To estimate the pulse wave, we first applied an averaging filter and subtracted it from each of the components. The window duration of the filter was empirically set to 1/7th of a second which effectively removed signal shifts and trends due to body motion while preserving BCG information. Then, a band-pass Butterworth filter of order two, with high and low cut-off frequencies of 4 and 11 Hz respectively, was applied to isolate the BCG changes. The different components of each sensor were then aggregated with a square root of the summation of the squared components to make the estimations robust to different body postures. Finally, a band-pass Butterworth filter of order two with cut-off frequencies of 0.66 and 2.5 Hz (corresponding to 40 and 150 beats per minute) was applied to obtain the final pulse wave. These parameters encompass a range of heart rates that might reasonably be expected in daily life