headsmess
Miniriders OG
another thread got me thinking about this again, its a subject thats been stewing away for years. i finally get it now.
fuzzy logic and EFI. http://rjhowlett.complexnet.co.uk/papers/2004-2.pdf
i actually cantacted the guy once, but it had just been a uni project on fuzzy logic, nothing really came of it.
now.... what the %$&! is fuzzy logic? lets see now.
consider "hot". what is hot? and what is cold?
and we want to measure it quickly, to say, control a heater. we could sit and calculate every setting for the heater needed to maintain temperature for any given set of circumstances. a lot of work.
thats basically what mapping on standard EFI is. working out each and every possible variation of sensors versus fuel flow.
and every piece of information takes up memory space...needs to be retrieved, processed... it does set a limit eventually.
now fuzzy logic works like this...
instead of saying 1 degree, two degree, three... we say cold. warm. hot.
we set cold to be from 0 to 20
warm is 10 to 30
hot is 20 to 40.
the centre points for each temp (10, 20 and 30) are given a value of 1 or fully on, whatever the processor likes best.
the outer limits are given values of 0 or off.
anywhere between the outer limits and centre point is a value somewhere between on and off...
theres obviously some overlap between the states, cold warm and hot.
so 15 degrees, say, would be "halfway to cold" and "halfway to warm" .
the controller does some simple maths,and can then send a signal to the heater to "turn on a fair bit but not full blast".
its hard to see how to program anything digital like that but its turning out to be quite easy. plenty of software, and a nifty little thing called a "microprocessor"(pic chip) for less than $1, that can be programmed easily, stuck in a circuit and used.
so, as seen in the link... the concept will work as an EFI controller. the hardest part is the initial setup. calibrating the air pressure, a decent throttle body, that sort of stuff.
you have two sensors. a crank angle/speed, and an air pressure. start with three set-points each sensor. so the speed is slow, half, full, and air pressure is high, medium and low.
one output. the injector.
you can have more sensors but it gets more complex. same as with "set-points" per sensor. but makes for more control.
an injector delivers a given volume of fuel at a fixed pressure when opened for so long. so working out how long it has to be opened for is pretty easy. they make tiny ones now, too!
for any given condition (ie, idle would be high pressure, low speed=not much fuel. WOT is low pressure +high speed=lots of fuel!) you have to set injector opening time. two sensors with three set points would give 9 possible "rules" or fixed injector opening times. only 9 calculated injector times....wow. (see how it can get complicated with too many inputs?)
not even calculated but given a rough guess for starters! its FUZZY for a reason!
any point between a fixed rule will either increase or decrease injector opening time marginally. these points are "fuzzy" but pretty close to whats needed(once tuned)!
you set minimum injector opening as so many milliseconds, maximum opening as so many more, and hopefully, all things working properly, you can get an engine running first go.
tuning could be done with a plug chop, or dyno. the software (fuzzytech)is available so programming is a matter of sliding a few graphs around for exact set points for smooth throttle transitions, and tweaking injector open times for mixture control.
im sorta visualising it as being like a carb with multiple jets... that you can adjust not only in size but position... quickly! without getting fuel in ya eye! and the paper does mention enhanced performance/economy....
whose interested?
its not true hi tech engine management but it could be quite simple and robust...small and lightweight.... cheap even...?
fug i need a rich uncle
fuzzy logic and EFI. http://rjhowlett.complexnet.co.uk/papers/2004-2.pdf
i actually cantacted the guy once, but it had just been a uni project on fuzzy logic, nothing really came of it.
now.... what the %$&! is fuzzy logic? lets see now.
consider "hot". what is hot? and what is cold?
and we want to measure it quickly, to say, control a heater. we could sit and calculate every setting for the heater needed to maintain temperature for any given set of circumstances. a lot of work.
thats basically what mapping on standard EFI is. working out each and every possible variation of sensors versus fuel flow.
and every piece of information takes up memory space...needs to be retrieved, processed... it does set a limit eventually.
now fuzzy logic works like this...
instead of saying 1 degree, two degree, three... we say cold. warm. hot.
we set cold to be from 0 to 20
warm is 10 to 30
hot is 20 to 40.
the centre points for each temp (10, 20 and 30) are given a value of 1 or fully on, whatever the processor likes best.
the outer limits are given values of 0 or off.
anywhere between the outer limits and centre point is a value somewhere between on and off...
theres obviously some overlap between the states, cold warm and hot.
so 15 degrees, say, would be "halfway to cold" and "halfway to warm" .
the controller does some simple maths,and can then send a signal to the heater to "turn on a fair bit but not full blast".
its hard to see how to program anything digital like that but its turning out to be quite easy. plenty of software, and a nifty little thing called a "microprocessor"(pic chip) for less than $1, that can be programmed easily, stuck in a circuit and used.
so, as seen in the link... the concept will work as an EFI controller. the hardest part is the initial setup. calibrating the air pressure, a decent throttle body, that sort of stuff.
you have two sensors. a crank angle/speed, and an air pressure. start with three set-points each sensor. so the speed is slow, half, full, and air pressure is high, medium and low.
one output. the injector.
you can have more sensors but it gets more complex. same as with "set-points" per sensor. but makes for more control.
an injector delivers a given volume of fuel at a fixed pressure when opened for so long. so working out how long it has to be opened for is pretty easy. they make tiny ones now, too!
for any given condition (ie, idle would be high pressure, low speed=not much fuel. WOT is low pressure +high speed=lots of fuel!) you have to set injector opening time. two sensors with three set points would give 9 possible "rules" or fixed injector opening times. only 9 calculated injector times....wow. (see how it can get complicated with too many inputs?)
not even calculated but given a rough guess for starters! its FUZZY for a reason!
any point between a fixed rule will either increase or decrease injector opening time marginally. these points are "fuzzy" but pretty close to whats needed(once tuned)!
you set minimum injector opening as so many milliseconds, maximum opening as so many more, and hopefully, all things working properly, you can get an engine running first go.
tuning could be done with a plug chop, or dyno. the software (fuzzytech)is available so programming is a matter of sliding a few graphs around for exact set points for smooth throttle transitions, and tweaking injector open times for mixture control.
im sorta visualising it as being like a carb with multiple jets... that you can adjust not only in size but position... quickly! without getting fuel in ya eye! and the paper does mention enhanced performance/economy....
whose interested?
its not true hi tech engine management but it could be quite simple and robust...small and lightweight.... cheap even...?
fug i need a rich uncle
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