One–Handed Control for Smartwatches Using Thumb Gestures to Ring

Users operate smartwatches with touch gestures (e.g., tap, double–tap, swipe); however, the displayed target’s small size causes tapping errors. Since the smartwatch’s input space is covered by the user’s finger, the user cannot verify the point to be tapped. In addition, users who wear smartwatches on their wrists must operate the smartwatch with the opposite hand, making it difficult to control the smartwatch when one hand is occupied. Therefore, we designed a one–handed control method that can execute operations by using the hand wearing a smartwatch and extending the input space. To detect thumb gestures, we designed a ring device equipped with photoreflectors. We implemented a system for detecting thumb gestures using time series data and the frequency power spectrum obtained by Fast Fourier Transformation of the time series data for Support Vector Machine. In a user study with five participants, the leave–one–participant–out cross–validation accuracy of the system to detect five thumb gestures was 87.33%.