@article {2017k-NesRobBueFra,
	title = {Decentralized Simultaneous Multi-target Exploration using a Connected Network of Multiple Robots},
	journal = {Autonomous Robots},
	volume = {41},
	year = {2017},
	month = {03/2016},
	pages = {989-1011},
	abstract = {This paper presents a novel decentralized control strategy for a multi-robot system that enables parallel multi-target exploration while ensuring a time-varying connected topology in cluttered 3D environments. Flexible continuous connectivity is guaranteed by building upon a recent connectivity maintenance method, in which limited range, line-of-sight visibility, and collision avoidance are taken into account at the same time.
Completeness of the decentralized multi-target exploration algorithm is guaranteed by dynamically assigning the robots with different motion behaviors during the exploration task. One major group is subject to a suitable downscaling of the main traveling force based on the traveling efficiency of the current leader and the direction alignment between traveling and connectivity force. This supports the leader in always reaching its current target and, on a larger time horizon, that the whole team realizes the overall task in finite time.
Extensive Monte~Carlo simulations with a group of several quadrotor UAVs show the scalability and effectiveness of the proposed method and experiments validate its practicability. },
	keywords = {Connectivity maintenance, Exploration, Motion control of multiple robots, Patrolling / Surveillance},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/1505.05441v3.pdf , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2016g-NesRobBueFra-exp.mp4 , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2016g-NesRobBueFra-empty.mp4 , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2016g-NesRobBueFra-office.mp4 , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2016g-NesRobBueFra-town.mp4},
	author = {Thomas Nestmeyer and Paolo Robuffo Giordano and Heinrich H. B{\"u}lthoff and Antonio Franchi}
}
@conference {2013d-SecFraBueRob,
	title = {Bilateral Control of the Degree of Connectivity in Multiple Mobile-robot Teleoperation},
	booktitle = {2013 IEEE Int. Conf. on Robotics and Automation},
	year = {2013},
	month = {05/2013},
	address = {Karlsruhe, Germany},
	abstract = {This paper presents a novel bilateral controller that allows to stably teleoperate the degree of connectivity in the mutual interaction between a remote group of mobile robots considered as the slave-side.
A distributed leader-follower scheme allows the human operator to command the overall group motion. The group autonomously maintains the connectivity of the interaction graph by using a decentralized gradient descent approach applied to the Fiedler eigenvalue of a properly weighted Laplacian matrix. 
The degree of connectivity, and then the flexibility, of the interaction graph can be finely tuned by the human operator through an additional bilateral teleoperation channel. Passivity of the overall system is theoretically proven and  extensive human/hardware in-the-loop simulations are presented to empirically validate the theoretical analysis.},
	keywords = {Bilateral Shared Control of Mobile Robots, Connectivity maintenance},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2013d-SecFraBueRob.pdf , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2013d-SecFraBueRob.mp4},
	author = {Cristian Secchi and Antonio Franchi and Heinrich H. B{\"u}lthoff and Paolo Robuffo Giordano}
}
@booklet {2013l-NesRobFra,
	title = {Human-assisted Parallel Multi-target Visiting in a Connected Topology},
	howpublished = {6th Int. Work. on Human-Friendly Robotics},
	year = {2013},
	month = {10/2012},
	address = {Rome, Italy},
	keywords = {Bilateral Shared Control of Mobile Robots, Connectivity maintenance, Motion control of multiple robots},
	author = {Thomas Nestmeyer and Paolo Robuffo Giordano and Antonio Franchi}
}
@booklet {2013h-NesRieLaeHarBotRobFra,
	title = {Interactive Demo: Haptic Remote Control of Multiple UAVs with Autonomous Cohesive Behavior},
	howpublished = {Int. Work. on Towards Fully Decentralized Multi-Robot Systems: Hardware, Software and Integration, at 2013 IEEE Int. Conf. on Robotics and Automation},
	year = {2013},
	month = {05/2013},
	address = {Karlsruhe, Germany},
	keywords = {Bilateral Shared Control of Mobile Robots, Connectivity maintenance, Middleware for robotics, UAV hardware platforms},
	url = {http://icra2013mrs.tuebingen.mpg.de/},
	author = {Thomas Nestmeyer and Martin Riedel and Johannes L{\"a}chele and Simon Hartmann and Fiete Botschen and Paolo Robuffo Giordano and Antonio Franchi}
}
@booklet {2012f-NesRobFra,
	title = {Multi-target Simultaneous Exploration with Continual Connectivity},
	howpublished = {2th Int. Work. on Crossing the Reality Gap - From Single to Multi- to Many Robot Systems, at 2013 IEEE Int. Conf. on Robotics and Automation},
	year = {2013},
	month = {05/2013},
	address = {Karlsruhe, Germany},
	keywords = {Connectivity maintenance, Exploration, Motion control of multiple robots},
	author = {Thomas Nestmeyer and Paolo Robuffo Giordano and Antonio Franchi}
}
@article {2013l-RobFraSecBue,
	title = {A Passivity-Based Decentralized Strategy for Generalized Connectivity Maintenance},
	journal = {The International Journal of Robotics Research},
	volume = {32},
	year = {2013},
	month = {03/2013},
	pages = { 299-323},
	abstract = {The design of decentralized controllers coping with the typical constraints on the inter-robot sensing/communication capabilities represents a promising direction in multi-robot research thanks to the inherent scalability and fault tolerance of these approaches. In these cases, connectivity of the underlying interaction graph plays a fundamental role: it represents a necessary condition for allowing a group or robots achieving a common task by resorting to only local information. Goal of this paper is to present a novel decentralized strategy able to enforce connectivity maintenance for a group of robots in a flexible way, that is, by granting large freedom to the group internal configuration so as to allow establishment/deletion of interaction links at anytime as long as global connectivity is preserved. A peculiar feature of our approach is that we are able to embed into a unique connectivity preserving action a large number of constraints and requirements for the group: (i) presence of specific inter-robot sensing/communication models, (ii) group requirements such as formation control, and (iii) individual requirements such as collision avoidance. This is achieved by defining a suitable global potential function of the second smallest eigenvalue λ2 of the graph Laplacian, and by computing, in a decentralized way, a gradient-like controller built on top of this potential. Simulation results obtained with a group of quadorotor UAVs and UGVs, and experimental results obtained with four quadrotor UAVs, are finally presented to thoroughly illustrate the features of our approach on a concrete case study.},
	keywords = {Bilateral Shared Control of Mobile Robots, Connectivity maintenance, Motion control of multiple robots},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2013l-RobFraSecBue-preprint.pdf , https://homepages.laas.fr/afranchi/robotics/sites/default/files/IJRRConn_MM_1_LQ.mp4},
	author = {Paolo Robuffo Giordano and Antonio Franchi and Cristian Secchi and Heinrich H. B{\"u}lthoff}
}
@conference {2011e-RobFraSecBue,
	title = {Bilateral Teleoperation of Groups of UAVs with Decentralized Connectivity Maintenance},
	booktitle = {2011 Robotics: Science and Systems Conference},
	year = {2011},
	month = {06/2011},
	address = {Los Angeles, CA},
	abstract = {In this paper, we present a decentralized passivity-based control strategy for the bilateral teleoperation of a fleet of Unmanned Aerial Vehicles (UAVs). The human operator at the master side can command the fleet motion and receive suitable force cues informative about the remote environment. By properly controlling the energy exchanged within the slave side (the UAV fleet), we guarantee that the connectivity of the fleet is preserved and we prevent inter-agent and obstacle collisions. At the same time, we allow the behavior of the UAVs to be as flexible as possible with arbitrary split and join maneuvers. The results of the paper are validated through semi-experiments.},
	keywords = {Bilateral Shared Control of Mobile Robots, Connectivity maintenance, Decentralized control, Distributed algorithms, Estimation, Force feedback, Haptics, Multi-robot systems, Teleoperation},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2011e-RobFraSecBue-preprint.pdf , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2011e-RobFraSecBue-almost_preprint.pdf , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2011e-RobFraSecBue.mp4},
	author = {Paolo Robuffo Giordano and Antonio Franchi and Cristian Secchi and Heinrich H. B{\"u}lthoff}
}
