Tactile rendering of textures by an electro-active polymer piezoelectric device: mimicking friction-induced vibrations

In order to mimic Friction-Induced Vibrations (FIV) and render the perception of textures, a tactile device, named PIEZOTACT, has been developed by a thin, lightweight and flexible Electro-Active Polymer (EAP) piezoelectric actuator. The presented signal processing strategy, exploiting the Transfer Function of the electro-mechanical device, allowed for mimicking and accurately reproducing the FIV stimuli, measured when touching real textures. The correct FIV reproduction, by the developed device, has been verified by comparing the spectra of the measured signals when touching real surfaces and the ones reproduced on the fingertip by the PIEZOTACT device. A pilot discrimination campaign, performed on a single subject, highlighted the capabilities of the device, being the subject able to discriminate the simulated textures with a low number of mistakes. Moreover, the errors in discrimination were consistent with the ones occurred when discriminating the corresponding real surfaces. The spectra of the induced vibrations (tactile stimuli) allowed as well for explaining the difficulties to discriminate certain textures.