Last issue
2016 (vol. 26) - Number 4


Andrzej Ruszewski:

Practical and asymptotic stability of fractional discrete-time scalar systems described by a new model



D. Krokavec, A. Filasova, P. Liscinsky:

On fault tolerant control structures incorporating fault estimation



Sundarapandian Vaidyanathan:

Hyperchaos, adaptive control and synchronization of a novel 4-D  hyperchaotic system with two quadratic nonlinearities



H. Górecki, M. Zaczyk:

Analytic solutions of transcendental equations with application to automatics



F. Mnif:

Predictor-based stabilization for chained form systems with input time delay



S. Daniar, R. Aazami, M. Shiroei:

Multivariable predictive control considering time delay for load-frequency control in multi-area power systems



T. Kaczorek:

Analysis and comparison of the stability of discrete-time and continuous-time linear systems



M. Rachik, M. Lhous:

An observer-based control of linear systems with uncertain parameters



L. Malinski:

Identification of stable elementary bilinear time-series model



V.V. Huynh:

New observer-based control design for mismatched uncertain systems with time-delay




ACS Abstract:

2003 (Volume 13)
Number 1
1. Robust compensator control of aerobic continuous fermentation processes with state estimation
2. An iterative identification based on the Youla-Kucera parameterisation without model reduction
3. An approach to decentralized adaptive control
4. The reachable sets concept applied to a class of min-max optimization problems
5. Multivariable CRHPC (constrained receding-horizon predictive control) algorithm with improved numerical properties
6. On the stability of one dimensional discrete-time jump linear systems
7. Direct stable fuzzy adaptive control of a class of SISO nonlinear systems


Robust compensator control of aerobic continuous fermentation processes with state estimationDownload full PDF article
Ivan Simeonov
(Bulgarian Academy of Sciences, Bulgaria)
Stoyan Stoyanov
(Technical University, Bulgaria)
Velislava Lubenova
(Bulgarian Academy of Sciences, Bulgaria)

The paper deals with robust compensator control of continuous aerobic fermentation processes described by a set of non-linear differential equations. For design purposes the non-linear model is transformed into a linear one with interval parameters. The robust state-space compensator is designed according to the internal model principle. Biomass concentration is estimated on-line by an observer. Substrate concentration is obtained by model-based or indirect measurement. The theoretical results are verified by simulations in different cases. Robustness and simple realisation are important features of the proposed algorithms.

keywords: fermentation processes, non-linear model, biomass and substrate concentration estimation, robust compensator control, simulation.

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An iterative identification based on the Youla-Kucera parameterisation without model reductionDownload full PDF article
Stefan Kozka, Jan Mikles and Miroslav Fikar
(Slovak University of Technology, Slovak Republic)

The aim of this paper is to present an iterative identification of the plant in the presence of feedback using input-output data, based on the Youla-Kucera parameterisation. When a reduced complexity model is identified then the controller is designed. Here the identified model is just a vehicle for the computation of a controller. The proposed iterative algorithm contains suitably selected filters and ensures that the model reduction of the identified model is not necessary as in the standard approach. This iterative approach simplifies the identification task of the Youla-Kucera parameter as only its numerator has to be estimated. An experiment with a continuous stirred tank reactor (CSTR), which represents a non-linear single input - single output (SISO) system, illustrate this feature. LQ controller design is used for stabilisation.

keywords: iterative identification, identification for control, continuous system, model reduction.

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An approach to decentralized adaptive controlDownload full PDF article
Karel Perutka and Vladimir Bobal
(Tomas Bata University, Czech Republic)

The paper presents a way of control of decentralized two inputs two outputs (TITO) systems. The base of the approach is usage of the set of one-dimensional self-tuning controllers with reduced orders, being tuned simultaneously, in contrast to methods using relays in feedback. A method of the recursive least squares with directional forgetting factor applied to the continuous-time system is used as the identification algorithm for the self-tuning controllers. It obtains data using the differential filters. Verification was done in MATLAB-SIMULINK on the systems with "P" and "V" structures. Two methods of tuning the controllers were used: the suboptimal linear quadratic tracking method, and the dynamics inversion method. This approach gives good results, and enables to use arbitrary method of tuning the controllers, in particular, to apply the approaches of control of SISO systems (single input single output), which are quite common for the multi-variable systems.

keywords: adaptive control, continuous time systems, decentralized control, dynamics inversion method, recursive least squares, suboptimal control.

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The reachable sets concept applied to a class of min-max optimization problemsDownload full PDF article
Tomasz Terlikowski
(Polish Academy of Sciences, Poland)

A multi-criteria control problem over the infinite time horizon for periodical system is considered. Our aim is to solve problems of this type using the known idea of reachable sets. The worst case approach applied concerns e.g. a system of water resources distribution. The min-max optimisation problem obtained occurs to fit naturally the scheme of reachable sets concept. Applicability of this concept to that particular case is discussed and the algorithm is presented.

keywords: reachable sets, min-max optimization, reference point method, periodical control problem.

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Multivariable CRHPC (constrained receding-horizon predictive control) algorithm with improved numerical propertiesDownload full PDF article
Maciej Ławryńczuk and Piotr Tatjewski
(Warsaw University of Technology, Poland)

This paper is concerned with the stabilising constrained receding-horizon predictive control algorithm (CRHPC) for multivariable processes. The optimal input profile is calculated by means of a new method the purpose of which is to avoid inverting usually ill-conditioned matrices. Additionally, relatively simple formulae for calculating free and forced output predictions for the ARX process model, as well as the analytical stabilising control law in the unconstrained case are derived, without the necessity of solving a matrix Diophantine equation.

keywords: model predictive control, stabilising terminal constraint, singular value decomposition, least-squares methods,ARX models.

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On the stability of one dimensional discrete-time jump linear systemsDownload full PDF article
Adam Czornik, Aleksander Nawrat and Szymon Rabsztyn
(Silesian University of Technology, Poland)

In this paper we present necessary and sufficient conditions for - moment stability and almost sure stability of one-dimensional discrete-time linear systems subject Markovian jumps. We show that if the Markov chain is ergodic then almost sure stability is equivalent to -moment stability for certain >0.

keywords: jump linear systems, almost sure stability, moment stability.

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Direct stable fuzzy adaptive control of a class of SISO nonlinear systemsDownload full PDF article
Salim Labiod and Mohamed Seghir Boucherit
(Ecole Nationale Polytechnique, Algeria)

For a class of unknown nonlinear single-input single-output (SISO) systems a stable direct adaptive controller which uses standard fuzzy systems is presented. The proposed scheme includes a proportional-integral-type adaptation law. Global boundedness of the overall adaptive system and tracking within a desired precision are established with the new adaptive scheme. This adaptive scheme allows for the incorporation of linguistic information from human experts directly into the controller. Simulations performed on two examples illustrate the approach and exhibit its performance.

keywords: fuzzy systems, fuzzy control, adaptive control, nonlinear systems.

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