Vortex phase matching as a strategy for schooling in robots and in fish

Area of Science:

• Biomechanics
• Hydrodynamics
• Animal Behavior

Background:

• Animals that fly or swim may use flows generated by neighbors to reduce energy expenditure.
• The precise mechanisms by which schooling fish coordinate movements to benefit from vortices remain unclear.

Purpose of the Study:

• To investigate how schooling fish coordinate movements to gain hydrodynamic advantages from neighbor-induced flows.
• To determine if a specific strategy, 'vortex phase matching,' explains energy savings in schooling fish.

Main Methods:

• Development of bio-mimetic fish-like robots to measure energy consumption in paired swimming.
• Experimental analysis of tailbeat phase differences in relation to front-back distance in robotic and free-swimming fish pairs.
• Assessment of the necessity of visual and lateral line systems for employing this strategy.

Main Results:

• Followers can achieve hydrodynamic benefits by synchronizing their tailbeats with neighbors through 'vortex phase matching.'
• This strategy is effective across various relative positions between individuals.
• Free-swimming fish naturally employ vortex phase matching, independent of visual or lateral line input.

Conclusions:

• Vortex phase matching is a key mechanism for energy conservation in schooling fish.
• The strategy is robust and does not rely on complex sensory systems.
• This finding supports the hypothesis that fish commonly utilize vortex phase matching for efficient locomotion.