How robots can feel more than humans

Researchers at the University of Southern California have demonstrated that a specially designed robot is capable of outperforming humans in identifying a wide range of natural materials.

The robot – modded by a team at USC’s Viterbi School of Engineering – is equipped with a new type of tactile sensor built to mimic the human fingertip. 

It also runs an advanced algorithm, allowing the robot to make decisions about how to explore the outside world by imitating human strategies.

Capable of other human sensations, the sensor can discern where and in which direction forces are applied to the fingertip – and even the thermal properties of an object being touched.

Like the human finger, USC’s BioTac sensor has a soft, flexible skin over a liquid filling. The skin even boasts fingerprints on its surface, greatly enhancing its sensitivity to vibration. 

Indeed, as the finger slides over a textured surface, the skin vibrates in characteristic ways. These vibrations are detected by a hydrophone inside the bone-like core of the finger. The human finger uses similar vibrations to identify textures, but the robot finger is even more sensitive.

When humans try to identify an object by touch, they use a wide range of exploratory movements based on their prior experience with similar objects. 

A famous theorem by 18th century mathematician Thomas Bayes describes how decisions might be made from the information obtained during these movements. Until now, however, there was no way to decide which exploratory movement to make next.

Built by USC’s (and SynTouch’s) Jeremy Fishel, the specialized robot was trained on 117 common materials gathered from fabric, stationery and hardware stores. When confronted with one material at random, the robot could correctly identify the material 95% of the time, after intelligently selecting and making an average of five exploratory movements. 

Interestingly enough, it was only rarely confused by pairs of similar textures that human subjects making their own exploratory movements were incapable of distinguishing.

Note: Original funding for development of the BioTac sensor was provided by the Keck Futures Initiative of the National Academy of Sciences to develop a better prosthetic hand for amputees. SynTouch also received a grant from the National Institutes of Health to integrate BioTac sensors with such prostheses. The texture discrimination project was funded by the US Defense Advanced Research Projects Agency (DARPA) and the material hardness study by the National Science Foundation.