Adaptive Output Feedback Control of a Nonlinear Aeroelastic Structure

Abstract

Based on a backstepping design technique, a new adaptive controller for the control of an aeroelastic system using output feedback is derived. The chosen dynamic model describes the nonlinear plunge and pitch motion of a wing. Theparameters of thesystem areassumed to becompletely unknown, and only the plunge displacement and the pitch angle measurements are used for thesynthesis of thecontroller. A canonical state variable representation of the system is derived, and e lters are designed to obtain the estimates of the derivatives of the pitch angle and the plunge displacement. Then adaptive control laws for the trajectory control of the pitch angle and the plunge displacement are derived. In the closed-loop system the state vector asymptotically converges to the origin. Simulation results are presented, which show that regulation of the state vector to the equilibrium state and trajectory following are accomplished using a single control surface in spite of the uncertainty in the aerodynamic and structural parameters. Nomenclature a = nondimensionalized distance from the midchord to the elastic axis bs = semichord of the wing ch = structural damping coefe cient in plunge caused by viscous damping ci, L, Li, = design parameters di, C ca = structural damping coefe cient in pitch caused by