Wearable, Vibrotactile Sensory Substitution Robot for Balance Rehabilitation

Our project aimed to create a wearable, assistive rehabilitation device for people with sensory impairment in the legs as a result of SCI, Stroke, MS, Diabetes, or other similar conditions. More specifically, we aimed to target patients with nerve damage in the sacral spine but not in the lumbar region. Sacral spine nerve damage could result in loss of force sensation in the bottom of the foot, impairing patients' balance. However, by redirecting force feedback to lumbar nerves that end in the top of the foot, our device was designed to restore balance via sensory substitution and neuroplasticity.

Research had been conducted into various methods of balance restoration, through various means. Various forms of feedback had been used, including visual and vibrotactile. Likewise, research had been conducted into sole sensing for gait monitoring. Our device was intended to be a novel combination of the two, allowing for both balance detection and sensory substitution in a single, compact package.

The device was designed to have three main components. Sensing was to take place in an insole containing an array of force sensing resistors (FSRs). An Arduino Nano, housed in an enclosure strapped to the patient's ankle, would read and interpret the real-time spatially-distributed weight data and control an array of piezo vibration motors mounted to the top of a wearable sock. To avoid excess computation by the Arduino board, the piezo vibrators were designed to share the same arrangement as the FSRs under the foot, and each FSR would have a corresponding piezo actuator.

By relaying underfoot force data to the top of the foot using vibrotactile feedback, we hoped to intuitively restore the patient's sense of weight distribution. As more force was applied to a given FSR, the magnitude of felt vibration would increase. The result was expected to improve gait, posture, and balance, better enabling patients' activities of daily life while reducing the risk of falling.