ReD shoes: actuated footwear for multisensory redirected walking in virtual reality

A major challenge in virtual reality (VR) is enabling users to navigate expansive virtual environments within confined real-world spaces. Although redirected walking (RDW) addresses this by manipulating users' walking paths, it is hindered by visual-vestibular inconsistencies, leading to reduced immersion, discomfort, and constrained detection thresholds (DTs). We introduce ReD Shoes, redirecting shoes for VR locomotion with dynamically adjustable inclination designed to enhance multisensory integration by providing haptic feedback directly to the feet. This feedback mitigates visual-vestibular inconsistencies by enhancing proprioceptive cues and aligning tactile sensations with visual stimuli, thereby improving self-motion perception, presence, and gait stability. We conducted two experiments with 30 participants: 10 in a pilot study to optimize inclination parameters and 20 in a main study to evaluate the DT, gait stability, and user experience under No Inclination, Low Inclination (1 cm), and High Inclination (1.5 cm) conditions. Low Inclination considerably expanded the DT (43.64%), enhanced the user's feel of presence, and maintained walking stability through effective multisensory alignment. In comparison, High Inclination showed a smaller DT expansion (33.86%), increased discomfort, reduced stability, and aggravated oculomotor symptoms due to intensified sensory conflicts. This study demonstrates the use of ReD Shoes in addressing key RDW limitations by enhancing DT, stability, and user presence through active haptic feedback. Our findings offer insights for developing advanced VR mobility solutions, supporting adaptive haptic footwear that improves RDW functionality and extends immersive VR applications in gaming, training, and rehabilitation.