Cool square. A stack of swiveling, programmable blocks like this one can arrange more blocks to replicate itself.

A Chip Off the Robotic Block

A stack of high-tech blocks can copy itself, engineers report. That seemingly simple accomplishment marks a step toward fully self-replicating robots.

Futurists and sci-fi aficionados have long dreamt of sophisticated machines that replicate themselves. But producing such machines remains a challenge. In the 1950s, mathematicians Lionel and Roger Penrose devised sets of interlocking tiles that could "self-replicate" by forcing other tiles into similar configurations. More recently, mechanical engineer Gregory Chirikjian and colleagues at Johns Hopkins University in Baltimore, Maryland, have built miniature bulldozers out of Legos that can assemble others of their kind by piecing together several previously assembled modules, such as chassis and tracks.

Now, other mechanical engineers have developed a system that conceptually falls somewhere between simple tiles and half-assembled machines. Victor Zykov, Hod Lipson, and colleagues at Cornell University in Ithaca, New York, built high-tech cubical blocks measuring about 10 centimeters on a side. Each block consists of two halves that can swivel against each other and latch onto other blocks with electromagnets. A microchip within the block tells it how to move when it finds itself surrounded by various arrangements of other blocks. By carefully programming the blocks, Lipson and colleagues found that they could make a stack of four blocks collect nearby blocks and assemble them into an identical stack. It's a modest start, Lipson says, but the blocks might be able to form far more complex structures if assembled in large numbers. And given the right tools, he says, such modular robots should be able to adapt to perform any task done by a more specialized robot--at least in principle.

Still, the blocks are a long way from self-replicating machines, Chirikjian says. They only arrange other blocks, he says, rather than making new ones. That far harder task is left to the researchers.

Related sites
See the blocks in action
Hod Lipson's Web site
Gregory Chirikjian's Web site