Finite time sliding sector control for spacecraft atmospheric entry guidance

The paper presents a novel variable structure control with finite time sliding sector for spacecraft atmospheric entry guidance. The finite time convergence of tracking error in the presence of system uncertainty can be guaranteed. In contrast with the normally used notion of asymptotic stability in conventional sliding sector, a finite time sliding sector for the entry guidance is designed as a subset of state space in which the Lyapunov function candidate satisfies the finite time stability condition. Then, the finite time sliding sector controller is designed to guarantee the tracking error to converge to a small region of zero. The chattering existing on the boundary of the sliding sector is further reduced by introducing inner sector and outer sector which are the subsets of the proposed sector. Finally, numerical simulation results are given to demonstrate the effectiveness of the proposed method.