## 2 Overall Structure of Fertilization and Spraying System
### Overall Design of the Work Vehicle  
This study presents the design of a three-wheeled high-clearance corn fertilization and spraying work vehicle, developed in line with the principles of agro-mechanical and agronomic integration. The machine is designed to perform both mid-tillage fertilization and pesticide spraying, adapting to the varying heights of maize plants as required. It can effectively apply fertilizer to four rows of maize with a row spacing of 50 to 60 cm and is capable of spraying across multiple rows simultaneously. As illustrated in Figure 1, the high-clearance design was chosen to adapt to the relatively high plant height of corn in the middle and late growth stages and avoid damage to the corn during the vehicle's driving process. In actual field operation, the three-wheel vehicle has flexible steering and is convenient to operate in narrow aisles and irregular terrains. Its turning radius is 30% smaller than that of the four-wheel vehicle, and the operational efficiency is increased by 20%. Meanwhile, the structure of the three-wheeled vehicle is relatively simple, reducing the manufacturing cost and maintenance difficulty, which are more suitable for the actual use conditions in rural areas. The vehicle utilizes a new energy pure electric power system, comprising six 12 V, 100 Ah lead-acid batteries connected in series. This configuration powers both the driving and control circuits, employing a 220 V, 2 kW high-torque servo motor and PLC control to ensure operation at a predetermined speed.  
The vehicle's structure consists of several key components: a battery and control panel, a seat, a frame, rear wheels, a battery pack, a liquid pesticide tank, a collapsible spraying lifting frame, a disc hole fixing and fertilizer application mechanism, a fertilizer tank, and a fertilizer lifting mechanism. As illustrated in Figure 2, the machine can be organized into six main sections: the overall frame structure, the driving and steering mechanism, the battery and electronic control panel, the fertilizer application and adaptive ground  
Figure 1: High-clearance structure.  
mechanism, the working width adjustment system, and the spraying mechanism. The design of the vehicle fully takes into account the characteristics of various corn varieties, ensuring the precision and effectiveness of fertilization and spraying. The adjustable working parameters greatly enhance the flexibility of operation. For corn varieties with relatively short plants and compact leaves, the spraying height can be lowered to reduce pesticide waste, and the fertilization width adjustment device can reduce the working width to adapt to the narrower planting row spacing. For varieties with taller plants and wider leaves, the vehicle height and spraying height can be increased to avoid damaging the plants. The spraying amount can be increased by 15-20% to ensure comprehensive coverage of the leaves. Operators can flexibly adjust the vehicle parameters according to the growth conditions of different varieties to achieve precise operation and improve efficiency.  
The vehicle's overall frame is constructed primarily from cut and welded steel tubes and sheet metal components, ensuring that it possesses the necessary strength to meet the operational demands. The six distinct parts of the vehicle are interconnected, creating a cohesive unit that facilitates various functions including vehicle movement, maize plant identification, fertilizer application, and hole spraying. The key design parameters for the truck are detailed in Table 1. The physical map of the work vehicle is shown in Figure 3.  
Figure 3: Physical map of the work vehicle.  
Figure 2: Overall structure of the work vehicle. 1—Front steering mechanism and control panel. 2—Seat. 3—Frame. 4—Rear wheel. 5—Battery pack. 6—Liquid pesticide tank. 7—Foldable spraying lifting frame. 8—Disc hole-pricking fertilizer applicator. 9—Fertilizer tank. 10—Fertilization lifting mechanism.