Decentralized Estimation and Control in High Precision Spacecraft Formations: Comparison Studies

Abstract

High-precision formation flying missions can implement very large science instruments, but require a very high level of coordination and control. Two coordination and control architectures are described and evaluated on two small prototypical formation flying missions. The first architecture is based on a decentralized, parallel estimation approach with every spacecraft in the formation maintaining an estimate of the entire formation state. Each spacecraft updates its estimator on the basis of local measurements and communicated information from other spacecraft. The second architecture uses a central spacecraft to maintain the formation estimate and calculate the required control actions for all other spacecraft. Communication is required to convey the measurements and actuation commands between the central spacecraft and the rest of the formation. These case studies illustrate that in the presence of small communication delays and communication channel noise, the decentralized architecture outperforms the centralized one, even in the case where it has fewer communication links.

Formation control for networked spacecraft in deep space: with or without communication delays and with switching topology

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In this paper, several formation controllers are developed with constant and variable connected communication topology for six-degree-of-freedom (6-DOF) networked spacecraft flying in deep space with constant and time-varying communication delays considered. In applications, a MIMO formulation gives better performance in the ideal case but communication amongst the spacecrafts is required [8]. The proposed control strategies allow that each spacecraft can track its desired position and attitude and simultaneously the whole group moves to the desired formation and obtain its desired relative attitudes with its neighbors.

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“…In applications, a MIMO formulation gives better performance in the ideal case but communication amongst the spacecrafts is required [8]. These categories are actually according to the communication model of the spacecraft in formation.…”