Flight Control for Flexible, High-Aspect-Ratio Flying Wings

Abstract

High-aspect-ratio flying wing configurations designed for high altitude, long endurance missions are characterized by high flexibility, which may lead to significant static aeroelastic deformation and coupling between aeroelasticity and flight dynamics. Using the concept of the mean axis, a 6-degree-of-freedom reduced-order model of the flight dynamics is constructed that minimizes the coupling between rigid-body modes and structural dynamics while accounting for the nonlinear static aeroelastic deformation of the flying wing. A multistep nonlinear dynamic inversion controller based on this reduced-order model is coupled with a nonlinear guidance law to design a flight controller for path following. The configuration of the flying wing used in the reduced-order model is updated at each time instant to account for static aeroelastic deformation. Simulation results presented in this paper show that the controller is able to successfully follow both straight line and curved ground paths while maintaining/moving to the desired altitude. The controller is also shown to be able to handle an abrupt change in the external loading, which is simulated by a step change in the payload mass.