Robotic ray driven by periodic ring snapping.

Area of Science:

• Robotics
• Bio-inspired Engineering
• Fluid Dynamics

Background:

• Animal locomotion, particularly fish swimming, offers efficient, maneuverable, and stealthy movement strategies refined by evolution.
• Existing underwater robots often face challenges in efficiency, maneuverability, and energy consumption.

Purpose of the Study:

• To develop an untethered, soft robotic fish inspired by the swimming gait of *Taeniura lymma*.
• To achieve continuous, stable, and directional underwater movement using a novel actuation mechanism.

Main Methods:

• Bio-inspired design mimicking *Taeniura lymma* swimming.
• Development of a soft robotic fish utilizing flexible rods and films.
• Elastic-snapping-induced shape transition for locomotion control via a single actuator.
• Theoretical analysis and numerical simulation of post-buckling morphological evolution.
• Fabrication and testing of physical prototypes to validate performance.

Main Results:

• The robotic fish demonstrates continuous, stable, and directional underwater movement.
• Locomotion is achieved through periodic, reversible mechanical deformation driven by elastic-snapping.
• The design allows for control with a single actuator, releasing stored elastic strain energy.
• Prototypes exhibit efficient, stable, and quiet swimming capabilities.
• The robotic ray shows moderate speed with substantially lower energy consumption compared to existing underwater robots.

Conclusions:

• The developed soft robotic fish offers an efficient and low-energy underwater locomotion solution.
• The bio-inspired design and single-actuator system hold promise for future shape-morphing robots and soft machines.
• This research validates the effectiveness of mimicking natural swimming gaits for robotic applications.