Nonlinear control of an actuated tethered airfoil

This paper focuses on the control of an aerial vehicle composed of an aerodynamic profile linked to a ground station by means of a tether cable. The vehicle is sustained only by the wind flowing on the aerodynamic surface. The control objective is to steer the vehicle to a desired reference point while satisfying the constraint of having the cable taut at all times. In this paper, a nonlinear state feedback with a state dependent saturation is proposed which, using Lyapunov theory, is proven to ensure regional asymptotic stability. Moreover, it is proven that this law, thanks to a state dependent saturation, ensures constraints satisfaction. The effectiveness of the proposed control strategy is shown through simulations based on the experimental aerodynamic data of a real airfoil.