  In this paper, we investigate distributed multi-agent tracking of a convex
set specified by multiple moving leaders with unmeasurable velocities. Various
jointly-connected interaction topologies of the follower agents with
uncertainties are considered in the study of set tracking. Based on the
connectivity of the time-varying multi-agent system, necessary and sufficient
conditions are obtained for set input-to-state stability and set integral
input-to-state stability for a nonlinear neighbor-based coordination rule with
switching directed topologies. Conditions for asymptotic set tracking are also
proposed with respect to the polytope spanned by the leaders.
