Tuesday, Nov 02, 2004 at 14:16
Excellent post Collyn.
>But with cars, it's the hardware not the software that goes wrong.
>If that hardwear fails, a kid has as much chance of fixing it as a
>90-year old plumber. In fact I'd probably back the plumber at least
>he'll know that a good hit with a hammer may fix a crook connector.
I’m with you, my monies on the plumber :)
>These days have gone. Nowadays things are so complex that it is
>customary to replace a complete system - or at least major
>sub-system.
Exactly. And that is the design philosophy employed by Bosch et al. It makes no sense to have a highly trained electronics technician hanging around a motor vehicle dealers with a bucketfull of very expensive
test gear for the occasions when the electronics blow up. Much more sensible to provide low tech. training to the vehicle automotive guys so that they diagnose to board level and do a board swap. Then send the board off to be repaired or thrown away.
>Re the relative reliability of space craft.
Two things: 1) as you say, life support systems will tend to use old technology because it’s tried and tested. Also because these systems take so long to design and
test, by the time you’ve completed them the technology which was new when you started is now old. 2) Typically life support system will have three levels of redundancy, so if level one fails you have two backup system – not always (pacemakers may not) but many critical systems do.
>Unmanned craft use super-sophisticated technology
You should see some of the defence stuff these days! A-bloody-mazing! :)
>What is interesting abut this debate is that the cautious are emerging
>as those who have worked in this field.
Modern day electronics are astonishingly reliable, no question – BUT when they fail are usually irreparable without specialised equipment and knowledge. As someone else said “so is a conrod through
the block” – quite true but the difference is I _must_ have a conrod and engine block but a remote area vehicle does not _have_ to have electronically controlled fuel injection or an O2 sensor etc. Why increase the number of critical systems? If _any one_ of them fails – you’re stuffed. This is really the nub of the thread: normally a vehicle is not a life support system but in remote regions it may be but manufacturers will _never_ want to acknowledge that for legal reasons and the fact that very few of their vehicles will fall into that category – but for those which do it’s a critical issue. And that’s why I would prefer not to have critical electronic systems in such a vehicle.
Mike Harding
mike_harding@fastmail.fm
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