@conference {2655, title = {Reflex Control of the Pisa/IIT SoftHand during Object Slippage}, booktitle = {IEEE International Conference of Robotics and Automation (ICRA2016)}, year = {2016}, pages = {1972 - 1979}, publisher = {IEEE}, organization = {IEEE}, address = {Stockholm, Sweden}, abstract = {
In this work, to guarantee the Pisa/IIT SoftHand{\textquoteright}s
grasp robustness against slippage, three reflex control modes,
namely Current, Pose and Impedance, are implemented and
experimentally evaluated. Towards this objective, ThimbleSense
fingertip sensors are designed and integrated into the thumb
and middle fingers of the SoftHand for real-time detection and
control of the slippage. Current reflex regulates the restoring
grasp forces of the hand by modulating the motor{\textquoteright}s current
profile according to an update law. Pose and Impedance reflex
modes instead replicate this behaviour by implementing an
impedance control scheme. The difference between the two
latter is that the stiffness gain in Impedance reflex mode is
being varied in addition to the hand pose, as a function of
the slippage on the fingertips. Experimental setup also includes
a seven degrees-of-freedom robotic arm to realize consistent
trajectories (e.g. lifting) among three control modes for the sake
of comparison. Different test objects are considered to evaluate
the efficacy of the proposed reflex modes in our experimental
setup. Results suggest that task-appropriate restoring forces
can be achieved using Impedance reflex due to its capability
in demonstrating instantaneous and rather smooth reflexive
behaviour during slippage. Preliminary experiments on five
healthy human subjects provide evidence on the similarity of the
control concepts exploited by the humans and the one realized
by the Impedance reflex, highlighting its potential in prosthetic
applications.
}, keywords = {Haptics, Robotics}, doi = {10.1109/ICRA.2016.7487344}, url = {http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=\&arnumber=7487344}, author = {A. Ajoudani and E. Hocaoglu and Altobelli, A and M. Rossi and E. Battaglia and N G Tsagarakis and A. Bicchi} }