Extended state observer-based third-order sliding mode finite-time attitude tracking controller for rigid spacecraft

Abstract

In this paper, the attitude tracking control problem for a rigid spacecraft in the presence of systemparameter uncertainties and external disturbances is addressed. First, a new nonsingular finite-time sliding surface is introduced and third-order sliding mode finite-time attitude control law is designed to achieve precise accurate tracking responses and robustness against inertia uncertainties and external disturbances.The stability of the closed-loop system is rigorously proved using the Lyapunov stability theory.Then, a new finite-time extended state observer is established to estimate total disturbances of the system.The extended stated observer-based sliding mode control technique yields improved disturbance rejection and high-precision attitude tracking. Moreover, this control law can avoid the unwinding phenomenon and overcome the input saturation constraint by introducing an auxiliary variable to compensate for the overshooting.A Lyapunov based analysis is provided to guarantee sufficiently small observation error and stabilization of the closed-loop system in finite time. Numerical simulations are conducted to verify the effectiveness of the proposed control method.