  Using quadrotors UAVs for cooperative payload transportation using cables has
been actively gaining interest in recent years. Understanding the dynamics of
these complex multi-agent systems would help towards designing safe and
reliable systems. In this work, we study one such multi-agent system comprising
of multiple quadrotors transporting a flexible hose. We model the hose as a
series of smaller discrete links and derive a generalized coordinate-free
dynamics for the same. We show that certain configurations of this
under-actuated system are differentially-flat. We linearize the dynamics using
variation-based linearization and present a linear time-varying LQR to track
desired trajectories. Finally, we present numerical simulations to validate the
dynamics, flatness, and control.
