Kinematics and Force Characterisation of a Knifefish-Inspired Mechanical Propulsor

The knifefish is a weakly electric eel that propels itself by passing waves along a median fin extending ventrally from jaw to tail. To study the forces generated by this fin, we built an undulating propulsion mechanism that mimics the waves passed along the biological fin using several crank-actuated fin rays. In this paper we explore the forces created by the fin and its performance as a propulsor when mounted on a floating pontoon. Thrust in the fish seems to be improved by increasing the amplitude of the wave as it travels along the body. Using our mechanism we look at the limit of thrust production. We proceed by iterative prototying to optimise the magnitude and along-axis directionality of the mechanism's thrust production.