ROBUST LONGITUDINAL AXIS FLIGHT CONTROL FOR AN AIRCRAFT WITH THRUST VECTORING

A full conventional envelope longitudinal axis control design is prese nted for a fighter aircraft capable of thrust vectoring. An inner-oute r loop modular control structure is used to provide good flying quanti ties in the presence of highly structured uncertainty across a wide fl ight envelope. Simple, low-order control laws are designed for a versi on of an F-18 aircraft model augmented with thrust vectoring nozzles. A minimal-order H-infinity design algorithm is used to aid in the desi gn of an inner loop equalization controller. Structured singular value synthesis is used to design outer loop implicit model-following contr ollers. Different control laws are found for high and low dynamic pres sure conditions, and controller commands are blended for a small regio n of dynamic pressure. Daisy-chaining is used to blend elevator and th rust vectoring commands. Structured singular values are used to analyz e stability robustness to structured parametric uncertainty, actuator and sensor unmodeled dynamics, and structured uncertainty correspondin g to controller blending. A nonlinear simulation is used to show that the aircraft performs well across the Right envelope during outer loop controller blending and thrust vectoring actuation.