Global Positioning System Reference
In-Depth Information
7.5.4 Smart Floors
Many research projects [8] have been experimenting with the idea of a smart floor
that can detect footfall and track the motion of people walking and dancing. The
smart floor is really a scaled-up version of the touch screen found on many
computer interfaces and they are potentially very accurate. Pressure sensors or
other transducers based on, for example, capacitance changes (see Section 7.6.2)
are mounted in a dense grid under a flooring surface so that the presence of feet
can be accurately located. The computational challenge is to follow the progress
of several people across a common area and to find methods to identify them. One
approach would be to use some sort of door access system to open the door to
known people. At the threshold, it is clear to the tracking computer to whom the
feet belong, so that the individual can then be tracked unambiguously. Anomalies
are possible if people jump, are carried, or if too many feet are in a very small
area, but the technique has many merits.
Perhaps the main attraction is that users do not need to carry any equipment
or to have any training. The system is invisible and it is possible (although
currently expensive) to make dedicated active flooring. New nanotechnology
materials are emerging that may be useful, for example, quantum tunneling
compound rubber. This conductive rubber is highly sensitive to pressure since it is
impregnated with nanoparticles of metal that when compressed into close
proximity, start to conduct electrons using the quantum tunneling effect.
In common with much research in ubiquitous computing, smart floors (and
smart furniture) are still emerging as products but are likely to have a major
impact on the future built environment. Already there are new art forms based on
dance and music seeking to exploit smart floors, which are effectively part of a
musical instrument, a computer interface, and a positioning system (see Section
5.7.1).
7.6 Positioning with Magnetic and Electric Fields
7.6.1 Magnetic Compasses
Since antiquity, positioning due to the Earth's magnetic field using permanent
magnet compasses has been a fundamental part of navigation. Today, small and
inexpensive magnetic field sensor chips are included in consumer products and
professional compasses are still used if only as a standby for when all else fails.
The electronic chips are based on thin magnetic films that change their electrical
properties when exposed to magnetic fields and are small enough to be
incorporated into conventional wristwatches. Some pre-GPS vehicle navigation
systems used electronic compasses, and electronic compasses are still a popular
vehicle accessory.
 
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