A QFT SUBSONIC ENVELOPE FLIGHT CONTROL-SYSTEM DESIGN

An aircraft's response to control inputs varies widely throughout its full flight envelope. Furthermore, the aircraft configuration impacts control response through variations in centre of gravity and moments o f inertia. Quantitative feedback theory (QFT) is a robust control syst em design method which provides a full-envelope flight control system design and gives the engineer direct control over compensator order an d gain. A full subsonic flight envelope FCS is designed for using QFT for four representative aircraft configurations. Flying qualities are embedded in the longitudinal design by using a control variable which varies with the aircraft's energy state throughout the flight envelope . Linear simulations with realistically large control inputs are used to validate the design. (C) 1997 by John Wiley & Sons, Ltd.