Aeroservoelastic Structural and Control Optimization Using Robust Design Schemes

Abstract

The procedure for structural and robust control design of multi-input/multi-output aeroservoelastic systems presented contains modeling of uncertainties, synthesis of a robust controller, and a unified structural and control optimization process under stress, flutter, and control performance constraints. Robust control design techniques can enhance the preliminary structural design for cases where certain system parameters are not known exactly or are uncertain. An aeroservoelastic interaction module is used for mediation between the structural optimization code and the control synthesis tools in an iterative coupled process. It provides the reduced-size state-space aeroelastic models needed for control synthesis, including model sensitivities to structural uncertainties, and integrates the resulting control model in structural optimization that includes robust-control considerations in terms of singular value constraints. The efficient uncertainty modeling developed is based on the readily available structural sensitivity data and the linear fractional transformation tools. Modeling of inertial uncertainties of the controlled structure was performed to account for relatively large inertial deviations of a fighter aircraft wing-tip missile. The numerical example clearly demonstrates the effectiveness of the proposed design scheme and its usefulness at preliminary design stages of aircraft with multiple external store loads.