VEMS Community Forum

VEMS => Calibration & Mapping => Topic started by: z0tya on January 18, 2010, 08:45:23 PM

Title: Interpolation
Post by: z0tya on January 18, 2010, 08:45:23 PM
Has anybody info about vems VE, Spark, Lambdatarget map interpolation?
What cells are involved, what weight, and what is happen at the map edges?

THx
Title: Re: Interpolation
Post by: dnb on January 19, 2010, 05:07:11 AM
Not sure what happens at map edges - I try not to go there!  (I suspect it simply "rails" to the last cell)

The interpolation is based on linear bivariate.  So it takes the 4 corner points for the "cell" you're in and weights them based on the distance from each corner.  You'll probably find a standard algorithm & explanation on wikipedia.
Title: Re: Interpolation
Post by: z0tya on January 19, 2010, 02:28:21 PM
Thx!

So no more than 4 points..
Title: Re: Interpolation
Post by: gunni on January 19, 2010, 03:28:13 PM
Personally I wouldn´t want more then 4 points.
Especially if the engine has quick changes in VE
Title: Re: Interpolation
Post by: mattias on January 19, 2010, 08:07:30 PM
Only 4 points yes. It will rail to the edges of the map if exceeding the bounds with one exception for ignition :
The cranking advance will interpolate from the cranking threshold rpm up to the first rpm bin in the ignition table. I found out the hard way that this was the normal and actually pretty ok behaviour.