@article {2021f-HamUsaSabStaTogFra,
	title = {Design of Multirotor Aerial Vehicles: a Taxonomy Based on Input Allocation},
	journal = {The International Journal of Robotics Research},
	volume = {40},
	year = {2021},
	pages = {1015-1044},
	doi = {10.1177/02783649211025998},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2021f-HamUsaSabStaTogFra.pdf},
	author = {Mahmoud Hamandi and Federico Usai and Quentin Sabl{\'e} and Nicolas Staub and Marco Tognon and Antonio Franchi}
}
@article {2019g-WalStaFraSas,
	title = {UVDAR System for Visual Relative Localization with application to Leader-Follower Formations of Multirotor UAVs},
	journal = {IEEE Robotics and Automation Letters},
	volume = {4},
	year = {2019},
	month = {02/2019},
	pages = {2637-2644},
	abstract = {A novel onboard relative localization method, based on ultraviolet light, used for real-time control of a leader- follower formation of multirotor UAVs is presented in this paper. A new smart sensor, UVDAR, is employed in an innovative way, which does not require communication and is extremely reliable in real-world conditions. This innovative sensing system exploits UV spectrum and provides relative position and yaw measurements independently of environment conditions such as changing illumination and presence of undesirable light sources and their reflections. The proposed approach exploits this re- trieved information to steer the follower to a given 3D position and orientation relative to the leader, which may be considered as the main building block of any multi-UAV system operating with small mutual distances among team-members. The proposed solution was verified in demanding outdoor conditions, validating usage of UVDAR in real flight scenario and paving the way for further usage of UVDAR for practical multi-UAV formation deployments.},
	doi = {10.1109/LRA.2019.2901683},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2019g-WalStaFraSas-preprint.pdf , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2019g-WalStaFraSas.mp4},
	author = {Viktor Walter and Nicolas Staub and Antonio Franchi and Martin Saska}
}
@conference {2018s-YanStaFraLee,
	title = {Modeling and Control of Multiple Aerial-Ground Manipulator System with Load Flexibility},
	booktitle = {2018 IEEE/RSJ Int. Conf. on Intelligent Robots and Systems},
	year = {2018},
	month = {10/2018},
	address = {Madrid, Spain},
	abstract = {The MAGMaS (Multiple Aerial-Ground Manipulator System) was proposed in [1] as a heterogeneous system composed of multiple ground (mobile) manipulators and aerial robots to collaboratively manipulate a long/large-size object and demonstrated therein for rigid load manipulation. Here, we extend this result of [1] to the case of load manipulation with flexibility, which is crucial for long/slender object manipulation, yet, not considered in [1]. We first provide a rigorous modeling of the load flexibility and its effects on the MAGMaS dynamics. We then propose a novel collaborative control framework for flexible load-tip pose tracking, where the ground manipulator provides slower nominal pose tracking with overall load weight holding, whereas the aerial robot faster vibration suppression with some load weight sharing. We also discuss the issue of controllability stemming from that the aerial robot provides less number of actuation than the modes of the load flexibility; and elucidate some peculiar conditions for this vibration suppression controllability. Simulations are also performed to demonstrate the effectiveness of the proposed theory.},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2018s-YanStaFraLee-preprint.pdf , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2018s-YanStaFraLee.mp4},
	author = {Hyunsoo Yang and Nicolas Staub and Antonio Franchi and Dongjun Lee}
}
@conference {2018l-WalSasStaFra,
	title = {Mutual Localization of UAVs based on Blinking Ultraviolet Markers and 3D Time-Position Hough Transform},
	booktitle = {14th IEEE International Conference on Automation Science and Engineering},
	year = {2018},
	month = {08/2018},
	address = {Munich, Germany},
	abstract = {A novel vision-based approach for indoor/outdoor mutual localization on Unmanned Aerial Vehicles (UAVs) with low computational requirements and without external infras- tructure is proposed in this paper. The proposed solution exploits the low natural emissions in the near-Ultra-Violet (UV) spectrum to avoid major drawbacks of the visible spec- trum.Such approach provides much better reliability while be- ing less computationally intensive. Working in near-UV requires active markers, which can be leveraged by enriching the infor- mation content through blinking patterns encoded marker-ID. In order to track the markers motion and identify their blinking frequency, we propose an innovative use of three dimensional Hough Transform, applied to stored position-time points. The proposed method was intensively tested onboard multi-UAV systems in real-world scenarios that are very challenging for visible-spectrum methods.The results of our methods in terms of robustness, reliability and precision, as well as the low requirement on the system deployment, predestine this method to be an enabling technology for using swarms of UAVs.},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2018l-WalSasStaFra-preprint.pdf , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2018l-WalSasStaFra.mp4},
	author = {Viktor Walter and Nicolas Staub and Martin Saska and Antonio Franchi}
}
@article {2018u-StaMohBicDelYaPraRobLeeFra,
	title = {The Tele-MAGMaS: an Aerial-Ground Co-manipulator System},
	journal = {IEEE Robotics and Automation Magazine},
	volume = {25},
	year = {2018},
	month = {12/2018},
	pages = {66-75},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2018u-StaMohBicDelYaPraRobLeeFra-preprint.pdf , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2018u-StaMohBicDelYaPraRobLeeFra.mp4},
	author = {Nicolas Staub and Mostafa Mohammadi and Davide Bicego and Quentin Delamare and Hyunsoo Yang and Domenico Prattichizzo and Paolo Robuffo Giordano and Dongjun Lee and Antonio Franchi}
}
@conference {2018g-BicStaSabAreMisFra,
	title = {Towards a Flying Assistant Paradigm: the OTHex},
	booktitle = {2018 IEEE Int. Conf. on Robotics and Automation},
	year = {2018},
	month = {05/2018},
	pages = {6997-7002},
	address = {Brisbane, Australia},
	abstract = {This paper presents the OTHex platform for aerial manipulation developed at LAAS{\textendash}CNRS. The OTHex is probably the first multi-directional thrust platform designed to act as Flying Assistant which can aid human operators and/or Ground Manipulators to move long bars for assembly and maintenance tasks. The work emphasis is on task-driven custom design and experimental validations. The proposed control framework is built around a low-level geometric controller, and includes an external wrench estimator, an admittance filter, and a trajectory generator. This tool gives the system the necessary compliance to resist external force disturbances arising from contact with the surrounding environment or to parameter uncertainties in the load. A set of experiments validates the real-world applicability and robustness of the overall system.},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2018g-BicStaSabAreMisFra-preprint.pdf , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2018g-BicStaSabAreMisFra.mp4},
	author = {Nicolas Staub and Davide Bicego and Quentin Sabl{\'e} and Victor Arellano-Quintana and Subodh Mishra and Antonio Franchi}
}
@conference {2017d-StaMohBicPraFra,
	title = {Towards Robotic MAGMaS: Multiple Aerial-Ground Manipulator Systems},
	booktitle = {2017 IEEE Int. Conf. on Robotics and Automation},
	year = {2017},
	month = {05/2017},
	pages = {1307-1312},
	address = {Singapore},
	abstract = {In this paper we lay the foundation of the first heterogeneous multi-robot system of the Multiple Aerial-Ground Manipulator System (MAGMaS) type. A MAGMaS consists of a ground manipulator and a team of aerial robots equipped with a simple gripper manipulator the same object. The idea is to benefit from the advantages of both kinds of platforms, i.e., physical strength versus large workspace. The dynamic model of such robotic systems is derived, and R Ro its characteristic structure exhibited. Based on the dynamical i structure of the system a nonlinear control scheme, augmented with a disturbance observer is proposed to perform trajectory tracking tasks in presence of model inaccuracies and external disturbances. The system redundancy is exploited by solving an optimal force/torque allocation problem that takes into account the heterogeneous system constraints and maximizes the force manipulability ellipsoid. Simulation results validated the proposed control scheme for this novel heterogeneous robotic system. We finally present a prototypical mechanical design and preliminary experimental evaluation of a MAGMaS composed by a kuka LWR4 and quadrotor based aerial robot.},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2017d-StaMohBicPraFra-preprint.pdf , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2017d-StaMohBicPraFra.mp4},
	author = {Nicolas Staub and Mostafa Mohammadi and Davide Bicego and Domenico Prattichizzo and Antonio Franchi}
}
@conference {2016l-YueStaFra,
	title = {Aerial Robots with Rigid/Elastic-joint Arms: Single-joint Controllability Study and Preliminary Experiments},
	booktitle = {2016 IEEE/RSJ Int. Conf. on Intelligent Robots and System},
	year = {2016},
	month = {10/2016},
	pages = {1667-1672},
	address = {Daejeon, South Korea},
	abstract = {We present the dynamic modeling, analysis, and control design of a Planar-Vertical Take-Off and Landing (PVTOL) underactuated aerial vehicle equipped either with a rigid- or an elastic-joint arm. We prove that in both cases the system is exactly linearizable with a dynamic feedback and differentially flat for the same set of outputs (but different controllers). We compare the two cases with extensive and realistic simulations, which show that the rigid-joint case outperforms the elastic-joint case for aerial grasping tasks while the converse holds for link-velocity amplification tasks. We present preliminary experimental results using a actuated joint with variable stiffness (VSA) on a quadrotor platform.},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2016l-YueStaFra-preprint.pdf},
	author = {Burak Y{\"u}ksel and Nicolas Staub and Antonio Franchi}
}
@conference {2015d-StaFra,
	title = {Battery-aware Dynamical Modeling and Identification for the Total Thrust in Multi-rotor UAVs using only an Onboard Accelerometer},
	booktitle = {2015 IEEE Int. Conf. on Robotics and Automation},
	year = {2015},
	month = {05/2015},
	pages = {3341-3346},
	address = {Seattle, WA},
	abstract = {We propose and experimentally validate a new class of models for the total thrust generation in multi-rotor UAVs which is suitable for low- and middle-end platforms. Differently from typical models assuming to instantaneously control the rotor spinning velocity, in the proposed class we consider that the total thrust has its own dynamics and its final value explicitly depends both on the pseudo-setpoint commands given to the motor driver and the measurement of the battery terminal voltage. We compare the different model instances within the class using a principled experimental setup in which the total thrust is precisely measured using a motion capture system as ground truth, instead of relying on a setup based or noise-prone force sensors. We then show that the use of a dynamical model that includes also the battery terminal voltage significantly improves the prediction ability of the model in terms of accuracy. Finally we show how the proposed model can be identified using on-board only acceleration measurements, achieving a surprisingly good accuracy when compared with the ground truth case. We expect that the use of the proposed model will be important both in case of precise flight control and in the case of aerial physical interactive tasks.},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2015d-StaFra-preprint_0.pdf , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2015d-StaFra.mp4},
	author = {Nicolas Staub and Antonio Franchi}
}
