An Estimation of Accuracy of Charef Approximation

  • Wojciech Mitkowski
  • Krzysztof OprzędkiewiczEmail author
Part of the Lecture Notes in Electrical Engineering book series (LNEE, volume 357)


In the paper a new accuracy estimation method for Charef approximation was presented. Charef approximation allows us to describe fractional-order systems with the use of integer-order, proper transfer function. The accuracy of approximation can be estimated with the use of comparison step responses of plant and Charef approximation. The step response of the plant was calculated with the use of an accurate analytical formula and it can be interpreted as a standard. Approach presented in the paper can be applied to effective tuning of Charef approximant for given plant. The use of proposed method does not require to know a step response of the modeled plant. The proposed methodology can be easily generalized to another known approximations. Results are by simulations illustrated.


Fractional order transfer function Charef approximation 



This paper was supported by the AGH (Poland)—project no


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© Springer International Publishing Switzerland 2016

Authors and Affiliations

  1. 1.Department of Automatics and Biomedical Engineering, Faculty of Electrotechnics, Automatics, Informatics and Biomedical EngineeringAGH University of Science and TechnologyKrakówPoland

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