Last issue
2017 (vol. 27) - Number 2

W. Bozejko, M. Wodecki:

Discrete Systems: Theory and Applications. Special issue.

G. Bocewicz, Z. Banaszak, I. Nielsen:

Delivery-flow routing and scheduling subject to constraints imposed by vehicle flows in fractal-like networks

W. Bozejko, A. Gnatowski, R. Idzikowski, M. Wodecki:

Cyclic flow shop scheduling problem with two-machine cells

W. Bozejko, M. Uchronski,, Z. Chaczko, M. Wodecki:

Parallel patterns determination in solving cyclic flow shop problem with setups

J. Brodny, S. Alszer, J. Krystek, M. Tutak:

Availability analysis of selected mining machinery

K. Chmielewska, D. Formanowicz, P. Formanowicz:

The effect of cigarette smoking on endothelial damage and atherosclerosis development - modeled and analyzed using Petri nets

A. Galuszka, J. Krystek, A. Swierniak, T. Grzejszczak, C. Lungoci:

Information management in passenger traffic supporting system design as a multi-criteria discrete optimization task

M. Kardynska, J. Smieja:

Sensitivity analysis of signaling pathway models based on discrete-time measurements

J. Kasprzyk, P. Krauze, S. Budzan, J. Rzepecki:

Vibration control in semi-active suspension of the experimental off-road vehicle using information about suspension deflection

M. Koryl, D. Mazur:

Towards emergence phenomenon in business process management

M. Koryl:

Active resources concept of computation for enterprise software

H. Krawczyk, M. Nykiel:

Mobile devices and computing cloud resources allocation for interactive applications

W. Mitkowski, W. Bauer, M. Zagórowska:

Discrete-time feedback stabilization

J. Pempera:

An exact block algorithm for no-idle RPQ problem

K. Rzosinska, D. Formanowicz, P. Formanowicz:

The study of the influence of micro-environmental signals on macrophage differentiation using a quantitative Petri net based model

K. Skrzypczyk , M. Mellado:

Vehicle navigation in populated areas using predictive control with environmental uncertainty handling

W. Bozejko, J. Pempera, M. Wodecki:

A fine-grained parallel algorithm for the cyclic flexible job shop problem

ACS Abstract:

2003 (Volume 13)
Number 4
1. Robot controller with a self-measurement capability enabling the identification of friction
2. The interval parabolic system
3. On controllability and minimum energy control of linear positive systems with delays
4. Active control of circular plate vibration by using piezoceramic actuators
5. Multivariable robust control applied to steering of three ship's velocities
6. Hierarchical control in a large scale stochastic system with nonclassical information structure
7. Errors of elementary floating-point operations in control algorithms

Robot controller with a self-measurement capability enabling the identification of frictionDownload full PDF article
Adam Wozniak, Wojciech Szynkiewicz and Cezary Zielinski
(Warsaw University of Technology, Poland)

This paper proposes an open controller structure which beside realising the diverse control tasks enables gathering of the identification data which in turn can be utilised for improving servo control algorithms. The authors are convinced that in the case of research-oriented controller architectures self-identification and self-measurement components should be included. Moreover the paper shows how the gathered data has been utilised in the modelling of friction. This problem has been investigated to increase the precision of motions of a robot equipped with a machinning head.

keywords: robot controller, servomechanism, friction model, identification.


The interval parabolic systemDownload full PDF article
Krzysztof Oprzedkiewicz
(University of Mining and Metallurgy, Poland)

In the paper a new interval model for the uncertain, parabolic time invariant system is presented. System under consideration is described by model with two dimensional uncertain parameters space. In this case the simple geometric interpretation of the system spectrum and it's decomposition can be presented. The proposed spectrum decomposition conditions are based on the geometric interpretation of the system spectrum. The results are by the examples depicted.

keywords: interval systems, parabolic systems,the exponential stability.


On controllability and minimum energy control of linear positive systems with delaysDownload full PDF article
Beata Sikora
(Silesian University of Technology, Poland)

The positive stationary dynamical systems with multiple delays in control are considered in the paper. The definition of the relative controllability for positive systems with delays and the criterions of their relative controllability are given. The minimum energy control problem for these systems is formulated and solved. Numerical examples illustrate the theoretical analysis. The example of real, technological positive dynamical system as a practical application of the theoretical results is presented.

keywords: positive dynamical systems, delay systems, relative controllability, admissible control, minimum energy control.


Active control of circular plate vibration by using piezoceramic actuatorsDownload full PDF article
Lucyna Leniowska and Ryszard Leniowski
(University of Rzesz?w, Poland)

An active vibration control system is proposed for suppressing small amplitude harmonic vibrations of a thin circular plate. This system integrates control algorithms, intelligent materials, hardware and software technologies. The mathematical model of the physical system is based upon the geometry and properties of an experimental set-up consisting of a hard-walled cylinder with a thin aluminium plate at one end. Primary excitation is provided by a low frequency loudspeaker installed centrally at the bottom of the cylinder. The vibrations of the plate are measured by the application of strain sensors. Intelligent materials such as 2-layer piezo disk elements (PZT) are used as the actuator. For the considered system, the OE ( Output Error ) method of discrete-time model identification for real-time active vibration control has been applied. On the basis of this model, the control algorithm based on pole-placement method has been developed. The obtained results show that the designed structure of a closed-loop system provides substantial vibration suppression.

keywords: active vibration control, feedback control, piezoceramic transducers, identification methods.


Multivariable robust control applied to steering of three ship's velocitiesDownload full PDF article
Witold Gierusz
(Gdynia Maritime University, Poland)

The main goal of this task was the synthesis of the regulator for precise steering of the real, training ship. One of possible ways to build a proper ship's controller can be the robust control theory approach. First part of the paper describes successively: the shiphandling training boat "Blue Lady", nonlinear simulation model of the vessel and the MIMO state ship model, identified for robust regulator synthesis after experiments on the presented simulation model. Second part of the paper presents: the way to calculate the multivariable controller via D-K iteration, final regulator and exemplary results of the real-time steering for verification of obtained closed-loop system.

keywords: training ship, simulation model, multivariable system, robust control, real-time steering.


Hierarchical control in a large scale stochastic system with nonclassical information structureDownload full PDF article
Zdzislaw Duda and Witold Brandys
(Silesian University of Technology, Poland)

In the paper a synthesis of a control law for a large scale stochastic system is presented. The system composed of coupled linear subsystems and quadratic performance index which should be minimized, is considered. The problem is solved in a two-level hierarchical control structure with a coordinator on an upper level and local controllers on a lower level. An algorithm, in which it is possible to partially decompose calculations and to realize decentralized control, is proposed. A simple example is presented.

keywords: large scale system, stochastic system, decentralized control, optimal control.


Errors of elementary floating-point operations in control algorithmsDownload full PDF article
Zbigniew Swider
(Technical University of Rzeszow, Poland)

The paper presents analytical development of error variances for elementary floating-point operations, i.e. quantization, multiplication, and addition, based on expressions for probability density distributions. Gaussian inputs are assumed and steps executed by the processor taken into account, particularly normalization of the mantissa to the interval [ 0.5 , 1 ). Uniform estimate (2kB) of the variance for the three elementary operations is obtained, where b denotes the number of mantissa bits. Error of Euler rectangular integrator (1kB), commonly used in digital controllers, is evaluated as well. For small sampling step the error depends primarily on precision of the addition executed by the integrator. Increase of the precision used in some small controllers is also considered. The results are verified for first-order transfer function subject to white noise, sinusoidal and constant-plus-noise inputs.

keywords: floating-point arithmetic, roundoff errors, delta-operator, stochastic systems.


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