Minimal-Order Distributed Observer for a Network of Heterogeneous Satellites with Flexible Appendages *

This paper deals with the distributed estimation and the attitude coordination problem for a network of heterogeneous satellites with flexible appendages. For the estimation task, the agents employ a distributed observer in a minimal-order formulation to obtain the angular rates of a non-collaborative target, starting from partial measurements of its angular positions. It is proven that, for an undirected topology, the estimation error asymptotically converges to zero if the consensus gain is greater than a certain threshold. The main feature of such an observer is the reduction of its order compared to other approaches in the literature when the observed system can be expressed in an integral state-space form. For the control task, a consensus protocol is shown to achieve attitude coordination among the satellites even though they share only their partial target information. Finally, the separation principle assures that the coupled implementation of the estimation and control procedures gives rise to a stable system. Numerical examples illustrate the results for a mixed network of sensing and non-sensing agents.