A few tips for people using PIDs: The best way (tm :-) to tune PIDs is by looking at the open loop response of the system. This isn't terribly hard to measure

A few tips for people using PIDs: The best way (tm :-) to tune PIDs is by looking at the open loop response of the system. This isn't terribly hard to measure in a live system but unfortunately very few PID implementations actually support this. You can do this with some commercial controllers. Once you do that (and assuming a close to linear system) you can see your stability margin and actually see the impact of changing the loop parameters on those. ( http://www.mathworks.com/help/slcontrol/ug/open-loop-response-of-control-system-for-stability-margin-analysis.html http://www.mathworks.com/help/slcontrol/ug/open-loop-respons... ) Without this it is very difficult to figure out the limiting factor. A lot of systems need additional filters over the PID. Expensive commercial motion controllers implement those in their control loops. Without those additional filters the performance you can get using PID in those systems will be very limited. Lastly feed-forward can really help closed loop systems. The closer you can get the system to follow your command using feed-forward the less your closed loop controller needs to deal with. The simplest example is acceleration feed-forward in motion control.