Simple method of tuning PI controllers for stable inverseresponse systems

Abstract

A simple method is proposed to design PI controllers for stable inverse response systems with and without delay. The method is based on (i) matching the corresponding coefficient of s in the numerator and in the denominator of the closed loop transfer function for a servo problem, and (ii) by specifying the initial (inverse) jump. This method gives simple equations for controller settings in terms of model parameters. PI controllers are also developed by IMC principles. A numerical optimization method is proposed to obtain the tuning parameters for the simple method. Simulation results are given for robust performance of the controllers for uncertainty in process gain, time constant and the location of zero. The performance of the proposed controllers is evaluated by simulation on nonlinear isothermal CSTR carrying out Van de Vusse reaction.