Input-to-state stability-based adaptive control for spacecraft fly-around with input saturation

摘要

This study is concerned with the six degrees-of-freedom (6-DOF) tracking control problem for spacecraft fly-around mission in the presence of input saturation and external disturbances. First, to describe the fly-around mission, a coupled 6-DOF relative motion dynamic model is established. Subsequently, a basic controller is designed based on input-to-state stability. To address the input saturation problem, a novel dead-zone operator-based model is introduced. Then, employing input-to-state practical stability theory, a saturated control scheme is technically proposed by incorporating the adaptive technique into backstepping design, which needs no prior knowledge of the external disturbances' bounds. Under this scheme, the system tracking errors can be stabilised to a small domain of convergence around zero. Moreover, the convergence domain can be adjusted by adjusting the control parameters. Finally, comparative simulation examples are carried out to validate the superiority of the proposed control approach.