“…A disadvantage is that the formation does not tolerate failures at the leader level, since the leader's trajectory is independent of the motion of the associated followers. Recently graph theoretic methods have been widely applied to formation problems: see for example [8,9,10,11,12,13,14] and the references therein. In [8], a swarm of satellites around a planet on a circular orbit, modelled as Clohessy-Wiltshire (CW) equations, is considered, and disturbance terms are assumed to be absent.…”