high-quality prosthesis that matches an individual."
Multimodal fabric-based tactile sensing skin prototype covering a 3D printed cylinder. (Source: Georgia Tech Healthcare Robotics Lab)
A completely different idea comes from Georgia Tech's Healthcare Robotics Lab. Like many robotic touch sensors, those in the team's multimodal fabric-based tactile sensing skin include force sensors. But the skin also has actively heated temperature sensors to measure heat transfer, plus passive, unheated temperature sensors. This combination of force sensing with active thermal sensing could help robots do a better, and safer, job of interacting with people.
"With force, some part of the robot, like an arm or hand, makes contact with the robot's environment," team leader Charles Kemp, associate professor of biomedical engineering, told Design News . "Force gives useful properties for knowing what the robot is touching. For instance, is the object soft or hard? It's also valuable to have an estimate of how much force it's applying, especially around people." The team also includes doctoral student Tapomayukh Bhattacharjee and masters student Josh Wade. A paper on this research can be found here.
Once the robot has contact with other objects, it can find out more than just whether an object is soft or hard. It can infer more and have more situational awareness, said Kemp. "Thermal sensing has real advantages in the different ways to do this. It tells you a lot about what an object is made of, but it's been underexplored." Active thermal sensors can recognize materials based on their thermal properties, while passive thermal sensors can recognize heat generating objects, like human bodies.
Design of fabric-based skin. (Source: Georgia Tech Healthcare Robotics Lab)
The team made a prototype skin embedded with these sensors, wrapped around a cylinder to emulate a robot arm. A carbon fiber heating strip carries current through it to heat the fabric skin, somewhat like the way an electric blanket works, said Wade. In between the sensors is a piezoresistive fabric layer. The resistance changes with changes in force. Surrounding all this is a standard, off-the-shelf, stretchable, athletic blue fabric that insulates. "The temperature sensors themselves are thermistors," said Wade. "These are very small resistors, and resistance changes as a function of temperature."
The technology can cover a large surface area, like an entire robot arm, where previous work in this area has focused on something as small as a finger, said Kemp. The team is also using the technology with robots. "Our focus is not sensor design so much as what can robots do once they have this type of information," he said. "We've tried this out in real-world settings, touching real objects. We haven't put this very latest multimodal fabric on a robot yet, but we have tested robot arms covered with our previous work in fabric force sensing technologies."
Healthcare-related applications could include adding force sensing to a prosthesis, which would not be challenging to do. "For a long time, robots weren't supposed to contact the world with their arms," said Kemp. "But especially with reaching for