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Anyone around in the early 1980s remembers the pop culture phenomenon that was the Rubik’s Cube. Introduced in 1980, the mechanical puzzle quickly became a source of pride—and a landmark challenge for teenagers looking to show off their puzzle-solving skills. Many public competitions were held to see how fast someone could solve the puzzle.

Now it turns out that a Lego robot can do it in just 12.5 seconds—with the help of an Android phone. At this week’s ARM Techcon 2010 developer conference in Silicon Valley, a Lego Mindstorms robotics kit paired with an ARM RISC CPU-powered HTC Nexus One smartphone did just that, DeviceGuru.com reports. Most attempts landed in the 15 second range, requiring 20 or 21 moves each.

Here’s a short (1:51) video showing a quick interview with Gilday as the Lego Mindstorms robot solves a puzzle for the camera. The phone itself is sitting in a slot at the top of the robot. Developer Dave Gilday places the Rubik’s Cube inside the robot, which then closes its arms around the puzzle and begins solving it:

The Nexus One was the one of the first Android phones to run a 1-GHz Qualcomm Snapdragon processor, as well as the very first phone to run Android 2.1. Google has since discontinued the phone after poor sales, thanks to Google’s unconventional (for the U.S., at least) sales and technical support setup. Many newer 1-GHz Android phones like the Droid X and the HTC Incredible would have no trouble running the same software, though.

Gilday’s latest creation improves on a Nokia N95-powered earlier attempt back in 2006 that could solve the puzzle in about 25 seconds. Gilday attributes the improvements mainly to the Nexus One’s much faster processor and 512MB of RAM, as opposed to the N95’s 332-MHz processor and 64MB RAM.

Think a 3×3 Rubik’s Cube isn’t that big a deal? Gilday has also spent the last 18 months refining his algorithms to work with larger V-Cube puzzles. “While demonstrating [the 3x3x3] robot to a few colleagues at ARM, I had some other puzzles lying on the desk including 4x4x4 and 5x5x5 Rubik’s Cubes,” he wrote in a blog post. “A number of people asked if the robot could solve any of these larger puzzles. I said ‘no’ and added that they would be physically much harder to solve than the 3x3x3 since the robot would have to be able to turn both the outer faces and also the second layer of pieces. I dismissed the thought until [a colleague] suggested a way of adapting the original mechanism to allow the second layer to be manipulated.”

To that end, Gilday created a more generalized, table-driven software algorithm that enabled “the size and combination of pieces in the groups solved at each stage to be chosen to make trade-offs between the number of stages, the number of table entries and the average and maximum length of move sequences at each stage,” the report said.

Check out this slightly longer (2:51) video of an 800-MHz Motorola Droid inside a much larger Lego Mindstorms NXT robot setup called the MultiCuber 777, solving a 7x7x7-sized cube. And don’t miss the blooper at the very end:

In real-life, the 7x7x7 cube takes a lot longer to solve—about 40 minutes and 500 moves—but we won’t put it past Gilday to try and speed this up, too.

Want to build your own 3x3x3 Rubik’s Cube-solving robot? Don’t miss DeviceGuru’s how-to guide; this one will do it in about six minutes and requires a Lego Mindstorms NXT kit.