@article {69,
	title = {Aerial Co-Manipulation With Cables: The Role of Internal Force for Equilibria, Stability, and Passivity},
	journal = {IEEE Robotics and Automation Letters, Special Issue on Aerial Manipulation},
	volume = {3},
	year = {2018},
	month = {07/2018},
	pages = {2577-2583},
	abstract = {<p>This letter considers the cooperative manipulation of a cable-suspended load with two generic aerial robots without the need of explicit communication. The role of the internal force for the asymptotic stability of the beam position-and-attitude equilibria is analyzed in depth. Using a nonlinear Lyapunov-based approach, we prove that if a nonzero internal force is chosen, then the asymptotic stabilization of any desired beam attitude can be achieved with a decentralized and communicationless master-slave admittance controller. If, conversely, a zero internal force is chosen, as done in the majority of the state-of-the-art algorithms, the attitude of the beam is not controllable without communication. Furthermore, we formally proof the output-strictly passivity of the system with respect to an energy-like storage function and a certain input-output pair. This proves the stability and the robustness of the method during motion and in nonideal. The theoretical findings are validated through extensive simulations.</p>},
	keywords = {admittance controller, aerial co-manipulation, asymptotic stability, cable-suspended load, communication-less, decentralised control, Lyapunov-based approach, passivity},
	issn = {2377-3766},
	doi = {10.1109/LRA.2018.2803811},
	author = {Marco Tognon and Chiara Gabellieri and Lucia Pallottino and Antonio Franchi}
}
