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A Muscle Synergy-Inspired Adaptive Control Scheme for a Hybrid Walking Neuroprosthesis.

Alibeji, Naji A and Kirsch, Nicholas Andrew and Sharma, Nitin (2015) A Muscle Synergy-Inspired Adaptive Control Scheme for a Hybrid Walking Neuroprosthesis. Front Bioeng Biotechnol, 3. 203 - ?. ISSN 2296-4185

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Abstract

A hybrid neuroprosthesis that uses an electric motor-based wearable exoskeleton and functional electrical stimulation (FES) has a promising potential to restore walking in persons with paraplegia. A hybrid actuation structure introduces effector redundancy, making its automatic control a challenging task because multiple muscles and additional electric motor need to be coordinated. Inspired by the muscle synergy principle, we designed a low dimensional controller to control multiple effectors: FES of multiple muscles and electric motors. The resulting control system may be less complex and easier to control. To obtain the muscle synergy-inspired low dimensional control, a subject-specific gait model was optimized to compute optimal control signals for the multiple effectors. The optimal control signals were then dimensionally reduced by using principal component analysis to extract synergies. Then, an adaptive feedforward controller with an update law for the synergy activation was designed. In addition, feedback control was used to provide stability and robustness to the control design. The adaptive-feedforward and feedback control structure makes the low dimensional controller more robust to disturbances and variations in the model parameters and may help to compensate for other time-varying phenomena (e.g., muscle fatigue). This is proven by using a Lyapunov stability analysis, which yielded semi-global uniformly ultimately bounded tracking. Computer simulations were performed to test the new controller on a 4-degree of freedom gait model.


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Details

Item Type: Article
Status: Published
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Alibeji, Naji Anaa33@pitt.eduNAA33
Kirsch, Nicholas Andrewnak65@pitt.eduNAK65
Sharma, NitinNIS62@pitt.eduNIS620000-0003-1872-0156
Date: 4 December 2015
Date Type: Acceptance
Journal or Publication Title: Front Bioeng Biotechnol
Volume: 3
Page Range: 203 - ?
DOI or Unique Handle: 10.3389/fbioe.2015.00203
Schools and Programs: Swanson School of Engineering > Mechanical Engineering and Materials Science
Refereed: Yes
Uncontrolled Keywords: adaptive control, functional electrical stimulation, hybrid neuroprosthesis, non-linear control, time-invariant synergies
ISSN: 2296-4185
Date Deposited: 03 Jul 2017 14:30
Last Modified: 30 Oct 2018 12:59
URI: http://d-scholarship.pitt.edu/id/eprint/32679

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