Identification and PID control for a class of delay fractional-order systems

Zhuoyun Nie, Qingguo Wang, Ruijuan Liu, Yonghong Lan

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)

Abstract

In this paper, a new model identification method is developed for a class of delay fractional-order system based on the process step response. Four characteristic functions are defined to characterize the features of the normalized fractional-order model. Based on the time scaling technology, two identification schemes are proposed for parameters U+02BC estimation. The scheme one utilizes three exact points on the step response of the process to calculate model parameters directly. The other scheme employs optimal searching method to adjust the fractional order for the best model identification. The proposed two identification schemes are both applicable to any stable complex process, such as higher-order, under-damped U+002F over-damped, and minimum-phase U+002F nonminimum-phase processes. Furthermore, an optimal PID tuning method is proposed for the delay fractional-order systems. The requirements on the stability margins and the negative feedback are cast as real part constraints U+0028 RPC U+0029 and imaginary part constraints U+0028 IPC U+0029. The constraints are implemented by trigonometric inequalities on the phase variable, and the optimal PID controller is obtained by the minimization of the integral of time absolute error U+0028 ITAE U+0029 index. Identification and control of a Titanium billet heating process is given for the illustration.

Original languageEnglish
Article number7589653
Pages (from-to)463-476
Number of pages14
JournalIEEE/CAA Journal of Automatica Sinica
Volume3
Issue number4
DOIs
Publication statusPublished - Oct 2016

Keywords

  • Fractional-order system
  • PID control
  • Titanium billet heating furnace
  • identification
  • time delay

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Information Systems
  • Artificial Intelligence

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