A Snake-Shaped Serpentine Robot For Rugged Terrain

By Roland Piquepaille

Engineers from the University of Michigan have developed a snake-like robot that conquers obstacles. It is composed of 5 segments of 8-inch diameter each and weighs 26 pounds. It is currently piloted by a human operator. And it can maneuver in extremely rugged terrain, climbing stairs and pipes. "It moves by rolling, log-style, or by lifting its head or tail, inchworm-like, and muscling itself forward." This robot will be used for industrial inspection and surveillance in hazardous environments, and also for military and urban search and rescue operations.

Here are the opening paragraphs of the U-M news release.

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.

Here is the home page of the OmniTread robot.

	Here is the OmniTread in action (Credit: University of Michigan). This is the fully working OT-8 version (5 segments of 8-inch diameter each).
	And this is a diagram showing the future version, the tetherless OmniTread OT-4, which will have 7 segments, each of them having a 4-inch diameter (Credit: University of Michigan).

Here are more details on how the system works.

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.

And what can really do this robot?

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.

For more information about the OmniTread serpentine robot, you can read this presentation (PDF format, 4 pages, 3.48 MB). The diagram of the future OT-4 comes from this presentation.

And if you have good bandwidth, you can watch this movie (Windows Media format, 6 minutes and 52 seconds, 37.4 MB).

Finally, this work appears in the March 18 edition of the International Journal on Industrial Robots, in a special issue on mobile robots, under the name "The OmniTread Serpentine Robot for Industrial Inspection and Surveillance." Here is a link to the full paper (PDF format, 11 pages, 567 KB).

Sources: University of Michigan news release, March 22, 2005; and various pages at U of M

Related stories can be found in the following categories.

• Engineering
  
• Military Applications
  
• Robotics
  
• Technology