ROBUST INTEGRATED FLIGHT PROPULSION CONTROL DESIGN FOR A STOVL AIRCRAFT USING ETA-INFINITY CONTROL DESIGN TECHNIQUES

Results are presented from an application of H(infinity) control design methodology to a centralized integrated flight/propulsion control (IFPC) system design for a supersonic Short Take-Off and Vertical Landing (STOVL) fighter aircraft in transition flight. The emphasis is on formulating the H(infinity) optimal control synthesis problem such that the critical requirements for the flight and propulsion systems are adequately reflected within the linear, centralized control problem formulation and the resulting controller provides robustness to modelling uncertainties and model parameter variations with flight condition. Experience gained from a preliminary H(infinity) based IFPC design study performed earlier is used as the basis to formulate the robust H(infinity) control design problem and improve upon the previous design. Detailed evaluation results are presented for a reduced order controller obtained from the improved H(infinity) control design showing that the control design meets the specified nominal performance objective as well as provides stability robustness for variations in plant system dynamics with changes in aircraft trim speed within the transition flight envelope.