🚀 go-pugleaf

In article <1992Dec3.183246.26746@colorado.edu> neves@chimay.cs.colorado.edu (NEVES RICHARD K) writes:
>In article <1992Dec3.013225.17152@mercury.cair.du.edu> jvilhube@diana.cair.du.edu (Jan Vilhuber) writes:
>>I've always sort of wondered why bother with ABS, since I presume that it
>>would LENGTHEN your break-distance, since it makes the breaks 'stutter'.
>
>I think you misunderstand the "theory" behind ABS.  The idea is that
>ABS will *decrease* your stopping distance because the wheels can't
>lock.  When you press on your breaks, the friction steadily increases
>and then when the wheels lock, BLAM, there goes all the friction.  ABS
>keeps the wheels (IN THEORY) just in the state before locking, thus
>decreasing your stopping distance.
>
>>You can just as easily do that yourself, if you are a good driver, 
>
>Not true.  In THEORY, no human can pump the breaks as fast as a
>computer which can sense the BLAM point (before the wheels lock).  So,
>IN THEORY, ABS breaks are much better than in driver in shortening the
>stopping distance.

If you read rec.autos, you will notice that the consensus is that a
good driver can beat ABS on *dry* clean pavement because of being able
to do threshold breaking much better than the ABS system (exactly
because s/he does not need to pump the breaks).
The ABS system has to lock the wheels, then release them, then lock
them again etc., i.e. it oscillates around the threshold point.
Once I noticed on US36 some skid marks that were like this:
	--   --   --   --   --
which I think was a good indication of somebody hitting the brake pedal
really hard on an ABS-equipped car.

For me, the real advantage of a good ABS system (i.e. one with sensors
on all 4 wheels) is that it can "sense" differences on the pavement,
for example when the wheels on one side hit ice/gravel/whatever.
In such situations, I believe no driver can beat an ABS system.

Panos

-- 
Panos Tsirigotis, CS grad                        
Pmail: Computer Science Dept., U. of Colorado @ Boulder, Boulder, CO 80309-0430
Email: panos@cs.colorado.edu