Research on body sway caused by matrix-shaped tactile stimuli on dorsum of foot

The human postural control function is determined by inputs from three senses, namely, vision, balance, and somatosensation. Many studies have attempted to induce body movements in arbitrary directions using external stimuli to maintain and improve postural control functions. Previous studies demonstrated that sensory information from the plantar region of the foot is involved in the understanding of front–back position and regulation of body movements. In the present study, we investigated a method to induce postural control and walking movements in an arbitrary direction by presenting matrix-shaped tactile stimuli (MSTS) to the plantar region of the foot. We developed a tactile stimulation device to investigate body sway when the MSTS was presented to the dorsal surface region of a foot in a standing posture. This device is envisioned to be used as a wearable guidance tool in the future. In addition, the measurement experiment used a high-speed camera and an accelerometer placed on the top of the subject’s head to track the subject’s movements in response to the MSTS presented by the device. In this paper, the relationship between the control parameters (L, T) of tactile stimulation MSTS and body sway and its direction was considered. The results showed that the introduction of MSTS on the sole of the foot could induce body sway. The results also suggest that it is possible to induce body sway in the respective expected directions by setting appropriate parameters (L, T).