Velocity-Free Attitude Control for Flexible Spacecraft With Global Finite-Time Convergence

In this brief, a global finite-time attitude control algorithm is proposed for flexible spacecraft without angular velocity measurement. First, a global finite-time observer is designed to estimate unknown angular velocity, eliminating the assumption that the derivative of attitude angle or initial angular velocity is bounded. Based on the proposed observer, a non-overestimated adaptive terminal sliding mode control (ATSMC) algorithm is designed to realize global finite-time attitude control. The main feature of this brief is that the upper bound of lumped uncertainty considered in this brief is related to angular velocity rather than constant, which is more practical. The stability of entire closed-loop system is guaranteed by Lyapunov function. Finally, numerical simulations are given to illustrate the efficiency of the proposed control algorithm.