Even on ice the car will be slowing (albeit extremely slowly).
Acceleromters can be extremely sensitive.
Matt
Bob Howard wrote:
>
> Matt,
> I can follow your logic if the skid is on pavement where at least one
> wheel has good grip. If all four wheels were on ice, how would it sense
> deceleration?
> Bob
>
> On Fri, 21 Jan 2000 08:43:47 -0500 Matt Pringle <pringlmm@mcmaster.ca>
> writes:
> > Actually sensing the difference between being stopped and skidding
> > with
> > all wheels locked is very simple and I'd be very surprised if they
> > don't
> > do it already. When you're skidding, you're still slowing down and
> > so
> > an accelerometer could easily sense this.
> >
> > Matt
> >
> > Chris Kotting wrote:
> > >
> > > Paul -
> > >
> > > Aha! You've discovered ABS's weak point. Allow me to ask a
> > question:
> > > How does ABS know that a wheel is locked? Think about this for a
> > second
> > > before reading the next line.
> > >
> > > Ready for the answer?
> > >
> > > By comparing rotional speeds of the four wheels.
> > >
> > > Now for the next question: How can an ABS system tell the
> > difference
> > > between these two states (a) all four wheels locked and sliding,
> > and (b)
> > > stopped?
> > >
> > > Answer? It can't.
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