[Diy_efi] RE: [Diy-efi] Traction Control System - In progress (Update 1)

[Nic van der Walt]

>Yes, the ABS setup on our Integra uses an inductive pick up. The manual
>states that it is an AC signal.

The voltage you read is a side effect of the inductive pickup, it does
not relate to speed
accurately but is an indication that the pickup works. You have to count
the frequency to
measure wheel speed. On my bike the frequency from the ABS sensor is
about 4400Hz at 200km/h.

First problem is converting the analog input to a nice square wave you
can measure. I'm sure a
search for variable reluctance sensors will give you something to work
with.

Having a PC measure 4 frequency's is harder. Easiest is to get a data
capture card with four counter
channels. If your run DOS the printer port can be sampled fast enough to
measure 5kHz, not trivial though.
Read up on Nyquist.

Remember that strictly speaking you don't need the absolute
frequency/speed, only the difference between the
wheels.

Using USB is not feasable, unless you get a USB based of the shelf
capture card. Still scarce though.

Serial is more than fast enough, if you have a micro doing the frequency
counting outside and sending you
the data every couple of milliseconds. By far the best/cheapest way, if
you can startup something like a
Atmel AVR (8515 or 8535 would be perfect).

N.



_______________________________________________
Diy_efi mailing list
Diy_efi at diy-efi.org
http://www.diy-efi.org/mailman/listinfo/diy_efi