fixed at 2m above the tree canopy, the deionized water pump pressure is constant, and the nozzles spray continuously without distinguishing between flower clusters and fruits, or adjusting for wind direction or droplet size. The fruit preservation agent formula used is the same as in Example 1.

[0038] After the operation, the flower drop rate of camellia was 28%, and the fruit retention rate of young fruit was 52%.

[0039] It can be seen that the present invention can be modified or integrated using existing commercial multi-rotor drone platforms without special equipment, and has good industrial applicability and promotion prospects. At the same time, it effectively solves the technical contradiction between fruit protection and flower protection during the flowering and fruiting period of Camellia oleifera, and can significantly improve the fruit setting rate and yield of Camellia oleifera. It is suitable for large-scale application in Camellia oleifera planting areas in hilly and mountainous areas of southern China.

[0040] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the present invention without departing from its framework and scope of application, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for coordinated fruit protection during the flowering and fruiting stages of camellia oleifera based on precision drone operations, characterized by: Includes the following steps: Step 1: Forest Stand Background Data Modeling and Flight Route Planning Using a multispectral camera mounted on a drone, the target camellia forest is pre-scanned to obtain information on plant distribution, canopy density, and terrain slope. Then, based on the spatial distribution of flower clusters and fruits during the flowering and fruiting period of camellia, key operation areas are delineated, and terrain-following flight routes are generated. Step 2: Real-time identification and classification of target features: During the operation of the UAV along the terrain-following flight route, the airborne visual sensor collects tree canopy information in real time and classifies the tree canopy information into three categories: A-type characteristic flower cluster concentration area, B-type characteristic fruit development area and C-type characteristic sparse branch and leaf area. Step 3: Dynamic decision-making for synergistic spraying parameters: Based on the identified tree canopy information characteristics, the following synergistic spraying decisions are made through the central control system using the prepared synergistic fruit-preserving agent: For the characteristics of type A, a weak wind and fine mist mode is adopted, the rotor speed is reduced, and the deionized water pump pressure is increased to generate micro-mist with a particle size of 50μm to 100μm. The nozzle swing is controlled by the servo motor to make the micro-mist drift and penetrate into the flower cluster. For the characteristics of type B, a strong wind penetration mode is adopted to increase the rotor speed to generate a strong downwash flow. At the same time, the deionized water pump pressure is adjusted to generate coarse mist with a particle size of 150μm to 250μm, so that the coarse mist penetrates the canopy and settles on the fruit surface. For Category C characteristics, the nozzles will automatically shut off to stop spraying; Step 4: Coupling adjustment of operating height and wind field angle During step three, based on the distance between the drone and the top of the tree canopy measured by the ultrasonic radar sensor, the drone is kept at a constant distance of 1.5m to 2.5m from the top of the tree canopy. When encountering changes in slope, the drone's pitch angle and nozzle servo angle are adjusted to ensure that the droplets enter the center of the canopy vertically.

2. The method for coordinated fruit protection during the flowering and fruiting stages of Camellia oleifera based on precision drone operations according to claim 1, characterized in that: In step one, the spatial distribution of flower clusters and fruits is specifically determined by using a multispectral camera mounted on an unmanned aerial vehicle to obtain the normalized vegetation index (NDI) value of the camellia oleifera forest, and then identifying the spatial distribution of flower cluster concentration areas and fruit development areas based on the spatial distribution differences of the NDI values.

3. The method for coordinated fruit protection during the flowering and fruiting stages of Camellia oleifera based on precision drone operations according to claim 1, characterized in that: In step two, the airborne vision sensor includes a high-resolution multispectral camera and an ultrasonic radar ranging sensor. The high-resolution multispectral camera is used to identify the reflected signals of white flowers and the shadows of dark green spherical fruits, while the ultrasonic radar ranging sensor is used to obtain information about the height of the tree canopy.

4. The method for coordinated fruit preservation during the flowering and fruiting stages of camellia oleifera based on precision drone operations according to claim 1, characterized in that: In step three, in the weak wind and fine mist mode, the servo motor controls the nozzle to swing within a range of ±30 degrees.

5. The method for coordinated fruit preservation during the flowering and fruiting stages of Camellia oleifera based on precision drone operations according to claim 1, characterized in that: In step three, under the strong wind penetration mode, the strong downwash generated by increasing the rotor speed causes the leaves on the surface of the tree canopy to flip, allowing the coarse fog to penetrate the closed canopy.

6. The method for coordinated fruit protection during the flowering and fruiting stages of Camellia oleifera based on precision drone operations according to claim 1, characterized in that: In step three, the synergistic fruit-preserving agent consists of the following components: potassium dihydrogen phosphate at a concentration of 1 g / L to 2 g / L, borax at a concentration of 0.5 g / L to 1 g / L, gibberellin at a concentration of 20 mg / L to 50 mg / L, and the remainder being deionized water.

7. The method for coordinated fruit protection during the flowering and fruiting stages of camellia oleifera based on precision drone operations according to claim 1, characterized in that: In step four, maintaining a constant distance between the drone and the top of the tree canopy is achieved by using the drone's altimeter and real-time dynamic positioning module to achieve centimeter-level positioning, and by adjusting the flight altitude based on feedback from the ultrasonic radar sensor in a closed loop.

8. The method for coordinated fruit protection during the flowering and fruiting stages of camellia oleifera based on precision drone operations according to claim 1, characterized in that: The drone adopts a six-axis multi-rotor structure or a four-axis multi-rotor structure and is equipped with a real-time dynamic positioning module. The central control system is an onboard edge computing module with a built-in collaborative control algorithm for executing collaborative spraying decisions.

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