A robot hand built from Lego pieces by a 16-year-old and his father can grab and move objects, displaying similar qualities to a leading robotic hand.

Jared Lepora, a student at Bristol Grammar School, UK, began developing the hand when he was 14 with his father, Nathan Lepora, who works at the University of Bristol.

The device borrows principles from cutting-edge robotic hands, including the Pisa/IIT SoftHand, but uses only off-the-shelf parts from Lego Mindstorms, a line of educational kits for building programmable robots.

“My dad’s a professor at Bristol University for robotics, and I really liked the designs [of robotic hands],” says Jared. “It just inspired me to do it in an educational format and out of Lego.”

The hand is driven by two motors using tendons, and each of its four fingers has three joints. A differential made from Lego clutch gears links the digits so they move together until they touch an object, then stop moving, similar to how humans grasp objects.

In tests, the Lego hand successfully grasped nine household items, including a plastic cup and bowl, as well as a soft toy weighing 0.8 kilograms.

A single finger on the hand can close fully in about 0.84 seconds and open in 0.97 seconds – around half as fast as a 3D-printed equivalent of the Pisa/IIT SoftHand using metal bearings. In static tests, a finger on the Lego hand could bear 5 newtons of load and push 6 newtons of weight, and had 1.8 newtons of closing force, compared with 8 newtons of load-bearing force, 7 newtons of weight-pushing force and 2 newtons of closing force for the 3D-printed version.

“You’re never going to get a hand that’s as good [as a 3D-printed hand] in terms of its capabilities with a hand made out of Lego,” says Nathan. The Lego hand is also significantly bigger: each of the four digits is 145 millimetres long and 30 millimetres wide.

Lego Mindstorms were discontinued in 2022, but Jared says the device can still be updated with different Lego pieces. “The way that I implemented the motors, they can easily be taken off, and newer motors can be added,” he says.

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