Robustness analysis of controllers designed for active flutter suppression

In this paper different controller design techniques are studied for a linear model of a two dimensional thin airfoil. The controller design methods considered here are, LQG, gap metric optimization, loop-shaping via weighted gap optimization, mixed sensitivity minimization via H/sup /spl infin// design and robust performance optimization via /spl mu/ synthesis. The results of flutter speed analysis are compared for each of these controllers. Also, the effects of unmodelled delays on closed loop stability are discussed with simulation results.