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Rationale, implementation and evaluation of assistive strategies for an active back-support exoskeleton

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Show simple item record Toxiri, Stefano Koopman, Axel S. Lazzaroni, Maria Ortiz, Jesús Power, Valerie de Looze, Michiel P. O'Sullivan, Leonard Caldwell, Darwin G. 2018-07-13T08:24:52Z 2018-07-13T08:24:52Z 2018
dc.description peer-reviewed en_US
dc.description.abstract Active exoskeletons are potentially more effective and versatile than passive ones, but designing them poses a number of additional challenges. An important open challenge in the field is associated to the assistive strategy, by which the actuation forces are modulated to the user’s needs during the physical activity. This paper addresses this challenge on an active exoskeleton prototype aimed at reducing compressive low-back loads, associated to risk of musculoskeletal injury during manual material handling (i.e., repeatedly lifting objects). An analysis of the biomechanics of the physical task reveals two key factors that determine low-back loads. For each factor, a suitable control strategy for the exoskeleton is implemented. The first strategy is based on user posture and modulates the assistance to support the wearer’s own upper body. The second one adapts to the mass of the lifted object and is a practical implementation of electromyographic control. A third strategy is devised as a generalized combination of the first two. With these strategies, the proposed exoskeleton can quickly adjust to different task conditions (which makes it versatile compared to using multiple, task-specific, devices) as well as to individual preference (which promotes user acceptance). Additionally, the presented implementation is potentially applicable to more powerful exoskeletons, capable of generating larger forces. The different strategies are implemented on the exoskeleton and tested on 11 participants in an experiment reproducing the lifting task. The resulting data highlights that the strategies modulate the assistance as intended by design, i.e., they effectively adjust the commanded assistive torque during operation based on user posture and external mass. The experiment also provides evidence of significant reduction in muscular activity at the lumbar spine (around 30%) associated to using the exoskeleton. The reduction is well in line with previous literature and may be associated to lower risk of injury. en_US
dc.language.iso eng en_US
dc.publisher Frontiers Media en_US
dc.relation SPEXOR
dc.relation.ispartofseries Frontiers in Robotics and AI;(5) article 53
dc.subject exoskeleton en_US
dc.subject powered en_US
dc.subject manual material handling en_US
dc.subject strategy en_US
dc.subject myocontrol en_US
dc.subject electromyography en_US
dc.title Rationale, implementation and evaluation of assistive strategies for an active back-support exoskeleton en_US
dc.type info:eu-repo/semantics/article en_US
dc.type.supercollection all_ul_research en_US
dc.type.supercollection ul_published_reviewed en_US
dc.identifier.doi 10.3389/frobt.2018.00053
dc.contributor.sponsor INAIL en_US
dc.contributor.sponsor ERC
dc.relation.projectid 608022
dc.relation.projectid 608979
dc.relation.projectid 608979
dc.relation.projectid 687662
dc.rights.accessrights info:eu-repo/semantics/openAccess en_US

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