HAPmini: 2D haptic feedback generation using single actuator device

This study aims to explore a feasible form of a haptic device for common users. We propose HAPmini, a novel graspable haptic device that enhances the user's touch interaction. To achieve this enhancement, the HAPmini is designed with low mechanical complexity, few actuators, and a simple structure, while still providing force and tactile feedback to users. Despite having a single solenoid-magnet actuator and a simple structure, the HAPmini can provide haptic feedback corresponding to a user's 2-dimensional touch interaction. Based on the force and tactile feedback, the hardware magnetic snap function and virtual texture were developed. The hardware magnetic snap function helped users perform pointing tasks by applying an external force to their fingers to enhance their touch interaction performance. The virtual texture simulated the surface texture of a specific material through vibration and delivered a haptic sensation to users. In this study, five virtual textures (i.e., reproductions of the textures of paper, jean, wood, sandpaper, and cardboard) were designed for HAPmini. Both HAPmini functions were tested in three experiments. First, a comparative experiment was conducted, and it was confirmed that the hardware magnetic snap function could increase the performance of pointing tasks to the same extent as the software magnetic snap function could, which is commonly used in graphical tools. Second, ABX and matching tests were conducted to determine whether HAPmini could generate the five virtual textures, which were designed differently and sufficiently well for the participants to be distinguished from each other. The correctness rates of the ABX and the matching tests were 97.3% and 93.3%, respectively. The results confirmed that the participants could distinguish the virtual textures generated using HAPmini. The experiments indicate that HAPmini enhances the usability of touch interaction (hardware magnetic snap function) and also provides additional texture information that was previously unavailable on the touchscreen (virtual texture).