Gravity Balancing Flexure Springs for an Assistive Elbow Orthosis

Martin Tschiersky, Edsko E.G. Hekman, Dannis M. Brouwer, Just Herder

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

In this paper, we propose a flexure spring based gravity compensation device which provides assistance to lift the forearm. Three different spring designs are obtained and evaluated. The synthesis method to obtain these is explained in detail and an experimental evaluation validates the desired gravity balancing properties. It is found that in comparison to a flexure spring with constant thickness, a variable thickness distribution along the spring leads to a drastic reduction of its width, which amounts to 81 % in the presented case, and offers an energy to weight ratio that is 94 % higher. Employing a nested spring design further increases the storable elastic energy of the variable thickness design by 145 % through utilization of the otherwise unused space within the original spring envelope. A proof-of-concept prototype is built to illustrate a practical implementation. The presented synthesis method provides a tool to obtain gravity balancing flexure springs that offer a promising solution for the design of assistive devices which aim to be both wearable and inconspicuous.
Original languageEnglish
Pages (from-to)177-188
JournalIEEE Transactions on Medical Robotics and Bionics
Volume1
Issue number3
DOIs
Publication statusPublished - 2019

Keywords

  • Gravity balancing
  • wearable device
  • assistive orthosis
  • arm support
  • flexure spring

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