Raviraj Nataraj; Musa L. Audu, PhD; Ronald J. Triolo, PhD

This article and any supplementary material should be cited as follows: Nataraj R, Audu ML, Triolo RJ. Center of mass acceleration feedback control of functional neuromuscular stimulation for standing in presence of internal postural perturbations. J Rehabil Res Dev. 2012;49(6):889–912. http://dx.doi.org/10.1682/JRRD.2011.07.0127

Slideshow ProjectDOI:10.1682/JRRD.2011.07.0127JSP

Center of mass acceleration feedback control of functional neuromuscular stimulation for

standing in presence of internal postural perturbations

Raviraj Nataraj; Musa L. Audu, PhD; Ronald J. Triolo, PhD

This article and any supplementary material should be cited as follows: Nataraj R, Audu ML, Triolo RJ. Center of mass acceleration feedback control of functional neuromuscular stimulation for standing in presence of internal postural perturbations. J Rehabil Res Dev. 2012;49(6):889–912. http://dx.doi.org/10.1682/JRRD.2011.07.0127

Slideshow ProjectDOI:10.1682/JRRD.2011.07.0127JSP

• Aim– Evaluate center of mass (COM) acceleration feedback

control of neuroprosthesis with functional neuromuscular stimulation (FNS) to restore standing balance to subject with spinal cord injury.

• Relevance– Neuroprosthesis users maintain balance by postural

corrections with upper-limb (UL) loads on assistive device or support surface (e.g., walker, countertop).

• This can compromise utility of standing with FNS by limiting functional use of hands and arms.

This article and any supplementary material should be cited as follows: Nataraj R, Audu ML, Triolo RJ. Center of mass acceleration feedback control of functional neuromuscular stimulation for standing in presence of internal postural perturbations. J Rehabil Res Dev. 2012;49(6):889–912. http://dx.doi.org/10.1682/JRRD.2011.07.0127

Slideshow ProjectDOI:10.1682/JRRD.2011.07.0127JSP

Methods• Created artificial neural network to map gain-

modulated changes in total body COM acceleration estimated from body-mounted sensors to optimal changes in stimulation required to maintain standing.

• Systematically tuned feedback gains to minimize UL loads applied by subject to instrumented support device during internally generated postural perturbations produced by volitional reaching and object manipulation.

This article and any supplementary material should be cited as follows: Nataraj R, Audu ML, Triolo RJ. Center of mass acceleration feedback control of functional neuromuscular stimulation for standing in presence of internal postural perturbations. J Rehabil Res Dev. 2012;49(6):889–912. http://dx.doi.org/10.1682/JRRD.2011.07.0127

Slideshow ProjectDOI:10.1682/JRRD.2011.07.0127JSP

Subject with spinal cord injury undergoing internal perturbations by volitionally moving object over level surface with one arm while stabilizing with other arm.

This article and any supplementary material should be cited as follows: Nataraj R, Audu ML, Triolo RJ. Center of mass acceleration feedback control of functional neuromuscular stimulation for standing in presence of internal postural perturbations. J Rehabil Res Dev. 2012;49(6):889–912. http://dx.doi.org/10.1682/JRRD.2011.07.0127

Slideshow ProjectDOI:10.1682/JRRD.2011.07.0127JSP

Results• Total body COM acceleration was accurately

estimated (>90% variance explained) from 3-D accelerometers mounted on pelvis and torso.

• Compared with clinical constant muscle stimulation, COM acceleration feedback control of stimulation improved standing performance by reducing UL loading required to resist internal postural disturbances by 27%.

This article and any supplementary material should be cited as follows: Nataraj R, Audu ML, Triolo RJ. Center of mass acceleration feedback control of functional neuromuscular stimulation for standing in presence of internal postural perturbations. J Rehabil Res Dev. 2012;49(6):889–912. http://dx.doi.org/10.1682/JRRD.2011.07.0127

Slideshow ProjectDOI:10.1682/JRRD.2011.07.0127JSP

Conclusions• This case study suggests that COM acceleration

feedback could be advantageous in standing neuroprosthesis.– Can be implemented with only a few feedback

parameters.– Requires minimal instrumentation for

comprehensive 3-D control of dynamic standing function.