Robustness of Discrete-Time Dynamical Systems: Application to the Multivariable Digital Control of Combat Aircraft

摘要

A method for computing optimal feedback laws, capable of maintaining accurate tracking despite constantly acting disturbances was developed and applied to flight control of combat aircraft. A formalism reduces robustness to preservation of stability in a properly augmented system. This leads to theoretical results which quantify the generalized structural robustness of a recurrent nonlinear multiple-loop system. After extending the Lyapunov criterion to systems having dynamical feedback, the classical concepts of stability margin and of gain and phase margins are generalized to the multivariable discrete case. Analytical expressions which enable margins to be evaluated when dynamical or nonlinear perturbations affect the feedback channels are given. By applying theorems on external stability to a recurrent system, the tolerable additive perturbations which do not destabilize the controlled system are quantified.