By Simon Hooper for CNN
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(CNN) -- If your idea of a robot is a metal-plated humanoid jerkily walking into walls then think again. Scientist are creating a new generation of "soft" machines that can change their shape and size, move in ever more agile ways and even split themselves into smaller robots.
Last month DARPA, the U.S. Defense Department's research agency, invited proposals from robotics experts to build a "chemical robot" made from soft, flexible materials and capable of squeezing through gaps smaller than its regular dimensions.
According to DARPA's research description, the robot should be about the size of a softball but capable of squeezing through a one centimeter hole and reconfiguring itself within 15 seconds.
"Nature provides many examples of ChemBot functionality," said DARPA. "Many soft creatures, including mice, octopi, and insects, readily traverse openings barely larger than their largest 'hard' component, via a variety of reversible mechanisms."
But while DARPA's "Terminator 2"-style morphing military robots may still be a long way off, many scientists are already working on robots that exhibit some of the characteristics required.
One of those is "Superbot," created by a team of researchers at the University of Southern California. Superbot is in fact a modular robotic system consisting of individual cube-shaped units as small as one square inch that are capable of attaching themselves to and communicating with other modules to create larger robots capable of carrying out a wide range of tasks.
"The idea is to have a robot made up of many autonomous modules that self-connect and change shape and size to accommodate different tasks in different environments, developer Wei-Min Shen told CNN.
At present, Superbot units respond to direct instructions, such as to form legs and climb a hill or reconfigure into a snake-like shape to go through a pipe.
But Shen said the ultimate goal was for Superbot to decide for itself the configuration best-suited to a particular task, describing them as "smart Transformers" after the shape-shifting cartoon toys.
"Each individual module is a complete robot. It can move forward, left and right, upside down, anything you want. Eventually, what we'd like to do is if they see a pipe or a very narrow gap they say, okay my body is too big, it will change to become a snake to go through it. If it needs to go up the stairs and it doesn't have legs it will grow legs. If the terrain is downhill it could simply become a ball and roll down."
Current applications for Superbot are being developed with space exploration in mind, but Shen said the technology could be usefully applied in any environment dangerous to humans such as for search and rescue tasks in mines or underwater -- although the laboratory is still working on a morphing robot capable of swimming.
"NASA has used many robots for doing different tasks but there are so many things, so the idea was to build one that can change shape and size depending on what NASA wants it to do," said Shen.
Dennis Hong, a robotics engineer at Virginia Tech, said research into "soft robotics" was part of a wider trend towards designing more flexible and innovative machines, such as his own "Whole Skin Locomotion" (WSL) robotic mechanism.
Inspired by amoeba-like single-cell organisms, WSL is a propulsion system that enables robots to squeeze through gaps smaller than its regular dimensions.
In an e-mail to CNN, Hong said WSL technology could one day be used in medical robots capable of performing delicate endoscopic surgical procedures, but warned: "A number of key component technologies must be addressed first, including unique soft actuators, power sources, and the proper soft 'skin' material that is very flexible and 'stretchy' while tough enough to withstand the direct interaction with the environment."
And, despite Superbot's impressive morphing abilities, Shen said DARPA's vision of a liquid-like robot was still a long way beyond existing technology.
"They want morphing and they want the body to be soft. Our body is hard components. So it would be nice to have a component that could change shape almost like liquid... but to make a robot have a different texture would obviously be a new dimension of robotics."