Soft Fluidic Actuator for Locomotion in Multi-Phase Environments

This letter presents the design, development, and experimental assessment of a soft fluidic actuator that can enable locomotion in a variety of aquatic and terrestrial environments. Most actuation strategies for amphibious locomotion rely on rigid, fast moving components to generate thrust and tractive forces. Our prototype, comprising soft materials, and relying on simple motion planning and control strategies, demonstrates two gaits, that we employ for locomotion in two vastly different scenarios, underwater swimming and moving on granular terrain with varying levels of water content. By adjusting its internal pressure, the actuator dynamically varies its stiffness and shape, and transitions between wheel and soft paddle form. Experimental results of locomotion in controlled laboratory conditions serve as proof-of-concept for the proposed actuator's efficacy. Using two different motion patterns and control schemes, we show that this prototype achieves both thrust and tractive forces.