Improved Clearance of a Flight Control Law Using µ-Analysis Techniques

Abstract

Some new tools are described for the clearance of flight control laws for highly augmented aircraft. The tools are developed from general μ-analysis methods and are applied to the clearance of a flight control law for a vertical/short takeoff and landing aircraft. Criteria and methods currently used in the industrial flight control law clearance process are described in detail. A physical approach to linear fractional transformation based uncertainty modeling is applied and validated on the nonlinear aircraft model. Stability robustness analysis results for the flight control law are presented in terms of the standard clearance criteria currently used by the European aerospace industry. Comparisons of the results obtained using μ-analysis and current approaches reveal that the new μ tools provide more rigorous and efficient analysis of worst-case aircraft stability characteristics in the presence of multiple sources of parametric uncertainty.