Active tactile sensor for detecting contact force and hardness of an object

We propose a new type of tactile sensor that can detect both the contact force and hardness of an object. It consists of a diaphragm with a mesa structure, a piezo-resistive displacement sensor on the diaphragm, and a chamber for pneumatic actuation. An array of these sensors can detect the two-dimensional contact force-distribution and hardness-distribution information and the surface texture of the contacted object. We theoretically analyzed the operation of the tactile sensor, and designed its specifications for a device for detecting the touch of a human finger. We fabricated devices of several different sizes by micromachining technologies to prove the principle. The sensor element is 6.0 turn x 6.0 mm x 0.4 mm, and it has a displacement sensor element of piezo-resistance at the periphery of the diaphragm structure. We experimentally confirmed the characteristics of the device by using pneumatic actuation. (C) 2003 Elsevier Science B.V. All rights reserved.