Robust H∞ Control for Hovering of a Quadrotor UAV with Slung Load

This paper proposes hovering flight control for a quadrotor UAV with slung load. A dynamic model considering the states of both quadrotor and slung load is established based on Euler-Lagrange equations. This model is simplified to several linear subsystems via reasonable assumptions. These subsystems are proved completely controllable. A robust H
_∞
controller is designed by utilizing the estimated states of the observer. Due to the lack of sensors to measure the swing angle of the slung load, a reduced order state observer is constructed to estimate these states. The validity of the proposed controller and observer is verified by simulation results.