@inbook {3155, title = {Teleimpedance Control: Overview and application}, booktitle = {Human and Robot Hands }, volume = {Springer Series on Touch and Haptic Systems}, year = {2016}, pages = {151-169}, chapter = {9}, abstract = {

In previous chapters, human hand and arm kinematics have been analyzed through a synergstic approach and the underlying concepts were used to design robotic systems and devise simplified control algorithms. On the other hand, it is well-known that synergies can be studied also at a muscular level as a coordinated activation of multiple muscles acting as a single unit to generate different movements. As a result, muscular activations, quantified through Electromyography (EMG) signals can be then processed and used as direct inputs to external devices with a large number of DOFs. In this chapter, we present a minimalistic approach based on tele-impedance control, where EMGs from only one pair of antagonistic muscle pair are used to map the users postural and stiffness references to the synergy-driven anthropomorphic robotic hand, described in chapter 6. In this direction, we first provide an overview of the teleimpedance control concept which forms the basis for the development of the hand controller. Eventually, experimental results evaluate the effectiveness of the teleimpedance control concept in execution of the tasks which require significant dynamics variation or are executed in remote environments with dynamic uncertainties.

}, keywords = {Robotics}, issn = {978-3-319-26705-0}, doi = {10.1007/978-3-319-26706-7}, author = {A. Ajoudani and S. B. Godfrey and N. G. Tsagarakis and A. Bicchi} } @article {2158, title = {Tele- Impedance based Assistive Control for a Compliant Knee Exoskeleton: Stiffness Augmentation and Motion Assistance}, journal = {Robotics and Autonomous Systems}, volume = {73 part A}, year = {2015}, note = {

special issue\ "Wearable Robotics"

}, month = {11/2015}, pages = {78-90}, abstract = {

This paper presents a tele-impedance based assistive control scheme for a knee exoskeleton device. The proposed controller captures the user{\textquoteright}s intent to generate task-related assistive torques by means of the exoskeleton in different phases of the subject{\textquoteright}s normal activity. To do so, a detailed musculoskeletal model of the human knee is developed and experimentally calibrated to best match the user{\textquoteright}s kinematic and dynamic behavior. Three dominant antagonistic muscle pairs are used in our model, in which electromyography (EMG) signals are acquired, processed and used for the estimation of the knee joint torque, trajectory and the stiffness trend, in real time. The estimated stiffness trend is then scaled and mapped to a task-related stiffness interval to agree with the desired degree of assistance. The desired stiffness and equilibrium trajectories are then tracked by the exoskeleton{\textquoteright}s impedance controller. As a consequence, while minimum muscular activity corresponds to low stiffness, i.e.\ highly transparent motion, higher co-contractions result in a stiffer joint and a greater level of assistance. To evaluate the robustness of the proposed technique, a study of the dynamics of the human{\textendash}exoskeleton system is conducted, while the stability in the steady state and transient condition is investigated. In addition, experimental results of standing-up and sitting-down tasks are demonstrated to further investigate the capabilities of the controller. The results indicate that the compliant knee exoskeleton, incorporating the proposed tele-impedance controller, can effectively generate assistive actions that are volitionally and intuitively controlled by the user{\textquoteright}s muscle activity.

}, keywords = {Robotics}, doi = {10.1016/j.robot.2014.09.027}, url = {http://www.sciencedirect.com/science/article/pii/S0921889014002127}, author = {N. Karavas and A. Ajoudani and N G Tsagarakis and J. Saglia and A. Bicchi and D. Caldwell} } @conference {1435, title = {Tele-Impedance based Stiffness and Motion Augmentation for a Knee Exoskeleton Device}, booktitle = {IEEE International Conference on Robotics and Automation (ICRA2013)}, year = {2013}, pages = {2194 - 2200}, keywords = {Robotics}, url = {10.1109/ICRA.2013.6630872}, author = {N. Karavas and A. Ajoudani and N G Tsagarakis and J. Saglia and A. Bicchi and D. G. Caldwell} } @conference {1666, title = {Teleimpedance Control of a Synergy-Driven Anthropomorphic Hand}, booktitle = {IEEE/RSJ International Conference on Intelligent Robots and Systems, IROS 2013}, year = {2013}, month = {November 3-7}, pages = {1985 - 1991}, address = {Tokyo, Japan}, keywords = {Haptics, Robotics}, doi = {10.1109/IROS.2013.6696620 }, author = {A. Ajoudani and S. B. Godfrey and M. G. Catalano and G. Grioli and N G Tsagarakis and A. Bicchi} } @conference {1238, title = {Tele-Impedance: Exploring the Role of Common-Mode and Configuration-Dependant Stiffness}, booktitle = {IEEE-RAS International Conference on Humanoid Robots}, year = {2012}, pages = {363-369}, address = {Osaka, Japan}, keywords = {Robotics}, author = {A. Ajoudani and M Gabiccini and N G Tsagarakis and A Albu-Schaeffer and A. Bicchi} } @article {ATB12, title = {Tele-impedance: Teleoperation with Impedance Regulation Using a Body-Machine Interface}, journal = {International Journal of Robotics Research}, volume = { 31 }, year = {2012}, month = {11/2012}, pages = {1643 - 1656}, chapter = {1643}, keywords = {Robotics}, author = {A. Ajoudani and N G Tsagarakis and A. Bicchi} } @conference {ATB12, title = {Tele-Impedance: Towards Transferring Human Impedance Regulation Skills to Robots}, booktitle = {International Conference of Robotics and Automation - ICRA 2012}, year = {2012}, month = {May 14 - 18}, pages = {382 - 388 }, address = {Saint Paul, MN, USA}, keywords = {Robotics}, author = {A. Ajoudani and N G Tsagarakis and A. Bicchi} } @conference {ATB11, title = {Tele-Impedance: Preliminary Results on Measuring and Replicating Human Arm Impedance in Tele Operated Robots}, booktitle = {IEEE International Conference on Robotics and Biomimetics - ROBIO 2011}, year = {2011}, note = {

Accepted, youtube: http://www.youtube.com/watch?v=KPO6IO7Tr-Q

}, month = {December 7 - 11}, pages = {216 - 223}, address = {Phuket, Thailand}, keywords = {Robotics}, author = {A. Ajoudani and N G Tsagarakis and A. Bicchi} }