  We present the modeling, design, fabrication and feedback control of an
earthworm-inspired soft robot capable of crawling on surfaces by actively
manipulating the frictional force between its body and the surface. Earthworms
are segmented worms composed of repeating units known as metameres. The muscle
and setae structure embedded in each individual metamere makes possible its
peristaltic locomotion both under and above ground. Here, we propose a
pneumatically-driven soft robotic system made of parts analogous to the muscle
and setae structure and can replicate the crawling motion of a single earthworm
metamere. A model is also introduced to describe the crawling dynamics of the
proposed robotic system and proven be controllable. Robust crawling locomotion
is then experimentally verified.
