Revisiting The Ziegler‐Nichols Tuning Rules For Pi Control

This paper presents new tuning rules for PI control of processes with essentially monotone step response that are typically encountered in process control. The rules are based on characterization of process dynamics by three parameters that can be obtained from a step response experiment. The rules are obtained by maximizing integral gain subject to a constraint on the maximum sensitivity. They are almost as simple as the Ziegler Nichols tuning rules but they give substantially better performance.