Adaptive algorithms

[Matthew Lee Franklin]

Robert wrote,

>My own research (PhD) is into very similar systems.  In fact a recent paper I
>preseneted at FISITA 94 in Beijing in October was all about self tuning AFR 
>control of a NG engine...

My search of optimization in the literature has been a little weak, so I 
was unaware of anything like that done at Ohio or Melbourne.  I'd be 
curious to get exact numbers for references on the subject.  Our system 
holds fuel injected per cycle constant during an eight revolution dither 
cycle.  The MAP is dithered about 1% high for four revs and back for four.  
This, while the spark goes through a two rev advanced two rev retarded 
repeating cycle. From this we estimate TORQUE fluctuation.  If there 
is a torque fluctuation a small correction is made in the direction of the 
improvement.  In this way we work toward the most efficient air fuel ratio 
and spark timing.  (Remember that if fuel flow is held constant the max 
torque equivalence ratio is also the most efficient.)  Corrections are 
extermely small because cycle to cycle variation is orders of magnitude 
larger than the fluctuation due to our dithering.  On average it works 
quite well.  The concept is similar to a lock-in amplifier, if you are 
familiar with those.  Future work will involve getting fast response 
without wild wander from the noise in our signal.  Also, we would like to 
try the system on an engine with single point fuel addition (TBI or 
carburetted).
RECENT REFERENCES:
US Patent 5168853
SAE 940546, 940547
ASME ICE-Vol. 22, p73-83, October 1994
(the system is running much better now than in any of those papers)

>I was wondering whether the system was put into a vehicle or even a real
>world stationary application (as our work was)...

And, no, we have not yet put this into a vehicle.  Probable the first 
application will be on a stationary cogeneration engine with an electronic 
controlled carb hopefully running on land fill gas.

Thanks for your interest.

Later,
Matt