Revisiting the Ziegler–Nichols step response method for PID control

The Ziegler–Nichols step response method is based on the idea of tuning controllers based on simple features of the step response. In this paper this idea is investigated from the point of view of robust loop shaping. The results are: insight into the properties of PI and PID control and simple tuning rules that give robust performance for processes with essentially monotone step responses.