  Unmanned Aerial Vehicles (UAVs) are now becoming increasingly accessible to
amateur and commercial users alike. An air traffic management (ATM) system is
needed to help ensure that this newest entrant into the skies does not collide
with others. In an ATM, airspace can be composed of airways, intersections and
nodes. In this paper, for simplicity, distributed coordinating the motions of
Vertical TakeOff and Landing (VTOL) UAVs to pass an airway is focused. This is
formulated as a tunnel passing problem, which includes passing a tunnel,
inter-agent collision avoidance and keeping within the tunnel. Lyapunov-like
functions are designed elaborately, and formal analysis based on invariant set
theorem is made to show that all UAVs can pass the tunnel without getting
trapped, avoid collision and keep within the tunnel. What is more, by the
proposed distributed control, a VTOL UAV can keep away from another VTOL UAV or
return back to the tunnel as soon as possible, once it enters into the safety
area of another or has a collision with the tunnel during it is passing the
tunnel. Simulations and experiments are carried out to show the effectiveness
of the proposed method and the comparison with other methods.
