Finite-time attitude stabilization of rigid spacecrafts based on control Lyapunov functions

In this paper, the control Lyapunov function (CLF) approach is adopted to investigate the finite-time attitude control of rigid spacecraft subject to parameter uncertainty and external disturbance. By using an extended state observer to estimate the parameter uncertainty and external disturbance, a finite-time CLF controller is proposed for attitude stabilization of the spacecraft system. The designed finite-time CLF controller includes two parts. The first part is a classical CLF based attitude controller, which is proposed to ensure the globally asymptotical stability of the nominal spacecraft system. The second one is a sliding mode controller, which is used to ensure the finite-time convergence performance of the spacecraft control system. The advantage of the designed controller is that the states of the system can converge into a small neighourhood of zero in finite time, and simultaneously the given performance index can be minimized. The practical finite-time stability of the resulted closed-loop system is proven via Lyapunov stability theory. Finally, simulation results illustrate the effectiveness of the developed finite-time controller.