Design of PID controllers for time-delay systems by the pole compensation technique

This paper is aimed at looking into the PID control design of systems with large time-delay. In a preliminary step, the system is modeled by a time-delay second order model. Time constants of the PID controller are determined on the basis of the obtained model using the pole compensation technique. The PID proportional gain results from the minimization of the settling time by the use of genetic algorithms as optimization tools. The stability study is then presented and discussed. Simulation results are conform with respect to theoretical ones. To test the robustness of the proposed PID controller, a study with respect parameter variations has been considered. It has been found that the closed loop system performances are unaffected by variations on the damping factor and the non damping pulsation of the system. However, these performances are slightly affected by variations on the system delay and its static gain.