Anti-Unwinding Time-Varying Sliding Mode Control With Arbitrary Convergence Time for Rigid Spacecraft

In this article, the attitude maneuver control with the arbitrary convergence time is investigated for rigid spacecraft. First, a time-varying sliding mode function expressed by a piecewise function is designed by using an exponential function. This designed sliding mode function contains two equilibria of the attitude control systems. Furthermore, an attitude control law is designed with the aid of this new sliding mode function such that the states of the closed-loop attitude system remain on the sliding mode surface from the initial time instant, and converge to the origin at an arbitrarily preset time. In addition, the unwinding phenomenon can also be avoided when the proposed control law is used.