  We study the problem of distance-based formation control in autonomous
multi-agent systems in which only distance measurements are available. This
means that the target formations as well as the sensed variables are both
determined by distances. We propose a fully distributed distance-only control
law, which requires neither a time synchronization of the agents nor storage of
measured data. The approach is applicable to point agents in the Euclidean
space of arbitrary dimension. Under the assumption of infinitesimal rigidity of
the target formations, we show that the proposed control law induces local
uniform asymptotic stability. Our approach involves sinusoidal perturbations in
order to extract information about the negative gradient direction of each
agent's local potential function. An averaging analysis reveals that the
gradient information originates from an approximation of Lie brackets of
certain vector fields. The method is based on a recently introduced approach to
the problem of extremum seeking control. We discuss the relation in the paper.
