The swimming soft robot from North Carolina State University maneuvers in water with the speed and efficiency of manta rays.
Benefits
- Increases speed
- Autonomous
Applications
- Undewater exploration
- Aerodynamics
The Challenge
Swimming soft robots have not been able to achieve speeds of more than one body length per second. Researchers studying aerodynamics use a dimensionless quantity, the Strouhal number, to assess swimming (or flying) efficiency. Strouhal numbers of between 0.2 and 0.4 occur when marine animals swim at their peak efficiencies, but swimming robots have not been able to achieve values within this range.
Innovation Details
Inflating and deflating chambers within the robot’s soft body causes it to bend, forcing the attached, pliable wings to snap rapidly between two stable states. The movement of these “bistable” wings back and forth simulates flapping, enabling the robot to swim at speeds of almost 4 body lengths per second and achieve Strouhal numbers within the 0.2 to 0.4 range of marine animals. When two of the soft bodies are connected together, they can each actuate a single wing asynchronously, allowing the robot to turn,enhancing its maneuverability.
Biological Model
Giant manta rays propel themselves forward by combining fin oscillations with undulations. The oscillations, or flapping, move the fins up and down, while the undulations send a traveling wave outward from its body to the fins’ tips. As giant rays flap in this manner, their fins shed vortices, which transfer momentum to the surrounding water and propel the animal forward.