Enhanced Design of PI-PD Controller based on Smith Predictor for Integrating Processes with Time Delay

Abstract

Proportional-Integral-Derivative (PID) controller is the most popular technique used in several industrial applications and has done more research work throughout many years. Being popular, the PID controller exhibits undesirable output response for some open loop unstable process such as integrating ones. This paper projects a design of smith predictor with an outer loop Proportional-Integral (PI) controller and interior loop Proportional-Derivative (PD) controller. The smith predictor uses plant process as a predictive model and it eliminates the delay part of the closed loop characteristic equation. Three various examples of integrating plants with time delay are carried out in simulation study to evaluate the obtained performance of projected method. The results from the simulation study are compared with the optimal PI-PD method. To illustrate the robustness of projected method, parameter uncertainties are included to the process and the following results are exhibited. The projected method is more robust to such dissimilarities. Disturbance of magnitude 0.1 and a white noise of 0.0001 magnitude are added to the system and the improved performance are shown in the simulation results. The proposed control algorithm will be designed and implemented in MATLAB/SIMULINK environment.