Transition activity recognition using fuzzy logic and overlapped sliding window-based convolutional neural networks

In this paper, we propose a novel approach that can recognize transition activities (e.g., turn to left or right, stand up, and travel down the stairs). Unlike simple activities, the transition activities have unique characteristics that change continuously and occur instantaneously. To recognize the transition activities with these characteristics, we applied convolutional neural network (CNN) that is widely adopted to recognize images, voices, and human activities. In addition, to generate input instances for the CNN model, we developed the overlapped sliding window method, which can accurately recognize the transition activities occurring during a short time. To increase the accuracy of the activity recognition, we have learned CNN models by separating the simple activity and the transition activity. Finally, we adopt fuzzy logic that can be used to handle ambiguous activities. All the procedures of recognizing the elderly’s activities are performed using the data collected by the six sensors embedded in the smartphone. The effectiveness of the proposed approach is shown through experiments. We demonstrate that our approach can improve recognition accuracy of transition activities.