On the stability and controller robustness of some popular PID tuning rules

In this note, we study the stability and controller robustness of some popular proportional-integral-derivative (PID) tuning techniques that are based on first-order models with time delays. Using the characterization of all stabilizing PID controllers derived in a previous paper, each tuning rule is analyzed to first determine if the proportional gain value dictated by that rule, lies inside the range of admissible proportional gains. Then, the integral and derivative gain values are examined to determine conditions under which the tuning rule exhibits robustness with respect to controller parameter perturbations.