Spacecraft Swarm Finite-Thrust Cooperative Control for Common Orbit Convergence

Abstract

A novel decentralized cooperative control protocol is proposed for the convergence of an autonomous spacecraft swarm to a common circular orbit using finite thrust. Guidance and consensus algorithms are designed and implemented in a decentralized fashion to drive agents to an orbit of prescribed semimajor axis and zero eccentricity, with the plane of orbital motion determined through consensus. The thrust-limited guidance and consensus schemes are designed separately and then readily combined to obtain asymptotic stability of the overall closed-loop system. Both the guidance and consensus protocols are designed in the presence of input saturation to satisfy the maximum available thrust magnitude constraint. The guidance law employs a switching strategy, whereas the consensus algorithm uses a smooth saturation function for bounded control input. Through rigorous analysis, it is shown that the multi-agent system converges to a common orbit with the desired eccentricity and semimajor axis when the communication topology is given by a connected and undirected tree or ring graph. In addition, numerical simulation studies are presented for a spacecraft formation around Earth, as well as for a formation with planet Ceres as the primary body, to highlight all of the technical aspects of this work.