Pages 207-208
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 2-by-2 conical feelers. Since the 2-by-2 conical feelers are detached from the acrylic board under too large horizontal force, the three-axis tactile sensor can detect friction coefficient of the object surface with limited range of horizontal force only. In the present paper, the authors proposed three sensing elements : in type-I element a columnar feeler has a conical feeler, in type-II one has 2-by-2 conical feelers; in type-III one has 8 conical feelers. To evaluate the these sensing elements, we conducted a series of experiments using an x-z stage and a two-axis force sensor. It was found that the element consisting of a columnar feeler and 8 conical feelers shows almost linear relationship between centroid movement and horizontal force. Therefore, the Type-III element is suitable for the present sensing method estimating horizontal force from centroid movement.
