Sensor-based Human Activity Recognition Using Graph LSTM and Multi-task Classification Model

Abstract

This paper explores human activities recognition from sensor-based multi-dimensional streams. Recently, deep learning-based methods such as LSTM and CNN have achieved important progress in practical application scenarios. However, in most previous deep learning-based methods exist potential challenges such as class imbalance and multi-modal heterogeneity with time and sensor signals. To handle those problems, we propose a graph LSTM and Metric Learning model (GLML) with multiple construction graph fusion by modeling the sensor-aspect signals and the graph-aspect activities. GLML is a semi-supervised co-training architecture, which can be seen as several iteratively pseudo-labels sampling processing in the unlabeled data. Specifically, we construct three graphs to capture the different relations in each timestamp. Meanwhile, the graph attention model and attention mechanism are proposed to integrate multiple graph interactions for different sensor signals. Furthermore, to obtain a fixed representation of hidden state units and their neighboring nodes, we introduce the Graph LSTM to learn the graph-aspect relations from graph-structured constructed graphs. Notably, we propose a multi-task classification model combining loss function for classification distribution with deep metric learning to enhance the representation ability of the multi-modal sensor data. Experimental results on three public datasets demonstrate that our proposed GLML model has at least 2.44% improved in average against the state-of-the-art methods.