Tactile Sensor without Wire and Sensing Element in the Tactile Region Based on EIT Method

We propose a novel soft areal tactile sensor made of pressure-sensitive conductive rubber, the principle of which is based on the inverse problem theory. The significant feature of this sensor is that it needs neither wire nor sensing element in the tactile region, because the distribution of applied pressure relating to the resistivity change in the tactile region can be estimated using electrical impedance tomography (EIT). This method enables us to make a very simple tactile sensor free from problems of wire breaks and electrodes peeling off from the rubber. The results of experiments with a have proved its effectiveness. We also discuss our computation technique to reconstruct stable pressure distribution by using the least squares method.

I. Introduction

Recently the idea of covering a robot's surface with a “skin” of soft tactile sensors has attracted the attention of researchers, and some human-interactive robots covered with such sensors have actually been made [1], [2]. However, most conventional tactile sensors need a large number of sensing elements and wires because every detection point needs one sensing element and wiring to an A/D converter. There are some studies aiming to overcome this wiring problem by using 2D surface communication or wireless communication [3], [4], but these are very complicated and expensive solutions.