What are the key components of agricultural drones?

I. Flight System: Ensuring Stable Flight of the Drone

1. Frame Structure
   • Material: Mostly made of carbon fiber composite materials (lightweight and high-strength) or engineering plastics (low-cost). It needs to balance impact resistance and lightweight design.
   • Structural Type: Common multi-rotor structures (such as 4-rotor and 6-rotor, which offer strong stability and are suitable for low-altitude operations). Some large-scale models adopt fixed-wing or vertical take-off and landing (VTOL) hybrid structures (with a wide coverage range, suitable for large-area mapping).
   • Design Features: Reserved installation positions for mission payloads (such as pesticide tanks and sensors) and consideration of waterproof and anti-corrosion properties (to cope with pesticides and rainwater).
2. Power System
   • Motors: Mostly brushless DC motors (high efficiency and long service life). The quantity matches the number of rotors (e.g., 4 motors for a 4-rotor drone). Power is selected based on load requirements (e.g., 200-300W motors for 10kg-class drones).
   • ESC (Electronic Speed Controller): Connects the motor to the flight control system, adjusts motor speed according to flight control commands, controls rotor lift, and realizes attitude adjustments (such as pitching and rolling).
   • Propellers: Mostly made of carbon fiber or nylon. They are designed with aerodynamic features (such as foldable or quick-release propellers) to improve efficiency, reduce noise, and adapt to different flight speeds (e.g., cruising and hovering).

II. Mission Payload System: Realizing Agricultural Operation Functions

1. Plant Protection Operation Payloads
   • Pesticide/Seed Tanks: Store pesticides, seeds, or fertilizers. The capacity is designed according to the drone’s load capacity (e.g., approximately 6-8L for 5kg-class tanks and 20-30L for 20kg-class tanks). The material must be resistant to chemical corrosion (such as polyethylene) and equipped with liquid level sensors (to provide real-time feedback on remaining quantity).
   • Spraying System
     • Water Pumps: Mostly diaphragm pumps or centrifugal pumps, with flow controlled by flight control (e.g., 0.5-2L/min) to adapt to different pesticide concentrations.
     • Nozzles: Adopt centrifugal or pressure nozzles, which can adjust droplet size (e.g., 50-300μm; small droplets are suitable for leaf adhesion, and large droplets reduce drift). Some are equipped with anti-drip designs (to avoid pesticide leakage when the drone is stationary).
     • Pipes: Corrosion-resistant hoses (such as PVC) with a layout that ensures uniform distribution (e.g., multiple nozzles installed symmetrically to guarantee even spraying coverage).
   • Sowing System: For sowing seeds/fertilizers, it includes hoppers, screw conveyors, and centrifugal spreading discs. The sowing quantity and range are adjusted by controlling the rotation speed (e.g., sowing 2-5kg of seeds per mu).
2. Monitoring and Mapping Payloads
   • Remote Sensing Sensors: Such as multispectral cameras (capturing crop spectral reflectance to analyze growth and pests/diseases), hyperspectral cameras (providing more detailed spectral data to identify crop nutritional status), and thermal imaging cameras (detecting crop water stress to determine drought areas).
   • GPS/RTK Modules: Cooperate with cameras to achieve precision mapping (e.g., generating 3D farmland maps and calculating areas). RTK (Real-Time Kinematic) can improve positioning accuracy to the centimeter level, ensuring that monitoring data is accurately matched with plot locations.
   • LiDAR: Equipped on some high-end models for topographic mapping (e.g., terraced field slopes) or 3D crop modeling (to evaluate plant height and density).

III. Control System: The “Brain” of the Drone for Autonomous Operations

1. Flight Control System (Flight Controller)
   • Core Module: Integrates MCU (Microcontroller Unit) or SOC (System on Chip) to process sensor data and output control commands, equivalent to the “brain center”.
   • Integrated Sensors:
     • IMU (Inertial Measurement Unit): Includes accelerometers, gyroscopes, and magnetometers to monitor the drone’s attitude in real-time (angular velocity, acceleration, and heading angle) and ensure stable hovering.
     • Barometer/Altimeter: Such as 24GHz radar altimeters (with strong anti-interference ability) or air pressure sensors to control flight height (e.g., maintaining a height of 1.5-3 meters above the ground during spraying).
     • GPS/Beidou Modules: Realize positioning and navigation, supporting autonomous route planning (e.g., AB point flight and automatic obstacle avoidance).
   • Functions: Support one-key takeoff/landing, fixed-height and fixed-speed flight, breakpoint respraying (continuing from the last position after operation interruption), and low-battery return.
2. Ground Station System
   • Hardware: Mostly mobile phone apps, tablets, or dedicated remote controllers, connected to the drone via wireless communication (such as 4G, Bluetooth, and data transmission radios).
   • Software Functions: Map mapping (demarcating operation areas), route planning (setting flight speed, height, and spraying quantity), real-time data monitoring (battery level, pesticide tank remaining quantity, position), and operation log recording (statistics of area and usage).

IV. Energy System: Providing Power Support

1. Batteries
   • Type: Mainstream is lithium polymer batteries (LiPo), characterized by high energy density (e.g., 200-250Wh/kg) and large discharge current (supporting high-power motors).
   • Specifications: Configured according to load requirements. For example, 10kg-class drones commonly use 6S (6 cells in series) lithium batteries with a capacity of 10000-20000mAh and an endurance of 15-25 minutes; large-scale models (30kg-class) may adopt multiple batteries in parallel, with an endurance of 30-40 minutes.
   • Protection Design: Equipped with overcharge, over-discharge, and short-circuit protection. Some support thermal management (to avoid high-temperature bulging).
2. Power Management Module (PMU)
   • Function: Distributes battery power to components such as flight control, motors, and mission payloads, monitors voltage and current of each module to ensure stable power supply, and triggers return commands when the battery level is below a threshold (e.g., 20%).

V. Communication and Data Transmission System: Enabling Human-Machine Interaction

1. Data Transmission Modules
   • Role: Transmit control commands (such as adjusting height and speed) and status data (position, battery level). They commonly use 2.4GHz or 900MHz frequency bands (with strong penetration, suitable for complex terrains) and have a transmission distance of generally 1-5 kilometers (up to more than 10 kilometers with high-power data transmitters).
2. Image Transmission Modules
   • Function: Real-time transmission of images from the drone’s camera (such as FPV first-person view), helping operators observe whether there are missed spraying areas or obstacles in the operation area. They commonly use 5.8GHz frequency bands (high-definition image transmission with a delay of less than 100ms).

VI. Auxiliary Components: Enhancing Safety and Reliability

1. Obstacle Avoidance System
   • Sensors: Mostly millimeter-wave radars (e.g., 24GHz), ultrasonic sensors, or visual cameras, which detect front/below obstacles (such as trees, telegraph poles, and field ridges) and trigger obstacle avoidance or hovering commands to prevent collisions.
2. Redundancy Design
   • Key components (such as flight control, motors, and GPS) may adopt dual backups. When one component fails, it automatically switches to the backup system to improve safety (e.g., a 6-rotor drone can maintain landing with the remaining 5 motors if one motor fails).
3. Heat Dissipation System
   • For heat-generating components such as motors, ESCs, and flight control, heat sinks, fans, or air duct designs are used to prevent high temperatures from affecting performance (especially during long-time operations in summer).

Summary