Robustness Assessment of Flight Controllers for a Civil Aircraft using mu-Analysis

Abstract

This presentation demonstrates an application of µ-analysis for stability robustness assessment of twelve flight controllers for a civil aircraft, designed with nine different synthesis methods, including root locus, eigenstructure assignment, multi model techniques, H_infty, and µ-synthesis. All designs had to satisfy the same set of performance and robustness objectives. The designers had to cope with varying aircraft mass and center of gravity location, and an uncertain computational time delay in the flight control computer. The designers also had to consider a considerable speed envelope. To assess the stability margins of the controllers in face of these (real) parameters, a µ-analysis is performed. In the first place, µ-analysis requires the setup of a Linear Fractional Transformation (LFT) model, representing the complete set of linear models as a function of the uncertainty Modeling (PUM) in Matlab.