Journal of Rehabilitation Research & Development (JRRD)

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Volume 49 Number 2, 2012
   Pages 279 — 296

Abstract — Center of mass acceleration feedback control for standing by functional neuromuscular stimulation: A simulation study

Raviraj Nataraj;1* Musa L. Audu, PhD;1 Robert F. Kirsch, PhD;2 Ronald J. Triolo, PhD1

1Motion Study Laboratory, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH; 2Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH

Abstract–The potential efficacy of total body center of mass (COM) acceleration for feedback control of standing balance by functional neuromuscular stimulation (FNS) following spinal cord injury (SCI) was investigated. COM acceleration may be a viable alternative to conventional joint kinematics because of its rapid responsiveness, focal representation of COM dynamics, and ease of measurement. A computational procedure was developed using an anatomically realistic, three-dimensional, bipedal biomechanical model to determine optimal patterns of muscle excitations to produce targeted effects upon COM acceleration from erect stance. The procedure was verified with electromyographic data collected from standing nondisabled subjects undergoing systematic perturbations. Using 16 muscle groups targeted by existing implantable neuroprostheses, we generated data to train an artificial neural network (ANN)-based controller in simulation. During forward simulations, proportional feedback of COM acceleration drove the ANN to produce muscle excitation patterns countering the effects of applied perturbations. Feedback gains were optimized to minimize upper-limb (UL) loading required to stabilize against disturbances. Compared with the clinical case of maximum constant excitation, the controller reduced UL loading by 43% in resisting external perturbations and by 51% during simulated one-arm reaching. Future work includes performance assessment against expected measurement errors and development of user-specific control systems.

Key words: acceleration, balance, center of mass, control system, feedback, functional neuromuscular stimulation, neuroprosthesis, posture, rehabilitation, spinal cord injury, standing.

View HTML  ¦  View PDF  ¦  Contents Vol. 49, No. 2
This article and all supplementary material should be cited as follows:
Nataraj R, Audu ML, Kirsch RF, Triolo RJ. Center of mass acceleration feedback control for standing by functional neuromuscular stimulation: A simulation study. J Rehabil Res Dev. 2012;49(2):279–96.

Last Reviewed or Updated  Wednesday, April 4, 2012 12:30 PM

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