Macro-Fiber Composite-Based Tactors for Haptic Applications

Haptic technology is a critical component of human-computer interfaces. Traditional haptic actuators are often unable to provide the broad frequency range and latency that is required in many advanced applications. To address this problem, we propose a new type of tactor based on macro-fiber composites (MFCs), composites of piezoelectric fibers. We propose a physics-based model for the actuation of the tactors, calibrated and validated through experiments. As our tactors are intended for haptic applications, we consider the role of skin on their response, an aspect seldom analyzed in the literature. In our experiments, we simulate the presence of the skin with a rubber membrane in contact with the tactor, with varying pre-stretch, mimicking different indentations of the tactor on the skin. The MFC-based tactor can always generate vibration amplitudes higher than skin discrimination thresholds, over the range of frequencies of interest for haptics, with a latency much smaller than traditional actuators. We theoretically investigate the effect of the skin on tactor vibrations, highlighting the individual roles of skin stiffness and damping and their combined effect across a series of pre-stretches. Our tactor shows promise in haptic applications, including assistive technologies and real-time feedback systems for training, safety, and monitoring.