Robust Adaptive Finite-Time Prescribed Performance Attitude Tracking Control of Spacecraft

In this paper, a novel adaptive fast nonsingular terminal sliding mode (FNTSM) control approach is proposed for the robust adaptive finite-time prescribed performance attitude tracking control of spacecraft subject to inertia uncertainties, external disturbances, and input saturation. First, a simple error transformation is introduced to guarantee the attitude tracking errors always stay within the predefined performance bounds. Then, a FNTSM surface is presented based on the transformed attitude tracking errors. Finally, an adaptive FNTSM controller is designed by using the adaptive updating law to estimate the square of the norm of the lumped uncertain term. Rigorous theoretical analysis for the practical finite-time stability of the resulting closed-loop system is provided. The proposed adaptive FNTSM controller can guarantee the attitude tracking errors converge to the arbitrarily small region about zero in finite time within the predefined performance bounds. Benefiting from the adaptive estimation technique, the proposed adaptive FNTSM controller is continuous and the unexpected chattering phenomenon is significantly reduced. Moreover, the prior knowledge on the upper bound of the lumped uncertain term is no longer needed in the control design. Simulation experiments illustrate the effectiveness and superiority of the proposed control approach.