Differential Flatness Analysis of Tethered Kite Dynamics Along Lemniscate Trajectories for Wind-Assisted Ship Propulsion

Airborne Wind Energy (AWE) systems leverage tethered kites flying lemniscate trajectories to harvest high-altitude winds, offering an innovative solution for reducing fuel consumption and emissions in maritime transport. This paper provides a novel representation of the nonlinear kite’s dynamics, based on the differential flatness property. In flat systems, all states and inputs can be expressed as functions of a suitably chosen set of outputs, referred to as flat outputs, and their derivatives. Through an explicit analytical derivation, an inverse dynamic model of the system is obtained, providing a foundation for the design of nonlinear feedforward control, path planning, and fault detection algorithms. These applications are particularly relevant for AWEs, where robustness and real-time performance are critical requirements.