Shaping Redirected Walking with Ankle-Based Vibrotactile Feedback

Redirected Walking (RDW) is a locomotion technique where users can explore large virtual environments while physically moving within a limited real-world space. Existing haptic redirection techniques often rely on infrastructure-heavy setups that limit deployability in real-world XR systems. In this work we investigate whether lightweight, ankle-based vibrotactile feedback can modulate perceptual sensitivity to RDW curvature manipulations. We present a wearable, wireless, gait-synchronized ankle-tendon vibrotactile system that delivers unilateral or bilateral cues during the swing phase of walking. In a within-subject study (N = 28) spanning 14 experimental conditions, we systematically evaluate how stimulation side, temporal profile (constant vs. gait-velocity modulated), and curvature direction affect curvature detection thresholds. Results show that RDW effectiveness is strongly state-dependent: slow walking was consistently associated with larger curvature gains, and spatially asymmetric (unilateral) ankle stimulation produces greater perceptual bias than bilateral cues. Movement-contingent stimulation further improves perceived naturalness, presence, and user acceptance. Together, these findings provide the first systematic investigation of ankle-based vibrotactile augmentation for RDW and demonstrate that portable lower-limb hapticscan meaningfully extend redirection capabilities without environmental instrumentation. We derive design guidelines highlighting the importance of locomotor-state adaptation, spatial asymmetry, and gait synchronized feedback for scalable redirected walking in XR.