[Diy_efi] 60-2 Toothwheel - Kalman Filter or ( EKF ) usage

[Adam Wade]

--- Bruce A Bowling <bbowling at earthlink.net> wrote:

> The one thing I have dropped a few times here but no
> one has questioned is why is there more error at low
> RPMs?

I'll give that one a shot.  :)

It's largely the same reason that using speed density
at idle without a lot of signal conditioning is a bad
idea.  Dynamic compression is at its lowest at idle,
and spark is at its most retarded as well.  Small
variances in the homogeneity of the intake mixture can
turn into much larger variances in power transmitted
to the crank during a power stroke; further, those
variances are a much larger percentage of the power
output of the engine at idle than the same variances
would be if the engine was under load (even as little
load as freeway cruise, although then you also have
issues with the low manifold pressure and what that
does to homogeneity and flame front propagation).

AND, if you are using a reluctor as your pickup, you
not only have lower peak voltage as signal out, but
you have a shallower (slower) voltage rise/fall on the
leading/trailing edge of the tooth passing the
reluctor.  You'd need to do a really nice job of
figuring out where the crossover is made from
non-triggered to triggered (and any minute changes in
crank speed because of inconsistencies with idle power
from cylinder to cylinder will change the slope as
well as the peak, and you have to have some way to
determine when the signal indicates the tooth has
actually passed its trigger point).  So that too (and
it would be wonderful to make a Hall-effect rig with a
wheel that had about 100 tiny magnets on it, but I
don't know if that would be feasible or not).

I could use the cash, but I'll settle for the medal
you don't want -- assuming I got it right.  ;)

| Kawasaki Zephyr 615 (Daphne)       Kawasaki Zephyr 550 (Velma)|
| "It was like an emergency ward after a great catastrophe; it  |
|   didn't matter what race or class the victims belonged to.   |
|  They were all given the same miracle drug, which was coffee. |
|   The catastrophe in this case, of course, was that the sun   |
|     had come up again."                    -Kurt Vonnegut     |
| M/C Fuel Inj. Hndbk. @ Amazon.com -  http://tinyurl.com/6o3ze |


 
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