PID controller with improved load-disturbance rejection

In this paper a two-degree-of-freedom (2DOF) IMC structure is considered for integrating process with deadtime to achieve improved load-disturbance response along with the set-point response. Set-point controller is designed considering desired speed of response of the closed-loop system. The load-disturbance controller is designed through direct synthesis approach and both the controllers are approximated to PID controller by approximate frequency response matching of the respective controllers at two low frequency points. The efficacy of the method is demonstrated through simulation of examples taken from the literature and the performance is compared with some of the prevailed methods.