TUNING OF PID-TYPE CONTROLLERS FOR STABLE AND UNSTABLE SYSTEMS WITH TIME-DELAY

A graphical technique for tuning PID-type controllers based on the met hod of D-partition is proposed for single-input-single-output linear t ime invariant systems. The tuning method shifts all the roots of the c haracteristic equation of the controlled system to a certain desirable region in the left half of the complex plane (LHP) to achieve a speci fied least absolute and least relative stability margin. The method ca n be used to tune a precompensator, in a two degree of freedom structu re, so as to improve tracking behaviour. The method can be used for bo th stable and unstable systems, for systems with significant time dela y and for various controller configurations, including derivative in t he feedback path.