Fixed-time control for high-precision attitude stabilization of flexible spacecraft

Abstract

This is a study of adaptive constraint attitude control for a flexible spacecraft in the presence of inertia uncertainties, unknown disturbance, actuator saturation and faults. The proposed controller is designed by incorporating a Prescribed Performance Control (PPC) and fixed-time sliding mode control. First, a novel Nonsingular Fast Fixed-time Sliding Surface (NFFTSS) is introduced. Not only is the settling time independent of initial conditions, but also it is shorter than existing fixed-time attitude controls. Second, different from the conventional complex PPCs in the literature, a simple structure attitude controller is proposed to satisfy the transient and steady-state performance is proposed through a novel log-type PPC. An inherently continuous adaptive switching control is then presented in order to avoid the a priori not to require accurate information of the fault occurrence. Numerical simulations demonstrate that the proposed controller successfully accomplishes attitude control with high attitude pointing accuracy and stability.