Classical and adaptive control of ex vivo skeletal muscle contractions using Functional Electrical Stimulation (FES)

PLoS One. 2017 Mar 8;12(3):e0172761. doi: 10.1371/journal.pone.0172761. eCollection 2017.

Abstract

Functional Electrical Stimulation is a promising approach to treat patients by stimulating the peripheral nerves and their corresponding motor neurons using electrical current. This technique helps maintain muscle mass and promote blood flow in the absence of a functioning nervous system. The goal of this work is to control muscle contractions from FES via three different algorithms and assess the most appropriate controller providing effective stimulation of the muscle. An open-loop system and a closed-loop system with three types of model-free feedback controllers were assessed for tracking control of skeletal muscle contractions: a Proportional-Integral (PI) controller, a Model Reference Adaptive Control algorithm, and an Adaptive Augmented PI system. Furthermore, a mathematical model of a muscle-mass-spring system was implemented in simulation to test the open-loop case and closed-loop controllers. These simulations were carried out and then validated through experiments ex vivo. The experiments included muscle contractions following four distinct trajectories: a step, sine, ramp, and square wave. Overall, the closed-loop controllers followed the stimulation trajectories set for all the simulated and tested muscles. When comparing the experimental outcomes of each controller, we concluded that the Adaptive Augmented PI algorithm provided the best closed-loop performance for speed of convergence and disturbance rejection.

MeSH terms

  • Algorithms
  • Animals
  • Electric Stimulation*
  • Male
  • Mice
  • Models, Biological
  • Muscle Contraction / physiology*
  • Muscle, Skeletal / physiology*

Grants and funding

This research work was funded by the National Science Foundation Division of Chemical, Bioengineering, Environmental and Transport Systems (CBET). Funds were awarded for the proposal No. 0828114 titled “Collaborative Research: Adaptive Control and Functional Electrical Stimulation for the Control and Understanding of Muscle Dynamics” and the proposal No. 1055315 titled “CAREER: Functional Electrical Stimulation to Aid Phonation in the Presence of Unilateral Vocal Fold Paralysis”. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.