NASA Developing "Snakebot" To Explore And Build In Space

The robot serpent, able to independently dig in loose extraterrestrialsoil, smart enough to slither into cracks in a planet's surface and capableof planning routes over or around obstacles, could be ready for spacetravel in five years, NASA engineers predict.

"The snake will provide us with flexibility and robustness in space," saidGary Haith, lead "snakebot" engineer at NASA's Ames Research Center locatedin California's Silicon Valley. "A snakebot could navigate over rough,steep terrain where a wheeled robotic rover would likely get stuck ortopple."

"One of our first steps was to make a simple mechanical test snake, and weconstructed it in less than a day thanks to previous work at other labs,"said Haith. "It is a direct model of a 'polybot' developed by Mark Yim ofXerox Palo Alto Research Center, Palo Alto, CA, with whom we arecooperating. We have slightly different electronics in our version."

"The test snake has a wire that carries communications and power to andfrom the computer brain," Haith explained. "All of the identical hinge-likemodules are easy to make, and we attached the snake segments together in achain. It has off-the-shelf hobby motors in its hinged segments that causeit to move. Each of the many motors takes a signal from the snake's maincomputer brain," he said.

"Our first test robot does what we tell it to do, no matter what theresults are. If it comes to an obstacle, the robot will continue to try togo over it, even if the task is impossible," he said. "We made the first,simple robot because we wanted a working snakebot in a day or two, a robotthat would help us to think about how a snakebot could and should move."

Robotic serpents can "inchworm" ahead, can flip themselves backward overlow obstacles, can coil and can side-wind, Haith said. "Future work willenable the snake to become a mast or a grasping arm. A rover would need tohave a dedicated mast and arm that would cost extra weight, money and time."

"A snakebot is not as good at some jobs as other robots, but you get a lotmore robot for the weight and the money," he said. "The problem is it'shard to tell the snakebot what to do. It is a complex robot that mustoperate independently, possibly far from Earth. Work on our secondsnakebot is aimed at making it capable of independent behavior."

"The key part of what we are striving for in the second snakebot versionand beyond is sensor-based control in which the robot uses its sensors todecide what to do,'" Haith said. "We made two little microcontrollers, tinycomputers, that we put in each hinged section that also includes a motor,electronics and gears to get the hinge to move to certain positions," heexplained.

The snakebot will have a main computer that will tell its little computersin each segment what to do in a higher, planning sense. The tiny computersin the segments could provide "reflexes" that take care of simple, butimportant jobs.

"In the next couple of months, we hope to simulate the snakebot in acomputer program so we can automatically develop computer routines that cancontrol the robot," Haith said. Engineers have added strain sensors to therobot on metal ribs inside the snake. "They will tell the snake whether ornot it is contacting anything, and where and how hard it is touching,"Haith explained.

"We hope to write software that allows the snake to learn on its own byexperience," he said. "Some lessons we hope it will learn are how to crawlfrom soft to hard surfaces, and how to go over rough surfaces that haverocks. We even hope to show that it can climb scaffolds and go intocracks. These abilities would help the robot look for fossils or water onanother planet," he added.

The snakebot can save spacecraft weight because the snake-like designenables the robot to do many tasks without much extra equipment, accordingto engineers. "One of the many advantages of the snake-based design isthat the robot is field-repairable. We can include a bunch of identicalspare modules with the snake on a space mission, and then we can fix thesnakebot much easier than a regular robot that needs specific parts," saidHaith. "Other benefits are: the snakebot can crawl off a spacecraft landerand doesn't need a ramp, the snake's moving parts can be sealed insideartificial skin to avoid exposure to the outside environment and the robotcan still function, even if one joint freezes."

"In coming years, we hope to make snakebot muscles out of artificialplastic or rubber materials that will bend when electricity is applied tothem," he added. "This design change will reduce the snake's weightconsiderably, and the robot would be very robust, like an automobile tire,"For more technical robotic snake information, please visit the NASAsnakebot Internet site at: http://ic-www.arc.nasa.gov/ic/snakebot/