A PID controller tuning rule for FOPDT process to achieve better load disturbance rejection based on maximum sensitivity

In this paper, the PID tuning rule for first order plus dead time (FOPDT) process has been proposed to achieve better load disturbance rejection. The tuning rule is derived in terms of maximum sensitivity (M
_s
) only which is based on the pole placement and frequency response matching criteria. The maximum sensitivity (M
_s
) is the only tuning parameter of the controller which is the desired robustness level and thus by fixing the M
_s
value the PID parameters can be directly evaluated. The proposed method is applicable to integrating plus dead time (IPDT) process by considering the poles very near to zero and approximating it to FOPDT process. The method is also applicable to higher order process by approximating the process to FOPDT process. The proposed method is illustrated through different examples and compared with some of the well known method available in the literature.