An assessment of robustness of variable structure control systems for advanced aircraft manoeuvres

The authors use a model-following VSCS (variable structure control system) design approach to provide an aircraft control system which exhibits parameter insensitivity with good disturbance rejection while enabling the pilot to perform an advanced aircraft maneuver. Eigenstructure assignment is used to define a model with these response characteristics. The authors also consider a definition and practical measures of the robustness of such a model-following VSCS. The VSCS technique is illustrated by considering the design of a lateral translational/yaw pointing control scheme for a conventional combat aircraft which has been augmented with a chin-fin to provide the required sideforce control. Analysis of the performance of this control scheme when subjected to a range of flight conditions is used to demonstrate application of the robustness criteria developed