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A Method for Identifying Physical Parameters with Linear Fractional Transformation

Authors: Ryosuke Ito, Goro Obinata, Chikara Nagai, Youngwoo Kim


This paper proposes a new parameter identification method based on Linear Fractional Transformation (LFT). It is assumed that the target linear system includes unknown parameters. The parameter deviations are separated from a nominal system via LFT, and identified by organizing I/O signals around the separated deviations of the real system. The purpose of this paper is to apply LFT to simultaneously identify the parameter deviations in systems with fewer outputs than unknown parameters. As a fundamental example, this method is implemented to one degree of freedom vibratory system. Via LFT, all physical parameters were simultaneously identified in this system. Then, numerical simulations were conducted for this system to verify the results. This study shows that all the physical parameters of a system with fewer outputs than unknown parameters can be effectively identified simultaneously using LFT.

Keywords: Identification, Linear Fractional Transformation, Right inverse system

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[1] L. Ljung, "System Identification Theory for the User Second Edition", Prentice-Hall, Chapter7, 2004.
[2] T. Katayama, "Introduction to System Identification", AsakuraPublishing, pp. 71-86, 1994.
[3] L. H. Lee, "Identification of Linear Parameter-Varying Systems via LFTs", Decision and Control, Proceedings of the 35th IEEE. Vol. 2, pp.1545-1550, 1996.
[4] G. Obinata, T. Kurosawa, and T. Kawai, "A Method of Identification for Physical Parameter using Advance Information (1st Report, A Proposition to The New Method of Identification)", Transactions of the Japan Society of Mechanical Engineers, Series C, Vol. 70, No. 691, pp. 714- 719, 2004.
[5] S. Dasgupta, and B. D. O. Anderson, "Identification of Physical Parameters in Structured Systems", Automatica, Vol. 24, No. 2, pp. 217-225, 1988
[6] F. Demourant, and G. Ferreres, "Controller Design for the Identification of an LFT model", Proceedings of the 15th IFAC Triennial World Congress, 2002.
[7] K. Zhou, J. C. Doyle and K. Glover, "Robust and Optimal Control", Prentice-Hall, Chapter3-6, 9, 10, 12, 1991
[8] H. Yanai and K. Takeuchi, "Projection Matrices, Pseudo Inverse Matrices, Singular Value Decompositions", University of Tokyo Press, Chapter1-3, 1991