Magellan Lego Robot
"[Magellan] must have been a man of great courage, valiant in
both his thoughts and in undertaking great things, although he was not of
imposing presence, since he was small in stature and did not appear to be
much."
—Dominican Friar Bartolome de Las
Casa
Magellan was a navigating and mapping Lego robot that Murat Görgüner and I built as our final project for the 1996 Building Intelligent Robots (CS148) course of the Brown University Computer Science Dept.
Magellan used custom infrared distance sensors to navigate around a brick "room," and remember a map of the walls. After he was done, Magellan could be plugged into a Sun SPARCstation to display the map via a Java program.
Magellan used differential drive, shaft-encoding, and a vertical body shape to support fairly precise in-place turns. He used IR LED emitters and phototransistors to sense distance from walls. One distance sensor was mounted on front to detect oncoming walls. Two sensors on the side allowed Magellan to acquire a wall to follow, maintaining a consistent distance and straight alignment.
The on-board computer was a 68HC11-based controller having its origins in the MIT 6.270 course. Magellan's control program was modeled as a finite state machine with state entry and exit actions and continuous activies. The majority of the control software effort was in compensating for the imprecision of the Lego mechanics. After you've played with Lego robots for awhile, it's kinda cool to see one drive in straight lines, take crisp 90-degree turns, and pretty robustly orient itself after acquiring a wall at an angle.
Magellan's brain was implemented in Interactive C. You can download file magellan-brain.c. There is also some offboard Java and Perl code for displaying and downloading the map, available on request.
A couple more glamour shots of our little bundle of joy. (Thanks to Mousumi for her photography on these photos, which was not done justice by the poor scans.)
Magellan valiantly exploring uncharted territory.
Magellan engaging warp drive. In reverse. Oops.
Poor little Magellan met an untimely demise at the hands of a marauding band of CS148 teaching assistants. He fought bravely, and ultimately sacrificed himself so that his parents could escape unscathed (and get their parts kit deposits back). Do not despair, for Magellan's spirit lives on in the hearts of all whose lives he touched.
Here are some people who link to Magellan's page.
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