Elastic Compliance Versus Joint Actuation in an Articulated Swimming Robot

Abstract

A planar swimming device comprising three rigid links with one actuated joint and one elastically compliant joint can achieve bi-directional translation as well as rotation solely through sinusoidal deformations of the actuated joint. In the context of an idealized model in which the surrounding fluid is assumed to be inviscid, the system's locomotion may be understood in terms of geometric phases associated with limit cycles in joint-angle space. In comparison to a system with actuators at both joints executing the same swimming motion, a singly actuated compliant swimmer exhibits superior energy efficiency in laboratory experiments.