Automatic control of tethered wings for airborne wind energy: Design and experimental results

A new approach to control tethered wings for airborne wind energy is described. A fixed length of the lines is considered, and the aim of the control system is to obtain figure-eight crosswind trajectories. The proposed technique is based on the notion of the wing's “velocity angle” and, in contrast with most existing approaches, it does not require a measurement of the wind speed or of the effective wind at the wing's location. Moreover, the proposed approach features few parameters, whose effects on the system's behavior are very intuitive, hence simplifying tuning procedures. Experimental results are presented, obtained by extensively testing the approach with a small-scale prototype.