  This study investigates deep offshore, pumping Airborne Wind Energy systems,
focusing on the kite-platform interaction. The considered system includes a 360
m2 soft-wing kite, connected by a tether to a winch installed on a
10-meter-deep spar with four mooring lines. Wind power is converted into
electricity with a feedback controlled periodic trajectory of the kite and
corresponding reeling motion of the tether. An analysis of the mutual influence
between the platform and the kite dynamics, with different wave regimes,
reveals a rather small sensitivity of the flight pattern to the platform
oscillations; on the other hand, the frequency of tether force oscillations can
be close to the platform resonance peaks, resulting in possible increased
fatigue loads and damage of the floating and submerged components. A control
design procedure is then proposed to avoid this problem, acting on the kite
path planner. Simulation results confirm the effectiveness of the approach.
