A hybrid deep convolutional and recurrent neural network for complex activity recognition using multimodal sensors

Complex activities refer to users' activities performed in their daily lives (e.g., having dinner, shopping, etc.). Complex activity recognition is a valuable issue in wearable and mobile computing. The time-series sensory data from multimodal sensors have sophisticated relationships to characterize the complex activities (e.g., intra-sensor relationships, inter-sensor relationships, and temporal relationships), making the traditional methods based on manually designed features ineffective. To this end, we propose HConvRNN, an end-to-end deep neural network for complex activity recognition using multimodal sensors by integrating convolutional neural network (CNN) and recurrent neural network (RNN). To be specific, it uses a hierarchical CNN to exploit the intra-sensor relationships among similar sensors and merge intra-sensor relationships of different sensor modalities into inter-sensor relationships, and uses a RNN to model the temporal relationships of signal dynamics. The experiments based on real-world datasets show that HConvRNN outperforms the existing complex activity recognition methods. (C) 2019 Published by Elsevier B.V.