Two-finger stiffness discrimination of a virtual object with haptic sensation enhancement via the stochastic resonance effect

We investigated the stiffness discrimination ability of two fingers with stochastic resonance. Haptic perception at the fingertip is known to improve when vibrotactile noise propagates to the fingertip, and this phenomenon is called stochastic resonance. The improvement of a fingertip’s haptic sensation depends on the intensity of the noise propagating to the fingertip. Therefore, to improve the haptic sensation at multiple fingertips, we do not need to attach noise sources, such as vibrators, to multiple fingertips. Even if only one vibrator is used, the haptic sensation at multiple fingertips may be improved by propagating noise to the fingertips. In this study, we focus on stiffness discrimination as a task using multiple fingers, in which the thumb and index finger are used to touch a virtual object and perceive its stiffness. Subsequently, we demonstrate that the stiffness perception is improved by propagating sufficiently intense noise to the thumb and index finger using a vibrator. Furthermore, this study considers the same task in a real-world situation to investigate the relationship between the stochastic resonance effect and the stiffness discrimination task. The findings indicate the possibility of improving the haptic sensation at multiple fingertips using one vibrator.