Tuning a Robust PID Controller as a Linear Quadratic Optimal Controller

Abstract

Structural, stability and sensitivity properties of a PID controller tuned as a linear quadratic optimal controller (LQOC) are presented. The solution of the LQOC control problem gives as a result a PID structure, only when a restricted class of models for the disturbance and the plant are considered. The concept of robustness is introduced for those models which can not be included in this desired set. This method gives as a result a set of simple tuning rules for PID controllers, which can be applied to a wide range of processes and disturbances.