Zero-pole and Padé finite-dimensional reduction of delayed controllers: A comparative study

Abstract

A comparative study of two approaches for simplification and rationalization of controllers with internal delays is presented in this paper. Delayed (or so-called anisochronic) controllers result from the use of compensatory or predictive control methods for time-delay systems. In this study - where the aim is to match the original infinite-dimensional controller with a simple finite-dimensional one - the Padé approximation of the whole transfer function and the methodology preserving dominant poles and zeros and asymptotic behavior are introduced and compared. Control of a circuit laboratory heating plant with delays in a special ring or proper and stable meromorphic functions is taken as an example for the comparison. The simple negative control feedback system and a control structure with two feedback controllers are implemented. Besides simulation results, real measurements on the laboratory appliance are presented as well.