Robot Tactile Perception

Abstract

In this paper we discuss some fundamental issues related to the development of an artificial tactile sensing system intended for investigating robotic active touch. The analysis of some psychological and psychophysical aspects of human tactile perception, and a system design approach aimed at effectively integrating the motor and sensory functions of the robot system, suggested to conceptually organize tactile exploratory tasks into a hierarchical structure of sensory-motor acts. Our approach is to decompose complex tactile operations into elementary sensory-motor acts, that we call “TACTILE SUBROUTINES”, each aimed at the extraction of a specific feature from the explored object. This approach simplifies robot control and allows a modular implementation of the system architecture: each function can be developed independently and new capabilities can easily be added to the system. All tactile exploratory procedures are selected and coordinated by a high-level controller, which also operates the integration of tactile data coming from sensors and from lower levels of the hierarchy.

Some experimental results will be presented demonstrating the feasibility and usefulness of tactile sensing in exploratory operations. A recently developed sensor will be briefly presented, which exploits force/torque information measured directly at the tip of the robot end-effector. This sensor is able to detect, besides the position of the contact point, the normal and tangential components of the contact force. Methods for characterizing the surface of manipulated objects, according to their hardness, texture and friction properties will also be discussed.