Tuning PID controllers for integrating processes

The paper extends the frequency domain PID controller design method, first proposed by Wang, Barnes, and Cluett (1995), by presenting a comprehensive treatment of integrating processes. The general class of integrating processes is divided into two types, based on the sign of the second coefficient of the Taylor-series expansion applied to the stable part of the process transfer function. In both cases, the closed-loop performance is specified in terms of the desired control-signal trajectory scaled with respect to the magnitude of this coefficient. In addition, explicit PID tuning rules are given, for integrating plus delay processes along with their associated gain and phase margins and allowable time delay variations