Virtual biomechanics: a new method for online reconstruction of force from EMG recordings

de Rugy, Aymar, Loeb, Gerald E. and Carroll, Timothy J. (2012) Virtual biomechanics: a new method for online reconstruction of force from EMG recordings. Journal of Neurophysiology, 108 12: 3333-3341. doi:10.1152/jn.00714.2012


Author de Rugy, Aymar
Loeb, Gerald E.
Carroll, Timothy J.
Title Virtual biomechanics: a new method for online reconstruction of force from EMG recordings
Journal name Journal of Neurophysiology   Check publisher's open access policy
ISSN 0022-3077
1522-1598
Publication date 2012-12
Sub-type Article (original research)
DOI 10.1152/jn.00714.2012
Open Access Status
Volume 108
Issue 12
Start page 3333
End page 3341
Total pages 9
Place of publication Bethesda, MD, United States
Publisher American Physiological Society
Collection year 2013
Language eng
Formatted abstract
Current methods to reconstruct muscle contributions to joint torque usually combine electromyograms (EMGs) with cadaver-based estimates of biomechanics, but both are imperfect representations of reality. Here, we describe a new method that enables online force reconstruction in which we optimize a "virtual" representation of muscle biomechanics. We first obtain tuning curves for the five major wrist muscles from the mean rectified EMG during the hold phase of an isometric aiming task when a cursor is driven by actual force recordings. We then apply a custom, gradient-descent algorithm to determine the set of "virtual pulling vectors" that best reach the target forces when combined with the observed muscle activity. When these pulling vectors are multiplied by the rectified and low-pass-filtered (1.3 Hz) EMG of the five muscles online, the reconstructed force provides a close spatiotemporal match to the true force exerted at the wrist. In three separate experiments, we demonstrate that the technique works equally well for surface and fine-wire recordings and is sensitive to biomechanical changes elicited by a modification of the forearm posture. In all conditions tested, muscle tuning curves obtained when the task was performed with feedback of reconstructed force were similar to those obtained when the task was performed with real force feedback. This online force reconstruction technique provides new avenues to study the relationship between neural control and limb biomechanics since the "virtual biomechanics" can be systematically altered at will.
Keyword Motor Control
Myoelectric control
Biomechanics
Reaching Movements
Sensorimotor transformation
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2013 Collection
School of Human Movement and Nutrition Sciences Publications
 
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Created: Fri, 18 Jan 2013, 11:33:29 EST by Deborah Noon on behalf of School of Human Movement and Nutrition Sciences