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 2
1. Adaptive Active Control of Noise and Vibration
2. A new method of on-line model identification and update for multichannel active noise control systems
3. Hybrid control system for an AVC unit
4. Vibration damping by structural friction controlled by piezoelectric elements
5. A hybrid active noise control system
6. Generation of effect of virtual unidirectional source of sound using adaptive techniques
7. Remote Active Noise Control Laboratory
8. Limited authority adaptive control in Active Noise Control systems

Adaptive Active Control of Noise and VibrationDownload full PDF article
M.O. Tokhi
(University of Sheffield, UK)

This paper presents the development of a unified approach to active control of noise and vibration. The design of an active control system is initially considered on the basis of a single-input single-output (SISO) structure. The design procedure is formulated so as to allow on-line adaptation and control, and accordingly an adaptive control algorithm is devised. The design is then extended to the case of a single-input multi-output (SIMO) control structure. The control strategies thus devised are verified in the cancellation of broadband noise in a free-field medium, and in vibration suppression in a cantilever beam in fixed-free and fixed-fixed modes. A comparative assessment of the results with SISO and SIMO control structures is presented and discussed.

keywords: active noise control, active vibration control, adaptive control, self-tuning control.


A new method of on-line model identification and update for multichannel active noise control systemsDownload full PDF article
Jaroslaw Figwer
(Silesian University of Technology, Poland)

In the paper a new method of on-line electro-acoustic plant model identification and update for adaptive multichannel feedforward ANC systems is presented. The proposed method uses external multivariate orthogonal multisine excitation added to the control signal. Properties of this excitation allow to decompose the overall multichannel identification problem into independent single-input single-output identification problems. Additionally, special time-domain averaging of signals efficiently reduces an influence of disturbances on identification results even for low signal-to-noise ratio.

keywords: discrete-time systems, model identification, adaptive systems, active noise control, multisine time-series, fast Fourier transform.


Hybrid control system for an AVC unitDownload full PDF article
George Juraj Stein
(Slovak Academy of Sciences, Slovak Republic)

The contribution summarises research on an active vibration control system for heavy loads. The system is modeled as a single DOF oscillatory system with residual damping and a parallel force generator. As the force generator a standard air spring is used, whose internal pressure is proportionally controlled either by a flow control valve or a pressure control valve. Either proportional electro-pneumatic transducer is governed by a control voltage generated by an analogue controller based on a hybrid combination of feed-back and feed-forward control circuits. Experimental results on actuator sub-system identification and whole system frequency response functions of both modifications are presented. By proper setting of the gains favorite course of FRF could be obtained with no resonance amplification, as assumed by simulation research.

keywords: active vibration control, electro-pneumatic system, hybrid analogue control, actuator identification, vibratory frequency response functions.


Vibration damping by structural friction controlled by piezoelectric elementsDownload full PDF article
Zdzislaw Galkowski
(Warsaw University of Technology, Poland)

In the paper analysis of the influence of structural friction and piezoelectric elements on damping of torsion vibration in a shaft is presented. The structural friction between the piezoelectric actuators and shaft is taken into account. For the purpose of the analysis the mathematical model of a permanent shaft-sleeve joint is formulated. The obtained differential equations of motion are solved by the asymptotic Bogolyubov-Krylov-Mitropolski method via developing relations for derivatives of the amplitude and phase. The obtained equations are solved for the case of harmonic excitation with the uniformly increasing frequency of the driving torque, and for the case of free vibration, in which the effect of the gain factor magnitude on the damping level is examined. On the grounds of numerical simulations the growth in the damping efficiency in the joint as a function of the gain factor is confirmed.

keywords: piezoelectric, structural friction, damping, vibrations.


A hybrid active noise control systemDownload full PDF article
Marek Pawelczyk
(Silesian University of Technology, Poland)

In this article a hybrid noise control system for active headsets is designed. It combines analogue and discrete feedback techniques. However, both of these contributing parts are analysed separately, before they are combined in a common system. The design of analogue controller starts from identifying continuous time system, choosing a proper controller structure, and finding its initial parameters with the aid of the system frequency characteristics. Final parameters are originally searched in an optimisation process with a cost function and appropriate constraints formulated. The controller is then practically realised in electronic circuit with a switched capacitor filter. The discrete controller requires in turn modelling of the discretised plant including analogue filters and converters. Well known Internal Model Control structure is used with Filtered-x LMS algorithm. The same structure operates in the hybrid system, where modelling of the analogue closed loop is required. Features of such systems are analysed. Efficiency of the algorithms is verified on a prototype of the active headsets. A variety of noises is considered, both generated and real-life. The experiments confirm good cooperation of the analogue and discrete techniques. The former is responsible for attenuating random broadband noise components. The latter, however, contributes to the overall attenuation, reducing deterministic components to the acoustic background. The main contribution of this article is thus: reported in details original design of analogue active noise control system, its combination with supervisory discrete controller, successful practical realisation and high attenuation level with possibility to easily tune basic performance parameters, what makes the system flexible and efficient in terms of various working environments.

keywords: active noise control, active headsets, feedback, analogue control, discrete control, hybrid control, practical realisation.


Generation of effect of virtual unidirectional source of sound using adaptive techniquesDownload full PDF article
Dariusz Bismor
(Silesian University of Technology, Poland)

One of the main differences between standard industrial automation plants and acoustic plants is the presence of acoustic feedback between the control value ("active" loudspeaker output) and measured disturbance value (reference microphone) [5]. There are several methods to avoid unwanted influence of this phenomenon, that is using a non-acoustic reference sensor or feedback neutralization. This paper presents the author's experience with another approach to the problem, namely virtual unidirectional source of sound [13].

keywords: digital signal processing, adaptive control, active noise control, system identification, adaptive filtering, LMS, FXLMS, unidirectional source of sound, process control.


Remote Active Noise Control LaboratoryDownload full PDF article
Jaroslaw Figwer and Krzysztof Czyz
(Silesian University of Technology, Poland)

The paper presents a remotely controlled Active Noise Control (ANC) laboratory located at the Institute of Automatic Control, Silesian University of Technology, Gliwice, Poland. The ANC laboratory is controlled over the Internet. In this laboratory control systems and algorithms used for creation of spatial zones of quiet in enclosures are developed and verified in real-world. Remote laboratory users may conduct identification and control experiments from remote workstations according to prepared instructions. They can also develop and test their own identification and control algorithms.

keywords: active noise control, remote laboratory, distance learning, internet.


Limited authority adaptive control in Active Noise Control systemsDownload full PDF article
Zbigniew Ogonowski
(Silesian University of Technology, Poland)

The idea behind Limited Authority Adaptive Control is presented in the context of Active Noise Control systems. The necessity of simplification of such systems is discussed in the paper, as well as an algorithm for the simplification with respect to the compact-size zones of quiet and three-dimensional zones of quiet. Identification aspects are discussed to solve the problem of testing the robustness of the system.

keywords: adaptive control, active noise control, identification.


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