Investigation on Perception of Fingertip Skin under Different Normal Force and Texture Spacing

The finger produces compression, tensile mechanical deformation when it is in contact with the surfaces of objects. It contains a wealth of tactile information in this process and has important significance on human perception of external environment. However, it is difficult to combine friction signals with subjective feelings in the previous studies. A UMT-II multi-specimen tribometer was used to load different normal force on index finger to simulate touch force. By changing the sample texture spacing, touch contact medium and diameter, the volunteers made their judgments about the stick amount of different samples. The results show that volunteers' friction perception can be reflected by the change of periodic pressure curves when fingertip slid over samples. The accuracy of judgment improved and perception ability enhanced with normal force and sample spacing increasing. The friction between fingertip and sample decreased as a result of the lubrication medium, thereby the accuracy of perception reduced. The sample of bigger diameter caused the larger fingertip deformation and volunteers' tactile perception were more sensitive.