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tetrahedra-based robots

I went to a really interesting seminar today on Tetrahedra-based Robotic Systems, presented by some scientists from Goddard. They make these robots out of tetrahedra, where each edge is a strut that can expand or contract in length. They move solely by dint of this expansion and contraction, adjusting centers of gravity so they tumble (in the case of forms with few tetrahedral elements) or slither (in the case of forms with hundreds of tetrahedral elements) along, ideally autonomously, on the surface of another planet. The large ones—‘complex’ seems like the wrong word given that they're all based on the same tetrahedron building block—can morph into a wide variety of shapes: an arm/hand to grip things, a wheel to roll along smooth surfaces, a snake to slither through a field of rocks, a climber to make its way up crevices, a high-gain antenna to beam its findings back to earth (!).

I wish the videos they showed us were on the 'net somewhere, because they were mesmerizing. With all the struts fully contracted, it would take up a small volume when it's launched or otherwise transported. Since it can conform to almost any surface and move over almost any terrain, you don't need to be particular about where you land it, either. They make it look so beautiful and simple, although some of the required technology is years or decades away. Right now they have a working prototype of a single-tetrahedron robot that's manually controlled (wirelessly via Bluetooth). Naturally, they brought it along, where it proved to be a popular demo. Pretty soon they'll finish building a 12-tet robot; they're also developing a tetrahedra-based robotic arm for upcoming lunar lander missions.

In other geometrical news, a Penn State math prof made a sculpture that depicts a 3-d shadow of a 4-d object. I don't know when I'll be returning to my alma mater next, but when I do I must check this out.



( 4 comments — Leave a comment )
Oct. 21st, 2005 08:47 pm (UTC)
That is such a cool idea! Wow, now I want to see pictures too.
Oct. 21st, 2005 08:53 pm (UTC)
building block
about the building block:

What's the control mechanism? Wires? RF?

Power source?


What kind of drive do they have to expand and contract?

And most importantly, is there an automatic control of these things? Aka an on-board computer that can autonomously perform simple tasks such as "go over there"? Because I know that, at least with Mars lander rovers, lag can be a heck of an issue between planets.
Oct. 21st, 2005 09:00 pm (UTC)
Re: building block
For the control mechanism, do you mean how a human controls it?

Power source: nuclear batteries were mentioned.

MTBF: I don't think they're far enough into the design to say. In their fancy video demo, they showed how a robot with a damaged strut could still move and how it could "grab" a replacement strut from another robot.

They're looking at all kinds of drives for the expansion and contraction—really anything you can imagine. (In other words, they had a long list of potential drive mechanisms, but I've forgotten the individual ones.)
Oct. 21st, 2005 09:05 pm (UTC)
Re: building block
Oops, I forgot your last question. Yes, ultimately they're planning to make these things autonomous. Algorithmically, they've figured out how to make the robot autonomous enough that it can "go over there". Their current 1-tet prototype isn't that smart; I wonder if the 12-tet one will be. I really hope to hear some updates about this.
( 4 comments — Leave a comment )