Design of a biomimetic pectoral fin joint in an artificial fish

Abstract

A biomimetic design of the muscle joint in a pectoral fish fin was produced based on comparisons with four design models. All four design models consisted of a mechanical joint connection and incorporated the functional operation of the pectoral fish fin rays when affected by specific actuators, such as induced contractions of conducting polymer strands. Design constraints of the joint were determined by the fundamental kinematic elements of motion determined in the Bioinstrumentation Laboratory. A mechanical pin-joint provided correct simulation of movements specialized for this phase of the development of an artificial fish fin. A compression spring with a spring coefficient of K=0.45 was used as a mechanical means to imitate the biological energy conservations produced by each stroke of the pectoral fin. The joint was designed to adhere to displacements by conducting polymer actuators that induced a 2.0% maximal strain on the fish fin ray.