Document Detail

A closed-loop stepper motor waist-pull system for inducing protective stepping in humans.
MedLine Citation:
PMID:  9672092     Owner:  NLM     Status:  MEDLINE    
Past approaches for inducing protective stepping to preserve standing balance in humans have either lacked the flexibility of control over the initial conditions of falling, or involved considerable mass which limits mobility of the system. This report describes the design and function of a stepper motor closed-loop waist-pull system for evoking protective stepping responses. Bench testing with applied load-motion profile combinations indicated performance degradation for force levels greater than 204 N which was well within the levels encountered in human experiments. An optical encoder feedback design allowed a positional accuracy of 0.00225 mm per step. A regression analysis of specified versus recorded velocities resulted in an acceptable fit (r2 = 0.99). The mean rise time was 63.0+/-18.0 (SD) ms and was consistent up to the load limits of the device. In human experiments repeated perturbations were consistently realized. Applied motion profiles were generally comparable at the pelvic level for subjects of different geometry, weight, and inertia despite a tendency for slight positional lag. The method allows flexible and accurate control of the initial conditions of a perturbation-induced fall to elicit steps. The system dimensions and moveability allow it to be implemented into clinical environments.
P E Pidcoe; M W Rogers
Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of biomechanics     Volume:  31     ISSN:  0021-9290     ISO Abbreviation:  J Biomech     Publication Date:  1998 Apr 
Date Detail:
Created Date:  1998-09-24     Completed Date:  1998-09-24     Revised Date:  2009-11-11    
Medline Journal Info:
Nlm Unique ID:  0157375     Medline TA:  J Biomech     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  377-81     Citation Subset:  IM; S    
Department of Physical Therapy, College of Associated Health Professions, University of Illinois at Chicago, USA.
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MeSH Terms
Accidental Falls / prevention & control*
Equipment Design
Middle Aged
Physiology / instrumentation*
Postural Balance / physiology*
Posture / physiology*
Walking / physiology*
Grant Support

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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