Design, Analysis, and Tests of an Impulsive Aquatic Jumping Mechanism Inspired by Frog Limbs

The Southeast Asia frog (Euphlyctis hexadactylus), a natural jumping expert in water, demonstrates exceptional jumping capability by contracting its leg muscles and coordinating its flippers to propel itself out of water, significantly aiding its hunting activities. This bionic behavior serves as a unique inspiration for the design of impulsive aquatic jumping robots. In this study, an impulsive aquatic jumping mechanism (IAJM) is proposed, which primarily consists of a single-degree-of-freedom (1-DOF) four-bar linkage, a streamlined head, two paddles, and an energy storage unit comprising several rubber bands and two clamps for energy release. Theoretical analysis and ADAMS simulations were conducted to investigate the kinematics and dynamics of the mechanism, and Fluent was used to simulate the fluid dynamics of the paddle design and the aquatic jumping process. A prototype was developed using 3D-printed parts made of polymer materials (PLA), with rubber bands serving as 'muscles' to provide the necessary energy for impulsive aquatic jumping. Finally, aquatic and terrestrial jumping tests were conducted, followed by a discussion to validate the performance of the IAJM. Remarkably, the jumping height achieved from the water surface was 60.5 cm, compared to 3.85 m from the land, indicating an energy loss of 85.62% during water propulsion.