  This paper studies a leader-follower formation tracking problem where the
leaders are moving at the same unknown bounded velocity. A distance-based
control law is proposed for follower agents to maintain the desired distances
in the formation and move at the leaders' velocity. The control law consists of
a component to handle the uncertainty of the leaders' velocity and a component
to achieve the desired distances in finite time. Numerical simulations are also
provided to support the theoretical results.
