This is the code used for the 2013 IROS submission 3-D Reciprocal Collision Avoidance on Physical Quadrotor Helicopters with On-Board Sensing for Relative Positioning. Please see http://arl.cs.utah.edu/research/orca_quad/ for more information. This package contains all the needed nodes to fly AR.Drone quadrotors in close proximity without collision. This is preformed using ORCA (http://gamma.cs.unc.edu/ORCA/), a custom Kalman filter, and a variety of helper nodes.