Enhanced nonlinear model and control design for a flexible wing

Aeroelastic instabilities due to the interaction between airflow and wings have long constrained the flight envelope of many types of aircrafts. A typical example of these phenomena is fluttering, a self-sustained oscillation in pitch, plunge or flap angle. Control systems and accurate models are then required to describe and suppress this undesired behaviour. However, traditional approaches are based on very simplified models that do not fully capture the complex dynamics associated with the instability, thus limiting the scope of application on real systems. In this paper, a more descriptive model for a flexible wing, taking explicitly into account the nonlinear behaviour of the wing material, the wing structural constraints (e.g. maximum flap deflection) and the unsteady behaviour of the airflow, is presented. Moreover, since the structural nonlinearity is usually not exactly known a priori, a dissipativity-based technique is proposed to simultaneously design the controller, optimally approximate the structural nonlinearity and estimate of the basin of attraction of the equilibrium in the origin.