EMG signals detection and processing for on-line control of functional electrical stimulation

The surface EMG signal detected from voluntarily activated muscles can be u sed as a control signal for functional neuromuscular electrical stimulation . A proper positioning of the recording electrodes in relation to the stimu lation electrodes, and a proper processing of the recorded signals is requi red to reduce the stimulus artefact and the non-voluntary contribution (M-w ave). Six orientations and six locations of the recording electrodes were i nvestigated in the present work. A comb filter (with and without a blanking windowing) was applied to remove the signal components synchronously corre lated to the stimulus. An operative definition of the signal to noise ratio and an efficiency index were implemented. It resulted that when the record ing electrodes were located within the two stimulation electrodes the best orientation was perpendicular to the longitudinal line. However the best ab solute indexes were obtained when the recording electrodes were located ext ernally of the stimulation electrodes, and in that case the best orientatio n was longitudinal. Concerning the filtering procedure, the use of a blanki ng window before the application of the comb filter, gave the best performa nce. (C) 2000 Elsevier Science Ltd. All rights reserved.