On communication in decentralized pole-placement formation control and parallel estimation

We consider a class of decentralized formation flying control algorithms that stem from assigning the closed loop poles for the multi-input-multi-output formation system, and examine the role communication plays. First we revisit Smith and Hadaegh [2007], where as many parallel estimators as there are spacecraft are used. We show an intuitive way of demonstrating the existing results, and by a re-interpretation of the quantities communicated, extend the results to the case where observability of the full formation state at each spacecraft is not available. Next we show that the pole-placement formation control can be carried out with only one estimator and no communication, for the double-integrator system used to model deep space formation flying. We treat the task of having one estimator on each spacecraft as separate from the task of control, and show how it can be accomplished with communication.