Idle Integral deadband or minmap

[fphil]

Even with the update VT help, I did not fully understand the difference between the IAC Integral Deadband and IAC Integral Minmap.

I am even more confused because I had to put non zero value to control the IAC idle since, on another hand, I always used deadband on target to filter high frequency noise (w/r to the actuator band), that is never on integral action which is low pass.

Philippe

[MWfire]

dead band. If rpm error is less than value, intergral value is frozen.
if map is less than int minmap, integral value is 0.

[fphil]

What is the integral value?
Is it  IAC_int the integral action which is added (or substracted) to IAC_ref ?
or
__int the time integral of the rpm error to the idle (moving) target?

That is, such as we get IAC_int = I*__int
where I is the chosen parameter of the PID.

Indeed one can frozen IAC_int or set it to zero, while the time integral __int is still integrating.
Do you know what's going on in our case?

[MWfire]

intergral value is intergral error. So sum of errors multy with PID int constant.

[fphil]

So this is IAC_int, and the question is
Is the sum (or the integral) of the error frozen (or set to zero) or not?
In another way, what is the value of IAC_int or of the sum when one gets out of the deadband in the 2 cases.

[MWfire]

error=target rpm- current rpm

IAC_int= sum of few error in the past*PID_int constant

if error< int deadband then IAC_int frozen(doesn't change)
if engine MAP <  Integral Minmap then IAC_int=0

[fphil]

Thanks for your explanations.
I do understand now the use of the Integral Minmap parameter.

As for the Integral Deadband, alright this is the sum which is frozen inside the deadband and by the way the IAC_int value.
However looking at the log file kindly given by DamiMuha (I have not found back his post)
http://www.vems.hu/files/DamirMuha/1.2.20/v3.7_n008036-2014.01.20-16.10.19.vemslog

One sees that for in integral deadband = 30, IAC_int is frozen @ -16 when entering the deadband,  time 0:22:03 and is still frozen at this value when leaving the deadband by low values, time 0:22:55.

On the same hand, it shows that this integral deadband leads to an undershoot with an IAC=29%
The steady idle at the begining of the log being given by IAC = 47%.

[MWfire]

That is my log . That car has DBW. On DBW it's much harder to set good idle. On normal 2wire idle motor that is a joke.
So, when map is less thena 20kPa, iac int is 0.
Then idle is to high, so int is lowered until  rpm are in range 870 and 930. In that range is frozen to value -16.

[fphil]

I see it frozen when rpm = 867 and idle target rpm = 920, time 0:22:55

[MWfire]

I see it frozen when rpm = 867 and idle target rpm = 920, time 0:22:55

Yes, i bit strange.

[VEMS]

Hi Phil / MWfire,

All the IAC pid parameters can be logged and their net effect on the IAC output dutycycle/position, when using recent firmwares (>1.2.15) and recent VemsTune. Check the channels in: Change gauge data -> IAC -> IAC Calc XX (Refpos, PE, IE, DE).

I hope these provide the desired insight in their effect on output.

Best regards, Dave

[VEMS]

VemsTune help has been updated to cover all IAC menu settings, run manual ini_update to fetch the latest files. Also available on: http://vems.hu/vt/help/v3/v3_idle_control_menu.html

Best regards, Dave

[fphil]

run manual ini_update to fetch the latest files.

I did Preferences/update files manually. I was asked to download 69 files so I replied NO.
I went to http://vems.hu/download/v3gui/ where I am used to find the latest VT update, no ini file there.
Where can one manually download the latest ini files?

[mattias]

In your opinion, what will go wrong if you reply YES ?

I have never downloaded any ini files manually, why would I when it can be done automatically in the software?

[fphil]

In your opinion, what will go wrong if you reply YES ?

Because I do not know and because I do not need 69 files I said no

I have never downloaded any ini files manually, why would I when it can be done automatically in the software?

Neither did I, I use to get it automatically as well (see Dave's message)