At the time of publishing, MindCuber was believed to be the fastest, completely autonomous, LEGO robot to solve the well known Rubik's Cube puzzle. Total solve time, including the scan, averages around 1 min 55 secs for the version shown in this video although the published version averages around 2 min 30 secs.
MindCuber's unique mechanical design allows the cube to be manipulated quickly and reliably using only two motors allowing the third motor to be used to move the colour sensor during the scan.
The software for the solver runs on the ARM7 microprocessor in the NXT "Intelligent Brick" using the LEGO colour light sensor to scan the cube. The ultrasonic sensor is used to detect when the cube is inserted to start the solve automatically.
MindCuber uses a table-driven solving algorithm that was developed to fit in the limited memory of the NXT while generating reasonably short solutions of around 30 to 40 moves.
Mike Dobson (Oscarworld, @RoboticSolutions), with whom I jointly created CubeStormer II, has kindly allowed me to use another of his wonderful musical creations, "Cube-essence", as backing for this video.
MindCuber was demonstrated publicly for the first time at the World Robot Olympiad in Abu Dhabi from 18th-20th November 2011.