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Filter-feeding Fish, Ant Pheromones, and Foraging: Biomimetic Robot Swarms

Inspiration: Ram-Filter Feeding Fish Inspiration: Ant Pheromones (Specific to Individual Ant)

Mechanism, Mobility, & Multifunctional Design Lab

Dr. Brian Trease, Adam Schroeder, Lauren Marshall

The UNIVERSITY of TOLEDO, DEPARTMENT of MECHANICAL, INDUSTRIAL, & MANUFACTURING ENGINEERING

Application: Filter Harmful Algae

Application: Robots’ ‘Trust’ Own Pheromone More or Less (Compared to Others’ Pheromone)

Big Idea: Robot Swarms Filter

and Collect Sub-Surface Harmful Algae

Inspiration: Animal Foraging using ‘Levy Flight’

Application: Robot Swarms Collect Harmful Algae

Questions:How to efficiently collect algae?

How to coordinate robot behavior?

Ants can detect and respond to pheromones deposited by other ants. These pheromones might be attractive, repulsive, or cause them to switch to a different behavior.

They also have the ability to distinguish their own pheromone and have been shown to prefer paths that they themselves marked. [Jessen and Maschwitz 1985, 1986]

Allow a robot swarm to communicate using virtual pheromones (not real pheromones like ants). Set a robot’s sensitivity to its own pheromone to be different than that to others’ pheromones.

What difference does the ratio of these sensitivities (let’s call it ‘vanity’, ν=Χself/Χother) make to general swarm-level behavior (e.g. mean square displacement) or task-specific performance (e.g. area coverage)?

Agent One’s Pheromone

Smooth transition in mean square displacement (MSD), as vanity varies

Bifurcations in area-coverage performance as vanity varies

Dominant Pheromone

General Swarm-Level Behavior

Task-Specific Swarm Performance

Unbiased Levy Flight[Schroeder et al 2017]

In Viswanathan’s 1996 seminal paper, he introduced idea of albatrosses performing Levy flight to forage for food. Levy flight means that frequent short paths are taken, with occasional very long paths.

Since 1996, Levy flight has been associated with marine predators [Sims 2008], fossil trails [Sims 2014], human hunter-gatherers [Raichlen 2013], and immune system T-cells [Harris 2012]

Robot swarm performs a biased random flight in direction of highest algae concentration.

As robots move, they collect algae, which is diffusing and advecting through the water. Total algae in the system is continually reduced.

Yellow-high concentrationNew algae entering work area

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Blue-low concentration, algae has been recently cleared.

Basking Shark

Ram-filter feeding fish can efficiently remove small food particles from the water. Their unique physiology allows vertices to form between ribs in their mouth. Food particles collect on surfaces (called gill-rakers) attached to these ribs, from which the fish can begin to process the food.

Algae Migration

Diffusion Advection

Robot collects algae as it moves through the water. Algae diffuses in the wake of the robot.

‘Basic’ Cone with circular opening works well, but also trying (i) ‘V-shaped’ opening, (ii) Manta-inspired oval opening, and (iii) Square opening. Performance of these ‘cross-flow’ filters can be compared to a ‘dead-end’ filter.

Filtering particles from open water is a novel and challenging application

In-lab Testing with Fluorescent Microsopheres

Field Testing with Real Algae (9/20/2017)

Above: Filter mostly submerged, moving through the water, which induces some verticesBelow: Filter after test. Algae is deposited on mesh between ribs.

Credit: Virginia Greene/virginiagreeneillustration.comCredit: Doug Perrine/SeaPics.com

Flow exits tang- ential to incoming flow, eventually exit -ing out the gills.[Sanderson 2016]

Total Algae

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