This paper proposes a method to improve the tactile sensitivity of the fingertip by placing multiple vibrators at a remote position away from the fingertip. It is known that a fingertip's tactile sensitivity improves when vibrotactile noise is applied to the fingertip or to a position away from the fingertip, such as the wrist. This is the application of stochastic resonance to the field of haptics. Preliminary experiments in this study have shown that the improvement of a fingertip's tactile sensitivity via remote vibrotactile noise depends on the propagation of the vibration on human skin. From the results of the preliminary experiments, it is expected that the larger the noise reaching the fingertip, the smaller the detectable input. Therefore, we consider that multiple vibrators at a remote position can propagate a larger noise to the fingertip and further improve the fingertip's tactile sensitivity compared to the use of only one vibrator as occurred in a previous study. Finite element analysis was performed so that the noises from multiple vibrators were properly superimposed at the fingertip. To synchronize the arrival of the noises at the fingertip from the multiple vibrators, we determined the positions of the vibrators and the time when each vibrator started generating noise. The results of a subject experiment confirmed that the proposed method significantly improved fingertip sensitivity compared to the case without SR or the case where only one vibrator was used.

This paper focuses on Stochastic Resonance (SR) for stiffness discrimination by two fingers. In particular, we show that the subthreshold vibrotactile noise applied on a remote position can improve tactile sensations of both index finger and thumb for a task requiring multiple fingers. We evaluate the user performances in a virtual environment (VE) by Weber fraction for stiffness perception under one of three different vibration source positions: on the index finger, on the thumb, and between the index finger and thumb. The results show that the stiffness discrimination ability increase under all three vibration source positions with the best performance obtained for the source location between index finger and thumb. The finding indicates the potential of using a single vibration source to enhance sensation of multiple fingers by the effect of SR.