Adaptive Single-Gain Non-Singular Fast Terminal Sliding Mode Control for a Quad-rotor UAV Against Wind Perturbations

This paper introduces a class of adaptive sliding mode controller for a quad-rotor unmanned aircraft vehicle. The control is based on a non-singular fast terminal surface, and an adaptive law involving only two parameters to be tuned, which produces a smoother gain dynamics. In return, a significantly reduction of undesired behavior such as chattering is achieved, while preserving the properties of robustness against perturbations and finite time convergence. Furthermore, in order to evaluate robustness, the proposed control technique along with a Von Kármán model based wind turbulence generator, are applied in a close-to-real-life scenario. This consists of a 310 meter trajectory inside a city block powered by Unreal Engine. Obtained results support the claim that this control scheme allows the quad-rotor to follow desired trajectories even in presence of wind perturbations. This displays the feasibility and robustness needed for such systems to enable more complex tasks while flying in urban environments.