GAN for Generating User-Specific Human Activity Data From An Incomplete Training Corpus

Walter Gerych, Harrison Kim, Joshua DeOliveira, MaryClare Martin, Luke Buquicchio, Kavin Chandrasekaran, Abdulaziz Alajaji, Hamid Mansoor, Elke A. Rundensteiner, Emmanuel Agu

Abstract: Human activity recognition (HAR), the task of predicting the activities performed by an individual using mobile sensor data, is an active and important area of research. Unfortunately, it is very costly to collect the data required to train robust HAR classifiers. To tackle this issue, there has been an increasing focus on generating synthetic HAR data for augmentation purposes. The state-of-the-art generative HAR approaches utilize Generative Adversarial Networks (GANs) to produce realistic synthetic HAR data. However, these solutions can not generate personalized data that matches the behavior of particular users, limiting their potential use cases. This is particularly problematic in the mobile health domain, where the target users are often elderly or disabled and are thus likely to have activity signals that are unique from the general population. To overcome this drawback, we propose a novel controllable GAN solution Control-HAR-GAN. Our approach learns user and activity signals independently, and when generating synthetic instances, practitioners can specify both the activity to be generated as well as the user the data should match. This has the added benefit in that our model supports novel user-activity pairs by generating examples that match the data that would have been recorded by a particular user if they had performed the target activity, even if the user never performed that activity during the data collection process. We show that our model outperforms the existing HAR GAN approach in generating observed user-activity pairs by up to 10%. Additionally, our approach can also perform the task of novel user-activity pair generation, which is impossible for existing approaches.