Observer-Based Output Feedback Attitude Stabilization for Spacecraft with Finite-Time Convergence

This brief investigates the problem of finite-time output feedback control for spacecraft attitude stabilization without angular velocity measurement. First, two new sufficient conditions for finite-time ultimate boundedness and local finite-time stability are derived, which reduce the conservativeness of the traditional conditions. Then, based on the two new sufficient conditions of the finite-time stability, a finite-time observer is proposed to estimate the unknown angular velocity by using the quadratic Lyapunov function method. Next, a finite-time attitude controller is designed based on the estimate of the angular velocity. The finite-time stability of the entire closed-loop system is analyzed through the Lyapunov approach. The rigorous proof shows that the observation errors and the spacecraft attitude will converge to a residual set of zero in finite time. Numerical simulation results illustrate the effectiveness of the proposed strategy.