Development aquatic frog robot with knee extension mechanism driven by dissected muscle

Abstract

This study aims to understand relationships between musculoskeletal structure of frogs and swimming performance without control of the nerves systems. Frogs generate great swimming performance by extension of the hind limbs. Extension of knee cannot only generate thrust but also give a load to the Plantaris longus (PL) muscle, which is ankle extensor muscle. We developed an aquatic frog robot, Xenopus-noid, which can extend the knee and is driven by the dissected PL muscle from Xenopus laevis. Xenopus-noid has the knee extension mechanism composed of electrical magnet, a torsion spring positioned in hip joint. An energy of a torsion spring is released by turning off of an electrical magnet. In this study, we confirmed that the knee extension of Xenopus-noid is similar to that of X.laevis. Xenopus-noid is expected to be a useful tool to understand the relationship between knee extension of frogs and swimming performance.