A Sensitive Skin Based on Touch-Area-Evaluating Tactile Elements

In this paper, we propose a new tactile sensor skin system. The system consists of two components. One is a sensor element which detects a contact area in addition to a contact force. The element is inspired by the fact that humans can discriminate sharpness of objects sensitively on any parts of their bodies in spite of their several-cm Two Point Discrimination Thresholds. We have developed the element that has such characteristics in a very simple structure; two layers of compressible insulators (urethane foam) sandwiched between three pieces of stretchable conductive sheets (conductive fabric). The other component is a sensor/communication chip. The chips are arranged at the boundaries of the elements, and the chips measure the capacitances between the conductive layers and send signals through the same conductive layers. The chips enable us to connect the elements and compose a soft robot skin including no long wires.