Estimation of surface and deep layer muscle activity using electrode array

It is generally difficult to estimate surface and deep layer muscle activity using surface electrodes. Because, EMG signals that was measured by surface electrode is sum of the signals that are observed in the close of the electrode. Thus, the mixture of surface layer muscle signal and deep layer muscle signal are observed. In previous study, we focused on propagation direction of EMG signal, and we could identify surface and deep layer muscle activity using propagation direction of surface EMG. However, observed EMG propagation velocity was faster than the typical EMG propagation velocity. The reason is that this measurement is monopolar lead. In monopolar lead, the measured signals are affected by position of the reference electrode. Therefore, in this study, we tried to determine propagation direction of EMG accurately by measurement independent of position of the reference electrode. In the result, we could obtain precise propagation direction of EMG, which shows appropriate propagation velocity.