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

[Mike]

At 08:15 PM 4/3/07, you wrote:
>Hello,
>
>I'm using a microcontroller with standard CAPTURE/COMPARE units in order to
>process a 60-2 crank wheel. I'm very concerned about noise and a single step
>Kalman Filter seems to be a very good tool for this application.

Not sure what u mean by a "60-2" though if you are not using it for synchronism
of fuel/ignition and only for a speed rpms derivation - albeit a good one then it might be ok.

>Does anybody have experience with that? Could you please point me to some
>articles or information on how that particular application of Kalman could
>be implemented? Is it really efficient as it sounds like?

Ive used a multistage kalman filter in a nucleonic ore flow gauge project where
two Co60 beams and counters measured mass flow rate of ore by absorption.
ie. Trying to data process two normal curves as they were affected by falling ore
and gravity was my first foray into 16 bit micros in 1980 or so. It was a bit over
my head but I struggled through it and we made the system work fine though we did
bring in a specialist mathematician from India's mining industry to lend a hand, his
command of english emabrrased us poor colloquial cohorts !

They were reasonably effective and the various coefficients and post processing supplied a total
flow rate that was within 1 to 3% *but* the short term accuracy was not better
than 20% or so as the various state variables took many cycles to clear or rather
'impose' their accumulations on the overall flow rate.

In other words I feel it not appropriate to use Kalman for speed measurements
and definitely nor for anything requiring any synchronicty at all under any circumstances.


>I'm still reading the basic literature about Kalman and Statistics.

it was tough for me 26 years ago,

I think you wont need it if you can address the h/w issue with respect to noise such
as cable routine, impedance of sensors, screening etc

Eg. The Crank signal for the EFI and ignition for an RB30 motor is passed in parallel more
or less with the spark wiring loom for a few cms, it might blow the odd sensor but doesnt seem to affect
noise on a cycle by cycle basis. ie The ignition is smooth and stable for working
sensors that dont get too hot...

rgds

Mike




>Much appreciated.
>Alex
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Regards from


Mike
Perth, Western Australia
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