Lego solves rubiks cube?

WBahn

Joined Mar 31, 2012
30,076
Wasn't this done quite some time ago? I seem to recall someone building a Rubik's Cube solver using the early Lego Mindstorms sets.

I know lots of non-Lego robots have done it -- the hard part is the data acquisition and the physical manipulation of the parts. The actual solution algorithm has been none since very shortly after the original came out.

The first robot I saw do it was extremely simple. It had the ability to rotate the cube 90° about two axes and about one of those axes could clamp the top layer so that only the bottom two rotated. It statically looked down with nine light sensors and then there were three lights that flashed alternatingly with red, green, and blue filters in front of different ones. The robot first rotated the cube so that each side was face up and so that it could determine the color pattern on each face. After that, it didn't need to check the patterns any more because it kept them updated in memory. Then it just moved the thing around in such a way that it only had to rotate the top layer 90° at any one time (which might be three successive rotations to accomplish a -90° rotation). It was fun to watch.

I seem to recall someone showing that if you knew the pattern on four of the sides (it might have been a specific four sides), that you could deduce the pattern of the remaining two.
 
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