Earthworms not only wriggle their bodies, but also move through the soil by sending peristaltic waves through their bodies. New bio-inspired robots that employ the same strategy could one day be used in underground exploration and even search-and-rescue missions.
An earthworm’s body is made up of individual fluid-filled segments called metameres, with circular muscles running around each segment. There are also longitudinal streaks that run along the length of the worm’s body.
When the circular muscles of the adjacent metamere contract, that portion of the worm lengthens and slims down. Longitudinal direction However, muscles in one area contract, but that part of the worm becomes shorter and thicker.
Thus, utilizing these two types of sequential sequences of contractions, an earthworm can essentially send a ‘fat wave’ from its nose to its tail. These waves, along with dirt-grabbing bristles called bristles, allow the animal to move through the soil.
A team of scientists from the Istituto Italiano di Tecnologia, led by Professor Barbara Mazzolai, set out to replicate the mechanism in a robot.
Italian Institute of Technology
The resulting 45 cm (17.7 in) long device consists of five connected “peristaltic soft actuators” (PSAs). Each of these consists of an inner bellows pipe (kind of like a miniature dryer vent hose), an outer soft elastomer skin, and a viscous fluid sealed in the space between the two.
The bellows lengthens when air is injected, stretching the skin and allowing the liquid to form a thin layer. In other words, PSA is long and lean. However, when air is drawn out, the bellows shortens and the compressed liquid pushes the skin outwards, making the PSA shorter and thicker.
By continuously activating the PSA in sequence, the robot can traverse flat surfaces, pass through pipes and navigate through granular media with the help of small external friction pads that take the place of bristles.
Italian Institute of Technology
Mazzolai and colleagues are currently working on further development of this technology.A paper on their research was recently published in a journal scientific report.
No, this isn’t the first robotic worm we’ve seen. Other examples using other mechanisms have been produced by teams at MIT and Cornell University.
Source: Italian Institute of Technology by EurekAlert
