Finite-time trajectory tracking control for entry guidance

In this paper, the trajectory tracking guidance problem is investigated for entry vehicle in the presence of uncertainty. First, a robust nonsingular fast terminal sliding mode control law is designed to guarantee the finite-time tracking performance under uncertainty. Then, to eliminate the need of prior information about uncertainty and mitigate the chattering, a novel adaptive nonsingular fast terminal sliding mode control is proposed by employing adaptive parameter tuning law. Furthermore, with the help of designed adaptation mechanism, the proposed adaptive nonsingular fast terminal sliding mode control can achieve finite-time convergence of both tracking errors and parameter estimation errors simultaneously. Finally, numerical simulations are given to demonstrate the effectiveness and high-precision tracking performance of the proposed controllers.