ROBUSTNESS EVALUATION OF A FLEXIBLE AIRCRAFT CONTROL-SYSTEM

The structured singular value analysis technique is used to generate stability and performance robustness guidelines for multivariable, flexible aircraft flight control systems. A stability augmentation and structural mode control system, designed using the same classical technique as on the original production aircraft, is evaluated to produce the new guidelines. Stability margins are computed for simultaneous gain and phase uncertainty in each of the control system feedback loops. Performance weighting filters are chosen specifically from military flying qualities specifications. The results of this research define exactly how robust a control system of this type should be, such that any performance improvements achieved using more advanced design techniques can be compared directly.