Comprehensive joint feedback control for standing by functional neuromuscular stimulation-A simulation study

Raviraj Nataraj, Musa L. Audu, Robert F. Kirsch, Ronald J. Triolo

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

Previous investigations of feedback control of standing after spinal cord injury (SCI) using functional neuromuscular stimulation (FNS) have primarily targeted individual joints. This study assesses the potential efficacy of comprehensive (trunk, hips, knees, and ankles) joint feedback control against postural disturbances using a bipedal, 3-D computer model of SCI stance. Proportional-derivative feedback drove an artificial neural network trained to produce muscle excitation patterns consistent with maximal joint stiffness values achievable about neutral stance given typical SCI muscle properties. Feedback gains were optimized to minimize upper extremity (UE) loading required to stabilize against disturbances. Compared to the baseline case of maximum constant muscle excitations used clinically, the controller reduced UE loading by 55% in resisting external force perturbations and by 84% during simulated one-arm functional tasks. Performance was most sensitive to inaccurate measurements of ankle plantar/dorsiflexion position and hip ab/adduction velocity feedback. In conclusion, comprehensive joint feedback demonstrates potential to markedly improve FNS standing function. However, alternative control structures capable of effective performance with fewer sensor-based feedback parameters may better facilitate clinical usage.

Original languageEnglish
Article number5594648
Pages (from-to)646-657
Number of pages12
JournalIEEE Transactions on Neural Systems and Rehabilitation Engineering
Volume18
Issue number6
DOIs
StatePublished - Dec 2010

Keywords

  • Control system
  • functional neuromuscular stimulation
  • rehabilitation
  • spinal cord injury
  • standing

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