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Explore the feasibility of feed-forward control systems in paralyzed muscles based on user's posture. Discover benefits of posture-dependent stimulation in standing neuroprostheses. This study compares controllers and their impact on reducing effort and improving efficiency. Findings suggest the potential for user-driven, task-dependent postures to enhance functional outcomes and balance in individuals with spinal cord injury.
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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
Aim • Use 3D biomechanical model of human standing to test feasibility of feed-forward control systems that vary stimulation to paralyzed muscles based on user’s posture and desire to effect postural change. • Relevance • Motor system neuroprostheses using functional neuromuscular stimulation can improve overall health and functional independence of individuals with paralysis from spinal cord injury.
Method • Controllers examined were— • Constant baseline stimulation: • Represented muscle activation required to maintain erect standing. • Posture follower: • Varied muscle activation as function of location of projection of whole-body center of mass on base of support.
Results • Posture-dependent control of stimulation demonstrated significant benefits over open-loop stimulation. • Compared with using upper-limb effort alone, both controllers result in >50% reduction in effort.
Conclusion • Control systems that facilitate user-driven, task-dependent postures can be more effective and efficient than conventional open-loop stimulation. • Obviate need for complicated posture-setting devices such as switches and joysticks. • Functional implications include potential to expand reachable workspace and better preparation for anticipated disturbances that could challenge balance over existing neuroprostheses for standing.