Researchers at North Carolina State University have developed a new soft robot inspired by manta rays, setting a new record for the fastest swimming soft robot. The device achieves speeds of up to 6.8 body lengths per second, nearly doubling the performance of its predecessor, which reached 3.74 body lengths per second. The innovation also allows the robot to navigate the full water column, a significant improvement over earlier models that could only swim at the surface.
The robot mimics the propulsion mechanics of manta rays, using fins that replicate the rays’ characteristic flapping motion. Its body includes a silicone chamber that inflates and deflates to create movement. Air pumped into the chamber bends the fins downward, simulating a downstroke, while releasing the air causes the fins to snap back to their original position, enabling rapid, energy-efficient actuation.
The study also examined the fluid dynamics underlying manta ray swimming to refine the robot’s control systems. By adjusting the actuation frequency, the researchers were able to manipulate the robot’s vertical trajectory. Faster fin flapping caused the robot to rise due to increased buoyancy, while slower movements allowed it to sink or maintain depth. The design relies on a single actuator, enhancing simplicity while allowing the robot to navigate complex underwater environments.
In tests, the robot demonstrated its capabilities by maneuvering through obstacles in a water tank and towing a payload while operating untethered. Future enhancements will focus on improving lateral movement and exploring additional actuation methods.
The research, led by Jie Yin, is detailed in the open-access paper, “Spontaneous Snapping-Induced Jet Flows for Fast, Maneuverable Surface and Underwater Soft Flapping Swimmer,” published in Science Advances. The collaborative effort involved experts from NC State, the University of Virginia, and the University of California, Riverside.
Photo credit: Jie Yin and Haitao Qing, NC State University
