Spacecraft Boresight Control with Spatiotemporal Constraints

This paper addresses the boresight control problem of spacecraft under spatial (pointing) and temporal (time) constraints. By using stereographic projection, this problem is transformed into an obstacle avoidance problem in a spherical world of two-dimensional Euclidean space. An integrated planning and control framework is proposed to solve the transformed problem. Specifically, a prescribed-time path planner is developed based on artificial potential field and time transformation techniques, yielding a smooth vector field that can navigate the mapped position vector from almost all initial positions in the free space toward the goal position at a user-specified time, while avoiding entry into augmented obstacle regions with safety margins. Subsequently, an adaptive funnel-following controller is designed, which achieves trajectory tracking along a predefined funnel around the reference trajectory, despite the presence of inertial uncertainties, external disturbances, and actuator faults. By designing the top radius of the funnel to be no larger than the obstacle safety margin and its settling time no larger than the user-specified time, we ensure that the mapped position vector converges to a small neighborhood of the goal position within the required task completion time while avoiding collision with any obstacles along the way. This implies that the proposed controller achieves prescribed-time, pointing-constrained boresight reorientation. Simulation results illustrate the constraint-handling capability of the proposed method.