Serpentine OmniTread robot scales many obstacles

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

OnmiTread, a virtually unstoppable snakebot developed by a U-M team, makes a test run. The 26-pound robot moves like a high-tech slinky as it climbs pipes and stairs and rolls over rough terrain. Research Professor Johann Borenstein, head of the mobile robotics lab, says the robot's unique design prevents it from stalling on rough ground. (Photo courtesy Johann Borenstein)

The 26-pound robot developed at the 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, says Research Professor Johann Borenstein, head of the mobile robotics lab at U-M.

Historically, scientists haven't had much success with wheeled and tracked robots on rough terrain because they constantly stall. To overcome this, the serpentine robot uses moving treads that cover 80 percent of its body. They prevent the snakebot from stalling or getting stuck on rough terrain because the treads propel the robot forward like a tire touching the road.

A human operator controls the snakebot via a joystick and umbilical cord, which also provides electric power. A smaller, self-contained version that is 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 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.

Borenstein says the robot is ideal for hazardous inspections or surveillance in industrial or military applications.

The research appears in 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, a graduate student research assistant in mechanical engineering (ME), and Grzegorz Granosik, an ME research fellow.

For a video of OmniTread, visit http://www.engin.umich.edu/research/mrl/00MoRob_6.html.