Hierarchical cooperative control framework of multiple quadrotor-manipulator systems

We propose an hierarchical control framework for multiple cooperative quadrotor-manipulator systems, which allows us to endow the common grasped object with a user-specified desired behavior (e.g., trajectory tracking, compliant interaction, etc.). To achieve this, our control framework consists of the following hierarchical layers: 1) object desired behavior design; 2) optimal cooperative force distribution; and 3) individual quadrotor-manipulator control based on object stiffness model, which can also take into account different dynamics characteristics of the (slower/coarse) quadrotor-platform and the (faster/fine) manipulator. Simulations of object transport and compliant interaction with three quadrotor-manipulator systems are performed to illustrate the theory.