  Unmanned Aerial Vehicles (UAVs) are now becoming increasingly accessible to
amateur and commercial users alike. The main task for UAVs is to keep a
prescribed separation with obstacles in the air. In this paper, a
collision-avoidance control method for non-cooperative moving obstacles is
proposed for a multicopter with the altitude hold mode by using a Lyapunov-like
barrier function. Lyapunov-like functions are designed elaborately, based on
which formal analysis and proofs of the proposed control are made to show that
the collision-avoidance control problem can be solved if the moving obstacle is
slower than the multicopter. The result can be extended to some cases of
multiple obstacles. What is more, by the proposed control, a multicopter can
keep away from obstacles as soon as possible, once obstacles enter into the
safety area of the multicopter accidentally, and converge to the waypoint.
Simulations and experiments are given to show the effectiveness of the proposed
method by showing the distance between UAV and waypoint, obstacles
respectively.
