Default PID Settings


 

Phillip P

TVWBB Fan
I apologize if this is listed somewhere, I have checked the wiki and done a couple of forum searches.

What are the default PID settings? When I was playing with them on my first trial run, I was a couple of beers in and didn't write them down before I started fiddling.

thanks!
 
I think Bryan made some changes in the default PID values recently, but those posted above are still "valid" for the HMv4.2.4, 'cause the way the PID values function hasn't changed as far as I know....
 
Why the change, Brian? Especially interested in the move to B = 0, but interested in the increase in P and I as well. Thanks.
 
The B was sort of a fudge term that I had originally included in my first HeaterMeter 1.0 when I was trying to work around the fact that the integral sum couldn't decrease if the output was already 0%. I didn't really understand at the time that the I term was what actually maintains the temperature and the P and D are correctional factors. I invented the B term because in my mind something had to drive the blower when maintaining a temperature, P factor and D factor would both be 0, and I thought the I factor would be teeny tiny. The reality is that the I term is supposed add up to be what the B term was originally invented to do.

The I was increased to decrease settling time. Based on the tuning algorithms, the old 0.005 I term was better suited for a system where the periods of oscillations were closer to 20-30 minutes. Based on my observations and nice folks posting their graphs, I see smaller oscillation periods so I increased the I term to better suit the data.

The P was also based on others who were doing the Closed Loop Tuning and posting their results. I've seen Ps come out of this in the 5-7 range, so I thought I'd bump up the default P but was concerned about going too far. 4 worked ok for my system and seemed like a safe increase.
 
That all makes good sense, Bryan. I've also observed the I increase over time to dominate a stable system at temp so I guess all is working as it should. Thanks for taking the time to explain.
 

 

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