Robust flight control design using dynamic inversion and structured singular value synthesis

A direct methodology for the design of flight control systems is introduced. The design approach uses a control selector and an inner/outer loop structure to achieve robustness and performance across the flight envelope. A control selector normalizes control effectiveness with respect to generalized inputs. An inner loop uses dynamic inversion to equalize plant dynamics across the flight envelope. An outer loop is designed around this equalized plant using μ-synthesis to achieve performance and robustness goals. The methodology is applied in the design of a manual flight control system for the lateral axis of a fighter aircraft. Analysis shows that the inner/outer loop approach produces designs which exhibit excellent performance and robustness for a broad range of operating conditions. The direct incorporation of design goals such as flying qualities requirements and the elimination of gain scheduling make this direct methodology an effective and efficient alternative to traditional flight control design approaches.