In a message dated 01/21/2000 10:57:47 AM Pacific Standard Time,
arabian@allegronet.com writes:
> A number of cars use accelerometers, but NOT for axial deceleration
> measurement
> generally. They are for lateral acceleration - i.e. cornering. The ABS
> operates slightly differently when cornering than when going straight (more
> braking on the inside wheels I think, but I could be way off base on that.
> Don't remember the specifics). Anyway, my guess based on my limited
> measurements experience is that accelerometers (or at least reasonably
> priced
> ones) are just too noisy to be used very well for axial deceleration.
>
As far as I know no ABS system uses accelerometers. the wheel speed sensor
uses a toothed wheel and some type of pickup (magnetic is the most common) A
magentic sensor generates a sine wave and the signal goes to an analog to
digital converter (typicaly a Schmit trigger) this A to D converter may be in
the control unit on in the sensor. The control unit is just looking at the
frequency of each wheel and calculates G force from changes in frequency of
each wheel.
Accelerometers are used in yaw control systems, my company car has one. I do
have one question, your comment about noisy? The sensor in my car is solid
state and as such is stone silent. How do the ones in your experience work?
Rick Ewald
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