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Snake robots slither to the rescue

Dean Irvine for CNN
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LONDON, England (CNN) -- For someone trapped under rubble after an earthquake the sight of something resembling a snake wriggling towards them would probably be the last thing they would want to see. But a new breed of life-saving robot is being developed that take their shape and movement from those limbless reptiles, and, it is hoped, will prove invaluable not only in search and rescue operations but also be a great asset to human surgery.

"So far we've really just scratched the surface of getting these robots to do all the things that they will be capable of. We can build purpose built devices that can climb or swim, which just demonstrates how versatile they are," Howie Choset, Associate Professor of Robotics at Carnegie Mellon University told CNN.

Choset and his team have designed a number of different snake robots that can undertake all manner of tasks from assisting in surgery to leading the way in rescue missions after earthquakes or collapsed mines.

Compared to existing robotic devices and traditional means of search and rescue using sniffer dogs, snake robots are packed with sensors and can use their unique shape and delicate movement to crawl over rubble and bend around obstacles.

Last year he and his team made a break-through by building a prototype enabling them to remotely climb up walls and around pipes.

"When it comes to main goal in search and rescue, location is the main aim, it's the main part of the game. Just locating a trapped victim can give so much hope. The ability for these robots to administer medication or water is secondary at the moment," said Choset.

"They've been used by search and rescue teams, the Indiana and New Jersey task forces, when they go on training scenarios. They've been very supportive. Seeing the robots explore tiny void spaces really blows them away."

"Ultimately, when the robots are able to be articulated and perform a number of tasks, they should be used as an invaluable tool in these scenarios."

The secret of Choset and his team's designs is in the degrees of freedom their robots have. While your elbow only has one degree of freedom, their articulated robots have 30, which Choset refers to as "hyper-redundant."

As well as providing advantages in the range and scope of what the robots can achieve, it also creates problems of how they are controlled.

"It's like having 30 dials which need to be turned at the same time," said Choset.

"You either need a lot of people working together with near telepathic communication and synchronization or you create an algorithm to control them."

The Carnegie Mellon team have gone for the latter and have created a sophisticated computer program that enables just one person to control the robot.

In Europe a different species is being developed by the Norwegian Institute of Technology to help fight fires. When their 3-meters long robot, nicknamed "Anna Konda", is connected to a fire hose the hydraulics enable it to project a powerful stream of water and give it enough power to lift 650 kilograms, strong enough, its developers believe, to punch a hole through a door or wall to get to the flames.

As well as search and rescue bots, Choset's team have designed small-scale devices for use in human surgery. They have faced the problem of making the same "hyper-redundant" mechanisms much smaller and without a loss of power or movement.

Others such as Russell H. Taylor, professor of Computer Sciences at Johns Hopkins University have tried another tack by making a tiny snake-like robot go where endoscopes have gone before and focused on making a fully articulated tip.

"We're not trying to replace or automate surgeons," said Taylor, "we want to work in partnership with them to help them do their work more effectively. Human hands are remarkable, but they have limitations."

Taylor and his team envisage their tiny serpent-like bots being used in areas such as throat operations, where they can bend easily and be used to make incisions and tie sutures with incredible dexterity and precision.

Their prototype is made of non-magnetic metals so can be used near magnetic imaging equipment and has been programmed to make up to 100 adjustments per second to be ultra precise in its movements.

Versatility then is winning feature of snake robots. Bomb disposal, bridge inspection and medical transportation are other areas that Choset and his team have designed for.

"We've demonstrated their versatility, but I want to see a robot that can climb over rubble, up walls and wriggle through gaps, where the environment isn't controlled," he said.

"The dynamics are a challenge, just like when Jackie Chan runs up a wall he gives himself a lift by using his arms, we have to give these robots the means to negotiate different obstacles."

"Also crucial is getting the robot to do the right thing and adapt to its situation and environment. Like when a plane lands, it doesn't just thump down onto the ground. These robots have an element of responsiveness when they touch something."

Currently the snake bots are battery powered, which limits both the distance they can travel and the length of time they can be operated. Advances in fuel cell technology could give them the range and power source that Choset has been looking for.

"The power source is one of the main challenges we face and we're currently doing the best we can with existing sources. As for fuel cells, there's a lot of talk about them, but they still need some serious development," he told CNN.

Coordinating all the degrees of articulation is also a slippery problem Choset and others are working on, as well as dealing with financial constraints.

However, while it may be another ten years before snake robots are consistently used in search and rescue operations or in medical situations, Choset believes they will one day be hugely valuable devices.

"We've currently only reached the tip of the iceberg with what we can do, but there is so much value to be had from these robots."


Attached to a mobile unit, a snake robot developed by Howie Choset investigates a hole during a training exercise.


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