@article {2021e-RylBicGiuLovFra,
	title = {FAST-Hex - A Morphing Hexarotor: Design, Mechanical Implementation, Control and Experimental Validation},
	journal = {IEEE/ASME Transactions on Mechatronics},
	year = {2021},
	doi = {10.1109/TMECH.2021.3099197},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2021e-RylBicGiuLovFra.pdf , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2021e-RylBicGiuLovFra.mp4},
	author = {Markus Ryll and Davide Bicego and Mattia Giurato and Marco Lovera and Antonio Franchi}
}
@article {2021d-HorHamGieFra,
	title = {Optimal Tuning of the Lateral-Dynamics Parameters for Aerial Vehicles with Bounded Lateral Force},
	journal = {IEEE Robotics and Automation Letters},
	volume = {6},
	year = {2021},
	pages = {3949-3955},
	doi = {10.1109/LRA.2021.3067229},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2021d-HorHamGieFra.pdf , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2021d-HorHamGieFra.mp4},
	author = {Dariusz Horla and Mahmoud Hamandi and Wojciech Giernacki and Antonio Franchi}
}
@article {2019l-GabTogPalFra,
	title = {A Study on Force-based Collaboration in Swarms},
	journal = {Swarm Intelligence},
	volume = {14},
	year = {2019},
	month = {11/2019},
	pages = {57-82},
	abstract = {Cooperative manipulation is a basic skill in groups of humans, ani- mals, and in many robotic applications. Besides being an interesting challenge, communication-less approaches have been applied to groups of robots in order to achieve higher scalability and simpler hardware and software design. We present a generic model and control law for robots cooperatively manipulating an object, for both ground and floating systems.
The control method exploits a leader-follower scheme and is based only on implicit communication (i.e., the sensing of contact forces). The control objective mainly consists of steering the object manipulated by the swarm of robots to a desired position and orientation in a cooperative way. For a system with just one leader, we present analytical results on the equilibrium configurations and their stability that are then validated by numerical simulations. The role of object in- ternal forces (induced by the robots through contact forces) is discussed in terms of convergence of the object position and orientation to the desired values. We also present a discussion on additional properties of the controlled system that were investigated using thorough numerical analysis, namely, the robustness of the system when the object is subject to external disturbances in non-ideal condi- tions, and how the number of leaders in the swarm can affect the aforementioned convergence and robustness.},
	doi = {10.1007/s11721-019-00178-7},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2019l-GabTogPalFra.pdf},
	author = {Chiara Gabellieri and Marco Tognon and Dario Sanalitro and Lucia Pallottino and Antonio Franchi}
}
@article {2019e-TogTelGasSabBicMalLanSanRevCorFra,
	title = {A Truly Redundant Aerial Manipulator System with Application to Push-And-Slide Inspection in Industrial Plants},
	journal = {IEEE Robotics and Automation Letters},
	volume = {4},
	year = {2019},
	month = {04/2019},
	pages = {1846-1851},
	abstract = {We present the design, motion planning and control of an aerial manipulator for non-trivial physical interaction tasks, such as pushing while sliding on curved surfaces {\textendash} a task which is motivated by the increasing interest in autonomous non-destructive tests for industrial plants. The proposed aerial manipulator consists of a multidirectional-thrust aerial vehicle {\textendash} to enhance physical interaction capabilities {\textendash} endowed with a 2-DoFs lightweight arm {\textendash} to enlarge its workspace. This combination makes it a truly-redundant manipulator going beyond standard aerial manipulators based on collinear multi- rotor platforms. The controller is based on a PID method with a {\textquoteleft}displaced{\textquoteright} positional part that ensures asymptotic stability despite the arm elasticity. A kinodynamic task-constrained and control-aware global motion planner is used. Experiments show that the proposed aerial manipulator system, equipped with an Eddy Current probe, is able to scan a metallic pipe sliding the sensor over its surface and preserving the contact. From the measures, a weld on the pipe is successfully detected and mapped.},
	doi = {10.1109/LRA.2019.2895880},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2019e-TogTelGasSabBicMalLanSanRevCorFra-preprint.pdf , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2019e-TogTelGasSabBicMalLanSanRevCorFra.mp4},
	author = {Marco Tognon and Hermes Tello Chavez and Enrico Gasparin and Quentin Sabl{\'e} and Davide Bicego and Anthony Mallet and Marc Lany and Gilles Santi and Bernard Revaz and Juan Cort{\'e}s and Antonio Franchi}
}
@article {2018h-TogGabPalFra,
	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},
	note = {Also selected for presentation at the 2018 IEEE Int. Conf. on Robotics and Automation, Brisbane , Australia},
	month = {02/2018},
	pages = {2577-2583},
	abstract = {This paper 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 non-zero internal force is chosen, then the asymptotic stabilization of any desired beam attitude can be achieved with a decentralized and communication-less 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 prove 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 non-ideal conditions. The theoretical findings are validated through extensive simulations.},
	doi = {10.1109/LRA.2018.2803811},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2018h-TogGabPalFra-preprint.pdf},
	author = {Marco Tognon and Chiara Gabellieri and Lucia Pallottino and Antonio Franchi}
}
@conference {2018p-GabTogPalFra,
	title = {A Study on Force-based Collaboration in Flying Swarms},
	booktitle = {11th Int. Conf. on Swarm Intelligence ANTS 2018},
	year = {2018},
	month = {10/2018},
	address = {Rome, Italy},
	abstract = {This work investigates collaborative aerial transportation by swarms of agents based only on implicit information, enabled by the physical interaction among the agents and the environment. Such a coordinating mechanism in collaborative transportation is a basic skill in groups of social animals. We consider cable-suspended objects transported by a swarm of flying robots and we formu- late several hypothesis on the behavior of the overall system which are validated thorough numerical study. In particular, we show that a nonzero internal force re- duces to one the number of asymptotically stable equilibria and that the internal force intensity is directly connected to the convergence rate. As such, the internal force represents the cornerstone of a communication-less cooperative manipula- tion paradigm in swarms of flying robots. We also show how a swarm can achieve a stable transportation despite the imprecise knowledge of the system parameters.},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2018p-GabTogPalFra-preprint.pdf},
	author = {Chiara Gabellieri and Marco Tognon and Lucia Palottino and Antonio Franchi}
}
@conference {2015c-GioMohFraPra,
	title = {A Force-based Bilateral Teleoperation Framework for Aerial Robots in Contact with the Environment},
	booktitle = {2015 IEEE Int. Conf. on Robotics and Automation},
	year = {2015},
	month = {05/2015},
	pages = {318-324},
	address = {Seattle, WA},
	keywords = {Aerial Physical Interaction, Aerial Robotics, Bilateral Shared Control of Mobile Robots},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2015c-GioMohFraPra-preprint.pdf , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2015c-GioMohFraPra.mp4},
	author = {Guido Gioioso and Mostafa Mohammadi and Antonio Franchi and Domenico Prattichizzo}
}
@conference {2014a-GioFraSalSchPra,
	title = {The Flying Hand: a Formation of UAVs for Cooperative Aerial Tele-Manipulation},
	booktitle = {2014 IEEE Int. Conf. on Robotics and Automation},
	year = {2014},
	month = {05/2014},
	pages = {4335-4341},
	address = {Hong Kong, China},
	abstract = {The flying hand is a robotic hand consisting of a swarm of UAVs able to grasp an object where each UAV contributes to the grasping task with a single contact point at the tooltip. The swarm of robots is teleoperated by a human hand whose fingertip motions are tracked, e.g., using an RGB-D camera. We solve the kinematic dissimilarity of this unique master-slave system using a multi-layered approach that includes: a hand interpreter that translates the fingertip motion in a desired motion for the object to be manipulated; a mapping algorithm that transforms the desired object motions into a suitable set of virtual points deviating from the planned contact points; a compliant force control for the case of quadrotor UAVs that allows to use them as indirect 3D force effectors. Visual feedback is also used as sensory substitution technique to provide a hint on the internal forces exerted on the object. We validate the approach with several human-in-the-loop simulations including the full physical model of the object, contact points and UAVs.},
	keywords = {Aerial Physical Interaction, Aerial Robotics, Bilateral Shared Control of Mobile Robots, Motion control of multiple robots},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2014a-GioFraSalSchPra-preprint.pdf , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2014a-GioFraSalSchPra.mp4},
	author = {Guido Gioioso and Antonio Franchi and Gionata Salvietti and Stefano Scheggi and Domenico Prattichizzo}
}
@booklet {2014l-GioSalFraMalSchMelRylBuePra,
	title = {The Flying Hand: a Teleoperation Framework for Cooperative Aerial Grasping and Transportation},
	howpublished = {Automatica.it 2014, Convegno Annuale dei Docenti e Ricercatori Italiani in Automatica},
	year = {2014},
	month = {09/2014},
	address = {Bergamo, Italy},
	keywords = {workshop},
	author = {Guido Gioioso and Gionata Salvietti and Antonio Franchi and Monica Malvezzi and Stefano Scheggi and L. Meli and Markus Ryll and Heinrich H. B{\"u}lthoff and Domenico Prattichizzo}
}
@conference {2014g-GagOriBueFra,
	title = {Image-based Road Network Clearing without Localization and without Maps using a Team of UAVs},
	booktitle = {2014 European Control Conference},
	year = {2014},
	month = {06/2014},
	pages = {1902-1908},
	address = {Strasbourg, France},
	abstract = {We address the problem of clearing an arbitrary and unknown network of roads using an organized team of Unmanned Aerial Vehicles (UAVs) equipped with a monocular down-facing camera, an altimeter, plus high-bandwidth short- range and low-bandwidth long-range communication systems. We allow the UAVs to possibly split in several subgroups. In each subgroup a leader guides the motion employing a hierarchical coordination. A feature/image-based algorithm guides the subgroup toward the unexplored region without any use of global localization or environmental mapping. At the same time all the entry-points of the the explored region are kept under control, so that any moving object that enters or exits the previously cleared area. Simulative results on real aerial images demonstrate the functionalities and the effectiveness of the proposed algorithm. },
	keywords = {Aerial Robotics, Exploration, Motion control of multiple robots, Patrolling / Surveillance, Pursuit-evasion / Clearing},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2014g-GagOriBueFra-preprint.pdf , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2014g-GagOriBueFra-video.mp4},
	author = {Matteo Gagliardi and Giuseppe Oriolo and Heinrich H. B{\"u}lthoff and Antonio Franchi}
}
@conference {2014b-GioRylPraBueFra,
	title = {Turning a Near-hovering Controlled Quadrotor into a 3D Force Effector},
	booktitle = {2014 IEEE Int. Conf. on Robotics and Automation},
	year = {2014},
	month = {05/2014},
	pages = {6278-6284},
	address = {Hong Kong, China},
	abstract = {In this paper the problem of a quadrotor that physically interacts with the surrounding environment through a rigid tool is considered. We present a theoretical design that allows to exert an arbitrary 3D force by using a standard near-hovering controller that was originally developed for contact-free flight control. This is achieved by analytically solving the nonlinear system that relates the quadrotor state, the force exerted by the rigid tool on the environment, and the near-hovering controller action at the equilibrium points, during any generic contact. Stability of the equilibria for the most relevant actions (pushing, releasing, lifting, dropping, and left-right shifting) are proven by means of numerical analysis using the indirect Lyapunov method. An experimental platform, including a suitable tool design, has been developed and used to validate the theory with preliminary experiments.},
	keywords = {Aerial Physical Interaction, Aerial Robotics, UAV hardware platforms},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2014b-GioRylPraBueFra-preprint.pdf , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2014b-GioRylPraBueFra.mp4},
	author = {Guido Gioioso and Markus Ryll and Domenico Prattichizzo and Heinrich H. B{\"u}lthoff and Antonio Franchi}
}
@booklet {2013m-GioFraSalSchPra,
	title = {Hand Driven UAV Formation for Cooperative Grasping and Transportation: the Flying Hand},
	howpublished = {RSS 2013 Work. on Aerial Mobile Manipulation},
	year = {2013},
	month = {06/2013},
	address = {Berlin, Germany},
	keywords = {Aerial Physical Interaction, Motion control of multiple robots},
	author = {Guido Gioioso and Antonio Franchi and Gionata Salvietti and Stefano Scheggi and Domenico Prattichizzo}
}
@conference {2013j-GraRieBueRobFra,
	title = {The TeleKyb Framework for a Modular and Extendible ROS-based Quadrotor Control},
	booktitle = {6th European Conference on Mobile Robots},
	year = {2013},
	month = {09/2013},
	address = {Barcelona, Spain},
	abstract = {The free and open source Tele-Operation Platform of the MPI for Biological Cybernetics (TeleKyb) is an end- to-end software framework for the development of bilateral teleoperation systems between human interfaces (e.g., haptic force feedback devices or gamepads) and groups of quadrotor Unmanned Aerial Vehicles (UAVs). Among drivers for devices and robots from various hardware manufactures, TeleKyb provides a high-level closed-loop robotic controller for mobile robots that can be extended dynamically with modules for state estimation, trajectory planning, processing, and tracking. Since all internal communication is based on the Robot Operating System (ROS), TeleKyb can be easily extended to meet future needs. The capabilities of the overall framework are demonstrated in both an experimental validation of the controller for an individual quadrotor and a complex experimental setup involving bilateral human-robot interaction and shared formation control of multiple UAVs.},
	keywords = {Middleware for robotics, UAV hardware platforms},
	url = {http://www.ros.org/wiki/telekyb},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2013j-GraRieBueRobFra-preprint.pdf},
	author = {Volker Grabe and Martin Riedel and Heinrich H. B{\"u}lthoff and Paolo Robuffo Giordano and Antonio Franchi}
}
@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}
}
