And of course bugs can sit there, unnoticed and undetected by test
procedures, until triggered by unusual events. The world of military
aviation might have some lessons here.
A modern fast jet comprises several computer systems flying in close
formation. There are systems to control everything, from navigation to
fuel flow. And sometimes they have bugs.
For example:
http://www.dailytech.com/Lockheeds+F22+Raptor+Gets+Zapped+by+International+Date+Line/article6225.htm
When a number of fighters crossed the International Date Line, all their
systems crashed. I don't quite see why some of these systems had to know
what day it was, but apparently it was important.
As far as I know, you can't drive across the International Date Line.
The next example may be more relevant.
The Israeli Air Force once found that the navigation systems of a
particular jet failed when the planes flew over the Dead Sea.
Investigation showed that the programmers has decided that planes could
not fly below sea level: they would be under water, wouldn't they? Well,
no -- there are plenty of places around the world where being below sea
level does not mean that you are under water, and the Dead Sea Valley is
only one of them. Lake Eyre is another: so if, in some future decade,
you decide to visit Lake Eyre in your Autopiloted 4WD, make sure that
you will be able to drive out again.
There are many more examples like this: planes that could not cross the
Equator because the navigation computer could not process negative
numbers for latitudes, systems that could not cope with time zone
changes -- and so on.
All of these problems were detected in actual use, and not by the
testing process.
I suspect that 2030 is a little optimistic for the widespread use of
autopiloted cars: maybe 2090 would be a more realistic estimate.
One of the reasons given for the development of autopiloted cars is the
potential reduction of the road toll. That might be a long time coming.
JH
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