Anchor-based Haptics: Portable Interfaces Leveraging Real Surfaces to Display Grounded Forces for 3D Shape Simulation in VR

Haptic interfaces enable shape simulation in virtual reality, making such content "tangible". Among existing haptic technologies, "grounded" interfaces simulate convincing grounded surfaces (like walls, tables, or other grounded shapes) but have limited workspaces, while "portable" interfaces are usable everywhere but struggle to display force feedback. In this paper, we formalize an alternative approach that we call "anchor-based haptics", which consists of portable interfaces capable of temporarily making contact with a real surface and leveraging it for grounded force feedback. To illustrate this approach, we present two new interfaces: T-Hank, which uses a reel-based extension mechanism to give height feedback from the surface, and R-Hank, which provides orientation feedback. The design of these interfaces is presented, and their potential interest in virtual reality has been investigated within two user studies by comparing them with vibrations in various 3D tasks. Overall, T-Hank and R-Hank enhance user experience for the exploration of 3D shapes and softness sensations. Taken together, results promote the use of the anchor-based haptic approach for VR applications in which both a large workspace and shape simulation play a prominent role.