Advances in Linear Systems I

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Control of Nested Systems

Authors:

Voulgaris P., - University of Illinois at Urbana-Champaign, USA

ABSTRACT

This paper presents an input-output point of view for the problem of optimal command following and disturbance rejection of systems which are comprised of subsystems that affect each other in a nested manner. In such a nested manner, a subsystem affects the subsystems that are exterior to it but not the subsystems that are interior to it. By using model matching methods the problem is shown to be convex. Techniques to solve this convex yet non-standard problem are discussed.

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On a general descriptor LQ problem

Authors:

Nikoukhah R., INRIA, France

Delebecque F., INRIA, France

Campbell S.L., North Carolina State University, USA

ABSTRACT

A discrete-time descriptor linear quadratic (LQ) optimization problem is considered. This problem can be con-sidered as a generalization of many standard LQ problems including Kalman filters. A complete recursive solution based on a novel Riccati equation is presented. The limiting case when the size of the interval goes to infinity is studied.

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Convolution Profiles for Noncausal Inversion of Multivariable Discrete-Time Systems

Authors:

Marro G., Universita di Bologna, Italy

Prattichizzo D., Universita di Siena, Italy

Zattoni E., Universita di Bologna, Italy

ABSTRACT

Noncausal inversion of discrete-time linear multivariable systems is analyzed in the geometric approach framework with the aim of computing convolution profiles that ensure perfect tracking with infinite preaction and infinite postaction time. It is shown how this computation is related to the concepts of multivariable output relative degree and invariant zeros of the plant. Then, a computational setting for the convolution profiles is derived by using the standard geometric approach tools.

Key Words. Geometric approach, noncausal inversion, discrete-time systems, convolution profiles.

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Design for Well Conditioning of Progenitor Models by Input, Output Reduction

Authors:

Karcanias N., City University, United Kingdom

Vafiadis K., City University, United Kingdom

ABSTRACT

Transfer function models used for early stages of design are large dimension models containing all possible physical inputs, outputs. Such models may be badly conditioned and possibly degenerate. The problem considered here is the selection of maximal cardinality subsets of the physical input, output sets, such as the resulting model is nondegenerate. This problem is part of the early design task of selecting well- conditioned progenitor models on which successive design has to be carried out. The established conditions for different type of degeneracy are used to define necessary and sufficient conditions required to guarantee nondegeneracy. A simple redesign procedure that guarantees transfer function and input, output nondegeneracy is suggested and parameterisation of all such solutions is given. The results provide the basis for selection of well-conditioned transfer function models, which may be used for subsequent control design.

Key Words. Integrated design, process control, system structure, linear systems.

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Non Integer Order Systems

Authors:

Nikolov E., Technical University of Sofia, Bulgaria

ABSTRACT

The novelty in this working is the suggested class of astatic control systems. The article proposes: DASCRONE and DASCRONE_GSC structures; synthesis algorithm; robast analysis. The synthesis is based on the wave disturbances absorbing principle, non integer differentiation, gain scheduled control, parametric and structure independence of the stability margin.

Keywords: robast control, non integer order disturbance absorbing systems, robast analysis.

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