Teen builds advanced robotic hand from LEGO parts

A talented teenager from the UK has built a four-fingered robotic hand from standard Lego parts that performs almost as well as research-grade robotic hands. The anthropomorphic device can grasp, move and hold objects with remarkable versatility and human-like adaptability.

Jared Lepora, a 16-year-old student at Bristol Grammar School, began working on the hand a couple of years ago with his father, who works at the University of Bristol. Called the Educational SoftHand-A, it is made entirely of LEGO MINDSTORMS components and is designed to mimic the shape and function of the human hand. The only non-LEGO parts are the cords that act as tendons.

The hand’s four fingers (an index, middle, pinkie and opposing thumb) and twelve joints (three on each finger) are driven by two motors that control two sets of tendons. One tendon opens the hand while the other closes it, similar to the push-pull system of our own muscles.

The key to its human-like adaptable grasp is a differential (a clever gearbox that splits power from one source to multiple outputs) made from LEGO clutch gears that mechanically links the motion of the joints within each finger. As described in a paper published on the arXiv preprint server, when the hand closes, the fingers move together.

If one finger hits an object first, such as the side of a cup, the force causes the gear to slip temporarily. This allows the motor’s force to redirect power to the other fingers, letting them continue to close. This mechanism, known as soft synergy, causes the hand to close automatically and the fingers to effectively wrap around an object.

During testing, Educational SoftHand-A successfully grasped and securely held a range of household objects, including soft toys, plastic cups and tape spools. The hand can fully close or open in about 1 second, and a single finger has a bearing capacity of 5 to 6 Newtons, sufficient to hold a load without giving way.

Educational tool

Ultimately, the aim of the project was not to outperform industrial robots, but to inspire children to learn about the frontiers of advanced technology in a fun way. “Constructing the Educational SoftHand-A has the potential to be an engaging and interesting project for children to learn about modern robotics,” wrote the authors of the paper, including Jared.

The research also showed that you don’t need to be in a cutting-edge lab to develop a sophisticated robotics concept. As Jared demonstrated, state-of-the-art technology can be built from one of the world’s most popular children’s toys.

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