Robust output feedback control of an aeroelastic system using modeling error compensation

Abstract

This paper presents an adaptive control system for the trajectory control and stabilization of an aeroelastic system with unstructured model uncertainties using output feedback. The equations of motion of the chosen aeroelastic system describe the plunge and pitch motion of a structurally nonlinear wing section. A single trailing edge flap is used for the purpose of control. For feedback only the pitch angle or the plunge displacement is measured. Unlike the linearly parameterized adaptive systems, in this study the structure of model uncertainties is unknown. Adaptive control laws for the trajectory control of the pitch angle and the plunge displacement are derived. The controller has the structure of an inverse (a feedback linearizing) control system. But the unknown function in the inverse control law arising from the uncertainties in the model is compensated using its estimate constructed by a high gain observer. Simulation results are presented which show that in the closed-loop system, trajectory control of the selected output (pitch angle or plunge displacement) is accomplished and the state vector converges to zero. Furthermore, it is observed that stability and trajectory tracking are preserved in the presence of measurement noise. ca h, hr Ia m U xa