Shen Mengqi, Tsui Kwok-Leung, Nussbaum Maury A, Kim Sunwook, Lure Fleming
IEEE J Biomed Health Inform. 2023 Apr;27(4):1891-1902. doi: 10.1109/JBHI.2023.3237077. Epub 2023 Apr 4.
Indoor fall monitoring is challenging for community-dwelling older adults due to the need for high accuracy and privacy concerns. Doppler radar is promising, given its low-cost and contactless sensing mechanism. However, the line-of-sight restriction limits the application of radar sensing in practice, as the Doppler signature will vary when the sensing angle changes, and signal strength will substantially degrade with large aspect angles. Additionally, the similarity of the Doppler signatures among different fall types makes classification challenging. To address these problems, we first present an experimental study to obtain Doppler signals under large and arbitrary aspect angles for diverse types of simulated activities. We then develop a novel, explainable, multi-stream, feature-resonated neural network (eMSFRNet) that achieves fall detection and a pioneering study of classifying seven fall types. eMSFRNet is robust to radar sensing angles and subjects, and is the first method that can resonate and enhance feature information from noisy/weak Doppler signatures. The multiple feature extractors - from ResNet, DenseNet, and VGGNet - extract diverse feature information with various spatial abstractions from a pair of Doppler signals. The resonated-fusion translates the multi-stream features to a single salient feature that is critical to fall detection and classification. eMSFRNet achieved 99.3% accuracy detecting falls and 76.8% accuracy classifying seven fall types. Our work is the firstmultistatic robust sensing system that overcomes the challenges associated with Doppler signatures under large and arbitrary aspect angles. Our work also demonstrates the potential to accommodate radar monitoring tasks that demand precise and robust sensing.
对于居家的老年人来说,室内跌倒监测具有挑战性,这是因为需要高精度且存在隐私方面的顾虑。多普勒雷达因其低成本和非接触式传感机制而颇具前景。然而,视线限制在实际应用中限制了雷达传感,因为当传感角度变化时,多普勒信号特征会有所不同,并且在大视角情况下信号强度会大幅下降。此外,不同跌倒类型之间多普勒信号特征的相似性使得分类颇具挑战性。为了解决这些问题,我们首先开展了一项实验研究,以获取在大角度和任意角度下针对各种模拟活动的多普勒信号。然后,我们开发了一种新颖的、可解释的、多流、特征共振神经网络(eMSFRNet),该网络实现了跌倒检测以及对七种跌倒类型进行分类的开创性研究。eMSFRNet对雷达传感角度和受试者具有鲁棒性,并且是第一种能够从嘈杂/微弱的多普勒信号特征中共振并增强特征信息的方法。多个特征提取器(来自ResNet、DenseNet和VGGNet)从一对多普勒信号中提取具有不同空间抽象的多样特征信息。共振融合将多流特征转化为对跌倒检测和分类至关重要的单一显著特征。eMSFRNet在跌倒检测方面的准确率达到99.3%,在对七种跌倒类型进行分类方面的准确率达到76.8%。我们的工作是首个克服了在大角度和任意角度下与多普勒信号特征相关挑战的多静态鲁棒传感系统。我们的工作还展示了适应需要精确且鲁棒传感的雷达监测任务的潜力。