> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On
Behalf
> Of rolf
> Sent: 23 November 2009 15:45
> To: Microcontroller discussion list - Public.
> Subject: Re: [OT] What happens when you get rear-ended
> 
> ditto to all that... Living in Canada I have similar experience
(though
> not
> so much with 'sand' more snow) .... and since snow is coming, it is
time
> to
> change mindset while driving.
> 
> I can say with some certainty that, in all situations (except snow and
> other loose surfaces), ABS is better than nothing. It is 'known' that
in
> snow, if you skid, the snow builds up a 'bow wave' in front of the
wheel,
> and helps the vehicle stop, but, with ABS, the vehicle's wheels will
> unlock, causing the wheel to roll over the snow, and take longer to
stop.
> Like Forrest says though, what you lose in stopping distance you more
than
> gain in control.
> 
> On the other hand, technically, in more normal situations and on more
> normal surfaces (including ice), an exceptional driver will be able to
> beat
> ABS in stopping distance always... in other words, a driver who is
able to
> apply the brakes with just the right pressure to keep the wheels
rolling
> while still braking to the 'max' will have the best stopping distance,
and
> still maintain control...
> 
> in other words, a skilled driver will be able to outperform ABS in
> stopping distance and control.

I'm really not a big fan of most driver aids, and the consequential
dumbing down of driving standards as a result.  The early ABS systems
were pretty poor and a decent driver could very likely give a better
performance (in terms of stopping distance) in many situations. 

Modern ABS systems have control over individual wheels that are locked,
so they have a big advantage over even the most skilled of drivers.

To correct a locked wheel without such a system, a driver would have to
reduce braking effort to all four wheels, which increases overall
stopping distance.  Since the maximum grip available from any particular
wheel will vary, to prevent (rather than correct) locking a driver will
have to reduce the total braking effort to the level of the wheel with
the lowest grip.  Having a higher braking effort to 3 wheels and
allowing the ABS to cope with the other one will very likely give
shorter stopping distances.

Regards

Mike

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