Implementation of Experimental Three-Axis Tactile Sensor System Applying Optical Waveguide Plate.

Abstract

The present paper describes the implementation of and experiments on a three-axis tactile sensor applying an optical wave guide plate. The sensor is comprised of a sparse array of columnar feelers and a dense array of conical feelers, which are formed on opposite sides of a silicon rubber sheet. The columnar feelers contact objects while the conical feelers contact the acrylic optical waveguide plate. Three components of a force vector applied to the columnar feeler are identified from contact areas of four conical feelers which are covered by one columnar feeler. Contact points of conical feelers photographed using a CCD camera are transferred into a frame memory board installed in a personal computer and they are memorized as 8-bit patterns. A one-bit pattern is quantized from the 8-bit pattern by utilizing a suitable threshold value; the contact areas of conical feelers are obtained from the total number of picture cells of the one-bit pattern. In evaluation experiments, several combinations of vertical and horizontal forces are applied to the columnar feeler through a probe attached to a three-axis force sensor. The experimental results show that the three components of the force vector can be calculated from the four contact areas, and that hard material is not favorable for the conical feelers but is suitable for columnar feelers.