Abstract
BackgroundAdvances in technology are allowing for the production of several viable wearable robotic devices to assist with activities of daily living and with rehabilitation. One of the most pressing limitations to user satisfaction is the lack of consistency in motion between the user and the robotic device. The displacement between the robot and the body segment may not correspond because of differences in skin and tissue compliance, mechanical backlash, and/or incorrect fit.FindingsThis report presents the results of an analysis of relative displacement between the user’s hand and a wearable exoskeleton, the HX. HX has been designed to maximize comfort, wearability and user safety, exploiting chains with multiple degrees-of-freedom with a modular architecture. These appealing features may introduce several uncertainties in the kinematic performances, especially when considering the anthropometry, morphology and degree of mobility of the human hand. The small relative displacements between the hand and the exoskeleton were measured with a video-based motion capture system, while the user executed several different grips in different exoskeleton modes.ConclusionsThe analysis furnished quantitative results about the device performance, differentiated among device modules and test conditions. In general, the global relative displacement for the distal part of the device was in the range 0.5–1.5 mm, while within 3 mm (worse but still acceptable) for displacements nearest to the hand dorsum. Conclusions over the HX design principles have been drawn, as well as guidelines for future developments.Electronic supplementary materialThe online version of this article (doi:10.1186/1743-0003-11-147) contains supplementary material, which is available to authorized users.
Highlights
In recent years there has been widespread use of robotic systems as advanced rehabilitation tools, both in clinical [1] and domestic environments [2]
The global relative displacement for the distal part of the device was in the range 0.5–1.5 mm, while within 3 mm for displacements nearest to the hand dorsum
The analysis has been conducted in terms of measured kinematic discrepancy between hand exoskeleton device (HX) and the wearer’s hand; kinematics were acquired with a video-based motion capture system, during several types of grip and with different operative conditions of the robot
Summary
In recent years there has been widespread use of robotic systems as advanced rehabilitation tools, both in clinical [1] and domestic environments [2]. Its main drawback is that mechanical stability may be lessened: the main undesired effect is the presence of significant backlash in the human-robot physical interaction. The analysis has been conducted in terms of measured kinematic discrepancy between HX and the wearer’s hand; kinematics were acquired with a video-based motion capture system, during several types of grip and with different operative conditions of the robot. The feasibility of measuring such small displacements, as the ones in the present study, using a video-based motion capture system has been already demonstrated [21]. Advances in technology are allowing for the production of several viable wearable robotic devices to assist with activities of daily living and with rehabilitation. The displacement between the robot and the body segment may not correspond because of differences in skin and tissue compliance, mechanical backlash, and/or incorrect fit
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