Title of Paper:Root locus of zeros of discrete time systems as a function of sample rate

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Affiliation of Author(s):能源与动力学院

Journal:Adv Astronaut Sci

Abstract:Root locus plots are one of the basic design tools in classical control. They help the designer tune control gains which appear linearly in the coefficients of the closed loop characteristic polynomial. And they give considerable intuition to the designer, based on the simple rules that root loci must follow. When designing a control system, one wants to know where the zeros are, but when designing a digital control system new issues appear. The original zero locations when mapped to discrete time are functions of the new parameter, the sample time T (as well as the pole locations). In addition, new zeros are usually introduced by the discretization process. The purpose of this paper is to give a general understanding of the nature of root loci of discrete time transfer function zeros as a function of this parameter T. We consider the complete range of values from T equal zero to infinity to understand the full plot. Reasonable sample rates will only use part of the plots. The characteristic polynomial coefficients are nonlinear functions of T so the usual root locus rules do not apply. One can be amazed at how the usual root locus rules are repeatedly violated, and what new kinds of unexpected behavior can be observed. © 2018 Univelt Inc. All rights reserved.

Discipline:Engineering

First-Level Discipline:Aeronautical and Astronautical Science and Technology

Document Type:J

ISSN No.:0065-3438

Translation or Not:no

Date of Publication:2018-01-01

Co-author:Longman, Richard W.

Correspondence Author:Longman, Richard W.,Zhou Wenxiang