  Many marine creatures, gastropods, and earthworms generate continuous
traveling waves in their bodies for locomotion within marine environments,
complex surfaces, and inside narrow gaps. In this work, we study theoretically
and experimentally the use of embedded pneumatic networks as a mechanism to
mimic nature and generate bi-directional traveling waves in soft robots. We
apply long-wave approximation to theoretically calculate the required
distribution of pneumatic network and inlet pressure oscillations needed to
create desired moving wave patterns. We then fabricate soft robots with
internal pneumatic network geometry based on these analytical results. The
experimental results agree well with our model and demonstrate the propagation
of moving waves in soft robots, along with locomotion capabilities. The
presented results allow fabricating soft robots capable of continuous moving
waves via the common approach of embedded pneumatic networks and requiring only
two input controls.
