Relationship between surface roughness and touch perception on the surfaces with randomly spaced, irregular features

The objective of the present study was to investigate the relationship between surface roughness and touch perception of surfaces with randomly spaced, irregular features. Two sets of specimens with top surfaces consisting of triangular peaks and valleys were modeled and 3D-Printed by varying the height of the peak, the depth of the valley, and the width between two intersections of the peak or valley with the center line. For one set of specimens, values of these variables were kept constant within a specimen but varied across specimens. For the other set of specimens, values of these variables were randomly selected in given ranges within a specimen while ranges were varied across specimens. The level of touch perception of each specimen was then measured using a questionnaire consisting of 16 adjectives related to touch perception and a 7-point Likert scale. Measured data were statistically analyzed and compared between different sets of specimens. Results indicated that it was inappropriate to directly apply findings of the previous studies for surfaces with regularly spaced, geometrically well-defined features to surfaces with randomly spaced, irregular features.