Journal of Rehabilitation Research & Development (JRRD)

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Volume 51 Number 3, 2014
   Pages 481 — 496

Abstract — Posture-dependent control of stimulation in standing neuroprosthesis: Simulation feasibility study

Musa L. Audu, PhD;* Steven J. Gartman, MS; Raviraj Nataraj, PhD; Ronald J. Triolo, PhD

Departments of Biomedical Engineering and Orthopedics, Case Western Reserve University, Cleveland, OH; Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH

Abstract — We used a three-dimensional biomechanical model of human standing to test the feasibility of feed-forward control systems that vary stimulation to paralyzed muscles based on the user’s posture and desire to effect a postural change. The controllers examined were (1) constant baseline stimulation, which represented muscle activation required to maintain erect standing, and (2) posture follower, which varied muscle activation as a function of the location of the projection of whole-body center of mass on the base of support. Posture-dependent control of stimulation demonstrated significant benefits over open-loop stimulation. Posture follower reduced upper-limb (UL) effort by an average of 50% compared with UL effort alone and by an average of 34% compared with baseline stimulation. On the other hand, reduction in UL effort was an average of 32% when using baseline stimulation. Compared with using UL effort alone, both controllers result in more than a 50% reduction in effort. The results of this study indicate that control systems that facilitate user-driven, task-dependent postures can be more effective and efficient than conventional open-loop stimulation. Also, they obviate the need for complicated posture-setting devices such as switches and joysticks. Functional implications include the potential to expand reachable workspace and better preparation for anticipated disturbances that could challenge balance over existing neuroprostheses for standing.

Key words: biomechanical model, FNS, functional neuromuscular stimulation, human standing, musculoskeletal modeling, neuroprosthesis, posture shifting, reaching, spinal cord injury, standing balance.


View HTML ¦ View PDF ¦ Contents Vol. 51, No.3
This article and any supplementary material should be cited as follows:
Audu ML, Gartman SJ, Nataraj N, Triolo RJ. Posture-dependent control of stimulation in standing neuroprosthesis: Simulation feasibility study. J Rehabil Res Dev. 2014;51(3):481–96.
http://dx.doi.org/10.1682/JRRD.2013.06.0150
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