> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On
Behalf
> Of Matt Pobursky
> Sent: 27 January 2008 00:02
> To: Microcontroller discussion list - Public.
> Subject: Re: [EE]:: ABS increases stopping distance by typically 20%+
> ongravel surfaces
> 
> 
> Truck ABS systems are quite a bit more interesting as the better ones
> integrate things like anti-rollover algorithms where they take
> accelerometer data into account along with wheel speed to sense
trailer
> sway and wheel lift and apply braking that counteracts the trailer
motion.
> You should see them test these systems, it's very cool! I asked one of
the
> test drivers how many trailers he's rolled over and his answer was
"too
> many to count". :-)

That sounds more like a stability control system than simple ABS, e.g.
similar to BMWs DSC system.

The one big advantage that the better anti-lock systems have over a
skilled driver is that the modulator has control over individual wheels,
so it can resolve a single locked wheel without affecting the rest of
the wheels.  Cadence braking releases pressure from all wheels,
decreasing the amount of valuable braking work they can achieve.

On loose surfaces optimum braking is often achieved by locking the
wheels and allowing the loose surface to pile up in front of the tyres,
so ABS often loses in these situations.  Another problem with some ABS
is on some rough road surfaces where the tyre can leave the road
intermittently which causes the ABS to activate far too quickly, and
gives a "driving on ice" feeling.

Regards

Mike

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