DYNAMIC SET POINT WEIGHTED PID CONTROLLER

Abstract

A new set point weighting technique is proposed to improve the set point response and load rejection characteristics of Ziegler―Nichols tuned PID controller (ZNPID). Instead of a fixed or multi-valued set point weighting factor, here dynamic set point weighting is suggested based on the change of error (Δe) of the controlled variable and normalized dead time (θ) of the process under control. Effectiveness of the proposed scheme is tested on high-order linear and nonlinear dead time processes for both set point change and load disturbances. Performance of the proposed PID controller with dynamic set point weighting (DSWPID) is compared with those of a PID controller with variable set point weighting (VSWPID) reported in the leading literature and ZNPID in terms of several performance indices. The result demonstrates a significantly improved overall performance of DSWPID. The proposed scheme can be easily incorporated in an existing control loop.