  In this paper, anti-unwinding attitude maneuver control for rigid spacecraft
is considered. First, in order to avoid the unwinding phenomenon when the
system states are restricted to the switching surface, a novel switching
function is constructed by hyperbolic sine functions such that the switching
surface contains two equilibriums. Then, a sliding mode attitude maneuver
controller is designed based on the constructed switching function to ensure
the robustness of the closed-loop attitude maneuver control system to
disturbance. Another important feature of the developed attitude control law is
that a dynamic parameter is introduced to guarantee the anti-unwinding
performance before the system states reach the switching surface. The
simulation results demonstrate that the unwinding problem is settled during
attitude maneuver for rigid spacecraft by adopting the newly constructed
switching function and proposed attitude control scheme.
