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Author (down) Berman, S.; Liebermann, D.G.; McIntyre, J.
Title Constrained Motion Control on a Hemispherical Surface – Path Planning Type Journal Article
Year 2014 Publication Journal of Neurophysiology Abbreviated Journal J Neurophysiol
Volume 111 Issue 5 Pages 954-968
Keywords Constrained motion; geodesics; path planning
Abstract Surface-constrained motion, i.e., motion constraint by a rigid surface, is commonly found in daily activities. The current work investigates the choice of hand paths constrained to a concave hemispherical surface. To gain insight regarding the paths and their relationship with task dynamics, we simulated various control policies. The simulations demonstrated that following a geodesic path is advantageous not only in terms of path length, but also in terms of motor planning and sensitivity to motor command errors. These stem from the fact that the applied forces lie in a single plane (that of the geodesic path itself). To test whether human subjects indeed follow the geodesic, and to see how such motion compares to other paths, we recorded movements in a virtual haptic-visual environment from eleven healthy subjects. The task was comprised of point-to-point motion between targets at two elevations (30 degrees and 60 degrees ). Three typical choices of paths were observed from a frontal plane projection of the paths: circular arcs, straight lines, and arcs close to the geodesic path for each elevation. Based on the measured hand paths, we applied k-means blind separation to divide the subjects into three groups and compared performance indicators. The analysis confirmed that subjects who followed paths closest to the geodesic produced faster and smoother movements, compared to the others. The 'better' performance reflects the dynamical advantages of following the geodesic path, as shown by the simulations, and may also reflect invariant features of the control policies used to produce such a surface-constrained motion.
Address Ben-Gurion University of the Negev
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-3077 ISBN Medium
Area Expedition Conference
Notes PMID:24259548 Approved no
Call Number Serial 72
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Author (down) Banina, M.C.; Molad, R.; Solomon, J.S.; Berman, S.; Soroker, N.; Frenkel-Toledo, S.; Liebermann, D.G.; Levin, M.F.
Title Exercise intensity of the upper limb can be enhanced using a virtual rehabilitation system Type Journal Article
Year 2020 Publication Disability and Rehabilitation. Assistive Technology Abbreviated Journal Disabil Rehabil Assist Technol
Volume Issue Pages 1-7
Keywords Stroke; difficulty; exercise therapy; intensity; personalized exercise; upper limb; virtual reality
Abstract Purpose: Motor recovery of the upper limb (UL) is related to exercise intensity, defined as movement repetitions divided by minutes in active therapy, and task difficulty. However, the degree to which UL training in virtual reality (VR) applications deliver intense and challenging exercise and whether these factors are considered in different centres for people with different sensorimotor impairment levels is not evidenced. We determined if (1) a VR programme can deliver high UL exercise intensity in people with sub-acute stroke across different environments and (2) exercise intensity and difficulty differed among patients with different levels of UL sensorimotor impairment.Methods: Participants with sub-acute stroke (<6 months) with Fugl-Meyer scores ranging from 14 to 57, completed 10 approximately 50-min UL training sessions using three unilateral and one bilateral VR activity over 2 weeks in centres located in three countries. Training time, number of movement repetitions, and success rates were extracted from game activity logs. Exercise intensity was calculated for each participant, related to UL impairment, and compared between centres.Results: Exercise intensity was high and was progressed similarly in all centres. Participants had most difficulty with bilateral and lateral reaching activities. Exercise intensity was not, while success rate of only one unilateral activity was related to UL severity.Conclusion: The level of intensity attained with this VR exercise programme was higher than that reported in current stroke therapy practice. Although progression through different activity levels was similar between centres, clearer guidelines for exercise progression should be provided by the VR application.Implications for rehabilitationVR rehabilitation systems can be used to deliver intensive exercise programmes.VR rehabilitation systems need to be designed with measurable progressions through difficulty levels.
Address Center for Interdisciplinary Research in Rehabilitation of Greater Montreal (CRIR), Feil and Oberfeld Research Centre, Jewish Rehabilitation Hospital, Laval, Canada
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Summary Language Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1748-3107 ISBN Medium
Area Expedition Conference
Notes PMID:32421460 Approved no
Call Number Serial 106
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