Alone, California black worms live an unmistakable life by eating microorganisms in ponds and serving as a tropical fish meal for aquarium lovers. But together, tens, hundreds, or thousands of centimeter-long creatures can work together to create a “worm blob,” that moves a shape that together protects its limbs from drying out and helping them escape threats such as overheating.
While other organisms create herds, schools, or servants for purposes such as mating, predation, and defense, the Lumbriculus variegatus worms are rare in their ability to bind themselves to perform tasks that unrelated humans cannot. . A new study reported by researchers at the Georgia Institute of Technology describes how the worms automatically organize as an “active matter,” creating a remarkable collection behavior whose principles have been engaged to help blobs of simple robots to develop their own locomotive.
The research, supported by the National Science Foundation and the Army Research Office, was reported Feb. 5 in the journal Proceedings of the National Academy of Sciences. Results from the work could help swarm robotics developers understand how emergency transport of active material can interfere with invisible, complex and potentially behavioral behavior. useful in a mechanical way.
Behavior together in worms
The spark for the search came several years ago in California, where Saad Bhamla was fascinated by blobs of worms he saw in a backyard pond.
“We were curious about why these worms would be like those living blobs,” said Bhamla, an assistant professor at Georgia Tech’s School of Chemical and Biomolecular Engineering. “We have now shown through mathematical models and biological experiments that the formation of blobs provides a kind of cohesiveness that enables worms in a larger blob to survive longer against desiccation. We have also shown that they can move together, a collective behavior that is not produced by any other organisms known to us at the macro scale. “
Such combined behavior in living systems is of interest to researchers who are exploring ways of applying the principles of living systems to human-designed systems such as swarm robots, in which individuals working together to create complex behaviors.
“The worm worm appears to have abilities that are greater than those of individuals, a good example of biological exposure,” said Daniel Goldman, Dunn Family Professor at Georgia Tech School of Physics, which studies the physics of living systems.
Why do the worms form blobs
The worm blob system was extensively studied by Yasemin Ozkan-Aydin, a research associate in the Goldman laboratory. Using bags of worms she ordered from a California aquarium supply company – and which is now building in Georgia Tech laboratories – Ozkan-Aydin put the worms through several experiments. These included the development of a “worm gymnasium” which allowed it to measure the strength of individual worms, knowledge that was important for understanding how small numbers of creatures can move a whole blob.
She began by taking the aquatic worms out of the water and monitoring their behavior. First, they began to search for water on their own. When that research failed, they created a ball-shaped blob in which individuals took advantage of the outer surface that was exposed to the air where evacuation was taking place – a behavior that she theorized reducing the exhaust effect on the collector. By examining the blobs, she learned that worms in a blob can survive out of the water 10 times longer than individual worms can.
“They would certainly want to minimize desiccation, but the manner in which they would do this is unclear and indicates some sort of general information in the system,” Goldman said. “They’re not just surface reduction tools. They’re looking to take advantage of good conditions and facilities.”
Using blobs to escape threats
Ozkan-Aydin also studied how worm blobs coped with both temperature gradient and intense light. The worms need a certain range of temperatures to survive and not be exposed to intense light. When a blob was placed on a heating plate, it slowly moved away from the hottest part of the plate to the cooler portion and under intense light created by tightly attached blobs. The worms seemed to share responsibilities for the movement, with some people pulling the blob while others helped lift the globe to slow down.
Similar to evacuation, the combined activity improves survival opportunities for the entire group, which can range from 10 worms up to as many as 50,000.
“For an individual worm going from hot to cold, survival depends on chance,” Bhamla said. “When they move like a blob, they move more slowly because they have to coordinate the mechanics. But if they move like a blob, 95% of them get to the cold side, so being like part of the blob brings many survival benefits. “
Gymnasium worm
The researchers noted that only two or three puller worms were needed to pull a 15-worm blob. That made them wonder how strong the creatures were, so Ozkan-Aydin created a series of poles and cantilevers in which she could measure the forces of individual worms. This “worm gymmium” allowed her to understand how the hauliers managed to get the job done.
“When the worms are happy and cool, they reach out and hold on to one of the poles with their heads and pull on,” said Bhamla. “When they drag. , you can see the illumination of the cantilever to which their tails were attached. Yasemin was able to use known weights to measure the forces generated by the worms. The measurement of the force shows that the individual worms are packing a lot of energy. “
Some worms were stronger than others, and as the temperature rose, the willingness to work out at the gym waned.
Applying worm principles to robots
Ozkan-Aydin also applied the principles observed in the worms to small robotic blobs made up of “smart active grains,” six 3D-printed robots with two arms and two sensors allowing light to shine. consciousness. She attached mesh wraps and pins to arms that allowed these “smarticles” to engage like the worms and test a number of gates and movements that could be programmed into them.
“Depending on the intensity, the robots will try to move away from the light,” Ozkan-Aydin said. “They generate aggressive behavior that is similar to what we saw in the worms.”
She noted that there was no communication among the robots. “Every robot does its own thing in a decentralized way,” she said. “By using just the mechanical interaction and traction of each robot for light intensity, we were able to control the robot’s blob.”
By measuring the energy consumption of an individual robot while performing various wiggle and crawl, she concluded that the wiggle dude uses less power than the crawl fare. The researchers anticipate that by taking advantage of leg differences, robotic swarms involved in the future could improve energy efficiency.
Expanding what robot swarms can do
The researchers hope to continue their study of the assembled dynamics of worm blobs and apply what they learn to swarm robots, which need to work together with very little communicate to accomplish tasks they could not do on their own. But these systems need to be able to operate in the real world.
“People often want to make robot swarms do certain things, but they tend to work in pristine environments with simple situations,” Goldman said. “With these blobs, the whole point is that they only work because of physical interactions among the individuals. That’s an interesting feature to introduce to robots.”
Challenges ahead include hiring graduate students who are willing to work with the worm blobs, which have the consistency of bread dough.
“The worms are really nice to work with,” Ozkan-Aydin said. “We can play with them and they are very friendly. But it will bring someone who is very comfortable working with live systems.”
The project shows how the biological world can provide perspectives that are beneficial to the field of robots, said Kathryn Dickson, program director on the Physiological Equipment and Biomechanics Program at the National Science Foundation.
“This finding demonstrates that observations of animal behavior in natural conditions, combined with biological experiments and modeling, can offer new insights, and how new knowledge gained from interdisciplinary research can help humans. , for example, in the robotic control applications that arise from this work, “she said.
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This research was supported by the National Science Foundation (NSF) under the grants of CAREER 1941933 and 1817334 and the Army Research Office under the grant of W911NF-11-1-0514. The opinions, conclusions, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the organizations that endorse it.
CITATION: Yasemin Ozkan-Aydin, Daniel I. Goldman, and M. Saad Bhamla, “Assembled dynamics in worm and robot worms.”Proceedings of the National Academy of Sciences, 2021). http: // www.