Effects of Ankle Tendon Electrical Stimulation on Detection Threshold and Applicability of Redirected Walking

Redirected walking (RDW) is a method for exploring virtual spaces larger than physical spaces while preserving a natural walking sensation. Expanding the range of visual manipulation gains that can be applied without causing discomfort is necessary to apply RDW in practice. Ankle tendon electrical stimulation (TES) can expand the range by inducing body tilt sensation and sway. Therefore, in this study, we proposed a locomotion method that applies ankle TES to RDW. In Experiment 1, we evaluated the effect of TES on the detection threshold (DT), which is the maximal gain at which visual manipulation remains unnoticed. The results indicated that the DT was expanded when TES was applied to induce the body tilt sensation in the same direction as the RDW's visual manipulation. Specifically, the pooled mean of the DT was expanded by more than 18%. In Experiment 2, we evaluated the applicability, a supplementary index for assessing locomotion techniques. The results demonstrated that ankle TES mitigates the reduction of the applicability, especially under a curvature gain of $\pm 0.3 [m^{-1}]$±0.3[m-1].