Specific Tracking Control of Rotating Target Spacecraft Under Safe Motion Constraints

This article considers a space mission that a chaser spacecraft approaches and tracks a rotating target at close range under safe motion constraints. The control objective is to keep the chaser hovering at the desired relative position above the specific point of the target and ensure the chaser's line-of-sight pointing to the target. During the proximity process of position and attitude maneuver, two kinds of safe geometric constraints are essential to be considered. One is collision avoidance for position constraint, and the other is the pointing forbidden zone for attitude constraint. Superquadrics curved surface is used to describe the position forbidden. Pointing forbidden is represented by inequality constraint based on SO(3). Combining the artificial potential function with backstepping control methodology and adaptive sliding-mode, a safety robust control law is designed. The proposed control scheme guarantees the chaser to track the target under safe geometric constraints. In addition, by using the dynamic specific point under observation, the proposed control scheme can be applied to other observation missions like close flying around. Finally, simulation results illustrate the effectiveness of the control scheme.