Can I get a source for PID from the other party. I think it will be different than what is posted above. If both parties can agree on the correct source/definition, the argument will be settled. I doubt that will happen, though, as fundamental differences in understanding and terminology exist.
P.I.D. is simply the first letter of each word in the how the controller works.
Proportional, Integral and Derivative.
Broken down EXTREMELY simply and written using the big fat crayons, so as not to bore you to death with it, it works like this. The PID controller corrects errors between what something is told to do and what it's actual output is.
The (P)roportional function is just what it sounds like. If it sees an error, it makes a correction that is PROPORTIONAL to that error. 5 to high, take 5 away.
The (I)ntegral funtion adds time to the correction. If I was 5 too high, it takes that 5 out over a period of time. To fast it overshoots, too slow it never achieves the desired value.
The (D)erivative function basically slows the rate of change to prevent an over shoot of the target value and throwing the system into an unstable condition.
Having the PID controls set up correctly smoothes the overall response to error corrections.
If your controls are set up to aggressively, the whole process is unstable and looks like a wave. Set up too conservatively and it can't react fast enough to errors, be it higher or lower than the desired value.
The (P) function is the easiest to establish. I have an error, I need to fix the error.
The (I) function is the hardest to setup, because you are making an estimate of how long it will take to correct an error.
The (D) function is the smoothing process. It's a multiple of the (P) and (I) functions. Essentially its the shock absorber...it's trying to dampen occurances of the error.
