Dynamics and Control of In-Flight Wing Tip Docking

Abstract

Project Link! is a NASA-led effort to study the feasibility of multi-aircraft aerial docking systems. In these systems, a group of vehicles physically link to each other during flight to form a larger ensemble vehicle with increased aerodynamic performance and mission utility. This paper presents a dynamic model and control architecture for a system of fixed-wing vehicles with this capability. The dynamic model consists of the six-degree-of-freedom fixed-wing aircraft equations of motion, a spring–damper–magnet system to represent the linkage force between constituent vehicles, and the NASA Burnham–Hallock wing-tip vortex model to represent the close-proximity aerodynamic interactions between constituents before the linking occurs. The control architecture consists of a guidance algorithm to autonomously drive the constituents toward their linking partners and an inner-loop angular rate controller. A simulation was constructed from the model, and the flight dynamic modes of the linked system were compared to the individual vehicles. The main contributions of this work are twofold. First is the introduction of close-proximity aerodynamic effects to create a realistic simulation framework for this problem. Second is the application of a sophisticated leader–follower guidance algorithm to achieve in-air wing-tip docking. Simulation results for both before and after linking are presented.