S2C-HAR: A Semi-Supervised Human Activity Recognition Framework Based on Contrastive Learning

IF 1.5 4区 计算机科学 Q3 COMPUTER SCIENCE, SOFTWARE ENGINEERING
Xue Li, Mingxing Liu, Lanshun Nie, Wenxiao Cheng, Xiaohe Wu, Dechen Zhan
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引用次数: 0

Abstract

Human activity recognition (HAR) has emerged as a critical element in various domains, such as smart healthcare, smart homes, and intelligent transportation, owing to the rapid advancements in wearable sensing technology and mobile computing. Nevertheless, existing HAR methods predominantly rely on deep supervised learning algorithms, necessitating a substantial supply of high-quality labeled data, which significantly impacts their accuracy and reliability. Considering the diversity of mobile devices and usage environments, the quest for optimizing recognition performance in deep models while minimizing labeled data usage has become a prominent research area. In this paper, we propose a novel semi-supervised HAR framework based on contrastive learning named S2C-HAR, which is capable of generating accurate pseudo-labels for unlabeled data, thus achieving comparable performance with supervised learning with only a few labels applied. First, a contrastive learning model for HAR (CLHAR) is designed for more general feature representations, which contains a contrastive augmentation transformer pre-trained exclusively on unlabeled data and fine-tuned in conjunction with a model-agnostic classification network. Furthermore, based on the FixMatch technique, unlabeled data with two different perturbations imposed are fed into the CLHAR to produce pseudo-labels and prediction results, which effectively provides a robust self-training strategy and improves the quality of pseudo-labels. To validate the efficacy of our proposed model, we conducted extensive experiments, yielding compelling results. Remarkably, even with only 1% labeled data, our model achieves satisfactory recognition performance, outperforming state-of-the-art methods by approximately 5%.

基于对比学习的半监督人类活动识别框架
由于可穿戴传感技术和移动计算的快速发展,人类活动识别(HAR)已成为智能医疗、智能家居和智能交通等各个领域的关键要素。然而,现有的HAR方法主要依赖于深度监督学习算法,需要大量高质量的标记数据,这极大地影响了它们的准确性和可靠性。考虑到移动设备和使用环境的多样性,在最小化标记数据使用的同时优化深度模型的识别性能已成为一个突出的研究领域。在本文中,我们提出了一种新的基于对比学习的半监督HAR框架,名为S2C-HAR,它能够为未标记的数据生成准确的伪标签,从而在只使用少量标签的情况下获得与监督学习相当的性能。首先,为更一般的特征表示设计了HAR的对比学习模型(CLHAR),该模型包含一个专门针对未标记数据进行预训练的对比增强转换器,并与模型不可知的分类网络结合进行微调。此外,基于FixMatch技术,将两种不同扰动下的未标记数据输入到CLHAR中,生成伪标签和预测结果,有效地提供了鲁棒自训练策略,提高了伪标签的质量。为了验证我们提出的模型的有效性,我们进行了大量的实验,得出了令人信服的结果。值得注意的是,即使只有1%的标记数据,我们的模型也取得了令人满意的识别性能,比最先进的方法高出约5%。
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来源期刊
Concurrency and Computation-Practice & Experience
Concurrency and Computation-Practice & Experience 工程技术-计算机:理论方法
CiteScore
5.00
自引率
10.00%
发文量
664
审稿时长
9.6 months
期刊介绍: Concurrency and Computation: Practice and Experience (CCPE) publishes high-quality, original research papers, and authoritative research review papers, in the overlapping fields of: Parallel and distributed computing; High-performance computing; Computational and data science; Artificial intelligence and machine learning; Big data applications, algorithms, and systems; Network science; Ontologies and semantics; Security and privacy; Cloud/edge/fog computing; Green computing; and Quantum computing.
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