AmphiHex-I: Locomotory Performance in Amphibious Environments with Specially Designed Transformable Flipper Legs

An amphibious robot can locomote in amphibious environments, including walking on rough terrains, maneuvering underwater, and passing through soft muddy or sandy substrates in the littoral area between land and water. However, developing an amphibious robot is challenging, especially when it requires a high locomotory performance in soft substrates and a combination of different propulsion methods. To tackle such a challenge, an amphibious robot, known as AmphiHex-I, with novel transformable flipper-leg composite propulsion mechanisms has been proposed and developed. In this paper, locomotory performance of the flipper legs in amphibious environments, especially in the muddy terrain, is extensively studied with a walking platform in terms of structural parameters, kinematic parameters, and environmental properties. The results indicate that there exist an optimal rotation speed of the flipper legs with various shapes for a higher locomotion speed of the walking model in muddy terrain, which guides the design and the control of the transformable flipper legs. Through the versatile gaits of AmphiHex-I in amphibious environments, outdoor locomotion experiments validate the platform study and demonstrate that the robot's transformable flipper-leg propulsion mechanisms make it highly adaptive to a littoral environment such as the muddy terrain. Locomotion ability of AmphiHex-I endows its broad applications in the areas of resource exploration, disaster rescue, and reconnaissance in complex environments.