Researchers in US build smallest chain robot

December 8, 2012 2:18pm

Researchers at the Massachusetts Institute of Technology have built the world's smallest chain robot, which they believe could be the robotic equivalent of a Swiss Army knife.

Dubbed "milli-motein," the robot is a caterpillar-sized assembly of millimeter-sized metal rings and strips, with a protein-inspired motorized design that lets it fold into complex shapes.

“It’s effectively a one-dimensional robot that can be made in a continuous strip, without conventionally moving parts, and then folded into arbitrary shapes,” said Neil Gershenfeld, head of MIT’s Center for Bits and Atoms, who helped conceive the device.

Researchers see the robot as being cheaper to produce and dynamically programmed to do various jobs instead of repeating a fixed one.

"This minuscule robot may be a harbinger of future devices that could fold themselves up into almost any shape imaginable," the MIT said.

It said the robot's development was supported by the US Defense Advanced Research Projects Agency’s Maximum Mobility and Manipulation and Programmable Matter projects.

Smallest chain robot

Gershenfeld, visiting scientist Ara Knaian and postdoctoral associate Kenneth Cheung conceived the device and described it in a paper presented recently at the 2012 Intelligent Robots and Systems conference.

To build the world’s smallest chain robot, the team built an electropermanent motor, which is small and strong, but able to maintain position even with power switched off.

MIT said the motor is similar in principle to giant electromagnets that lift cars.

Such electromagnets have a powerful permanent magnet that requires no power and a weaker magnet whose magnetic field direction can be flipped by an electric current in a coil.

The force of the powerful magnet can be turned off at will, such as to release a suspended car, without having to power an enormous electromagnet the whole time, MIT said.

In the robot, a series of permanent magnets paired with electromagnets are arranged in a circle to drive a steel ring.

"They do not take power in either the on or the off state, but only use power in the changing state," Knaian said.

Folding robot

The milli-motein concept follows up on a paper published last year, which delved into the possibility of assembling any desired 3-D shape by folding a long string of identical subunits.

Co-authored by Cheung, MIT professor Erik Demaine, alumnus Saul Griffith, and former Computer Science and Artificial Intelligence Laboratory research scientist Jonathan Bachrach, the paper mathematically proved it was possible for any 3-D shape to be reproduced by folding a sufficiently long string.

“We showed that you could make such a universal system that’s very simple,” Cheung says.

Demaine added folding the shape does not need to be sequential, moving along the string one joint at a time.

Other researchers, including some at MIT, explored fashioning reconfigurable robots from a batch of separate pieces that could self-assemble into different configurations.

Programmable matter

MIT quoted Hod Lipson, an associate professor of mechanical and aerospace engineering and computing and information science at Cornell University, as saying this can bring people "closer to the idea of programmable matter — where computer programs and materials merge to form a new kind of matter whose shape and function can be programmed — not unlike biology."

For now, Gershenfeld said the milli-motein is part of a family of devices being explored at size scales ranging from protein-based “nanoassemblers” to a version where the chain is as big as a person.

Knaian added a reconfigurable robot should be “small, cheap, durable and strong,” though it may not be possible at this time. — LBG, GMA News