Closed-loop PI/PID controller tuning for stable and unstable processes

The proposed PID tuning method has similar approach to the recently published paper of Shamsuzzoha and Skogestad (2010). It is one step procedure to obtain the PI/PID setting which gives the better performance and robustness. The method requires one closed-loop step setpoint response experiment using a proportional only controller with gain K
_c0
. On the bases of simulations for a range of first-order with delay processes, simple correlations have been derived to give PI/PID controller settings. The controller gain (K
_c
/K
_c0
) is only a function of the overshoot observed in the setpoint experiment. The controller integral and derivative time (τ
_I
and τ
_D
) is mainly a function of the time to reach the first peak (t
_p
). The proposed tuning method shows better performance than Shamsuzzoha and Skogestad [1] for broad range of processes.