Fractional-Order Control for Robust Position/Yaw Tracking of Quadrotors With Experiments

Quadrotors are highly maneuverable lightweight drones, which are prone to aerodynamic disturbances, vibrations, and uncertainties. These factors stand for a problem that demands robust control laws. For position tracking, the control problem is exacerbated, because the plant is underactuated in the coordinates of interest, requiring a high-performance attitude tracking to resolve underactuation. In this brief, a novel fractional-order controller is proposed by considering a well-posed map that relates the position/yaw control to the desired attitude references. The attitude control is continuous and enforces and sustains a sliding motion in finite time for exponential convergence of the tracking errors to fulfill a "virtual" position controller. The resulting closed-loop system is robust against the continuous disturbances that are not necessarily differentiable in the conventional sense. A numerical study based on the simulations is presented to analyze the advantages of the fractional actions to design a physically realizable controller, and the experiments are discussed to expose the reliability of the proposed fractional scheme implemented in an "X" configuration quadrotor.