Direct reduced order discretization of continuous-time controller

B. D.O. Anderson, K. Chongsrid, D. J.N. Limebeer, S. Hara

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


In this paper, we investigate the problem of closed-loop approximation of a continuous-time controller by a low-order discrete-time controller with sample and hold devices and an anti-aliasing filter. The problem is first reduced to an open-loop problem of sampled-data controller reduction with continuous-time weights. The operator representing the error in approximation can be approximated (arbitrarily closely) by a time-invariant discrete-time system resulting from applying fast sampling and lifting. We propose a method for obtaining a low-order discrete-time controller which makes small the approximation error based on recasting the approximation problem as a four-block H problem. The latter can be solved efficiently by the method proposed by Glover et al. We also give a numerical example to verify the effectiveness of the method.

Original languageEnglish
Pages (from-to)143-155
Number of pages13
JournalInternational Journal of Robust and Nonlinear Control
Issue number3
Publication statusPublished - Mar 1999
Externally publishedYes

ASJC Scopus subject areas

  • Control and Systems Engineering
  • General Chemical Engineering
  • Biomedical Engineering
  • Aerospace Engineering
  • Mechanical Engineering
  • Industrial and Manufacturing Engineering
  • Electrical and Electronic Engineering


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