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:

2010 (Volume 20)
Number 2
1. Pointwise completeness and pointwise degeneracy of standard and positive hybrid linear systems described by the general model
2. Continuous-time dynamic system identification with multisine random excitation revisited
3. Robust control and modal analysis of flexible rotor magnetic bearings system
4. Exponential stability of networked control systems with network-induced random delays
5. On generalization of integral control to a class of nonlinear uncertain system
6. Quasi-optimal PZT distribution in active vibration reduction of the triangular plate with P-F-F boundary conditions
7. Backstepping/DTC control of a double star synchronous machine drive
8. Reachability of linear hybrid systems described by the general model


Pointwise completeness and pointwise degeneracy of standard and positive hybrid linear systems described by the general modelDownload full PDF article
T. Kaczorek
(Bialystok University of Technology, Bialystok, Poland)

Necessary and sufficient conditions for the pointwise completeness and pointwise degeneracy of the standard and positive hybrid linear systems described by the general model are established. It is shown that the standard general model is always pointwise complete and it is not pointwise degenerated and the positive general model is pointwise complete if and only if its matrix A2 is diagonal.

keywords: pointwise completeness, degeneracy, standard, positive, general model, hybrid system

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Continuous-time dynamic system identification with multisine random excitation revisitedDownload full PDF article
J. Figwer
(Silesian University of Technology, Gliwice, Poland)

The paper presents a new, revisited and unified approach to a linear continuous-time dynamic single-input single-output system identification using input and output signal samples acquired with a deterministic constant or random sampling interval. The approach is based on a specially designed identification experiment with excitation of the form of a continuous-time multisine random excitation and digital processing of the corresponding signal samples obtained without analogue antialiasing filtration in the case of disturbances satisfying or not satisfying the Shannon's sampling theorem. Properties of the proposed approach are discussed taking into account nonlinearity of the excitation generation and data acquisition systems with a focus on model identification in the case of input and output signal levels comparable with data acquisition system accuracy. Methods reducing influence of the disturbances (including aliasing) as well as nonlinearities of the excitation generation and data acquisition systems on identification results are proposed, too.

keywords: continuous-time dynamic system identification, multisine random process, system excitation, signal sampling and reconstruction

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Robust control and modal analysis of flexible rotor magnetic bearings systemDownload full PDF article
A. Mystkowski
(Bialystok University of Technology, Bialystok, Poland)

The paper presents capability of  µ-synthesis control method of active magnetic bearings (AMBs) to improve vibrations control performance. For proper design of the control law, the FEM rotor model was obtained and the modal analysis of flexible rotor supported by AMBs was performed. The vibrations compensation in wide range of rotation speed changes was performed successfully. The µ-controllers have good vibrations damping, disturbance rejection and robustness to the plant structural uncertainty. All designed control systems with  µ-controllers were stable and able to realize a high bandwidth.

keywords: active magnetic bearings, uncertainty design, flexible rotor model, bending modes, m-synthesis control, rotor vibrations control

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Exponential stability of networked control systems with network-induced random delaysDownload full PDF article
D. Krokavec
(Technical University of Kosice, Kosice, Slovak Republi)
A. Filasova
(Technical University of Kosice, Kosice, Slovak Republi)

In this paper, the problem of exponential stability for the standard form of the state control, realized in a networked control system structure, is studied. To deal with the problem of stability analysis of the event-time-driven modes in the networked control systems the delayed-dependent exponential stability conditions are reformulated and proven. Based on the delay-time dependent Lyapunov-Krasovskii functional, exponential stability criteria are derived. These criteria are expressed as a set of linear matrix inequalities and their structure can be modified to use the bilinear inequality techniques.

keywords: networked systems, stability analysis, time-delay systems, linear matrix inequality, state feedback

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On generalization of integral control to a class of nonlinear uncertain systemDownload full PDF article
Z. Zwierzewicz
(Marine University of Szczecin, Szczecin, Poland)

The paper concerns a new view on the problem of integral control in the context of nonlinear uncertain systems. It is demonstrated that a standard integral action applied to the linear control system with so-called load disturbances, can be generalized to comprise a class of linearly parameterized nonlinear SISO systems with functional uncertainty. In this case the integral action is turned out to be in fact an adaptation law of unknown parameters. It has been found that the obtained proportional-integral controller's variable gains are the basis functions of the system unknown nonlinearity approximator.

keywords: nonlinear control, uncertain systems, adaptive control, integral action, approximator, functional uncertainty

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Quasi-optimal PZT distribution in active vibration reduction of the triangular plate with P-F-F boundary conditionsDownload full PDF article
A. Branski
(Technical University of Rzeszow, Rzeszow, Poland)
S. Szela
(University of Rzeszow, Rzeszow, Poland)

An active reduction of transverse vibration of the triangular plate with P-F-F boundary conditions is considered. The cracked plate is idealized research model as partially clamped on one edge with varying clamped length. The active reduction is realised with PZTs. In the paper, assuming the detached base clamped length, the influence of PZTs distribution on the bending moment and the shearing force at the clamped edge is investigated. To realize the purpose two cases are considered. At the former the PZTs are attached at points in which the curvatures of the surface locally take their maximum (MC sub-areas or quasi-optimal ones). At the latter, the PZTs are somewhat shifted. The plate is excited with harmonic plane acoustic wave. The second mode is considered only.
The active vibration reduction study with a finite element method (FEM) is carried out. The numerical calculations show that better results are obtained for MC distribution of the PZTs.

keywords: triangular plate, PZT (piezoelectric zirconate titanate actuator), P-F-F (partial-free-free) boundary condition, active vibration reduction

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Backstepping/DTC control of a double star synchronous machine driveDownload full PDF article
D. Boudana, L. Nezli, A.Tlemcani, M.O. Mahmoudi, M. Tadjine
(LCP, Alger, Algeria)
M. Djemai
(ECS, ENSEA, Cergy-Pontoise Cedex, France)


Direct torque control (DTC) allows for very high quality torque control  without a need for current controllers tuning or using coordinate transformation. However, barge torque ripples arise as well as inconstant inverter switching frequency due to the hysteresis of comparators. This paper present a backstepping/DTC control based on the space vector modulation (SVPWM) for double star synchronous machine (DSSM) to reduce the torque, flux, current and speed pulsations during steady state. By the coordinate transformation the DSSM models are presented in view of control. Then a conventional DTC is developed to get a decoupled system and a PI controller is designed to control the speed. To improve the static and dynamic control performance of the DSSM, the speed controller is designed using a backstepping/DTC procedure in conjunction with SVPWM. Simulation results with the conventional DTC and proposed backstepping/DTC are presented and compared. Results show the effectiveness and the robustness of the approach proposed.

keywords: double star synchronous machine, direct torque control, backstepping/DTC, space vector modulation, robustness

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Reachability of linear hybrid systems described by the general modelDownload full PDF article
T. Kaczorek, K. Rogowski
(Bialystok University of Technology, Poland)

The reachability of standard and positive hybrid linear systems described by the general model is addressed. Necessary and sufficient conditions for the reachability of the standard general model are established. Sufficient condition is given for the reachability of positive hybrid system described by the general model. The considerations are illustrated by numerical
examples.

keywords: reachability, standard, positive, general model, hybrid system, piecewise constant control

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