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 ftxed-wing vehicles with this capability. The dynamic model consists of the 6 degree-of-freedom ftxed-wing aircraft equations of motion, a spring-damper-magnet system to represent the linkage force between constituent vehicles, and the NASA-Burnham-Hallock wingtip 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 towards 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 wingtip docking. Simulation results for both before and after linking are presented.

Data‐assisted control: A framework development by exploiting NASA Generic Transport platform

“…By using estimates of the generalized force-moment vector as a measure of the system's state, we can consider other parameters such as control inputs, generalized velocity, their products, and nonlinear terms as possible observables. 102,103 Through analysis of the relation between observables and the state, we can estimate the damping derivatives, control derivatives, static force-moment, and nonlinear terms participation.…”

Safety Analysis and Simulation Validation of Hose Whipping Phenomenon in Air Refueling

“…From the functional control structure in Figure 1, it is easy to derive the key objects of simulation validation: hose cone dynamic model, the reel mechanism control model, the tanker vortex field model, and the atmospheric turbulence model. Drawing on the relevant literature [6,18,19], the hose cone dynamic model adopts the multi-rigid body dynamic model based on the centralized parameter principle [6]; the reel mechanism control model considers the driving mechanism of the constant force spring; the tanker vortex field model employs the Hallock-Burnham model [19]; the atmospheric turbulence model uses the Dryden model [18]. On this basis, a 24-section hose cone was adopted.…”

“…By these methods, a complex system is treated as a complete body, and causal factors are analyzed from all levels, and the relationship between system components are clarified, shedding new lights on the safety analysis of complex systems [15][16][17]. The results of these methods could be validated by simulation with models like hose-drogue model [5] and auxiliary model [6,18,19].…”

Experimental Control of Two Connected Fixed Wing Aircraft

“…That is, if the controllability matrix is computed for any aircraft configuration, the matrix is full rank [24]. The challenge of connecting in flight poses a difficult problem with the presence of atmospheric disturbances but using vision based feedback can help mitigate this problem [25,26]. Work has been done on unlinking UAVs mid-flight [27] in support of the High Altitude Long Endurance (HALE) projects [28] as well as Project Link [26]!…”