PMID- 34673496 OWN - NLM STAT- MEDLINE DCOM- 20220405 LR - 20220613 IS - 1940-9990 (Electronic) IS - 1932-4545 (Linking) VI - 15 IP - 6 DP - 2021 Dec TI - Q-PPG: Energy-Efficient PPG-Based Heart Rate Monitoring on Wearable Devices. PG - 1196-1209 LID - 10.1109/TBCAS.2021.3122017 [doi] AB - Hearth Rate (HR) monitoring is increasingly performed in wrist-worn devices using low-cost photoplethysmography (PPG) sensors. However, Motion Artifacts (MAs) caused by movements of the subject's arm affect the performance of PPG-based HR tracking. This is typically addressed coupling the PPG signal with acceleration measurements from an inertial sensor. Unfortunately, most standard approaches of this kind rely on hand-tuned parameters, which impair their generalization capabilities and their applicability to real data in the field. In contrast, methods based on deep learning, despite their better generalization, are considered to be too complex to deploy on wearable devices. In this work, we tackle these limitations, proposing a design space exploration methodology to automatically generate a rich family of deep Temporal Convolutional Networks (TCNs) for HR monitoring, all derived from a single "seed" model. Our flow involves a cascade of two Neural Architecture Search (NAS) tools and a hardware-friendly quantizer, whose combination yields both highly accurate and extremely lightweight models. When tested on the PPG-Dalia dataset, our most accurate model sets a new state-of-the-art in Mean Absolute Error. Furthermore, we deploy our TCNs on an embedded platform featuring a STM32WB55 microcontroller, demonstrating their suitability for real-time execution. Our most accurate quantized network achieves 4.41 Beats Per Minute (BPM) of Mean Absolute Error (MAE), with an energy consumption of 47.65 mJ and a memory footprint of 412 kB. At the same time, the smallest network that obtains a MAE 8 BPM, among those generated by our flow, has a memory footprint of 1.9 kB and consumes just 1.79 mJ per inference. FAU - Burrello, Alessio AU - Burrello A FAU - Pagliari, Daniele Jahier AU - Pagliari DJ FAU - Risso, Matteo AU - Risso M FAU - Benatti, Simone AU - Benatti S FAU - Macii, Enrico AU - Macii E FAU - Benini, Luca AU - Benini L FAU - Poncino, Massimo AU - Poncino M LA - eng PT - Journal Article PT - Research Support, Non-U.S. Gov't DEP - 20220217 PL - United States TA - IEEE Trans Biomed Circuits Syst JT - IEEE transactions on biomedical circuits and systems JID - 101312520 SB - IM MH - Algorithms MH - Artifacts MH - Heart Rate/physiology MH - *Photoplethysmography MH - Signal Processing, Computer-Assisted MH - *Wearable Electronic Devices EDAT- 2021/10/22 06:00 MHDA- 2022/04/05 06:00 CRDT- 2021/10/21 21:06 PHST- 2021/10/22 06:00 [pubmed] PHST- 2022/04/05 06:00 [medline] PHST- 2021/10/21 21:06 [entrez] AID - 10.1109/TBCAS.2021.3122017 [doi] PST - ppublish SO - IEEE Trans Biomed Circuits Syst. 2021 Dec;15(6):1196-1209. doi: 10.1109/TBCAS.2021.3122017. Epub 2022 Feb 17.