What Is A Smart Dust?
'Smart dust' —
sensor-laden networked computer nodes that are just cubic millimetres in
volume. The smart dust project envisions a complete sensor network node,
including power supply, processor, sensor and communications mechanisms, in a
single cubic millimetre. .Smart dust
motes could run for years , given that a cubic millimetre battery can store 1J
and could be backed up with a solar cell or vibrational energy source .
The Mems Technology In
Smart Dust
Smart dust requires mainly revolutionary advances in
miniaturization, integration & energy management. Hence designers have
used MEMS technology to build small
sensors, optical communication components, and power supplies. Microelectro
mechanical systems consists of extremely tiny mechanical elements, often
integrated together with electronic circuitory. They are measured in
micrometers, that is millions of a meter. They are made in a similar fashion as
computer chips. The advantage of this manufacturing process is not simply that
small structures can be achieved but also that thousands or even millions of
system elements can be fabricated simultaneously. This allows systems to be
both highly complex and extremely low-cost.
Active-Steered Laser
Systems
For mote-to-mote
communication, an active-steered laser communication system uses an onboard
light source to send a tightly collimated light beam toward an intended
receiver. Steered laser communication has the advantage of high power density;
for example, a 1-milliwatt laser radiating into 1 milliradian (3.4 arcseconds)
has a density of approximately 318 kilowatts per steradian (there are 4
steradians in a sphere), as opposed to a 100-watt lightbulb that radiates 8
watts per steradian isotropically. A Smart Dust mote’s emitted beam would have
a divergence of approximately 1 milliradian, permitting communication over
enormous distances using milliwatts of power. Each mote must carefully weigh
the needs to sense, compute, communicate, and evaluate its energy reserve
status before allocating precious nanojoules of energy to turn on its
transmitter or receiver.
Abstract
Advances in hardware technology have enabled very compact,
autonomous and mobile nodes each having one or more sensors, computation and communication
capabilities, and a power supply. The
Smart Dust project is exploring whether an autonomous sensing, computing, and
communication system can be packed into a cubic-millimeter mote to form the
basis of integrated, massively distributed sensor networks. It focuses on
reduction of power consumption, size and cost. To build these small sensors,
processors, communication devices, and power supply , designers have used the
MEMS (Micro electro mechanical Systems) technology.
Major Challenges
1. To incorporate all these functions while
maintaining a low power consumption
2. Maximising operating life given the limited
volume of energy storage
Listening To A Dust
Field
Many Smart Dust
applications rely on direct optical communication from an entire field of dust
motes to one or more base stations. These base stations must therefore be able
to receive a volume of simultaneous optical transmissions. Further,
communication must be possible outdoors in bright sunlight which has an
intensity of approximately 1 kilowatt per square meter, although the dust motes
each transmit information with a few milliwatts of power. Using a narrow-band
optical filter to eliminate all sunlight except the portion near the light
frequency used for communication can partially solve this second problem, but
the ambient optical power often remains much stronger than the received signal
power.
No comments:
Post a Comment