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Summary: 3rd
TEMPUS-INTCOM Symposium, September 9-14, 2000, Veszprém, Hungary. 1
SOME REMARKS ON PADÉ-APPROXIMATIONS
M.Vajta
Department of Mathematical Sciences
University of Twente
P.O.Box 217, 7500 AE Enschede
The Netherlands
e-mail: m.vajta@math.utwente.nl
ABSTRACT
Padé approximations are widely used to approximate a dead-time in continuous control systems. It provides
a finite-dimensional rational approximation of a dead-time. However, the standard Padé approximation
(recommended in many textbooks) with equal numerator- and denominator degree, exhibits a jump at time
t=0. This is highly undesirable in simulating dead-times. To avoid this phenomena we shall reconsider the
Padé approximation with different numerator degrees.
Keywords: Padé approximation, rational functions.
1. INTRODUCTION
There are many physical processes with dead-time. For example virtually all chemical processes involves
some time delay and all transport processes also exhibit dead-time [3,12]. Control systems with dead-time
are difficult to analyze and simulate. One of the reasons is that a closed-loop control system with dead-time
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