Tiny hydraulics for powered orthotics.

William Durfee, Jicheng Xia, Elizabeth Hsiao-Wecksler

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


Untethered, powered orthotics require an actuation system with power supply and control, transmission line and actuator. Fluid power has unmatched force-to-weight and power-to-weight compared to electromechanical systems, but it is unclear if those same advantages hold for small systems in the 10 to 100 W range. A systems analysis approach suggests that a fluid power system will be lighter than an electromechanical system with the same output power and efficiency if the fluid power is run at pressures over about 200 psi. A theoretical analysis of small bore cylinders suggests that eliminating the piston seal will result in a higher efficiency actuator if the clearance gap is small. A demonstration, battery powered electrohydraulic actuator assembled from off-the-shelf components had the force and power suited to a powered ankle orthosis, but is too large and too heavy, suggesting the need to develop custom components.

Original languageEnglish (US)
Pages (from-to)5975473
Number of pages1
JournalIEEE ... International Conference on Rehabilitation Robotics : [proceedings]
StatePublished - 2011
EventRehab Week Zurich 2011 - 2011 IEEE International Conference on Rehabilitation Robotics, ICORR 2011 - Zurich, Switzerland
Duration: Jun 27 2011Jul 1 2011

PubMed: MeSH publication types

  • Journal Article
  • Research Support, U.S. Gov't, Non-P.H.S.


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