An Insight on Mud Behavior Upon Stepping

Abstract

In this research we show a characterization of mud behavior under vertical stepping. We showed that mud stiffness can vary 45-fold and the energy spent to generate equivalent impulse can vary 2-fold depending on the mud water content, but also that stepping faster on mud leads to lower peak forces and higher energy consumption. Next, we showed that the peak force generated can be increased by 33% by changing the foot stiffness, but is reduced by 18% if stepping is repeated on the same spot. We then demonstrated how force control can be used to achieve identical force profiles on very different muds. These results will help to design mechanical parts or control strategies for legged robot locomotion on mud.

Maneuvering on non-Newtonian fluidic terrain: a survey of animal and bio-inspired robot locomotion techniques on soft yielding grounds

“…We refer to hydrostatic-like pressure as a pressure that increases proportionally with depth ( Aguilar and Goldman, 2016 ). It has been shown that different flowable materials, when stepped upon, generate a reaction force that is almost proportional to the depth of intrusion ( Sharpe et al., 2013 ; Godon et al., 2022 ; Ma et al., 2022 ). In the horizontal direction, thrust can be generated by relying on the cohesion and adhesion of the medium particles with the body.…”

“…Additionally, stiffening the foot after sinkage allows for more shear force to be generated. Another experiment tested different stepping parameters on muds and found that foot compliance increased the generated force on mud, and that lower speeds lead to higher forces ( Godon et al., 2022 ).…”