An approximate inverse system for nonminimum-phase systems and its application to disturbance observer

Xinkai Chen, Guisheng Zhai, Toshio Fukuda

Research output: Contribution to journalArticle

28 Citations (Scopus)


This paper proposes an approximate inverse system for nonminimum-phase dynamical systems based on the least-square approximation method. The nonminimum-phase systems are approximated by minimum-phase systems. The proposed formulation is applied to the disturbance observation problems for multivariable nonminimum-phase systems with arbitrary relative degrees. The disturbances, which are assumed bounded, are the combination of the external disturbances, the nonlinearities and the model uncertainties of the system. The estimation error of the disturbances is controlled by the design parameters. Furthermore, the accuracy of the estimation also depends on the frequencies of the disturbances. Simulation results show the effectiveness of the proposed method.

Original languageEnglish
Pages (from-to)193-207
Number of pages15
JournalSystems and Control Letters
Issue number3-4
Publication statusPublished - 2004 Jul 1



  • Approximate inverse system
  • Disturbance observer
  • Least-square approximation
  • Multivariable systems
  • Nonminimum-phase dynamical systems

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Computer Science(all)
  • Mechanical Engineering
  • Electrical and Electronic Engineering

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