Visualizing wakes in swimming locomotion of Xenopus-noid by using PIV

Abstract

Frogs can swim adaptively in the water dexterously utilizing interactions between body biomechanics and fluid dynamics. We have been developing an aquatic frog robot, Xenopus-noid, which has similar musculoskeletal structure as its biological counterpart, Xenopus laevis. This robot allows us to study the interaction between the biomechanical structure of the frog and the fluid dynamics during swimming locomotion in a natural context. In this report, particle image velocimetry (PIV) is used for visualizing wakes generated by the Xenopus-noid. Experimental results demonstrate that the robot can produce appropriate wakes for swimming if we implement a rigid beam that mimics the function of the Semimembranosus (SM) muscle in Xenopus laevis. The function is utilized for proper posture, that is to say, this muscle prevents a hyperextension of the knee.