Biomimetic omnidirectional multi-tail underwater robot

Biomimetics adopted as a basis for underwater robotic design to enhance locomotion efficiency, maneuverability, and adaptability has shown an extraordinary vitality and enormous growth potential in the field of underwater robotics. However, most designs are focused on mimicry of a specific aquatic organism or its specific function. Biomimetic approaches to underwater robot design that incorporate combination and coordination of multiple individuals could provide a powerful vehicle to build robotic systems that could go far beyond simply mimicking a specific aquatic organism, which remains largely unexplored. With an increasing requirement of underwater robots in context of professional explorations, measurements, and inspections, the demand for underwater robots with high stability and maneuverability has become more urgent. To this end, this study aims at presenting a novel biomimetic design of an omnidirectional underwater robot with multiple tails. This designed underwater robot with multiple tails is capable of combining different advantageous locomotion modes from fish, frog, octopus, fish swarm, and dolphin formation. Swimming locomotion modes including forward motion, steering, sinking, rising and their combinations can be realized flexibly. The robot can easily switch between arbitrary locomotion modes to achieve fast changes of swimming directions in 3D space. Full demonstrations of swimming locomotion modes and their flexible switch are presented to show the robot's excellent performance on stability, mobility, and maneuverability. The maximum forward velocity and steering angular velocity of the designed robot in this study can correspondingly reach 1.160 m/s (1.93BL) and 115.7 ^∘/s. The resulting prototype is experimentally verified in a laboratory water tank with waves. The robot could be the first of its kind achieving higher stability, mobility, and maneuverability of great potential in working in complex dynamic water environments, and thus would present an alternative and new insight into underwater robotic design and control, focusing on complex water environments.