Eco concept with recycling symbol and garbage on wooden table background top view

Recycling robot that sorts waste by ‘touch’ built by scientists

Image credit: Vadim Ginzburg |

Researchers at Massachusetts Institute of Technology’s (MIT) CSAIL have developed a recycling robot that uses sensors in its hand to determine the nature of a waste item and sort it accordingly.

MIT graduate Lillian Chin and her colleagues at the Computer Science and Artificial Intelligence Lab at MIT have developed a robot arm with soft grippers that picks up objects from a conveyor belt and identifies what they are made from by touch.

Daniela Rus, an MIT professor involved in the robot’s creation, said: “Computer vision alone will not be able to solve the problem of giving machines human-like perception, so being able to use tactile input is of vital importance.”

The robot, called RoCycle, uses capacitive sensors in its two pincers to sense the size and stiffness of the materials it handles, allowing it to distinguish between different metal, plastic, and paper objects. A strain sensor gauges an object's size, while two pressure sensors determine how squishy that object may be, whether it's easily-crushed paper or more rigid plastic. Also, as the sensors are conductive, the hand on the robot can detect the presence of metal.

In a mock recycling-plant setup, with objects passing on a conveyor, RoCycle correctly classified 27 objects with 85 per cent accuracy.

The hands themselves are made out of custom auxetics – materials that get wider when stretched – that twist when cut. Each finger in the robot’s hand includes “left-handed” and “right-handed” auxetics that counter each other’s rotation, allowing for more dynamic movement than a typical robot hand without having to resort to the air pumps and compressors of soft robots.

Recycling robot created by MIT  can sort paper and plastic by touch

Image credit: Jason Dorfman, MIT CSAIL

Chin believes that such robots could be appropriate in places such as apartment blocks or on university campuses to carry out first-pass sorting of people’s recycling, cutting down on contamination. Other companies are developing robots that sort materials by sight, for example, it is the primary tech behind AMP Robotics system that’s been used at a Denver, Colorado recycling facility. However, the team believes that using touch is more accurate.

“When you’re sorting through a huge stream of waste, there’s a lot of clutter and things get hidden from view,” Chin said. “You can’t really rely on image alone to tell you what’s going on.”

In March 2019, researchers at MIT and Harvard’s Wyss developed a soft robotic gripper capable of handling delicate objects and picking up things up to 100 times its own weight. In the same month, MIT research developers designed a “mini cheetah” robot that is capable of trotting over uneven terrain about twice as fast as an average person’s walking speed.

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