00686nas a2200217 4500008004100000022001400041245011700055210006900172260001200241653001200253653001300265100001400278700002000292700001900312700001400331700001500345700001600360700001300376700001500389856006400404 2017 eng d a1070-993200aThe SoftHand Pro-H: A Hybrid Body-Controlled, Electrically Powered Hand Prosthesis for Daily Living and Working 0 aSoftHand ProH A Hybrid BodyControlled Electrically Powered Hand  c11/201710aHaptics10aRobotics1 aPiazza, C1 aCatalano, M. G.1 aGodfrey, S. B.1 aRossi, M.1 aGrioli, G.1 aBianchi, M.1 aZhao, K.1 aBicchi, A. uhttp://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=811063402465nas a2200217 4500008004500000245006700045210006600112260002800178300001600206520181400222653001202036653001302048100001702061700001702078700001702095700001402112700001802126700002002144700001502164856006802179 2016 engldsh 00aReflex Control of the Pisa/IIT SoftHand during Object Slippage0 aReflex Control of the PisaIIT SoftHand during Object Slippage aStockholm, SwedenbIEEE a1972 - 19793 a

In this work, to guarantee the Pisa/IIT SoftHand’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’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.

10aHaptics10aRobotics1 aAjoudani, A.1 aHocaoglu, E.1 aAltobelli, A1 aRossi, M.1 aBattaglia, E.1 aTsagarakis, N G1 aBicchi, A. uhttp://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=748734401921nas a2200181 4500008003900000245007200039210006900111260004900180300001600229520133600245653001201581653001301593100001901606700001701625700001401642700001501656856006801671 2015 d00aEffect of Homogenous Object Stiffness on Tri-digit Grasp Properties0 aEffect of Homogenous Object Stiffness on Tridigit Grasp Properti a Milano, Italy, August 25th-29th, 2015bIEEE a6704 - 67073 a
This paper presents experimental findings on how humans modulate their muscle activity while grasping objects of varying levels of compliance. We hypothesize that one of the key abilities that allows humans to successfully cope with uncertainties while grasping compliant objects is the ability to modulate muscle activity to control both grasp force and stiffness in a way that is coherent with the task. To that end, subjects were recruited to perform a grasp and lift task with a tripod-grasp device with contact surfaces of variable compliance. Subjects performed the task under four different compliance conditions while surface EMG from the main finger flexor and extensor muscles was recorded along with force and torque data at the contact points. Significant increases in the extensor muscle (the antagonist in the task) and co-contraction levels were found with increasing compliance at the contact points. These results suggest that the motor system may employ a strategy of increasing cocontraction, and thereby stiffness, to counteract the decreased stability in grasping compliant objects. Future experiments will examine the extent to which this phenomenon is also related to specific task features, such as precision versus power grasp and object weight.
 
10aHaptics10aRobotics1 aGodfrey, S. B.1 aAltobelli, A1 aRossi, M.1 aBicchi, A. uhttp://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=731993105694nas a2200193 4500008004500000245008600045210006900131260004300200300001200243520507000255653001205325653001305337100001405350700001705364700001905381700001705400700001505417856006805432 2015 engldsh 00aElectromyographic Mapping of Finger Stiffness in Tripod Grasp: a Proof of Concept0 aElectromyographic Mapping of Finger Stiffness in Tripod Grasp a  aSingapore, 11 – 14 August 2015bIEEE a181-1863 a

Effective execution of a manipulation task using prosthetic or robotic hands requires that the motion and the impedance profiles of the fingers be appropriately commanded. This, however, brings some design and control challenges regarding the individual planning and realization of the finger motion and stiffnesstrajectories. It appears that the central nervous system solves for this complexity in an effective and coordinated manner which has been well-recognized under the concept of hand synergies. While the exploitation of this concept in kinematic coordinates has lead to the development of several successful robotic designs and control strategies, its extension to dynamic coordinates, such as coordinated stiffening of the fingers, remains to be investigated. Indeed, in this study we provide preliminary evidence on the existence of such coordinated stiffening patterns in human fingers and establish initial steps towards a real-time and effective modelling of the finger stiffness in a tripod grasp. To achieve this goal, the endpoint stiffness of the thumb, index and middle fingers of five healthy subjects are experimentally identified and correlated with the electromyography (EMG) signals recorded from a dominant antagonistic pair of the forearm muscles. Our findings suggest that: i) the magnitude of thestiffness ellipses at the fingertips grows in a coordinated way, subsequent to the co-contraction of the forearm muscles; ii) the length of the ellipses' axes appears to have a nearly linear relationship with the co-contraction level of the antagonistic muscle pair.

10aHaptics10aRobotics1 aRossi, M.1 aAltobelli, A1 aGodfrey, S. B.1 aAjoudani, A.1 aBicchi, A. uhttp://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=7281196