Vibrotactile Balance Rehabilitation Gait Assist Device

Abstract

Visual, vibrotactile, and auditory cues have proven successful in numerous applications to supplement or in some cases completely replace missing sensory information. Sensory substitution using vibrotactile stimulation has been effective in improving postural stability during stationary tasks and tasks involving perturbed stance. The challenge increases, however, when designing a wearable device that provides meaningful information during a dynamic task such as walking. Techniques that directly apply the feedback strategies effective in stance (trunk tilt) to walking have largely proven ineffective (excluding heel-to-toe walking, which is essentially a series of standing balance tasks). We have demonstrated a device for correcting vestibulopathic gait using a novel feedback methodology that was co-developed with physical therapists specializing in balance rehabilitation. The device supplies vibrotactile cues based on factors during walking that are considered important by physical therapists, including gait velocity, stride length, and gaze. The device consists of three independent units, each consisting of an inertial measurement unit (IMU), vibrotactile display, and microprocessor. Head tilt (which approximates eye gaze), trunk tilt, stride length, and velocity are estimated by the IMUs and displayed to the patient in the form of vibrotactile cues on the head, trunk, and tibia, respectively. Algorithms were developed to estimate stride length and gait velocity in real time from measured heel-strike and toe-off events. Feedback of the head pitch angle is provided continuously to the subject, while gait velocity and stride length feedback are provided during heel strike events only. Preliminary results demonstrate that healthy subjects can interpret this feedback to correct their head pitch and adjust their stride length and gait velocity.