available to manage real
time events on the robot due to "latency" (time lost) between
the Personal Computer Robot (PCR) and the controlling PC. This time
loss is primarily due to the time spent handshaking, or coordinating
the communication between the PCR and PC. This handshaking time loss
occurs in other applications, such as between laptops and hospital
wireless networks, but does not pose a problem in those cases since
there are no near real-time or nearly instantaneous mechanical or
sensor systems being managed. Fortunately real time control of electro-mechanical
and sensor systems can be achieved readily and inexpensively using
today's MCU's.
Ten to fifteen years ago, embedded systems using
MCU's were in their infancy. Today low cost embedded systems have
given us electronic fuel injection, anti-lock braking, air bag deployment,
active suspensions, etc. to name just a few applications from the
automotive industry. To achieve this penetration into the automotive
industry's tremendous market, semiconductor IC manufacturers such
as Hitachi, Motorola, Siemens, MicroChip, Atmel, etc. have reduced
the cost of their MCU's to commodity pricing.
Now plentiful, these low cost embedded systems
enable us to control real-time events and operations on board the
mobile robot inexpensively and reliably. These real time events may
be as simple as maintaining constant robot movement in spite of transitions
from tile to carpet in homes and workplaces to as complex as scanning
and reading an array of multiple range finding infrared and ultrasonic
sensors. Consequently low cost embedded systems now easily manage
most, if not all, real-time (near instantaneous) supervision activities
of mobile robots in general, and personal robots specifically. Sony
has sold over 100,000 Aibo's in less than two years using this reliable
and inexpensive approach to motion control and multiple sensor interpretation
in its new consumer electronics product line of personal toy (entertainment)
robots.
The Hardware Cost Breakthrough
Perhaps the most significant example of the recent
technological confluence directly benefiting mobile robots is in the
dramatic cost reduction in RF data communications. Less than ten years
ago, mobile telephones were analog with each costing thousands of
dollars. With the astonishing popularity of cordless phones followed
by cell phones, the analog bandwidth available in RF communications
was rapidly nearing saturation. Using digital data-compression technologies
the communication companies not only opened up sufficient bandwidth
for millions of customers, but also dramatically reduced power and
dollar costs.
Only five years ago, RF data communications of
9600Bps to an end-point, cost several hundred dollars and were not
power efficient. With the proliferation of digital cordless phones,
digital cell phones, PDA's, laptops, and desktop PC's, today's RF
data rates reach ten megabytes at retail prices in the range of $70
to $120 per end-point. Since many RF LAN (IEEE standard 802.11b) data-communication
devices plug into cell phone, PDA, or laptop where battery life is
extremely important. Their power consumption is low, while bandwidth
has increased and costs, in both power and dollar, has decreased dramatically,
without sacrificing range.
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