High speed surface scanning using a robotic manipulator equipped with an optical three-axis tactile sensor

Abstract

An optical three-axis tactile sensor is comprised of a silicone-rubber sheet, an acrylic plate, a CCD camera and a light source. A silicone-rubber sheet has an array of 8×9 sensor cells consisting of a columnar feeler and conical feelers. In the present paper, the authors evaluated a new sensing element having a columnar feeler and 8 conical feelers proposed in the previous paper. For the sensing element, normal and shearing forces are calculated from integrated gray scale value and centroid displacement caused by conical feeler's contacts. In the present experiments, the tactile sensor was mounted on an articulated manipulator and the manipulator scanned on precise abrasive paper. It was found that obtained shearing force increased with increase of particle size of the abrasive paper and degreased with increase of scanning velocity. Contrarily, in the case of Teflon tape, shearing force was almost constant in spite of velocity increasing. The above-mentioned results show grinding phenomena discussed on theory of machining and Coulomb friction caused on dry surface.