Structure design, kinematics modeling, and motion planning of novel ray-inspired amphibious robots

Amphibious robots have been received significant attention due to their ability to operate in both aquatic and terrestrial environments. However, existing methods for such robots mostly utilize switching driven systems to satisfy the requirements of cross medium (aquatic and terrestrial environments), leading to complex structures and additional switching control methods that increase the control difficulty. Inspired by the locomotion patterns of ray, this paper proposes a novel amphibious robot that utilizes wave-like driven patterns to simultaneously satisfy the requirements of both aquatic and terrestrial environments. To begin, wave-like driven principles are employed to design the structures of ray-inspired amphibious robots, and dual wave-like driven mechanisms are arranged side by side to address steering control issue. Subsequently, to satisfy underwater driving while maintaining waterproofing, ray-inspired fin structures are designed and connected to the wave-like driven mechanisms on one side to achieve synchronous driven with the motion patterns of wave-like driven mechanisms, thereby translating the driven force from wave-like driven mechanisms into ray-inspired fins. Next, a kinematic model of ray-inspired amphibious robots is established, and numerical simulations are conducted to analyze aquatic motion performance. Additionally, to achieve robot autonomous motion in complex environments, scenarios involving obstacles in aquatic, terrestrial, and the in-between transition zones are constructed. Then, a path planning algorithm with A* algorithm considering safe areas is proposed, and a minimum snap method is utilized to acquire smooth trajectories. Finally, the environmental adaptability of self-established ray-inspired amphibious robots has been verified through experiments.