A YouTube video appeared earlier this week showing a robot solving the Rubik’s Cube in world record time. It was so fast that you can miss it in the blink of an eye. The official time noted was 0.38 seconds. The robot was made by MIT robotics student Ben Katz and software developer Jared Di Carlo.
Katz used motors from other robotics projects and bought some off eBay in addition ti two $7 PlayStation Eye cameras. These cameras were placed on opposite corners so all the faces of the cubes were visible.
“We used the cheapest cube we could find on Amazon Prime because we thought we’d end up destroying many of them, but somehow ended up only going through four cubes and hundreds of solves.” Di Carlo writes in a blog post. You can watch the video of the failed attempt here:
The pair largely attributes the impressive time to using better motors. “We noticed that all of the fast Rubik’s Cube solvers were using stepper motors, and thought that we could do better if we used better motors,” Di Carlo explains. “So we did.” Specifically, the pair used six Kollmorgen ServoDisc U9-series motors. These need only 10 ms to perform a quarter turn of the cube, reaching a rotation of 1,000 rpm in that time.
The min2phase algorithm is used by the robot to solve the puzzle. It takes in data from the cameras and converts it into moves for the motors. But, it was more complicated than that and a lot of work needed to be done to synchronize the motors to prevent collisions when making moves.
They found the solution in tightening the cube to make it harder. “When the cube is loose (like it would be if a person were trying to solve it fast), the outer faces just cam outwards when you try to turn the center faces quickly,” Katz explains in a blog post. “It took tightening the cube way past what intuitively felt appropriate, in order to stop the camming action from happening.”
Katz believes that further tuning could decrease the time even further but the pair does not feel like trying it anytime soon. “For the time being, Jared and I have both lost interest in playing the tuning game,” writes Katz. So, the position to make improvements is open and if you feel you can accomplish, why not take a go at it. You can watch the record-breaking video below: