Nonlinear Tactile Element to Sense Contact Force and Area

Abstract

In this paper, we propose a new tactile sensor element to realize practical robot skins. The element acquires not only a contact force but also a contact area within its several-cm-sq. sensing area. By arraying the elements, we can cover a large area with a small number of them, and collect rich tactile information. The structure of the element is very simple; two layers of compressible insulators (urethane foam) which are sandwiched between three pieces of stretchable conductive sheets (conductive fabric). The structure enables us to obtain the contact force and area from the capacitances between the conductive layers. We also propose a method to connect the elements with no long wires. Sensor/communication chips are arranged at the boundary of the elements. The chips measure the capacitances between the conductive layers and send signals through the same layers.