A piezoelectric-based advanced wearable: obstacle avoidance for the visually impaired built into a backpack

Visual impairment constitutes a compelling issue for our society. The aging of our population will cause a rise in the number of individuals affected by these debilitating conditions, which often challenge people in their daily routine and bear significant healthcare costs and consequences on society at large. Technological progress offers unique means to improve life conditions for the visually impaired, who still rely on low-tech systems, such as canes and service dogs. Here, we present a novel design for a piezoelectric belt integrated into a backpack, which can provide vibrotactile stimulation to the abdomen to signal the presence of obstacles. The belt is composed of an array of ten macro-fiber composite (MFC) actuators, arranged in a matrix of five columns by two rows. Obstacle identification and localization is afforded by a computer vision system, developed by our collaborators. The output from the array of actuators is controlled by the computer vision system, such that, if an obstacle is identified in a certain "capture field", the corresponding actuator in an egocentric and spatiotopically preserved fashion is activated. The actuators comprise an encapsulated aluminum-backed MFC, driven by a tunable astable multivibrator. The resonance frequency of the actuators is tailored by adding a variable mass to a hollow cylinder fashioned as a protusion secured to the tactor, transmitting vibrations from the MFC to the skin of the human-in-the-loop. This new design allows us to enhance the peak-to-peak displacement of actuators of more than a tenfold factor over the 10-200 Hz frequency range, thereby surpassing, with a robust margin, the 50 μm threshold necessary for reliable discrimination given abdominal somatosensation.