Decoupling of systems with nearly singular I-O maps and control of aircraft

The author treats the control of a class of nonlinear systems using state variable feedback whose input-output map is nearly singular. A decoupling scheme is presented which gives rise to a singularly perturbed system describing the fast dynamics of the control vector. The quasi-steady-state solution of the system gives a control law which decouples the system in an approximate way. The controller includes a servocompensator and a reference trajectory generator. From this result a control law for approximate decoupling of roll angle, angle of attack, and sideslip in rapid, nonlinear airplane maneuvers is derived. Simulated responses of the closed-loop system show that large, simultaneous lateral and longitudinal maneuvers can be accurately performed in spite of uncertainty in stability derivatives.<>