Abstract: Robust stability of the aeroservoelastic systems subjected to the perturbation of uncertainties is very important for elastic flight vehicles with automatic flight control systems. A method to build the state-space model ofaeroservoelastic systems is developed based upon linear fractional transformation (L FT) . The whole aeroservoelasticsystem is divided into several subsystems, and the subsystems are modeled considering responding parametric and unparametric uncertainties, respectively. Then the model of the closed-loop system is constructed by assembling theL FT blocks of the subsystems. The structured singular value is used to analyze robust stability according to the μ-method. Two examples are given, and the results show that the aeroservoelastic modeling method is reasonable andthe μ-method is promising in robust stability analysis for aeroservoelastic systems.

Key words: aeroelasticity, aeroservoelasticity, robust stability, μ analysis