Biography
Biography: Masahiro Ohka
Abstract
To enhance robotic performance, robots should obtain information about the environment and objects in it via multi-modal sensations such as vision, hearing and tactile sensing. Since tactile sensation is required to achieve dexterous manipulation, several tactile sensor designs have been proposed in robotics. Our three-axis tactile sensor is produced with a unique design that can measure not only normal force but also tangential force distribution caused by contact between a robotic finger and an object. The three-axis sensor is composed of small cylindrical sensing elements of rubber, an aluminum dome, an acrylic dome, a light source, a fiberscope and a CCD camera. The aluminum dome has 41 holes arranged concentrically, into which the sensing elements are inserted; the acrylic dome illuminated by a light source is inserted into the aluminum dome beneath the sensing elements. When an object touches the array of sensing-element tips, the sensing-element bottoms touch the acrylic dome. Since diffusion reflection occurs at the contact points, which are observed by the CCD camera, tactile information between the object and sensing-element tips is obtained as image data. The normal and tangential forces are obtained from integrated gray-scale values and centroid movement of brightness distribution. We produced a dual hand-arm robot equipped with three-axis tactile sensors on it fingertips. To evaluate the three-axis tactile sensor, we are conducting experiments using the robot to perform such tasks as cap twisting, block assembly and passing an object from the robotic hand to a person’s hand.