@conference {2012i-FraRob,
	title = {Decentralized Control of Parallel Rigid Formations with Direction Constraints and Bearing Measurements},
	booktitle = {51th IEEE Conference on Decision and Control },
	year = {2012},
	month = {12/2012},
	pages = {5310-5317},
	address = {Maui, HI},
	abstract = {In this paper we analyze the relationship between scalability, minimality and rigidity, and its application to cooperative control. As a case study, we address the problem of multi-agent formation control by proposing a distributed control strategy that stabilizes a formation described with bearing (direction) constraints, and that only requires bearing measurements and parallel rigidity of the interaction graph. We also consider the possibility of having different graphs modeling the interaction network in order to explicitly take into account the conceptual difference between sensing, communication, control, and parameters stored in the network. We then show how the information can be {\textquoteleft}moved{\textquoteright} from a graph to another making use of decentralized estimation, provided the parallel rigidity property. Finally we present simulative examples in order to show the validity of the theoretical analysis in some illustrative cases.},
	keywords = {Decentralized control, Distributed algorithms, Estimation, Formation control, Motion control of multiple robots, Multi-robot systems},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2012i-FraRob-preprint.pdf},
	author = {Antonio Franchi and Paolo Robuffo Giordano}
}
@article {2012q-FraMasGraRylBueRob,
	title = {Modeling and Control of UAV Bearing-Formations with Bilateral High-Level Steering},
	journal = {The International Journal of Robotics Research, Special Issue on 3D Exploration, Mapping, and Surveillance},
	volume = {31},
	year = {2012},
	month = {10/2012},
	pages = {1504-1525},
	abstract = {In this paper we address the problem of controlling the motion of a group of UAVs bound to keep a formation defined in terms of only relative angles (i.e., a bearing-formation). This problem can naturally arise within the context of several multi-robot applications such as, e.g., exploration, coverage, and surveillance. First, we introduce and thoroughly analyze the concept and properties of bearing-formations, and provide a class of minimally linear sets of bearings sufficient to uniquely define such formations. We then propose a bearing-only formation controller requiring only bearing measurements, converging almost globally, and maintaining bounded inter-agent distances despite the lack of direct metric information. The controller still leaves the possibility to impose group motions tangent to the current bearing-formation. These can be either autonomously chosen by the robots because of any additional task (e.g., exploration), or exploited by an assisting human co-operator. For this latter {\textquoteleft}human-in-the-loop{\textquoteright} case, we propose a multi-master/multi-slave bilateral shared control system providing the co-operator with some suitable force cues informative of the UAV performance. The proposed theoretical framework is extensively validated by means of simulations
and experiments with quadrotor UAVs equipped with onboard cameras. Practical limitations, e.g., limited field-of-view, are also considered.},
	keywords = {Bilateral Shared Control of Mobile Robots, Decentralized control, Force feedback, Formation control, Haptics, Motion control of multiple robots, Multi-robot systems, Teleoperation},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2012q-FraMasGraRylBueRob-preprint.pdf},
	author = {Antonio Franchi and Carlo Masone and Volker Grabe and Markus Ryll and Heinrich H. B{\"u}lthoff and Paolo Robuffo Giordano}
}
@conference {2012g-ZelFraAlgBueRob,
	title = {Rigidity Maintenance Control for Multi-Robot Systems},
	booktitle = {2012 Robotics: Science and Systems Conference},
	year = {2012},
	month = {07/2012},
	address = {Sydney, Australia},
	abstract = {Rigidity of formations in multi-robot systems is important for formation control, localization, and sensor fusion.  This work proposes a rigidity maintenance gradient controller for a multi-agent robot team.  To develop such a controller, we first provide an alternative characterization of the rigidity matrix and use that to introduce the novel concept of the rigidity eigenvalue.  We provide a necessary and sufficient condition relating the positivity of the rigidity eigenvalue to the rigidity of the formation.  The rigidity maintenance controller is based on the gradient of the rigidity eigenvalue with respect to each robot position.  This gradient has a naturally distributed structure, and is thus amenable to a distributed implementation.  Additional requirements such as obstacle and inter-agent collision avoidance, as well as typical constraints such as limited sensing/communication ranges and line-of-sight occlusions, are also explicitly considered.  Finally, we present a simulation with a group of seven quadrotor UAVs to demonstrate and validate the theoretical results.},
	keywords = {Decentralized control, Formation control, Motion control of multiple robots, Multi-robot systems, Rigidity mainenance},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2012g-ZelFraAlgBueRob-preprint.pdf},
	author = {Daniel Zelazo and Antonio Franchi and Frank Allg{\"o}wer and Heinrich H. B{\"u}lthoff and Paolo Robuffo Giordano}
}
@article {2012f-FraSecRylBueRob,
	title = {Shared Control: Balancing Autonomy and Human Assistance with a Group of Quadrotor UAVs.},
	journal = {IEEE Robotics and Automation Magazine, Special Issue on Aerial Robotics and the Quadrotor Platform},
	volume = {19},
	year = {2012},
	month = {09/2012},
	pages = {57-68},
	abstract = {In this paper, we present a complete control framework and associated experimental testbed for the bilateral shared control of a group of quadrotor UAVs. This control architecture is applicable to any task and allows to integrate: i) a decentralized topological motion control (responsible for the mutual interactions in the UAV formation), ii) a human assistance module (allowing human intervention, whenever needed, on some aspects of the UAV group behavior), and iii) a force-feedback possibility (increasing the telepresence of the human assistants by providing suitable haptic cues informative of the UAV behavior). 
We will show, as worked-out case studies, how to specialize the topological motion controller to the relevant cases of constant, unconstrained and connected group topologies, and how to let a human operator intervening at the level of single UAVs or of the whole group dynamics.
A detailed description of the experimental testbed is also provided with emphasis on the quadrotor UAV hardware and software architectures. Finally, the versatility of the proposed framework is demonstrated by means of experiments with real UAVs. Although quadrotors are used as actual robotic platforms, the proposed framework can be straightforwardly extended to many different kinds of UAVs with similar motion characteristics.},
	keywords = {Bilateral Shared Control of Mobile Robots, Decentralized control, Force feedback, Formation control, Haptics, Middleware for robotics, Motion control of multiple robots, Multi-robot systems, UAV hardware platforms},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2012f-FraSecRylBueRob-preprint.pdf},
	author = {Antonio Franchi and Cristian Secchi and Markus Ryll and Heinrich H. B{\"u}lthoff and Paolo Robuffo Giordano}
}
@conference {2011i-FraMasBueRob,
	title = {Bilateral Teleoperation of Multiple UAVs with Decentralized Bearing-only Formation Control},
	booktitle = {2011 IEEE/RSJ Int. Conf. on Intelligent Robots and Systems},
	year = {2011},
	month = {09/2011},
	pages = {2215-2222},
	address = {San Francisco, CA},
	abstract = {We present a decentralized system for the bilateral teleoperation of groups of UAVs which only relies
on relative bearing measurements, i.e., without the need of distance information or global localization. The properties of a 3D bearing-formation are analyzed, and a minimal set of bearings needed for its definition is provided. We also design a novel decentralized formation control almost globally convergent and able to maintain bounded and non-vanishing inter-distances among the agents despite the absence of direct distance measurements. Furthermore, we develop a multimaster/multi-slave teleoperation setup in order to control the overall behavior of the group and to convey to the human operator suitable force cues, while ensuring stability in presence of delays and packet losses over the master-slave communication channel. The theoretical framework is validated by means of extensive human/hardware in-the-loop simulations using two force-feedback devices and a group of quadrotors.},
	keywords = {Bilateral Shared Control of Mobile Robots, Decentralized control, Force feedback, Formation control, Haptics, Motion control of multiple robots, Multi-robot systems, Teleoperation},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2011i-FraMasBueRob-preprint.pdf , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2011i-FraMasBueRob.mp4},
	author = {Antonio Franchi and Carlo Masone and Heinrich H. B{\"u}lthoff and Paolo Robuffo Giordano}
}
@booklet {2011o-Fra,
	title = {Decentralized Bilateral Aerial Teleoperation of Multiple UAVs - Part I: a Top-Down Perspective},
	howpublished = {RSS 2011 Workshop on 3D Exploration, Mapping, and Surveillance with Aerial Robots},
	year = {2011},
	month = {06/2011},
	address = {Los Angeles, CA},
	keywords = {Bilateral Shared Control of Mobile Robots, Decentralized control, Force feedback, Formation control, Haptics, Multi-robot systems, Teleoperation},
	author = {Antonio Franchi}
}
@conference {2011b-LeeFraRobSonBue,
	title = {Haptic Teleoperation of Multiple Unmanned Aerial Vehicles over the Internet},
	booktitle = { 2011 IEEE Int. Conf. on Robotics and Automation},
	year = {2011},
	month = {05/2011},
	pages = {1341-1347},
	address = {Shanghai, China},
	abstract = {We propose a novel haptic teleoperation control framework for multiple unmanned aerial vehicles (UAVs) over the Internet, consisting of the three control layers: 1) UAV control layer, where each UAV is abstracted by, and is controlled to follow the trajectory of, its own kinematic virtual point (VP); 2) VP control layer, which modulates each VP{\textquoteright}s motion according to the teleoperation commands and local artificial potentials (for inter-VP/VP-obstacle collision avoidance and inter-VP connectivity preservation); and 3) teleoperation layer, through which a remote human user can command all (or some) of the VPs{\textquoteright} velocity while haptically perceiving the state of all (or some) of the UAVs over the Internet.
Master-passivity/slave-stability and some asymptotic performance measures are proved. Semi-experiment results are presented to validate the theory.},
	keywords = {Bilateral Shared Control of Mobile Robots, Decentralized control, Force feedback, Formation control, Haptics, Multi-robot systems, Teleoperation},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2011b-LeeFraRobSonBue-preprint.pdf , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2011b-LeeFraRobSonBue-low_qlty.mp4},
	author = {Dongjun Lee and Antonio Franchi and Paolo Robuffo Giordano and Hyoung Il Son and Heinrich H. B{\"u}lthoff}
}
@conference {2010c-FraSteDirOri,
	title = {Distributed Target Localization and Encirclement with a Multi-robot System},
	booktitle = {7th IFAC Symposium on Intelligent Autonomous Vehicles},
	year = {2010},
	month = {09/2010},
	address = {Lecce, Italy},
	abstract = {This paper presents a control scheme for localizing and encircling a target using a multi-robot system. The task is achieved in a distributed way, in that each robot only uses local information gathered by on-board relative-position sensors assumed to be noisy, anisotropic, and unable to detect the identity of the measured object. Communication between the robots is provided by limited-range transceivers.  Experimental results with stationary and Multi-robot systems, distributed control, mutual localization, encirclement.moving targets support the theoretical analysis.  
},
	keywords = {Decentralized control, Distributed algorithms, Estimation, Formation control, Multi-robot systems},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2010c-FraSteDirOri-preprint.pdf},
	author = {Antonio Franchi and Paolo Stegagno and Maurizio Di~Rocco and Giuseppe Oriolo}
}
@conference {2010a-FraOriSte,
	title = {On the Solvability of the Mutual Localization Problem with Anonymous Position Measures},
	booktitle = {2010 IEEE Int. Conf. on Robotics and Automation},
	year = {2010},
	month = {05/2010},
	pages = {3193-3199},
	address = {Anchorage, AK},
	abstract = {This paper formulates and investigates a novel problem called Mutual Localization with Anonymous Position Measures. This is an extension of Mutual Localization with Position Measures, with the additional assumption that the identities of the measured robots are not known. A necessary and sufficient condition for the uniqueness of the solution is presented, which requires O(n^2/\log n) to be verified and is based on the notion of rotational symmetry in R^2. We also derive the relationship between the number of robots and the number of possible solutions, and classify the solutions in a number of equivalence classes which is linear in n. A control law is finally proposed that effectively breaks symmetric formations so as to guarantee unique solvability of the problem is also proposed; its performance is illustrated through simulations.},
	keywords = {Estimation, Formation control, Localization, Multi-robot systems},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2010a-FraOriSte.pdf , https://homepages.laas.fr/afranchi/robotics/sites/default/files/ICRA10-Final.mp4},
	author = {Antonio Franchi and Giuseppe Oriolo and Paolo Stegagno}
}
@mastersthesis {60,
	title = {Decentralized Methods for Cooperative Task  Execution in Multi-robot Systems},
	year = {2009},
	month = {12/2009},
	school = {"La Sapienza" University of Rome},
	type = {PhD},
	keywords = {Coverage, Decentralized control, Distributed algorithms, Estimation, Exploration, Formation control, Localization of ground robots, Middleware for robotics, Motion control of multiple robots, Multi-robot systems, Patrolling / Surveillance, Pursuit-evasion / Clearing},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2009-Franchi_PhDThesis.pdf},
	author = {Antonio Franchi}
}
