Geometric control of cooperating multiple quadrotor UAVs with a suspended payload

This paper investigates tracking controls for an arbitrary number of cooperating quadrotor unmanned aerial vehicles with a suspended load. Assuming that a point mass is connected to multiple quadrotors by rigid massless links, control systems for quadrotors are constructed such that the point mass asymptotically follows a given desired trajectory and quadrotors maintain a prescribed formation, either relative to the point mass or with respect to the inertial frame. These are developed in a coordinate-free fashion to avoid singularities and complexities associated with local parameterizations. The desirable features are illustrated by several numerical examples, including a flying inverted spherical pendulum on a quadrotor.