FIGHTER AIRCRAFT LATERAL DIRECTIONAL AXES FULL ENVELOPE CONTROL LAW DESIGN

A decoupled wide envelope lateral/directional axes control design is p resented for a supermanoeuvrable version of an F-18 aircraft. A contro l structure is developed that separates gain scheduling issues from ai rcraft performance issues. Flight condition dependent state and contro l effectiveness variations are accounted for by an inner loop controll er designed using eigenstructure assignment. Structured singular value synthesis is used to design an implicit model following outer loop co ntroller that addresses flying qualities performance specifications. A control selector is designed that generates lateral/directional aerod ynamic and thrust vectoring commands from generalized control inputs o f roll and yaw acceleration. Flying qualities and robustness analyses show that the control system performs well despite neglected dynamics and system uncertainties. Nonlinear simulations are presented showing excellent decoupling of roll and yaw responses.