Adaptive fractional-order control for flying robots under wind and ground effect

Quadrotor trajectory tracking under wind gusts and ground effect remains challenging due to unknown disturbances, model uncertainties, and the system’s underactuated nature. This paper presents an adaptive fractional-order terminal integral sliding mode control (AFOTISMC) to address these challenges. The controller integrates fractional-order Riemann-Liouville operators into an integral terminal sliding surface, ensuring finite-time convergence while eliminating chattering and singularity. Adaptive laws estimate unknown disturbance bounds without requiring prior knowledge. Lyapunov analysis proves global finite-time stability. Comprehensive simulations under wind-like disturbances, 30% parametric uncertainties in mass and inertia, and ground effect show that AFOTISMC reduces Integral Absolute Error (IAE) by up to 53% for position and 77% for yaw compared to conventional SMC, and by 12–31% compared to recent fractional-order SMC methods. Control energy consumption is reduced by 20–40% across all channels. These results confirm the practical significance of AFOTISMC for safe quadrotor operation in real-world windy environments and during landing in ground effect.