Orbit control for a power generating airfoil based on nonlinear MPC

The Airborne Wind Energy paradigm proposes to generate energy by flying a tethered airfoil across the wind flow. An essential problem posed by Airborne Wind Energy is the control of the tethered airfoil trajectory during power generation. Tethered flight is a fast, strongly nonlinear, unstable and constrained process, motivating control approaches based on fast Nonlinear Model Predictive Control. In this paper, a computationally efficient 6-DOF control model for a high performance, large-scale, rigid airfoil is proposed. A control scheme based on receding-horizon Nonlinear Model Predictive Control to track reference trajectories is applied to the proposed model. In order to make a real-time application of Nonlinear Model Predictive Control possible, a Real-Time Iteration scheme is proposed and its performance investigated.