Unstoppable Creepy Crawlers

Snakebot climbing over rock
A virtually unstoppable “snakebot” developed by a University of Michigan team that resembles a high-tech slinky as it climbs pipes and stairs, rolls over rough terrain and spans wide gaps to reach the other side. Credit: U. Michigan.

A virtually unstoppable “snakebot” developed by a University of Michigan team that resembles a high-tech slinky as it climbs pipes and stairs, rolls over rough terrain and spans wide gaps to reach the other side.

The 26-pound robot developed at the U-M College of Engineering is, called OmniTread. It moves by rolling, log-style, or by lifting its head or tail, inchworm-like, and muscling itself forward. The robot’s unique tread design prevents it from stalling on rough ground, said Research Professor Johann Borenstein, the head of the mobile robotics lab at U-M.

The snake-shaped serpentine robot is propelled along by moving treads that cover 80 percent of its body. These treads prevent the snakebot from stalling or becoming stuck on rough terrain because, similar to a tire touching a road, the treads propel the robot forward like a tire touching a road. Historically, scientists haven’t had much success with wheeled and tracked robots on rough terrain because they constantly stall.

Snakebot climbing over rock
The flexible, adaptable snakebot design class has a NASA version which can move through rough terrain inaccessible to wheeled rovers. Credit: NASA/Dominic Hart.

A human operator controls the snakebot via a joystick and umbilical cord, which also provides electric power, which sends commands to specially designed software. A smaller, but more self-contained version that is now under development will carry on-board power for one hour of tetherless operation.

The OmniTread is divided into five box-shaped segments connected through the middle by a long drive shaft spine that drives the tracks of all segments. Bellows in the joints connecting the sections inflate or deflate to make the robot turn or lift the segments. The bellows provide enough torque for the OmniTread to lift the two front or rear segments to climb objects.

In one test, the OmniTread climbed an 18-inch curb, which is over more than twice its height. It also crossed a 66-centimeter trench, which is half its length. In another test, it inched up a pipe by pushing against opposite walls.

“A snakebot is not as good at some jobs as other robots, but you get a lot more robot for the weight and the money,” said Gary Haith, lead “snakebot” engineer at NASA’s Ames Research Center located in California’s Silicon Valley. “The problem is it’s hard to tell the snakebot what to do. It is a complex robot that must operate independently, possibly far from Earth. Work on our second snakebot is aimed at making it capable of independent behavior.”

Robotic serpents can “inchworm” ahead, can flip themselves backward over low obstacles, can coil and can side-wind, Haith said.

The Michigan robot is ideal for hazardous inspections or surveillance in industrial or military applications Borenstein said. The research was to appear in the appears on the March 18 edition of the International Journal on Industrial Robots, in a special issue on mobile robots. The paper, “The OmniTread Serpentine Robot for Industrial Inspection and Surveillance,” was written by Borenstein and co-authors Malik Hansen and Grzegorz Granosik.


Related Web Sites

Serpentine Robotics Project (NASA Ames Research Center)
Polybot Project (Xerox Palo Alto Research Center)
Snakebot links (Institute for Autonomous intelligent Systems/GMD)
Squaring off with Robotic Serpent

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