Unwinding-Free Performance of a Sliding-Mode Spacecraft Pose Controller Designed by Fully Actuated System Approaches

This study designs a sliding mode controller via the fully actuated system (FAS) methodology for spacecraft pose (position and attitude) control and executes a comparison between the designed FAS controller (the sliding mode controller) and a sliding mode controller designed by the state space approaches. The controller design is based on a dual-quaternion-based FAS deduced by the FAS methodology. The comparison reveals the superiority of the FAS methodology in eliminating the unwinding phenomenon. Because the designed FAS controller has a special structure, it is free from the effect of the double cover property of the dual-quaternion-based pose description. This effect results in the unwinding phenomenon, which significantly increases the input consumption. Nevertheless, since conventional sliding mode controllers designed by the state space approaches are not immune to this effect, these controllers fail to prevent the unwinding phenomenon. The unwinding-free performance of the designed sliding mode controller is verified through analyses and simulations.