Model reference adaptive control system design for linear time-varying systems with unstructured and bounded varying functions

Kouichi Hidaka, Hiromitsu Ohmori, Akira Sano

Research output: Contribution to journalArticle

Abstract

In recent years, many methods of model reference adaptive control system (MRACS) for a linear time-varying (LTV) plant have been proposed. These methods assumed that the structure of plant parameters is known in advance. However, it is difficult to get a priori information of plant parameters. In this paper, an MRACS design for an LTV system based on high-order estimator (HOE) is proposed. By applying dynamic certainty equivalence (DyCE) to LTV plants, a new MRAC law of LTV system is derived without knowing the structure of the plant parameters. The MRACS law is generated by using high-order derivatives of an estimated parameter, so that robust HOE with a normalization signal and σ modification for the system introduced. Our proposed method can attain better performance than conventional methods, such as estimation with variable forgetting factor (VF) and the gradient projection method (GPM). The robust HOE establishes the boundedness of all of the estimated parameters under the condition that the estimated parameter and the first derivative of the parameter are bounded. It is shown that all signals in the adaptive loop are bounded and the output error converges to a closed set. The proposed method is compared to the familiar schemes, the gradient projection method and the estimation based on forgetting factor through numerical simulations, and the effectiveness of our proposed method is shown.

Original languageEnglish
Pages (from-to)87-98
Number of pages12
JournalElectrical Engineering in Japan (English translation of Denki Gakkai Ronbunshi)
Volume130
Issue number4
DOIs
Publication statusPublished - 2000 Mar

Keywords

  • Adaptive control
  • High-order estimation
  • Linear time-varying system
  • Normalization signal

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Electrical and Electronic Engineering

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