Robust Attitude Control with Sigmoid Function Based ESO Compensation for Morphing Aircrafts

To solve the problem of compound perturbation in flight, such as parameter perturbations and deformation interference, a high-precision attitude control method with the SESO(SESO, Sigmoid-based ESO) compensator for a variable back-swept aircraft is studied. Firstly, a control-oriented mathematical model for the morphing aircraft control is established. Secondly, based on the back-stepping theory, the control problem of high-order complex nonlinear systems for such aircraft is decomposed into the design of control laws for low-order subsystems. And the back-stepping sliding-mode control law is designed for the attitude angle and angular velocity system; additionally, considering the large uncertainty in parameter perturbations and strong deformation interference, a composite extended state observer SESO is utilized to estimate the lumped disturbances and compensate them into the control law. Finally, the stability of the closed- loop system is proved based on Lyapunov theory, and the effectiveness of the proposed method is verified through mathematical simulation.