Fig. 3

An example of how cluster representation in serial 5-s periods changes over time in the signals without stimulation. A Dominant cluster label (orange or green) obtained from the first principal component coefficients is shown for the median accelerometer signal amplitude and B for the median rectified EMG in each channel per 5-s period. C The first principal component coefficients corresponding to the three accelerometer axes. D The labels for the time segments assigned to each of the two clusters. E The corresponding three-dimensional cluster division from the first principal component coefficients