Page 134 - Anatomy of a Robot

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COMPUTER HARDWARE 119
Voltage
Processors are available that work on various different voltages. Some processors can
work on very low voltages, as low as 1 volt (although this is rare). Moving to a lower-
voltage operation can be done for two reasons. The first is power savings, which we’ll
discuss shortly. The second reason is to match the battery voltage (if a battery is used
in the system). A considerable amount of power-supply circuitry can be taken out of the
design if the circuitry can accept the battery voltage directly.

Space

Sometimes space is at a premium inside a robot. If so, consider the space taken up by
the processor chip and any heat sinks or fans that may be required.

Reliability

Some robots are sent to space or other relatively inaccessible places. They may be sub-
ject to extreme environmental stress, including temperature, vacuum, vibration, and
radiation. There may be no opportunity to even service the robot. If reliability is key,
then consider the choice of processors carefully. Spacecraft designers, for instance,
often choose older, proven processors that have been tested for years. There are several
good articles on the special considerations must be taken into account:

www.klabs.org/DEI/Processor/index.htm
http://klabs.org/DEI/References/design_guidelines/design_series/1248.pdf
www.gd-ais.com/Products/srs/process/isc.pdf
www.spacecoretech.org/coretech2000/Presentations/Software/ISC_Case_
Study/sld001.htm

Reprogramming
Some computers have onboard memory. Make sure to check if this can be repro-
grammed or not. Even if it can be reprogrammed, check and see which features the
processor has to facilitate it. How will the processor be accessed, downloaded, and
restarted?

Benchmarks
We’ve discussed benchmarks and how to determine the “horsepower” of a processor. It
makes sense to list benchmarks on this checklist.