State Estimation of a Tethered Airfoil for Monitoring, Control and Optimization * *This work was supported by CNPq through grants 480931/2013-5 and 406996/2013-0, and CAPES, Brazil.

Abstract This paper presents an estimation scheme for Airborne Wind Energy systems based on the Extended Kalman Filter and on a simple, yet representative, dynamic model of the wing flight. Besides estimating the airfoil position, velocity, and acceleration, the filter also estimates the wind vector and the aerodynamic forces acting on the wing. Even though our setup currently fuses ground based measurements only, it could be easily extended to employ measurements from airborne sources such as GPS receivers, ranging devices, accelerometers and airspeed sensors. Moreover, our approach allows for the straightforward computation of other important variables such as the angle of attack and the equivalent aerodynamic efficiency. An established simulation model is used to validate the filter, which is later evaluated on experimental data from a field test. Finally, we discuss the possibility of applying the proposed approach in the context of system monitoring, control, and optimization.