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128 CHAPTER FOUR
Bulbs
Bulbs with filaments are quite fragile and will fail quicker than most. Even if the robot
does not move, bulbs are likely to fail at a rate similar to those in households. Gaseous
bulbs will also fail over time, much like overhead fluorescent bulbs do. Consider white
light-emitting diodes (LEDs) for illumination in a robot design. Many LEDs are specif-
ically designed to provide usable reading light.

Moving Parts

Moving parts are particularly subject to wear. Further, as they wear out, they may shed
debris. Lubricants, like oil, have to be used with extreme caution. They can easily
migrate to connectors and cause contact failure. Consider life testing any moving part
to a number of repetitions well beyond its expected lifetime count. Life testing involves
subjecting the relevant components with conditions that simulate years of use in a much
shorter test time. The following web site has a very nice treatment of reliability issues:
www.itl.nist.gov/div898/handbook/apr/apr.htm.

Safety

If the auto industry were like the computer industry, a car would now cost $5, would
get 5,000 miles to the gallon, and at random times would explode, killing all its
passengers.
— John Chambers
Safety issues can be divided into a few different categories. Human safety is paramount.
I suppose that’s why they started shooting chimps into space first! After human safety,
we consider the safety of the mission, so it runs to completion.

HUMAN SAFETY
Robots come in all shapes and sizes. Some popular TV robot warriors are a couple of
stories tall and spit flames. Certainly, these robots present a threat to human safety, just
from their physical prowess. That said, I’ve opened up my son’s broken Furby robot.
Though furry and small, it did die an ugly death by catching fire, emitting smoke, and
landing outside the house in a snowdrift. Further problems were probably forestalled
because the toy was properly designed to conform to applicable safety regulations,
which limit the size of such fires. And all this happened just when I was getting used to
speaking Furbish with the little guy.