Time-Varying Aerodynamic Model and Adaptive Control of the High Angle-of-Attack Maneuvering Flight for Fixed-Wing AAVs

To enhance the autonomous maneuverability of aircraft, it is urgent to develop high angle-of-attack (AOA) maneuvering flight methods suitable for fixed-wing autonomous aerial vehicles (AAVs). Addressing the issue that most existing methods neglect the nonlinearity of the flow field under high AOA conditions, this article considers the hysteresis loop phenomenon that represents the unsteady aerodynamics due to stall. Inspired by the correlation between aerodynamic coefficients and the change rate of the AOA, a time-varying aerodynamic model is established. It utilizes time-varying parameter equations to describe the aerodynamic coefficients and combines them with the fixed-wing aircraft’s longitudinal dynamics model. To address the uncertainties arising from the established model, a Lyapunov-based adaptive maneuvering controller is developed for the nonlinear time-varying system. With the prior knowledge that aerodynamic coefficients are bounded, a projection operator based on convex set theory is designed to achieve real-time bounded estimation of the unknown time-varying parameters. Additionally, the designed switching cascaded control strategy enables the aircraft to restore steady flight autonomously. The comparing simulations under parameter perturbation demonstrate that the proposed controller can effectively enhance the AAV’s tracking performance for high AOA maneuver commands.