Identification of various kinds of papers using multi-axial tactile sensor with micro-cantilevers

Various kinds of papers have been identified by active touch of a multi-axial tactile sensor which has micro-cantilevers with strain gauge film on Si. When fine surface of the standard surface roughness scale and the printed stripe pattern on a banknote have been scanned by the tactile sensor, it allows to measure such fine roughness as a resistance change of the gauge film, and the triangular unevenness could be obtained down to 20 μm. Transient responses of the resistance change have been obtained when the sensor was pushed and moved on various kinds of blank papers successively. Some features are extracted from the response by a principal component analysis and the papers are classified in four clusters.