Biomedical Engineering Reference
In-Depth Information
their neighbors, and they make sure to keep the
right distance from one another—not too close
and not too far away. Actually, this behavior is
not that different from the way human beings
behave when we are in a flock, e.g., when trave-
ling by cars on highways. However, when cars
become robotic, they need control systems that
ensure a smooth and effective traffic flow. The
study of the behavior of birds and fish in flocks
gives input to a decentralized control mode that
is expected to increase the density of automatic
vehicles. Another application is realistic com-
puter animations of bird flocks, fish flocks, and
grazing animal herds.
Section
13.3
looked at how collective decision
making is found in insect societies, where many
individuals live together. Ants leave volatile
pheromones on their trails, which help them
determine the shortest paths to food sources.
The same principle can be used to make com-
puter programs that solve logistic problems.
Honeybees follow an almost democratic proce-
dure whereby new nests are found based on
discussions between scouts that advertise in
favor or against a site. This principle is also
useful for decision making in computer pro-
grams and it is seen in social media on the
Internet, where user recommendations deter-
mine the sales success of products. Political
polls increasingly control public decision mak-
ing. However, a difference is that scouting bees
have clear criteria for the selection of nest sites,
in contrast to political polls, where selection
criteria are unclear.
Section
13.4
treated the building of large
structures such as the termite towers that are not
only spectacular because of relative size. Just as
impressive is the apparent lack of a master plan
and centralized structure. Part of the explana-
tion lies in the concept of stigmergy, whereby
the actions of individuals modify the environ-
ment and the modification affects the behavior
of other individuals. Stigmergy is also seen in
the behavior of human beings, for example, in
the unwanted concentration of litter at highway
pull-up areas. Once someone has left their litter
on the side of the road, others are more willing
to do the same. Attention to this type of behav-
ior can be used in designing public places such
as playgrounds and stadiums.
A positive use of similar principles is seen
when temporary findings are put on display in
design work. Colleagues notice and follow the
work, providing criticism that can be beneficial
for the creators, but the critics also pick up good
ideas. The graphical display of works in pro-
gress is of mutual benefit and certainly shapes
the designs made by all the involved parties.
Section
13.5
looked at swarm intelligence that
underlies the clever collective behavior seen
when a large number of autonomous agents
work together. The swarm can achieve better
results than is possible for the individual mem-
bers. Strangely enough, the behavior in bee and
ant swarms is controlled solely on a local level.
Each member knows how to deal with problems
when they occur, without consulting a higher-
level control authority. Similar strategies for dis-
tributed local control are used to design robotic
swarms that behave purposefully without any
interference from a central controlling com-
puter. Such robotic swarms can be much more
robust than centralized controlled systems and
much less vulnerable to communication
problems.
Sealing problems was the topic of Section
13.6
.
A general problem for all types of containers that
hold gas or liquids is the risk of leakage. Both
animals and plants have mechanisms that
quickly close leakages and seal them before the
actual healing takes place. The two-component
plugging mechanism that is the first step in
blood clotting could potentially be used for self-
sealing pneumatic structures such as car tires.
However, the question is whether the process
can be made to react quickly enough to preserve
a high enough working pressure. Another seal-
ing mechanism found in plants that uses internal
pressure in foam-like structures has proved
workable for low-pressure pneumatic structures.
