[Diy_efi] OT: ABS retrofit into older car...

[Amenson Scott (AC/ESC4)]

"The problem is that ABS systems require very serious
testing and certification before they are allowed to be used on a road going
car, most of this testing is quite destructive and very expensive, hence
only worth while for a large production."

Actually...if testing goes well;) there is very little destruction involved.
Although it is very expensive.


"PS: I'm not sure of the exact method used by the manufacturers for their
ABS
systems but would imagine it's some kind of bang-bang controller, ie it
allows full brake pressure until the tires almost lock up, then bleeds the
pressure off and repeats the process.  I get this from the pulsing feeling
when heavily decelerating in most ABS fitted cars."


That is true for all but the most recent systems.  In order to reduce the
pulsing that the driver feels on the gas pedal, systems are moving away from
bang-bang/PWM control toward a more proportional control.  In an effort to
completely eliminate system pedal feedback, brake by wire systems have been
developed and installed in some high end cars.

Scott

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