Soft robotics is an emerging bioinspired concept of actuation, with promising applications for robotic locomotion and manipulation. Focusing on actuation by pressurized embedded fluidic networks, existing works examine quasi-static locomotion by inviscid fluids. This paper presents analytic formulation and closed-form solutions of an elastic actuator with pressurized fluidic networks, while accounting for the effects of solid inertia and elasticity, as well as fluid viscosity. This allows modeling the system's step response and frequency response as well as suggesting mode elimination and isolation techniques. The theoretical results describing the viscous-elastic-inertial dynamics of the actuator are illustrated by experiments. The approach presented in this paper may pave the way for the design and implementation of soft robotic legged locomotion that exploits dynamic effects.

This paper studies the hybrid dynamics of simple biped robot models under stick-slip transitions. Unlike most of existing works in the literature that assume sticking contact, we explore the case of insufficient friction which induces foot slippage. Numerical simulations of passive dynamic walking reveal the onset of stable periodic solutions involving stick-slip transitions. In the case of a biped with joint torques actuation, we demonstrate how one can induce and stabilize stick-slip gaits which significantly reduce the energetic cost of walking and enforce slippage even for large friction.