Effects of the Amplitude of High-Frequency Oscillator on Perceived Slipperiness and Coefficient of Friction

Abstract

A reduction in friction is one of the illusions related to the sense of touch. This effect is experienced when a finger comes in contact with an object that vibrates at a frequency greater than or equal to approximately 20 kHz. The reduction in frictional force is greater for vibrating objects than for objects that are not vibrating and when the finger is unable to follow the object’s movement. New tactile devices can potentially be developed using this friction reduction effect by controlling the friction coefficient. Therefore, in this study, we aim to develop a device that can measure the frictional force exerted by a vibrating object and clarify the effect of amplitude on the subjective slipperiness and dynamic friction coefficient. In an experiment involving ten male and female participants, the slipperiness of an object vibrating at 40 kHz with amplitudes of 0-2.5 μm was evaluated by the participants through touching with their index fingers. The experimental results suggested that subjective slipperiness can be controlled in four steps by changing the amplitude. Furthermore, it was found that factors other than the dynamic friction coefficient may affect subjective slipperiness.