  Aerial manipulator, which is composed of an UAV (Unmanned Aerial Vehicle) and
a multi-link manipulator and can perform aerial manipulation, has shown great
potential of applications. However, dynamic coupling between the UAV and the
manipulator makes it difficult to control the aerial manipulator with high
performance. In this paper, system modeling and control problem of the aerial
manipulator are studied. Firstly, an UAV dynamic model is proposed with
consideration of the dynamic coupling from an attached manipulator, which is
treated as disturbance for the UAV. In the dynamic model, the disturbance is
affected by the variable inertia parameters of the aerial manipulator system.
Then, based on the proposed dynamic model, a disturbance compensation robust
$H_{\infty}$ controller is designed to stabilize flight of the UAV while the
manipulator is in operation. Finally, experiments are conducted and the
experimental results demonstrate the feasibility and validity of the proposed
control scheme.
