Reproducing Ascending and Descending Sensations in Virtual Reality Through Crossmodal Interactions with a Slanted Handrail

Numerous past studies have been conducted on the perception of horizontal movements, such as Redirected Walking (RDW). However, reproducing the sensation of vertical movement has been challenging. Many conventional methods physically replicate steps or slopes, but this can be dangerous and induce fear in cases where head-mounted displays (HMDs) obstruct vision. Our objective was to reproduce the sensation of walking a slope while walking on a flat surface. This is accomplished by providing the tactile perception of a tilted handrail, similar to those found on ramps or escalators. For this purpose, we developed a walker-type handrail device that can be tilted at arbitrary angles. By combining the tactile stimulation provided by this hardware with an HMD-based visual stimulation of walking up a sloped scene, we induced a crossmodal effect that strengthened the slope sensation. The results indicated that fear decreased and enhanced the sensation of walking up a slope.