Design and simulation of a pesticide spraying quadcopter

Conventional agricultural spraying exposes farmers to significant health hazards and often produces non-uniform chemical application. This creates an urgent need for safer, automated solutions. Although unmanned aerial vehicles (UAVs) offer a practical alternative, many pesticide-spraying drones lack rigorously tested flight-control designs and rely on empirical gain tuning. This study presents the modelling, simulation, and performance evaluation of a pesticide-spraying quadcopter using a cascaded proportional-integral-derivative (PID) architecture. A high-fidelity six-degree-of-freedom (6-DOF) dynamic model based on Newton-Euler formulation was developed in MATLAB/Simulink. Unlike standard static models, this framework incorporates a time-varying payload to represent the dynamic discharge of pesticides. A hierarchical PID structure was implemented with an inner-loop attitude stabilizer and an outer-loop position-altitude controller. Results indicate robust stabilization with attitude settling times below 0.35 s. Furthermore, the system maintained smooth altitude tracking without overshoot during significant payload mass reduction. The developed framework provides a reliable baseline for autonomous implementation, reducing the risks and costs associated with physical prototyping. The study’s primary novelty lies in the systematic validation of cascaded control laws specifically under the influence of continuous mass depletion, a critical factor for precision agricultural missions.