Quaternion-based finite time control for spacecraft attitude tracking

This paper investigates the spacecraft attitude tracking control problem. Two robust sliding mode controllers based on the quaternion and Lagrange-like model are proposed to solve this problem both in the absence of model uncertainties and external disturbances as well as in the presence of these. The controllers can guarantee the convergence of attitude tracking errors in finite time rather than in the asymptotic sense, where time tends to infinity. By constructing a particular Lyapunov function, the convergences of the proposed controllers for the closed-loop systems are proven theoretically. To alleviate the chattering phenomenon while at the same time guaranteeing the finite convergence during the process of attitude tracking, a new function is introduced into the controller. Numerical simulations are finally provided to illustrate the performance of the proposed controllers.