@article {2019b-YueSecBueFra,
	title = {Aerial Physical Interaction via IDA-PBC},
	journal = {The International Journal of Robotics Research},
	volume = {38},
	year = {2019},
	pages = {403{\textendash}421},
	abstract = {This paper proposes the use of a novel control method based on IDA-PBC in order to address the Aerial Physical Interaction (APhI) problem for a quadrotor UAV. The apparent physical properties of the quadrotor are reshaped in order to achieve better APhI performances, while ensuring the stability of the interaction through passivity preservation. The robustness of the IDA-PBC method with respect to sensor noise is also analyzed. The direct measurement of the external wrench {\textendash} needed to implement the control method {\textendash} is compared to the use of a nonlinear Lyapunov-based wrench observer and advantages/disadvantages of both methods are discussed. The validity and practicability of the proposed APhI method is evaluated through experiments, where for the first time in the literature, a light-weight all- in-one low-cost F/T sensor is used onboard of a quadrotor. Two main scenarios are shown: a quadrotor responding external disturbances while hovering (physical human-quadrotor interaction), and the same quadrotor sliding with a rigid tool along an uneven ceiling surface (inspection/painting-like task).},
	doi = {10.1177/0278364919835605},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2019b-YueSecBueFra-preprint.pdf , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2019b-YueSecBueFra.mp4},
	author = {Burak Y{\"u}ksel and Cristian Secchi and Heinrich H. B{\"u}lthoff and Antonio Franchi}
}
@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}
}
@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 {2017g-TogYueBuoFra,
	title = {Dynamic Decentralized Control for Protocentric Aerial Manipulators},
	booktitle = {2017 IEEE Int. Conf. on Robotics and Automation},
	year = {2017},
	month = {05/2017},
	pages = {6375-6380},
	address = {Singapore},
	abstract = {We present a control methodology for underactuated aerial manipulators that is both easy to implement on real systems and able to achieve highly dynamic behaviors. The method is composed by two parts: i) a nominal input/state trajectory generator that takes into account the full-body dynamics of the system exploiting its differential flatness property; ii) a decentralized feedback controller acting on the actuated degrees of freedom that confers the needed robustness to the closed-loop system. We demonstrate that the proposed controller is able to precisely track dynamic trajectories when implemented on a standard hardware. Comparative experiments clearly show the benefit of using the nominal input/state generator.},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2017g-TogYueBuoFra-preprint.pdf , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2017g-TogYueBuoFra.mp4},
	author = {Marco Tognon and Burak Y{\"u}ksel and Gabriele Buondonno 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 {2016k-YueBuoFra,
	title = {Differential Flatness and Control of Protocentric Aerial Manipulators with Any Number of Arms and Mixed Rigid-/Elastic-Joints},
	booktitle = {2016 IEEE/RSJ Int. Conf. on Intelligent Robots and System},
	year = {2016},
	month = {10/2016},
	pages = {561-566},
	address = {Daejeon, South Korea},
	abstract = {In this paper we introduce a particularly relevant class of aerial manipulators that we name protocentric. These robots are formed by an underactuated aerial vehicle, a planarVertical Take-Off and Landing (PVTOL), equipped with any number of different parallel manipulator arms with the only property that all the first joints are attached at the Center of Mass (CoM) of the PVTOL, while the center of actuation of the PVTOL can be anywhere. We prove that protocentric aerial manipulators (PAMs) are differentially flat systems regardless the number of joints of each arm and their kinematic and dynamic parameters. The set of flat outputs is constituted by the CoM of the PVTOL and the absolute orientation angles of all the links. The relative degree of each output is equal to four. More amazingly, we prove that PAMs are differentially flat even in the case that any number of the joints are elastic, no matter the internal distribution between elastic and rigid joints. The set of flat outputs is the same but in this case the total relative degree grows quadratically with the number of elastic joints. We validate the theory by simulating object grasping and transportation tasks with unknown mass and parameters and using a controller based on dynamic feedback linearization.},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2016k-YueBuoFra-preprint.pdf , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2016k-YueBuoFra-tech_report.pdf , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2016k-YueBuoFra.mp4},
	author = {Burak Y{\"u}ksel and Gabriele Buondonno and Antonio Franchi}
}
@conference {2015f-YueMahSecBueFra,
	title = {Design, Identification and Experimental Testing of a Light-Weight Flexible-joint Arm for Aerial Physical Interaction},
	booktitle = {2015 IEEE Int. Conf. on Robotics and Automation},
	year = {2015},
	month = {05/2015},
	pages = {870-876},
	address = {Seattle, WA},
	abstract = {In this paper we introduce the design of a light- weight novel flexible-joint arm for light-weight unmanned aerial vehicles (UAVs), which can be used both for safe physical interaction with the environment and it represents also a preliminary step in the direction of performing quick motions for tasks such as hammering or throwing. The actuator consists of an active pulley driven by a rotational servo motor, a passive pulley which is attached to a rigid link, and the elastic connections (springs) between these two pulleys. We identify the physical parameters of the system, and use an optimal control strategy to maximize its velocity by taking advantage of elastic components. The prototype can be extended to a light-weight variable stiffness actuator. The flexible-joint arm is applied on a quadrotor, to be used in aerial physical interaction tasks, which implies that the elastic components can also be used for stable interaction absorbing the interactive disturbances which might damage the flying system and its hardware. The design is validated through several experiments, and future developments are discussed in the paper.},
	keywords = {Aerial Physical Interaction, Aerial Robotics},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2015f-YueMahSecBueFra-preprint_0.pdf , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2015f-YueMahSecBueFra.mp4},
	author = {Burak Y{\"u}ksel and Saber Mahboubi and Cristian Secchi and Heinrich H. B{\"u}lthoff and Antonio Franchi}
}
@conference {184,
	title = {A Nonlinear Force Observer for Quadrotors and Application to Physical Interactive Tasks},
	booktitle = {IEEE/ASME International Conference on Advanced Intelligent Mechatronics},
	year = {2014},
	month = {07/2014},
	pages = {433-440},
	address = {Besan{\c c}on, France},
	abstract = {In order to properly control the physical interactive behavior of a flying vehicle, the information about the forces acting on the robot is very useful. Force/torque sensors can be exploited for measuring such information but their use increases the cost of the equipment, the weight to be carried by the robot and, consequently, it reduces the flying autonomy. Furthermore, a sensor can measure only the force/torque applied to the point it is mounted in. In order to overcome these limitations, in this paper we introduce a Lyapunov based nonlinear observer for estimating the external forces applied to a quadrotor. Furthermore, we show how to exploit the estimated force for shaping the interactive behavior of the quadrotor using Interconnection and Damping Assignment Passivity Based Controller (IDA-PBC). The results of the paper are validated by means of simulations.},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2014h-YueSecBueFra-preprint.pdf},
	author = {Burak Y{\"u}ksel and Cristian Secchi and Heinrich H. B{\"u}lthoff and Antonio Franchi}
}
@conference {2014d-YueSecBueFra,
	title = {Reshaping the Physical Properties of a Quadrotor through IDA-PBC and its Application to Aerial Physical Interaction},
	booktitle = {2014 IEEE Int. Conf. on Robotics and Automation},
	year = {2014},
	month = {05/2014},
	pages = {6258-6265},
	address = {Hong Kong, China},
	abstract = {In this paper we propose a controller, based on an extension of Interconnection and Damping Assignment Passivity Based Control (IDA-PBC) framework, for shaping the whole physical characteristics of a quadrotor and for obtaining a desired interactive behavior between the robot and the environment. In the control design, we shape the total energy (kinetic and potential) of the undamped original system by first excluding external effects. In this way we can assign a new dynamics to the system. Then we apply damping injection to the new system for achieving a desired damped behavior. Then we show how to connect a high-level control input to such system by taking advantage of the new desired physics. We support the theory with extensive simulations by changing the overall behavior of the UAV for different desired dynamics, and show the advantage of this method for sliding on a surface tasks, such as ceiling painting, cleaning or surface inspection.},
	keywords = {Aerial Physical Interaction, Aerial Robotics},
	attachments = {https://homepages.laas.fr/afranchi/robotics/sites/default/files/2014d-YueSecBueFra-preprint.pdf , https://homepages.laas.fr/afranchi/robotics/sites/default/files/2014d-YueSecBueFra.mp4},
	author = {Burak Y{\"u}ksel and Cristian Secchi and Heinrich H. B{\"u}lthoff and Antonio Franchi}
}
