Adaptive RBF observer-sliding mode controller design for a two dimensional aeroelastic system with unsteady aerodynamics

An adaptive RBF observer-sliding mode controller is designed for the vibration suppression of a two-dimensional aeroelastic system, using a single trailing-edge control surface. The prototypical aeroelastic model describes the plunge and pitch motion of a wing, including cubic nonlinear structural stiffness and unsteady aerodynamics. The unsteady aerodynamics are modeled with an approximation to Theodorsen's theory. It's assumed that only the pitch angle is measured and the remaining state variables needed for full state feedback are estimated by the designed observer. A neural-network is employed to approximate the nonlinear dynamics of the observer system, and then a sliding surface is put forward on the estimation space. The finite-time reachability of the predesigned sliding surface is guaranteed by the designed sliding mode control law. The effectiveness of the proposed strategy is finally demonstrated by simulation results.