  Transporting objects using aerial robots has been widely studied in the
literature. Still, those approaches always assume that the connection between
the quadrotor and the load is made in a previous stage. However, that previous
stage usually requires human intervention, and autonomous procedures to locate
and attach the object are not considered. Additionally, most of the approaches
assume cables as rigid links, but manipulating cables requires considering the
state when the cables are hanging. In this work, we design and control a
catenary robot. Our robot is able to transport hook-shaped objects in the
environment. The robotic system is composed of two quadrotors attached to the
two ends of a cable. By defining the catenary curve with five degrees of
freedom, position in 3-D, orientation in the z-axis, and span, we can drive the
two quadrotors to track a given trajectory. We validate our approach with
simulations and real robots. We present four different scenarios of
experiments. Our numerical solution is computationally fast and can be executed
in real-time.
