Minimizing the integral squared error (ISE) criterion to get the optimal controller parameters
results in a PD controller for integrating processes. The PD controller gives good servo
response but fails to reject the load disturbances. In this paper, it is shown that satisfactory
closed loop performances for a class of integrating processes are obtained if the ISE
criterion is minimized with the constraint that the slope of the Nyquist curve has a specified
value at the gain crossover frequency. Guidelines are provided for selecting the gain …

The proposed tuning method for integrating processes, which is based on Magnitude
optimum criterion, has been extended to PID types of controllers. The method requires either
the process transfer function (in frequency-domain) or the measurement of process steady-
state change (in time-domain). The PID controller parameters are calculated analytically by
solving fourth-order polynomial. By changing reference-weighting parameter b, the user can
favour tracking (higher b) or control performance (lower b). The proposed method has been …