Researchers at the Robotic Systems Lab have taught a four-legged ANYmal to solve a large Rubik's Cube on its own. It turns the layers with its front legs while balancing on its hind legs.
At the Robotic Systems Lab of ETH Zurich, a team led by Professor Marco Hutter had a four-legged ANYmal D robot solve an oversized Rubik's Cube, using only its feet. According to heise, the cube weighs around 4.6 kilograms. The work has been published as a preprint on arXiv and has not yet been peer reviewed.
The robot first turns the cube with its front legs and scans each side with its camera. It calculates the solution with the well-known Kociemba algorithm. It then turns the individual layers with its feet while keeping its balance on its hind legs. The layers of the cube are weighted so that the bottom stays in place while turning.
Learned rather than programmed
The robot learned the movements through reinforcement learning, meaning many rounds of trial with a reward for successful movements, rather than having each step programmed individually. On the real hardware it achieved three complete solutions without intervention, each with around 30 moves in eight to nine minutes.
That is not fast. It is still exciting, because legged robots have so far mainly been used for inspection.