EAS IX: Tyler MacCready on Swarm Science

Dean Sigler Electric Aircraft Components, Sustainable Aviation Leave a Comment

One of your editor’s favorite books is An Exaltation of Larks, James Lipton’s compilation of venereal terms (not what you think) for plurals of animals.  Squires who aspired to become knights had to learn over 100 such terms, according to Sir Walter Scott.  Terms of venery (references to animal flesh) include a school of fish, a litter of puppies, and a nest of vipers (going back to at least the King James version of St. Paul’s words).

One lesser known term, a murmuration of starlings, relates to Tyler MacCready’s talk on how control of the Future Crowded Skies at EAS IX might mimic the flocks of birds we see swarming and precipitously changing directions in swooping formations.

Obviously, the numbers of Sky Taxis envisioned by Dr. Brien Seeley will not come close to equaling the flocks of starlings over Rome or any other major city, but we’ve also seen that air traffic control is becoming saturated with increased traffic and that Sky Taxis would have to rely on something that would transcend current sequencing and separation protocols.

According to the Cornell Lab of Ornithology, “In 2010, Andrea Cavagna and colleagues at the National Council of Research and the University of Rome used advanced computational modeling and video analysis to study this question. They found that starling flocks model a complex physical phenomenon, seldom observed in physical and biological systems, known as scale-free correlation.”

Cavagna’s researchers found there was not necessarily a single leader, but the flock acted as an indivisible whole, and “that starlings in large flocks consistently coordinate their movements with their seven nearest neighbors.   They determined that starlings coordinated through a form of group communication that has a high signal-to-noise ratio.

Concepts being studied at MacCready’s Ocean Lab, at least part of which is devoted to “enabling the future’s crowded skies.”  The Lab’s study of collective behavior will be instructive in defining how to deal with the potentially successful CAFE Foundation vision that would have 10 times the number of current airports, 10 times the airplanes at each airport and thousands of aircraft aloft during rush hour.  The management challenges might seem staggering, based on today’s central control philosophy.

Each pilot takes his or her cues from a central controller in an air traffic control (ATC) facility, whether it’s a Flight Service Station or control tower.  Distributing that control would allow greater flexibility of individual movement, suggested by the “free flight” movement that would take aircraft away from federal airways, where pilots could create unique navigation solutions for varying weather and other circumstances.  ADS-B, or Automatic Dependent Surveillance – Broadcast is one approach to giving greater freedom of flight, but still relies on broad area controls  from central authorities and GPS position reporting.  Based on other aircraft GPS reports, ADS-B helps keep different craft separate.

Birds and fish may have visual acknowledgement of their fellow creatures near them and the seemingly random movements of large “swarms” of those creatures.  As perhaps hundreds of Sky Taxis converge on or depart from a pocket airpark, the closeness of so many aircraft will require different kinds of flight management.  Even GPS and ADS-B may have difficulty in meeting this complex management challenge.

Tyler’s Ocean Lab web site defines several goals of his group.  “Our Mission is to facilitate the growth of the Swarm Robotics industry. We are developing systems for distributed mapping and distributed intervention in aquatic settings.

“Our approach is based on managing complexity to effectively guide a group of vehicles without being distracted by the detailed behavior of the individuals. We are developing hardware, software and methods to make swarms useable. We call these solutions Swarm Tools™ and they include:

“Swarm-appropriate vehicles – We follow a philosophy of group support that seeks to keep individual vehicles as simple as possible and maximize the benefits of being in a group, such as distributed sensing and more accurate relative positioning.

“Distributed architecture – Our proprietary neighbor-sensing technology enables highly redundant system integration and situational awareness, able to accommodate the limitations of aquatic communication.

“Scalable logistics – We have solutions for handling large numbers. At the front end we are developing solutions for group charging and set-up. At the back end we are developing solutions for group data collating.

“Applications – collaboration with oceanographers we are pioneering applications where a swarm yields superior results over single AUV methods.

“Management interface – We seek to maximize swarm agility while protecting the operator from complexity. Our swarms can be guided as a large, fluid mass. For oceanographers, the group delivers a map of real-time distributed data and can be actively guided to target areas of maximum interest.”

Birds might show a solution for crowded skies, according to Tyler.  Flocking algorithms devised by programmers like Craig Reynold, whose web page on “Boids” is illuminating, shows that birds rely on separation, alignment and cohesion to navigate in large groups and to interface with man-made objects in their path.  Tamas Vicsek of the Department of Biological Physics, Eotvos University in Budapest, Hungary took the Boids algorithms and expanded on them to understand how pigeon flocks, among other avian creatures, also used hierarchies to determine group flight paths.

Tyler explained that factors of attraction, orientation and repulsion between birds are distance dependent, with the birds repelled by close neighbors and attracted by distant neighbors.  This might help them have a simultaneous view of the overall shape of the flock with more detailed views of their immediate neighbors.

Started negatively, crowds are a problem, but through following laws of attraction and repulsion, can end positively.  Birds prefer groups which allow them a greater situational awareness, with neighbors acting as sensors.  This cooperative flight can manifest itself in acts such as lift sharing, as shown by Phil Barnes’ albatross or flocks of pelicans overlapping the downwash from their wingtips.

Such biomicry will certainly be useful in finding ways to provide safe arrivals and departures at pocket airparks in the future.

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