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

[Alex Ruiz]

Bruce,

That is exactly the point where I must start doing some digging.

Appreciated the information.

Alex


2007/4/3, Bruce A Bowling <bbowling at earthlink.net>:
>
> In the MegaSquirt MS-II version, we have implemented a simple form of the
> kalman filter known as an "Alpha-Beta-Gamma Tracking Filter".
>
> http://www.megamanual.com/ms2/alphabeta.htm
>
> Note that this is just another form of a predictor-corrector algorithm. In
> fact, originally we implemented a full-blown kalman filter, but quickly
> realized that since all of the sample datapoints had the exact same
> statistical error the a-b-g filter implementation would suffice. Full-up KF
> are used to determine the best answer for the next state from many different
> sources of measurements (with corresponding variances) and process model
> sources.
>
> Tracking filters are used everywhere, from missle track determination,
> machine vision, to brushless commutation of DC motors. A side benefit is
> that they are extremely easy to implement and are not very computationally
> intensive - in fact they can be easily synthesized in programmable logic.
>
> - Bruce
>
>
>
>
> -----Original Message-----
> >From: Mike <niche at iinet.net.au>
> >Sent: Apr 3, 2007 8:58 AM
> >To: diy_efi at diy-efi.org
> >Subject: Re: [Diy_efi] 60-2 Toothwheel - Kalman Filter or ( EKF ) usage
> >
> >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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