September 28, 2015

A light Touch: Embedded optical sensors could make robotic hands more dexterous

Carnegie Mellon Creates Sensor-rich Robotic Hand and New Stretchable Sensor

(September 28, 2015)  Optical sensors may be uniquely suited for use in robotic hands, according to Carnegie Mellon University researchers who have developed a three-fingered soft robotic hand with multiple embedded fiber optic sensors. They also have created a new type of stretchable optical sensor.
By using fiber optics, the researchers were able to embed 14 strain sensors into each of the fingers in the robotic hand, giving it the ability to determine where its fingertips are in contact and to detect forces of less than a tenth of a newton. The new stretchable optical sensing material, not incorporated in this version of the hand, potentially could be used in a soft robotic skin to provide even more feedback.
“If you want robots to work autonomously and to react safely to unexpected forces in everyday environments, you need robotic hands that have more sensors than is typical today,” said Yong-Lae Park, assistant professor of robotics. “Human skin contains thousands of tactile sensory units only in the fingertip and a spider has hundreds of mechanoreceptors on each leg, but even a state-of-the-art humanoid such as NASA’s Robonaut has only 42 sensors in its hand and wrist.”

The new stretchable optical sensor coud be used in
a soft rotobic skin to detect contact and measure force.

Adding conventional pressure or force sensors is problematic because wiring can be complicated, prone to breaking and susceptible to interference from electric motors and other electromagnetic devices. But a single optical fiber can contain several sensors; all of the sensors in each of the fingers of the CMU hand are connected with four fibers, although, theoretically, a single fiber could do the job, Park said. And the optical sensors are impervious to electromagnetic interference.

The Carnegie Mellon researchers will discuss the robotic hand, developed together with researchers at Intelligent Fiber Optic Systems Corp., with support from NASA, Sept. 29 at the IEEE International Conference on Intelligent Robots and Systems, IROS 2015, in Hamburg, Germany. A report on the highly stretchable optical sensors will be presented Oct. 1 at the same conference.

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