  Unmanned Aerial Vehicles (UAVs) are now becoming increasingly accessible to
amateur and com-mercial users alike. Several types of airspace structures are
proposed in recent research, which include several structured free flight
concepts. In this paper, for simplic-ity, distributed coordinating the motions
of multicopters in structured airspace concepts is focused. This is formulated
as a free flight problem, which includes convergence to destination lines and
inter-agent collision avoidance. The destination line of each multicopter is
known a priori. Further, Lyapunov-like functions are designed elaborately, and
formal analysis and proofs of the proposed distributed control are made to show
that the free flight control problem can be solved. What is more, by the
proposed controller, a multicopter can keep away from another as soon as
possible, once it enters into the safety area of another one. Simulations and
experiments are given to show the effectiveness of the proposed method.
