The use of deep learning for smartphone-based human activity recognition

• Published in: Frontiers in public health Vol. 11; p. 1086671
• Main Authors: Stampfler, Tristan, Elgendi, Mohamed, Fletcher, Richard Ribon, Menon, Carlo
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 28.02.2023
• Subjects: activity recognition; Adolescent; Adult; data science; Deep Learning; digital health; Employment; Human Activities; Humans; Middle Aged; Public Health; Smartphone; Young Adult; deep learning; digital health; smartphone; data science; wearable technology; public health; activity recognition; physical activity
• ISSN: 2296-2565; 2296-2565
• DOI: 10.3389/fpubh.2023.1086671

The emerging field of digital phenotyping leverages the numerous sensors embedded in a smartphone to better understand its user's current psychological state and behavior, enabling improved health support systems for patients. As part of this work, a common task is to use the smartphone accelerometer to automatically recognize or classify the behavior of the user, known as human activity recognition (HAR). In this article, we present a deep learning method using the Resnet architecture to implement HAR using the popular UniMiB-SHAR public dataset, containing 11,771 measurement segments from 30 users ranging in age between 18 and 60 years. We present a unified deep learning approach based on a Resnet architecture that consistently exceeds the state-of-the-art accuracy and F1-score across all classification tasks and evaluation methods mentioned in the literature. The most notable increase we disclose regards the leave-one-subject-out evaluation, known as the most rigorous evaluation method, where we push the state-of-the-art accuracy from 78.24 to 80.09% and the F1-score from 78.40 to 79.36%. For such results, we resorted to deep learning techniques, such as hyper-parameter tuning, label smoothing, and dropout, which helped regularize the Resnet training and reduced overfitting. We discuss how our approach could easily be adapted to perform HAR in real-time and discuss future research directions.