Precision Control of a Firefighting Drone with Extinguisher for Flame Targeting

This paper presents a robust control framework for an underactuated quadrotor-based aerial firefighting system equipped with a dry chemical extinguisher. The system addresses two coupled phenomena that arise during active aiming and targeted suppressant discharge: jet-induced reaction force, and time-varying mass loss. To manage these challenges, we propose a modular Linear Parameter-Varying (LPV) control strategy that decouples the drone's flight stabilization and nozzle targeting subsystems. Using polytopic modeling and gain scheduling, the LPV controllers adapt to non-linear coupling and time-varying parameters, including the nozzle angle, reaction force magnitude, system mass, drone inertial position, and pitch angle. In simulation, the LPV controller reduces translational mean tracking error by at least 97.7\% and maximum absolute error by more than 83\% compared to a cascaded PID controller during dynamic targeting. Against a state-of-the-art disturbance observer (DOB)-based controller under force-only conditions, the LPV design achieves at least 99.9\% reduction in mean error and 88\% reduction in maximum error. These results validate the LPV framework as a resilient solution for dynamic aerial firefighting missions in constrained and disturbance-rich environments.