Adaptive Control of Advanced Fighter Aircraft in Nonlinear Flight Regimes

Abstract

When advanced fighter aircraft fly at high angles of attack, unsteady aerodynamic effects, wing rock, and saturation of aerodynamic effectors can lead to difficulty in control and maneuverability. A novel adaptive output feedback control design based on dynamic inversion is investigated for aircraft which are operated in highly nonlinear flight regimes, where uncertainties in the form of both unmodeled parameter variations and unmodeled dynamics are common. The stability of the design is analyzed and validated with simulations using a modified NASA F-15 simulation. The simulation includes thrust vectoring and a differential stabiliator to provide increased control authority at high angles of attack and relaxed static stability to increase pitch maneuverability. The control designs include the use of pseudocontrol hedging techniques to exclude adaptation to control saturation.