Model and experimental validation of ocean kite dynamics and controls

Abstract

This submission includes two peer-reviewed papers from researchers at North Carolina State University presenting the modeling and lab-scale experimentation of the dynamics and control of a tethered tidal ocean kite. Below are the abstracts of each file included in the submission.

Alvarez ECC ? Flight and Tether Dynamics
This paper models the dynamics of a marine tethered energy harvesting system focusing on exploring the sensitivity of the kite dynamics to tether parameters. These systems repetitively reels a kite out at high tension, then reels it in at low tension, in order to harvest energy. The kite?s high lift-to-drag ratio makes it possible to maximize net energy output through periodic cross-current flight. Significant modeling efforts exist in the literature supporting such energy maximization. The goal of this paper is to address the need for a simple model capturing the interplay between the system?s kite and tether dynamics. The authors pursue this goal by coupling a partial differential equation (PDE) model of tether dynamics with a point mass model of translational kite motion.

Siddiqui JDSMC ? Lab-scale closed-loop model and validation
This paper presents a study wherein we experimentally characterize the dynamics and control system of a lab-scale ocean kite, and then refine, validate, and extrapolate this model for use in a full-scale system. Ocean kite systems, which harvest tidal and ocean current resources through high-efficiency cross-current motion, enable energy extraction with an order of magnitude less material (and cost) than stationary systems with the same rated power output. However, an ocean kite represents a nascent technology that is characterized by relatively complex dynamics and requires sophisticated control algorithms. In order to characterize the dynamics and control of ocean kite systems rapidly, at a relatively low cost, the authors have developed a lab-scale, closed-loop prototyping environment for characterizing tethered systems, whereby 3D printed systems are tethered and flown in a water channel environment.