Disturbance rejection control of morphing aircraft based on switched nonlinear systems

The problem of disturbance rejection control for the longitudinal dynamics of a morphing aircraft is investigated based on switched nonlinear systems. A disturbance observer with nonlinear gains composed of two distinct linear regions is first designed, which adopts the idea of the extended state observer to provide the estimations of disturbances and can reduce the peaking value problem. To achieve disturbance rejection via the designed disturbance observer, two separate controllers are then designed for the velocity and altitude subsystem of the longitudinal motion model, where the altitude subsystem is modeled as switched nonlinear systems in lower triangular form and the backstepping design technique is applied. Furthermore, a modified dynamic surface is introduced at each step of the backstepping method to avoid the explosion of complexity' problem. It is proven rigorously that all signals of the closed-loop system remain bounded by the developed control scheme. Finally, comparative simulations validate the effectiveness of the proposed approach.