Sensate Hand Design
We have currently created a new articulated hand for Leonardo consisting of integrated tactile sensor circuit boards on the palm, back, and side of the hand as well as a PIC based 64 Channel A/D converter board housed inside the hand. We are in the process of developing algorithms which will begin to treat clusters of FSRs as receptive fields for higher level processing. These "cortical-level" fields will be capable of processing motion, direction, and orientation as well determing the centroid of an object placed on the skin. This framework is being design using the hands as a test case but with the final design of a full-body sense of touch in mind.
Sensate Skin
The human skin is the largest sensory organ of our body and of profound importance to how we interact with the world and with others. Yet despite its significance in living systems, the sense of touch is conspicuously rare if not absent in robots.

Giving the robot a sense of touch will be useful for detecting contact with objects, sensing unexpected collisions, as well as knowing when it is touching its own body. Other important tactile attributes relate to affective content---whether it is pleasure from a hug, a ticking gesture, or pain from someone grabbing the robot's arm too hard, to name a few.

The goal of this project is to develop a synthetic skin capable of detecting temperature, proximity, and pressure with acceptable resolution over the entire body, while still retaining the look and feel of its organic counterpart. Toward this end, we are experimenting with layering silicone materials (such as those used for make-up effects in special effects industry) over force sensitive resistors (FSR), quantum tunneling composites (QTC), temperature sensors, and capacitive sensing technolgoies.

In addition to developing the sensate skin technology, we are developing a distributed computational infrastructure to quickly read in large number of sensors throughout the body.

We are also developing a computational somatosensory cortex with low level feature extractors and pattern recognition algorithms to implement these tactile perception abilities.

Working closely with the artists at Stan Winston Studio, we are developing a tactile sensing system where FSRs are placed over the robot's core and under the silicone skin and fur.

Using the homunculus distribution of sensing resolution as a guide, we are varying the density of sensors so that the robot will have greater resolution in areas that are frequently in contact with objects or people.

A distributed network of tiny processing elements is also being developed to lie underneath the skin to acquire and process the sensory signals.

This movie shows Leonardo responding to touch. Capacitive sensing technology is used near the ear, and force resistive sensing is used in the hand.

Papers
W. D. Stiehl, L. Lalla, and C. Breazeal (2004). “Applying a Somatic Alphabet Approach to Inferring Orientation, Motion and Direction in Clusters of Force Sensing Resistors."  Proceedings of the 2004 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS-04).

W. D. Stiehl, L. Lalla, and C. Breazeal (2004). “A Somatic Alphabet Approach to Sensitive Skin for Robots.” Proceedings of the 2004 IEEE International Conference on Robotics and Automation (ICRA-04). 2865—2870, New Orleans, LO.

Stiehl, W.D & Breazeal, C. (2006) “A Sensitive Skin for Robotic Companions Featuring Temperature, Force and Electric Field Sensors.” In Proceedings of the 2006 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS-06). 1952-1959.

Walter Daniel Stiehl, Sensitive Skins and Somatic Processing for affective and Sociable Robots based upon a Somatic Alphabet Approach, May 2005. S. M. Media Arts and Sciences.

This movie (.mov file, 8711KB) shows Leonardo's new hand design with FSR's responding to pressure being applied by different objects.
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