TY - JOUR
T1 - Posture-dependent control of stimulation in standing neuroprosthesis
T2 - Simulation feasibility study
AU - Audu, Musa L.
AU - Gartman, Steven J.
AU - Nataraj, Raviraj
AU - Triolo, Ronald J.
PY - 2014
Y1 - 2014
N2 - 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.
AB - 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.
KW - Biomechanical model
KW - FNS
KW - Functional neuromuscular stimulation
KW - Human standing
KW - Musculoskeletal modeling
KW - Neuroprosthesis
KW - Posture shifting
KW - Reaching
KW - Spinal cord injury
KW - Standing balance
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UR - http://www.scopus.com/inward/citedby.url?scp=84903318058&partnerID=8YFLogxK
U2 - 10.1682/JRRD.2013.06.0150
DO - 10.1682/JRRD.2013.06.0150
M3 - Article
C2 - 25019669
AN - SCOPUS:84903318058
SN - 0748-7711
VL - 51
SP - 481
EP - 496
JO - Journal of Rehabilitation Research and Development
JF - Journal of Rehabilitation Research and Development
IS - 3
ER -