Relaxation Assessment Based on Heart Rate Variability and Heart Rate Using Photoplethsmograms

This paper proposes a method in order to assess the level of relaxation of the subjects based on the photoplethysmograms (PPGs). Here, the PPGs are classified into five relaxation levels. In particular, the proposed system composes of a PPG acquisition device, a five class classification algorithm and a cloud system. The PPG acquisition device consists of a photo sensor operating at 880nm. For the algorithm, first three measurements are taken each time at the finger tip. Second, the PPGs are denoised. Third, the feature extraction is performed. More precisely, the heart rate (HR) and the heart rate variability (HRV) are extracted as the features. Fourth, the features are smoothed. Finally, the classification is performed via the random forest. For the cloud system, the PPGs are transmitted to the cloud system via the Wifi and the above processing is performed in the cloud system. Since our proposed system is non-invasive and wearable, it can provide the guideline on the relaxation level to the general public.