Snapping for high-speed and high-efficient butterfly stroke-like soft swimmer

Area of Science:

• Robotics
• Biomimetics
• Fluid Dynamics

Background:

• Natural selection optimizes flying and swimming animals within a narrow design space for high power efficiency (0.2 < Strouhal number < 0.4).
• Achieving high speed and efficiency in soft swimmers is challenging due to design constraints and soft body compliance.

Purpose of the Study:

• To develop bioinspired soft flapping-wing swimmers that achieve high performance comparable to biological counterparts.
• To leverage snapping instabilities for enhanced propulsion in soft robotic swimmers.

Main Methods:

• Designed a lightweight, butterfly stroke-like soft swimmer (2.8 g).
• Utilized snapping instabilities inspired by animal flapping motions for propulsion.
• Evaluated performance metrics including speed, power efficiency, and maneuverability.

Main Results:

• The soft swimmer achieved a record speed of 3.74 body lengths/s, 4.8 times faster than previous soft swimmers.
• Demonstrated high power efficiency within the optimal range (Strouhal number = 0.25).
• Exhibited low energy consumption and high maneuverability with a turning speed of 157°/s.

Conclusions:

• Snapping instabilities offer a viable mechanism for creating high-performance soft robotic swimmers.
• The developed swimmer rivals biological counterparts in speed, efficiency, and maneuverability.
• This approach overcomes limitations in soft robotic locomotion, opening new avenues for underwater applications.