Parameters that affect subjective hardness in the acceleration response of a stylus when hitting an object

Abstract

We can hit an object with a stylus held in our hand to judge the hardness of the object. In order to realize this motion with a teleoperation system, it is necessary to clarify the factors that affect subjective hardness when hitting an object with a stylus. Therefore, we conducted a perceptual experiment to compare subjective hardness and a collision experiment to measure the acceleration response when hitting a block with a stylus. We confirmed that subjective hardness when hitting an object with low stiffness is related to Young’s modulus, which largely agrees with intuitive understanding. In contrast, we also confirmed that the subjective hardness when hitting an object with high stiffness varied depending on the material of the stylus and in some case objects with high stiffness may be perceived softer. This was caused by the double-strike phenomenon of the stylus, and we found that the subjective hardness changed according to the strength of the stimulation due to the double-strike phenomenon. Consequently, we found that the double striking phenomenon appearing in the acceleration response of the stylus can be one a measure for assessing subjective hardness.