Vibration-Induced Friction Control for Walkway Locomotion Interface

Falls represent a major challenge to mobility for the elderly community, a point that has motivated various studies of balance failures. To support this work, we are interested in mechanisms for the synthesis of ground environments that can be controlled to exhibit dynamic friction characteristics. As a first step, we investigate the design and development of such a variable-friction device, a hybrid locomotion interface using a cable-driven vibrotactile mechanism. Measurements on our prototype, consisting of an aluminum tile covered with low-friction polytetrafluoroethylene (PTFE), demonstrate that it can effectively simulate a low coefficient of static friction. As part of the design, we also investigated the role that induced vibration plays in modifying the coefficient of friction. Measurements of sliding on a PTFE-covered tile in a tilted configuration showed a significant influence of normal low-frequency vibration, particularly for frequencies around 20 Hz, regardless of the user's weight.