Quasi-stationary state transportation of a hose with quadrotors

A hose is a flexible almost unidimensional object. Transportation of a hose by means of a team of collaborating robots poses a new multi-robot control paradigm, because the hose introduces strong non-linear interaction effects in the dynamics of the overall system. In this paper, we consider that a team (n >= 2) of unmanned aerial robots, specifically quadrotors, carry out the hose transportation task. A hose is a Deformable Linear Object (DLO). In this paper, a hose hanging from hovering quadrotors, after reaching a quasi-stationary state is modeled by a catenary curve. We consider the control problem of driving the entire system to a state in which each robot is subjected to the same vertical force (i.e. weight), thus each robot energy consumption will be the same, aiming to prevent that any robot runs out of energy much earlier than the others. This problem can be posed only when we deal with multicatenary systems (n >= 3). We have taken care of defining visually measurable system parameters, allowing visual servoing in real life experimentation. In this paper we present the system model, its dynamic simulation, and the derivation of a control system reaching the desired equiload state. (C) 2014 Elsevier B.V. All rights reserved.