inFORCE: Bi-directional `Force' Shape Display for Haptic Interaction

While previously proposed hardware on pin-based shape display has improved various technical aspects, there has been a clear limitation on the haptic quality of variable 'force' feedback. In this paper, we explore a novel haptic interaction design space with 'force' controlled shape display. Utilizing high performance linear actuators with current reading functionality, we built a 10 x 5 'force' shape display, named inFORCE, that can both detect and exert variable force on individual pins. By integrating closed-loop force control, our system can provide real-time variable haptic feedback in response to the way users press the pins. Our haptic interaction design space includes volumetric haptic feedback, material emulation, layer snapping, and friction. Our proposed interaction methods, for example, enables people to "press through'' computationally rendered dynamic shapes to understand the internal structure of 3D volumetric information. We also demonstrate a material property capturing functionality. Our technical evaluation and user study assesses the hardware capability and haptic perception through interaction with inFORCE. We also discuss application spaces that 'force' shape display can be used for.