The Context - Artificial Human Sensors: Science and Applications - page 36

for the human operator in a complex system, e.g., in industrial, monitoring and
surveillance operations. On the other hand, the human aspect can be used as a
sensor node and make human based sensing. The sensing information is then com-
municated into the decision system, Pavlin (2007). The human supporting system
approach makes the system redundant and very dynamic, knowing that people
will report any unusual and threatening events to a computer system in a convinc-
ing and communicative way. This direction introduces a new methodology, where
human perception is supportive as sensors in a complex system. Also a mixture
of the basic directions above can be an attractive solution in designing a system's
operational principle by using the best properties from both groups.
Following this direction of the discussion, then there is a predetermined struc-
tural pattern of how things around us behave in certain situations that seems
understandable in how they act.
The observation of non-verbal behaviour of humans, animals, or even vegetation, could
provide powerful and indirect measurement clues about environmental information.
Essential parameters that may provide useful information are, e.g., ambient smell,
radiation, air and water contamination, and extreme spectrum vibrations. All of
these could be difficult or hard to measure by instruments but are naturally de-
tected by humans, animals, or vegetation. Historical examples of applications may,
for example, be canaries and mice, which were used for centuries as methane gas
and carbon monoxide detectors in coal mines to provide warnings for explosion
and potential poisoned air, Petriu (2008). Rats and other animals are well-known
to sense low frequency vibrations indicating earthquakes or volcano eruptions be-
fore these happen, Garces (2000). Also humans may be sensitive to sound waves,
which they normally do not apprehend outside their hearing spectra. We are vul-
nerable to low frequency sound even if it is outside our hearing range. A feeling
of discomfort, sorrow and fear appears, and evokes shiver when music is mixed
with additional infra-sound. Leaf coloration and growth levels of plants and trees
can be used, as qualitative indicators of the environment status, also additional
qualitative parameters like air and water pollution levels, as well as temperature
changes.
This sensing methodology indicates that there are additional aspects to con-
sider, that can be used as advanced external structures for indirectly providing
indicative and qualitative measures as a complement to humans and their limited
perceptual performance.
Nowadays, nature-based biological indicators are being measured by addi-
tional new technology devices that have successfully increased the human assess-
ment. The new emerging development of human self-diagnostics is an interesting
future direction. New and specific sensors may be applied on the body, or built in
the clothes, to detect, for example, if the human health status or its environment
has changed. Sensors are then able to measure parameters such as blood pres-
sure, heart and breathing activities and extreme loads of body parts. Also, the
conditions of the interacting environment can be monitored in order to detect