Path controller implementation for airborne wind energy systems

The implementation of a path controller to a two-line kite model is presented. Within the first chapter, an introduction to Airborne Wind Energy systems and the discussion of some typical control methods can be found. The following chapter deals with the mathematical model of a two line kite. This model considers a kite-surf size kite that can be controlled via two equal tethers. Some thoughts and explanations on the model are included. Thereafter, an open loop control law capable of allowing figure of eight trajectories is defined. Accordingly, an analytical expression for such figure of eight orbits is presented. Some insight on Floquet theory is required in order to properly understand the physics behind periodic orbits. A general purpose predictor-corrector algorithm for periodic orbit propagation determines a set of feasible initial conditions that yield a periodic orbit for a given control law. By means of this tool, it is possible to obtain a periodic orbit applying the control law that has been previously defined. A discussion on such orbit is included, together with its stability analysis. At this point, it is of interest to perform a parametric analysis with the aim of understanding how the stability and the trajectory respond to variations in the control law. Finally the path controller scheme is presented in the form of an optimal control problem. The latter selection was triggered by the failure in implementing a proportional-derivative runtime controller. The results of the project are a deep understanding on the kite sensitivity to variation of tether lengths, i.e. their controls, together with a controller capable of determining optimal control laws for any given desired target path.Ingeniería Aeroespacial (Plan 2010