Path planning and guidance algorithms for formation reconfiguration

This paper presents innovative approaches for guidance of spacecraft formations during reconfiguration. The proposed strategies are developed under the paradigms of cluster autonomy and safe maneuverability. To that end, a task-assignment algorithm identifies the satellites that need to be rearranged in order to minimize the total propellant consumption. The decision process relies on convex optimization procedures aimed at estimating for each candidate satellite the control law and the maneuvering trajectory that satisfy constraints imposed by the thruster technology and collision avoidance. Two different versions of the path-planning algorithm are proposed. In the centralized approach, the reconfiguration strategy is elaborated by a single unit: the maneuvering trajectories are generated considering solely collision avoidance constraints at expenses of computational costs. The alternative method is conceived such that each satellite autonomously determines its tasks. This de-centralized architecture allows the algorithm to run faster, but entails a higher traffic on the intersatellite communication link. In addition, collision avoidance is approximated to render each optimization independent from the other. For the preliminary validation of the developed routines, a specific mission scenario is considered, with a distributed Synthetic Aperture Radar in a low Earth orbit that has to be reconfigured for tomographic applications. Simulation results show that, once remote-sensing requirements are specified within the limits set by standard products, the developed algorithms can manage autonomously the manoeuvre towards the corresponding operative pattern.