FrictShoes: Providing Multilevel Nonuniform Friction Feedback on Shoes in VR

Many haptic feedback methods have been proposed to enhance realism in virtual reality (VR). However, friction on the feet in VR, which renders feedback as if walking on different terrains or ground textures or stepping on objects is still less explored. Herein, we propose a wearable device, FrictShoes a pair of foot accessories, to provide multilevel nonuniform friction feedback to feet. This is achieved by the independent functioning of six brakes on six wheels underneath each FrictShoe, which allows the friction levels of the wheels from each to be either matched or to vary. We conducted a magnitude estimation study to understand users' distinguishability of friction force magnitudes (or levels). Based on the results, we performed an exploratory study to realize how users adjust and map the multilevel nonuniform friction patterns to common VR terrains or ground textures. Finally, a VR experience study was conducted to evaluate the performance of the proposed multilevel nonuniform friction feedback to the feet in VR experiences.