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

Alex Ruiz arsoftware
Tue Apr 3 13:33:15 UTC 2007

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

I mean the toothweel 60-2 ( 60 minus 2 or 58 teeth wheel ) very common on
Boch EFIs ( VW ). 36-1 and 24 toothweels are also going to be recognized by
the system. The signal is conditioned by a lm1815 in case a VR sensor is
used and a comparator with hysteresis if a HALL sensor is used.

It will be used to do crank angle estimation/measurement in a EFI system.
Low pass filters and comparators with hysteresis are used but, I'm afraid
noise is still going to hit my capture unit, witch is more likely to
happen... There's a SAE article that uses Kalman filter to process signal
from a crankshaft of a Scooter engine. I'll check it if I can get that
article to have an idea of how that was implemented.


2007/4/3, Mike <niche at iinet.net.au>:
> 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
> VK/VL Commodore Fuse Rail panel that wont warp, twist or melt,
> guaranteed  !
> Twin tyres for most sedans, trikes and motorcycle sidecars
> http://niche.iinet.net.au
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