Active pitch control of tethered wings for airborne wind energy

A study on the aerodynamics and on the active pitch control of curved tethered wings for airborne wind energy is presented. Computational fluid dynamics techniques, previously validated with experimental data, are used to derive the aerodynamic coefficients of a curved kite as a function of the angle of attack. In contrast with previous results, such analysis indicates that the kite efficiency is quite flat over a wide range of values of the angle of attack. Based on such analysis, an active pitch control strategy is proposed, which is able to maximize the generated traction force during operation without requiring neither an estimate of the angle of attack, nor an accurate model of the system's dynamics.