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Doing the Worm

Worms move a lot like people swallow: a cascading contraction of muscles in the esophagus creates a smooth, continuous wave that pushes food the length of the passageway to the stomach.


To replicate the wave in a crawling robot, researchers at Case Western Reserve wove the sheathing of bicycle brake cables into a smooth, flexible mesh tube that, at rest, is about 3.5 feet long and 10 inches in diameter.

They then wove in 10 steel loops perpendicular to the floor. Each loop was connected to a motor at the back of the robot. When the motor tugs on a loop, the diameter of that part of the robot tightens, forcing the nearby mesh to elongate along the floor. When the loop is loosened and expands, the mesh contracts. The motor pulls and loosens the steel loops in sequence, creating waves that flow the length of the robot and generate a forward crawl.

The prototype can travel six body lengths per minute, which is more than three times the speed of the older model—about twice the speed of a real worm.

This model was built for crawling only. Chiel and Quinn plan to add loops and individual motors, providing more control and enabling the robot to raise sections of its body, turn, curl and twist—the types of movements needed to travel and burrow in the real world

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