%0 Journal Article
%T Equilibrium-point control of human elbow-joint movement under isometric environment by using multichannel functional electrical stimulation
%A Kazuhiro Matsui
%A Yasuo Hishii
%A Hiroaki Hirai
%A Fumio Miyazaki
%J Frontiers in Neuroscience
%D 2014
%I Frontiers Media
%R 10.3389/fnins.2014.00164
%X Functional electrical stimulation (FES) is considered an effective technique for aiding quadriplegic persons. However, the human musculoskeletal system has highly non-linearity and redundancy. It is thus difficult to stably and accurately control limbs using FES. In this paper, we propose a simple FES method that is consistent with the motion-control mechanism observed in humans. We focus on joint motion by a pair of agonist-antagonist muscles of the musculoskeletal system, and define the ˇ°electrical agonist-antagonist muscle ratio (EAA ratio)ˇ± and ˇ°electrical agonist-antagonist muscle activity (EAA activity)ˇ± in light of the agonist-antagonist muscle ratio and agonist-antagonist muscle activity, respectively, to extract the equilibrium point and joint stiffness from electromyography (EMG) signals. These notions, the agonist-antagonist muscle ratio and agonist-antagonist muscle activity, are based on the hypothesis that the equilibrium point and stiffness of the agonist-antagonist motion system are controlled by the central nervous system. We derived the transfer function between the input EAA ratio and force output of the end-point. We performed some experiments in an isometric environment using six subjects. This transfer-function model is expressed as a cascade-coupled dead time element and a second-order system. High-speed, high-precision, smooth control of the hand force were achieved through the agonist-antagonist muscle stimulation pattern determined by this transfer function model.
%K functional electrical stimulation (FES)
%K equilibrium-point control
%K EAA ratio
%K EAA activity
%K muscle synergy
%U http://www.frontiersin.org/Journal/10.3389/fnins.2014.00164/abstract