LTR design of proportional-integral observers

Hans Henrik Niemann, Jakob Stoustrup, B. Shafai, S. Beale

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This paper applies the proportional-integral (PI) observer in connection with loop transfer recovery (LTR) design for continuous-time systems. We show that a PI observer makes it possible to obtain time recovery, i.e., exact recovery for t -+ -, under mild conditions. Based on an extension of the LQG/LTR method of
proportional (P) observers, a systematic LTR design method is derived for the PI observer. Our recovery design method allows time recovery and frequency (normal) recovery to be done independently. Furthermore, we give explicit expressions for the recovery error when asymptotic recovery cannot be
obtained. A design example demonstrates the advantages of time recovery in the nonminimum phase case.
Original languageEnglish
JournalInternational Journal of Robust and Nonlinear Control
Pages (from-to)671-693
Publication statusPublished - 1995


  • Loop transfer recovery
  • Proportional- integral observer
  • Non- minimum phase systems

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