A New Tuning Method for PI Controllers using Features of Step Response Pattern

Abstract

This paper proposes a new tuning method for PI( proportional plus integral ) controllers based on partial model matching to refer to the standard 2nd order lag model.
The method consists of four steps : (1) to measure step responses of a 1st order lag plus dead time process controlled by PI controller, (2) to extract features of the step responses, (3) to estimate damping coefficient ζ and natural angular frequency ω_n of the control system, and (4) to change control parameters Kp, Ti to adjust the damping coefficient and the natural angular frequency to the desired values.
The result of simulation show that this method is so practical that prediction errors to step responses after changing parameters are small and it is easy to evaluate characteristics of the control system after changing parameters.