Exactly. Somebody on ETO spent a lot of time with me. I think he was also controlling air pressure, but he was working with automotive carburation/fuel injection. His problem was controlling a AC motor with phase angle firing.

PID is simple. I did that in the 1980's. I did strange stuff back then with our version of PID. I did another project where I used the proportional band -10 to +10 of one controller as my -100,100% of another PID loop using an RTD sensor. I modified the chamber's setpoint +-10 degrees to control the temperature of a surface RTD.

Never did auto-tuning.

 

yes set point control as said above so say the pressure output is 5 vdc and that is equal to 50 KPA pressure and i want 70Kpa pressure in the controlled environment. therefor the output from the op amp would (without gain appied) 2 VDC, this 2 volt dc would be commanding an EC motor using its 0 to 10vdc input to drive it to 20% if its speed. next we add gain as maybe the 20% speed is not enough to increse the pressure. Yes i know PID using a micro as a set point controller would give the best option however i am just looking for a simple version where exact pressure in the controlled area is not important.