Self-propelled swimming simulations of bio-inspired smart structures

Area of Science:

• Robotics and Biomechanics
• Fluid Dynamics
• Hydrodynamics

Background:

• Designing self-propelled aquatic robots requires understanding locomotion principles.
• Foldable structures offer compact storage but need efficient unfolding and undulation for movement.
• Optimizing undulation kinematics is crucial for speed and energy efficiency in aquatic robots.

Purpose of the Study:

• To simulate and analyze the self-propelled swimming of a foldable, box-shaped aquatic structure.
• To guide the design of such structures by evaluating kinematic parameters for optimal locomotion.
• To understand how different undulation strategies impact swimming speed and propulsive efficiency.

Main Methods:

• Systematic variation of kinematic parameters in self-propelled swimming simulations.
• Parameters included wave type (standing vs. traveling), undulation smoothness (smooth vs. rigid links), undulation mode (carangiform vs. anguilliform), and amplitude.
• Analysis conducted in the low Reynolds number (Re) regime.

Main Results:

• Standing wave undulations resulted in slow and inefficient swimming due to poor thrust generation.
• Carangiform undulations achieved higher speeds, while anguilliform undulations demonstrated greater economic efficiency (distance per power).
• Smoothly undulating structures were more efficient than those with rigid links, generating higher added-mass forces.

Conclusions:

• Carangiform and anguilliform undulation modes offer distinct trade-offs between speed and efficiency for foldable aquatic robots.
• Smooth undulations are superior to rigid-link undulations for improved propulsive and power efficiency.
• The wake structure at low Re is complex and cannot reliably predict overall swimmer performance.