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. Author manuscript; available in PMC: 2019 Feb 15.
Published in final edited form as: IEEE Sens J. 2017 Dec 27;18(4):1665–1674. doi: 10.1109/jsen.2017.2787628

Fig. 4.

Fig. 4

(a). RMSE from PEP estimated from features obtained from accelerometers placed on the sternum (Str), below the right clavicle (RC), point of maximal impulse (PMI), and below the left clavicle (LC)for both the dorsoventral axis (z-axis) and head-to-foot and dorsoventral axes combined (z+x axes). (b) RMSE from PEP estimated from features obtained from the best performing combination of accelerometer locations. It can be observed that adding more sensors does not substantially reduce the error obtained using one sensor below the left or right clavicle. (c) RMSE from PEP estimated from accelerometers placed on the sternum with different interfacing techniques: in the middle of a silicone rubber sheet placed along on the sternum (fstr), directly on the sternum (Str), and two accelerometers coupled by a rigid plastic mold and placed on the upper sternum (US) and lower sternum (LS). (d) Ranking of best 15 features obtained from the combination of sensors and axis that rendered the lowest RMSE (Str+LC axis z).