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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.
Sony understands this paradigm shift. Aibo, their new lion
cub, and SDR personal robots have an RF LAN slot for brains off board. Cye has brains off board using a low bandwidth RF modem link. The AmigoBot and iRobot, while having brains on board, also have an RF LAN expansion capability.

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16.4 2002

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