  Stabilization of a quadrotor without a controller based on cascade structure
is a challenging problem. Besides, due to the dynamics and the number of
underactuation, an energy shaping controller has not been designed in 3D for a
quadrotor. This paper presents a novel solution to the potential energy shaping
problem for a quadrotor utilizing the Interconnection and Damping Assignment
Passivity Based Control (IDA-PBC) approach. For the first time, we extend the
solution of PDEs from the 2D case to the full 3D scenario. This advancement
seems to be a significant step forward for stabilization of underactuated
aerial vehicles without a cascade controller. The results are verified via
simulation on a typical quadrotor.
