Five years ago, the Mars Rover Spirit got stuck in sandon the red planet. Spirit is one of the American spaceagency’s two motorized vehicles on Mars. Recently, the other vehicle – Curiosity -- had to go a long way toavoid another sandy area. These incidents led somescientists to develop ways to keep the costly robotsfrom being trapped in the sand. These scientists lookedto nature for their ideas.
The researchers flew deadly snakes to Zoo Atlanta inAtlanta, Georgia. The snakes, called sidewinderrattlers, are native to the southwestern United States.
The creatures were put in a specially designedsandbox with inclines that could be raised up orlowered. The scientists used high-speed videocameras to record the position of the snakes as they moved sideways updifferent inclines. Their movement is called sidewinding.
Daniel Goldman teaches physics at the Georgia Institute of Technology inAtlanta. He says the snakes moved easily in the sand -- even when the sandbegan moving.
“They were quite good at climbing angles, even close to the angle where thesand begins to cascade.”
Mr. Goldman and other researchers wrote about their findings in the journalScience. They are said to be the first to explain this kind of snake movement.
“We noticed that the animals were in fact sidewinding, using the same kind ofpattern of sidewinding they use on hard ground, but laying instead of only afew points of contact on the body contacting the ground, they were essentiallylaying more and more snake body down on the hill as the incline angleincreased.”
Researchers then performed experiments with a robot developed at CarnegieMellon University in Pennsylvania. The robot is called MOD-Snake. It is onemeter long, and has 16 parts or modules. Each module is 6 centimeters wide.Daniel Goldman says the robot has a long history of getting in and out of tightplaces.
"It turned out they had actually been using the sidewinding gait in their robotfor many years to traverse all kinds of ground, but always had trouble onsandy dune inclines."
Researchers wanted to get the MOD-Snake to climb in the same way as thesidewinder rattlers.
“And those same waves existed in the robot and allowed it to make itsmaneuvers and allowed us to modify those waves to make the kind ofmaneuvers that the snake did on sand dunes of different inclines -- that is,laying down more robot as the hill angle increased.”
The researchers performed the same experiment with other snakes closelyrelated to the rattlers. But all of those creatures failed to slide up the inclines.
Joe Mendelson is research director at Zoo Atlanta. He says the robot modelhelped explain why those snakes have trouble climbing.
“We found a really fascinating system where the snake informs what the robotcan do, and then we can manipulate the robot to do the things that either thesnake won’t do or can’t do. And so we have this self-informing system that has really opened up new parameters within snake biology and robotics.”
Mr. Mendelson adds that the next generation of Mod-Snake may be used tosave lives or explore unexplored areas on Earth or even in space.
“Robots are expensive. And a robot gets stuck in the sand, that’s a problem,especially if that sand happens to be, say, on one or another planet, or verydistant from an exploration post. And you realize, part of going into this, werealize that sidewinders never ever, ever get stuck on sand!”
The researchers hope the new sidewinder robot will travel up and down sanddunes just as well.