The Pentagon's DARPA research unit has supported development of a stealthy worm-like robot by researchers at the Massachusetts Institute of Technology and Harvard University, and Seoul National University in South Korea that could one day be employed for reconnaissance purposes.

The skin of the Meshworm robot is a tube fabricated from a polyetheretherketone (PEEK) resin mesh. The flexible robot can traverse small openings and reconstitute shape, and also survive large impact forces on falling.

The 20-cm long, 2-cm diameter worm robot is powered by a LiPo battery, that operates an "artificial muscle" made out of nickel and titanium wire wrapped around the PEEK tube skin that is designed to stretch and contract with heat. The flexible nature of the robot allows it to squeeze through tight spaces and conform its shape to rough terrain.

Using a worm-like motion helps reduce noise. Previous attempts to create such robots have reportedly relied on gears and air-powered or pneumatic pumps. But besides generating noise, these add to the bulk of the robots, making them less practical for real-world uses.

By wrapping the dual-metal wire around a mesh-like tube the engineers were able to replicate the circular muscle fibers of an earthworm, creating different segments in the process. When a current was applied to part of the wire it contracted, squeezing the tube. The research team created an algorithm to send a contraction wave across each of the machine's five segments in turn, squeezing the tube and propelling it forward. This replicates the movement of its biological counterpart.

The researchers were able to make the robot move at a rate of about 5 mm per second (0.2 inches/second). Two additional "muscles" were added to the sides of the robot to pull it left and right, allowing its direction to be controlled.

The researchers also stated that the soft nature of the robot's body allowes it to be subjected to hammer blows and be trod on without sustaining any damage because its shape changed to help absorb the blows. More details have been  published in the journal IEEE/ASE Transactions on Mechatronics. —[email protected]