Flight control for mixed-amplitude commands

Abstract

A longitudinal¯ight control law is derived that provides desirable precision aircraft-tracking response for small-amplitude commands and desirable gross acquisition response for large-amplitude commands. Dynamic inversion and proportional-plus-integral command compensation provide precision attitudetracking control, and time-optimal control provides gross acquisition augmentation. Continuous transition between the control modes, without control power saturation, is accomplished using Lyapunov function level sets of the nominal small-amplitude closed-loop system. The control law directly relates design parameters to the closed-loop characteristic equation and¯ying qualities transfer function parameters. The control strategy is applied to an F-16 aircraft model augmented with thrust vectoring. The feedback control law exhibits satisfactory stability and performance robustness shown through linear analysis and nonlinear simulation.