Roger Highfield
London Telegraph
Friday, November 17, 2006

Video: Wounded robot battles on

It sounds like a robot straight out of the Terminator films: scientists have designed a crawling machine that can sense and recover from damage to its own body, an ability that should help the creature explore dangerous and unforgiving terrain.

Animals can compensate for injuries by changing their movements, for example they can limp to take the pressure off a painful leg.

advertisementNow Hod Lipson’s team at Cornell University in Ithaca, New York, has invented starfish like “resilient robots” that can mimic this feat.

For example, they can detect a missing leg and invent a new way to walk.

First, the Starfish moves around and observes its own motion using sensors in its joints.

Then, it creates a “virtual” version of its body on its internal computer with virtual Lego.

As it explores the possibilities, it constantly updates the model to work out its precise shape.

"At the beginning it has no clue as to whether it is a snake or a spider,” said Mr Lipson.

Then the robot used the model to work out how to crawl, which it does in a slightly sinister way.

“We thought it would end up walking like a spider,” he said, surprised at the result.

The fascinating part, described in the journal Science, came when Mr Lipson and his colleagues Victor Zykov and Josh Bongard shortened one of the legs of the starfish.

The creature responded by shifting its gait, so it could still move about.

The robot did this by taking account of the damage to its body, revising its model of its body shape, then using the revised model with a shortened leg to “think up” new movements.

“Whether or not animals do this is debated,” said Lipson.

“While it is clear that higher animals have some sort of predictive internal model of themselves, it is not clear how this model is used, and if it is innate or it is acquired.

“Also, a real starfish - which has five legs - is much better than our robot at recovering from injury, because it can actually regrow its legs,” added Mr Bongard, who is now at the University of Vermont.

Whether or not this robot is adapting nature’s methods, Mr Bongard believes it can find a wide range of applications, from strolling on the sea bed to exploring the solar system - the work is backed by the US space agency Nasa.

“There is a need for planetary robotic rovers to be able to fix things on their own,” he said.

“The research is essential for Nasa who plan to continue using robots for planetary missions.

"Robots on other planets must be able to continue their mission without human intervention in the event they are damaged and cannot communicate their problem back to Earth.

"Our robot is able to detect -- without a camera -- that something is wrong, and teach itself to continue to walk in spite of incurred damage.”

The study builds on earlier work in which Lipson created an automatic way to evolve, improve and finally build a variety of simple mobile creatures without any significant human intervention, marking a milestone in a field called artificial life.

Measuring a few inches long, the robots consisted of a dozen or so plastic parts, have a rudimentary nervous systems and move like primitive inchworms.