On Sat, 26 Jan 2008 17:08:27 -0200, Gerhard Fiedler wrote:
> Funny NYPD wrote:
>
>> this is not surprise at all. GM canceled the ABS as a standard
>> equipment on all its America models couple of years ago, because  of
>> the poor performance and constant issue it created.
>>
>
> ABS may not be (and probably isn't) ABS. This seems to be a rather tricky
> control feature, and I'm sure there are big differences between different
> ABS manufacturers.
>
> Gerhard

Ding, Ding, Ding! We have a winner!

One of my major clients makes ABS systems for trucks and for the past
several years I've been designing test and diagnostic equipment for them as
well as some aftermarket add-ons. I'm not an ABS expert by any means but I
have observed a lot of test data can tell you that the level of what passes
for ABS hugely varies between the automotive companies.

GM makes the most "brain dead" ABS system on the market for use with their
"mainstream" models. It uses the cheapest and fewest wheel sensors,
relatively crude brake modulators and the simplest braking algorithm. The
reason they pulled ABS as standard was two-fold: 1) Cost and 2) It only
worked well if you just hammered the brake pedal to the floor and kept it
there (letting the ABS system totally control the braking). They had a lot
of problems with drivers pumping the brakes (as they were taught to do),
which caused the ABS system to modulate braking on top of the user
modulating it... very bad. There were accidents (and legal actions) caused
by this so it's no wonder GM no longer supplies it as standard equipment.
On the other hand, I've heard the ABS systems on Cadillacs and Corvettes
are quite excellent. Amazing, huh?

The ABS systems you see from BMW, Mercedes, Acura, Lexus are much more
sophisticated and generally tied in with the other traction and throttle
control functions. Toyota and Honda are somewhere in the middle and the
rest of the U.S. manufacturers bring up the rear. Generally, the more
quality and engineering oriented auto companies have the best ABS systems
(big surprise, huh?).

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". :-)

Matt Pobursky
Maximum Performance Systems

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