  In this paper, we propose a reachable set based collision avoidance algorithm
for unmanned aerial vehicles (UAVs). UAVs have been deployed for agriculture
research and management, surveillance and sensor coverage for threat detection
and disaster search and rescue operations. It is essential for the aircraft to
have on-board collision avoidance capability to guarantee safety. Instead of
the traditional approach of collision avoidance between trajectories, we
propose a collision avoidance scheme based on reachable sets and tubes. We then
formulate the problem as a convex optimization problem seeking suitable control
constraint sets for participating aircraft. We have applied the approach on a
case study of two quadrotors and two fix-wing aircraft collision avoidance
scenario.
