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Old 04-10-2021, 02:18 PM   #28
HarryCaveMan
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Member#: 509998
Join Date: Dec 2019
Subaru Stars

Quote:
Originally Posted by cianuro View Post
You'd need to be able to open the 09 map, transfer all the tables to excel, then paste them to the OTS map. You can't apply an OTS 09 map to an 08.
When I say combine that is essentially what I mean, to build a new map that has features of both. I can populate the PID tables in the 08 map with the values from the 09 map.
**Update:
I see..... I'm unable to open the 2010 map in my version of AT which is for a 2008, So I'll have to get the values from some other source...

What I would want to consult an engineer for would be to learn how changing the turbo affects the math, here's an example:

First of all, I'm not quite certain what the "proportion" metric means in this case.

When I did PID before (one time in undergrad quadcopter project) P was for "position" which essentially meant "magnitude and direction of deviation from desired position" or (desired gyro signal - actual gyro signal (in degrees (signed int))). The I and D were just the Integral (cumulative sum) and Derivate (change/timestep) of the same metric WRT time. Here are guesses I came up with based on my previous experience:

- Boost Error (Target-MAP)?
- marginal or "proportional" boost error (Boost Error/Target)
- marginal or "proportional" boost error (Boost Error/MAP)

Then there's the graphs, does the line represent the coefficient to be used under the conditions defined on the axes?

Understanding things like this can help me start to build the complete picture and figure out what assumptions I can test, for example:

- With a larger wastegate port on the VF (or another future turbo). It seems like this would primarily affect the way Derivative maps to WGDC, because a smaller change in WGDC would result in a larger change in flow... well, maybe, under certain conditions... I don't know xD. It would definitely mean that you would need less WGDC to achieve the same bypass volume, and bypass volume is certainly related to the derivative of compressor RPM which is related to the derivative of boost pressure...

When I look at the tables, it appears to be a PI system only and not a PID system, is this the case?

Anyhow, even this conversation is great because rubber ducking with people helps me think things through...
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Last edited by HarryCaveMan; 04-11-2021 at 01:19 PM.
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