  Locomotion is typically studied either in continuous media where bodies and
legs experience forces generated by the flowing medium, or on solid substrates
dominated by friction. In the former, centralized coordination is believed to
facilitate appropriate slipping through the medium for propulsion. In the
latter, slip is often assumed minimal and thus avoided via decentralized
controls. We discover in laboratory experiments that terrestrial locomotion of
a meter scale multi-segmented/legged robophysical model resembles undulatory
fluid swimming. Experiments varying waves of limb stepping and body bending
reveal how these parameters result in effective terrestrial locomotion despite
seemingly ineffective isotropic frictional contacts. Dissipation dominates over
inertial effects in this macroscopic-scaled regime, resulting in essentially
geometric locomotion akin to microscopic-scale swimming. Theoretical analysis
demonstrates that the high-dimensional multi-segmented/legged dynamics can be
simplified to a centralized low-dimensional model, which reveals an effective
Resistive Force Theory with an acquired viscous drag anisotropy. We extend our
low-dimensional, geometric analysis to illustrate how body undulation can aid
performance in non-flat obstacle-rich terrains and also use the scheme to
quantitatively model how body undulation affects performance of biological
centipede locomotion (the desert centipede S. polymorpha) moving at relatively
high speeds (~0.5 body lengths/sec). Our results could facilitate control of
multilegged robots in complex terradynamic scenarios.
