New sensors provide robots sense of touch

Scientists, including one of Indian origin, have given robots greater sensitivity and dexterity by mounting sensors on the grippers of their arms.
The new sensor technology, called GelSight, uses physical contact with an object to provide a remarkably detailed 3D map of its surface.
The GelSight sensor developed by researchers at Massachusetts Institute of Technology (MIT) in the US consists of a block of transparent rubber, one face of which is coated with metallic paint.
When the paint-coated face is pressed against an object, it conforms to the object's shape, said researchers, including Mandayam Srinivasan, a senior research scientist at MIT.

The metallic paint makes the object's surface reflective, so its geometry becomes much easier for computer vision algorithms to infer.
Mounted on the sensor opposite the paint-coated face of the rubber block are three coloured lights and a single camera.

"(The system) has coloured lights at different angles, and then it has this reflective material, and by looking at the colours, the computer can figure out the 3D shape of what that thing is," said Ted Adelson from MIT's Computer Science and Artificial Intelligence Laboratory (CSAIL).
A GelSight sensor was mounted on one side of a robotic gripper, a device somewhat like the head of a pincer, but with flat gripping surfaces rather than pointed tips.

For an autonomous robot, gauging objects' softness or hardness is essential to deciding not only where and how hard to grasp them but how they will behave when moved, stacked, or laid on different surfaces, researchers said.
Tactile sensing could also aid robots in distinguishing objects that look similar, they said.