Abstract
This research presents a new concept vehicle called the Tethered Uni-Rotor Network (TURN). The system is intended to attain eternal flight, by collecting enough solar power during the day to stay aloft through the night. This capability enables atmospheric satellites, which offer the same services as existing satellites, but permits increased capabilities from their close proximity and low signal latency. There is a great commercial interest in achieving this goal, and several research groups are striving for this aviation milestone, but existing designs encounter severe limitations. This document introduces a novel concept vehicle which captures the best features of both rotorcraft and glider design methodologies, while reducing their respective limitations. The vehicle is a tethered system, with complex nonlinear dynamics, interactions between multiple rigid bodies, and requires a unique perspective to implement the controller architecture. First, the plant dynamics are established, which models the entire nonlinear system, formulates the dynamics acting on each subcomponent, establishes a multibody dynamic structure within a matrix framework, and develops novel trimming and linearization processes applicable to such a multibody system. Then, the control system is derived, which presents the overall control methodology, and develops an LDS based model reference adaptive control (MRAC) architecture, which is implemented on three distinct control loops. An extensive simulation study outlines the vehicle sizing and parameters, reviews the disturbance rejection capabilities, formulates multisine signal injection for system identification, investigates parameter convergence within the LDS based MRAC system, evaluates reference tracking for an output feedback embodiment, and discusses inertial translation by coordinating maneuvers among several of the rigid body components. This initial effort is part of a larger spiral development process, so a future testing plan is laid out for a series of prototype vehicles. The outcome of this research will show that the TURN approach is a feasible concept design, capable of being adequately controlled, while offering greatly increased aerodynamic efficiency. It has immediate commercialization potential at a smaller scale, can alleviate design issues inherent in airborne wind energy platforms, and may be the answer to achieving eternal flight.
