Investigating Subcutaneous Muscle Displacement Based on Innervation Zone Obtained by Decomposition of High-density...

High-density surface electromyography (HD sEMG) signals have been extensively explored for decoding motion intent, but it is known to be susceptible to the relative position of electrodes and muscles. Previous studies have shown that changes in the position of subcutaneous muscles may have an effect on surface EMG signals. However, it is difficult to quantify relative displacement directly in many studies where electrode-muscle shift occurs. The study further investigates the effect of electrodes position offset caused by shifts on the HD sEMG signals by quantifying the quantitative relationship between subcutaneous muscle displacement and innervation zone (IZ) displacement. In this study, the displacement of IZ obtained by HD sEMG was used as the predicted value and the subcutaneous muscle displacement obtained by ultrasound images was the true value. A total of eight able-bodied subjects were recruited for the data collection phase of the test. The positive correlation between subcutaneous muscle displacement and IZ displacement of the flexor carpi radialis was demonstrated by Pearson's correlation coefficient (r=0.9383). This provides a new idea for indirectly measuring the amount of muscle displacement and it may be possible to use IZ displacement instead of electrode-muscle shift in future studies.