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

Abstract

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.

Human Activity Recognition Using Convolutional Autoencoder and Advanced Preprocessing

“…For ResNet with SelectConv, the accuracy rates are 97.28%, 82.36%, 78.25%, 98.52%, and 94.33% on UCI-HAR, OPPORTUNITY, UniMib-SHAR, WISDM, and PAMAP2 respectively. A unified deep learning approach [16], based on ResNet, was applied to the UniMiB-SHAR dataset for two classification scenarios: binary and multi-class. For binary classification, the proposed method achieves an accuracy rate of 99.87% using 5-fold cross-validation (CV) and 98.48% using the leave-one-subjectout (LOO) method.…”