Deep Ensemble Learning for Human Activity Recognition UsingWearable Sensors via Filter Activation

During the past decade, human activity recognition (HAR) using wearable sensors has become a new research hot spot due to its extensive use in various application domains such as healthcare, fitness, smart homes, and eldercare. Deep neural networks, especially convolutional neural networks (CNNs), have gained a lot of attention in HAR scenario. Despite exceptional performance, CNNs with heavy overhead is not the best option for HAR task due to the limitation of computing resource on embedded devices. As far as we know, there are many invalid filters in CNN that contribute very little to output. Simply pruning these invalid filters could effectively accelerateCNNs, but it inevitably hurts performance. In this article, we first propose a novelCNN for HAR that uses filter activation. In comparison with filter pruning that is motivated for efficient consideration, filter activation aims to activate these invalid filters from an accuracy boosting perspective. We perform extensive experiments on several public HAR datasets, namely, UCI-HAR (UCI), OPPORTUNITY (OPPO), UniMiB-SHAR (Uni), PAMAP2 (PAM2), WISDM (WIS), and USC-HAD (USC), which show the superiority of the proposed method against existing state-of-the-art (SOTA) approaches. Ablation studies are conducted to analyze its internal mechanism. Finally, the inference speed and power consumption are evaluated on an embedded Raspberry Pi Model 3 B plus platform.