Even when tuning PID loops for chemical plants as a controls engineer, myself and my colleagues (across multiple companies) generally just set the D term to zero. If the D term (derivative) was needed, tuning that one loop would often be assigned a whole formal project by itself. When I hear people say "PID loop" I almost always subconsciously translate it to hear "PI loop" in my head unless there's evidence that it's a truly complex system.
Re:PID Controllers in Unity3D
by polishdude20 on Tuesday January 16, 2024 @10:17PM
(#39022820)
I've had to use the D term recently in a self guided model rocket project.
When the rocket had an angle error it needed to point it's thrust to rotate itself back to 0. There is no built in stopping force that stops the rocket rotating when the thrust is not angled. So a D term was needed in order to take into account how fast the rotation was happening. When it was rotating to 0 degrees of error, it needed that d term to not overshoot. With the d term, the thrust would swing in the opposite direction to prevent it overshooting.
Where you do you get the derivative? If you have to differentiate the input, and there is noise, the raw derivative will have huge variations. Then you need a low pass filter before the differentiator. This introduces lag. So you now have both D gain and filter frequency to tune.
See any classical control theory book for the theory on this.