How animal swarms respond to threats

Date:
March 8, 2022
Source:
University of Konstanz
Summary:
With the help of microrobots, physicists decode how swarms of
animals respond effectively to danger.



FULL STORY ==========================================================================
A herd of antelope feeds peacefully on a meadow. Suddenly, a
lion shows up, and the herd flees. But how do they manage to do so collectively? Konstanz physicist Chun-Jen Chen and Professor Clemens
Bechinger, a member of the Cluster of Excellence "Centre for the Advanced
Study of Collective Behaviour," asked themselves how animals must
behave in order to initiate an efficient flight response. In a study
using microrobots that act like a group of animals, the researchers demonstrate: A swarm of animals -- taken as a whole - - completes an
optimum flight response, even if individual animals do not notice the
threat or they react the wrong way. The study was published on 7 March
2022 in the New Journal of Physics (NJP).


==========================================================================
A microrobotic swarm The starting point for the researchers' work was
to consider a group of peacefully swirling animals and what would happen
if it suddenly encountered a dangerous situation.

For their experiments, the researchers used a system of microrobots,
which are comprised of glass balls that are programmable, active, and
spread out finely within a certain area. When the beads are lit using a
focused laser beam, one side of them warms up and causes them to move,
like animals. "We are able to target each individual bead and adjust its movement to fit that of its neighbours," explains Chen, who is completing
his doctorate in Bechinger's research team and who was mainly responsible
for completing the experiments.

"The robots in our swarm are programmed to avoid collisions. They also
received the information that they were to orient their motion based on
the location of the approximate middle of the group. With the help of
these rules, the robots organized themselves into a swirl," and Bechinger
adds: "The microrobotic swarm reproduces the movements of real animal
swarms surprisingly well." The flight behaviour of microrobots As soon
as a predator appears, the microrobots change their movements, Bechinger
says. However, the change in direction is only minimal and does not cause
each member of the swarm to move directly away from the predator at any
given time. It is striking, however, that the group as a whole moves in
a straight line away from the predator. "This feat in which individuals
move in a way that is not ideal for each one of them, but where the group
as a whole behaves optimally, is based on a collective decision-making
process or "swarm intelligence" where information is constantly being
exchanged between different members of a group," Bechinger states.

"One direct consequence of this behaviour is that the efficiency
of the flight response remains virtually unchanged, even if half
of the microrobots -- or animals -- do not respond to the threat,"
Chen explains. "This shows that missing or incomplete information from individual members of a group can be compensated by other members." The physicists think this could possibly be one of the reasons why animals
organize themselves in herds, even though herds are significantly easier
for predators to spot than individual animals.

Animal behaviour relevant for other applications In addition to gaining
a better understanding of the basis for decision-making in groups of
animals, the research results are also relevant for applications in
the field of microrobotics. At the moment, different scenarios are
being discussed in which multiple autonomous robots complete a useful
task together and in which disruptions to communication between the
robots would automatically cause problems. With the knowledge gained
from this study, a robotic swarm could work well even if, for example,
the sensors in individual robots were to fail. Bechinger adds: "The other microrobots would simply compensate for those with broken sensors, giving
such systems a very high level of robustness." Video on the microrobotic simulation of the animal flight response: https:// youtu.be/01Fcau5wxII
Author background and funding
* Professor Clemens Bechinger is a member of the Cluster of Excellence
"Centre for the Advanced Study of Collective Behaviour" at the
University of Konstanz. He is also a professor in the Department
of Physics.

* Chun-Jen Chen is completing his doctorate in the "Colloidal Systems"
research team led by Bechinger.

* Project funding: Centre for the Advanced Study of Collective
Behaviour

========================================================================== Story Source: Materials provided by University_of_Konstanz. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Chun-Jen Chen, Clemens Bechinger. Collective response of
microrobotic
swarms to external threats. New Journal of Physics, 2022; 24 (3):
033001 DOI: 10.1088/1367-2630/ac5374 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/03/220308115806.htm

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