MIMO State Prediction Based Adaptive Control of Aeroelastic Systems with Gust Load

Abstract

This article presents a state predictor-based composite adaptive flutter control system for a nonlinear multi-input multi-output (MIMO) aeroelastic system. The plunge and pitch motion of this 2-D airfoil is controlled by trailing- and leading-edge control flaps. All of the model parameters are assumed to be unknown. The uncontrolled airfoil shows limit cycle oscillations (LCOs) if the freestream velocity exceeds certain specific value. First, an adaptive flutter control module is derived for the model including pitch-axis and plunge-axis structural nonlinearities. Second, the design of a state predictor is presented and a composite adaptation control law is derived. Unlike traditional certainty-equivalence adaptive (CEA) systems, the composite adaptation law uses information not only on the plunge and pitch tracking errors, but also on the state prediction error. Through the Lyapunov analysis, it is shown that the state vector as well as the state prediction error converge to zero. Third, simulation results for the closed-loop system including wind gust are presented. The results show stabilization of oscillatory plunge and pitch motion despite parameter uncertainties and wind gust.