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:

2009 (Volume 19)
Number 4
1. Windup prevention for MIMO systems in the frequency domain
2. Probabilistic design and tuning of LQ control
3. Stochastic robust flight control under windshear by reduced-order anisotropic controller
4. Dynamical analysis of the free-free damped transverse vibratory beam in transportation
5. Design of a path following controller for an underactuated AUV
6. A note on model matching for nonrealizable nonlinear systems
7. Research and development of seat suspensions for working machines


Windup prevention for MIMO systems in the frequency domainDownload full PDF article
Peter Hippe, Joachim Deutscher
(Universität Erlangen-Nürnberg, Nürnberg, Germany)

Input saturation can have an undesired influence on the transients of the closed loop system and it can even lead to an unstable behavior. Controller windup is caused by badly damped or unstable modes in the compensator and controller windup is due to fast dynamics of the closed loop system. In a two-step approach one can first prevent controller windup by the so-called observer technique and if, in addition, there exists the danger of plant windup one adds an additional dynamic element to prevent it. There also exists a one-step approach that prevents controller and plant windup at the same time. This paper shows how both approaches to windup prevention can be designed directly in the frequency domain without recourse to time domain arguments. A simple example demonstrates the windup effects and their prevention.

keywords:  windup prevention, nonlinear systems, polynomial approach, MIMO systems

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Probabilistic design and tuning of LQ controlDownload full PDF article
Kvìtoslav Belda
(Academy of Sciences of the Czech Republic, Prague, Czech Rep.)

Important point of each control design is a selection of suitable weight parameters, that balance various control aims assigned by user. This paper proposes the new way to set control parameters automatically by evaluation of system response in comparison with system model. Considering stochastic nature of real-life applications, fully probabilistic design is used. It employs complex information on controlled system behavior by means of  probabilistic description.

keywords: adaptive control, closed-loop control, dynamic programming, state-space realization, tuneable filters

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Stochastic robust flight control under windshear by reduced-order anisotropic controllerDownload full PDF article
Michael M. Tchaikovsky
(Russian Academy of Sciences, Moscow, Russia)

This paper is devoted to design of stochastic robust anisotropy-based reduced-order controller for longitudinal flight control in landing approach under the influence of both deterministic and stochastic external disturbances. The control aims at disturbance attenuation and stabilizing aircraft longitudinal motion along some desired glidepath. The controller design procedure consists of two steps. At first, the full-order optimal controller is obtained as the solution to normalized anisotropy-based stochastic  H optimization problem. Then, the optimal controller is reduced via a truncation-like technique. The results of comparison of reduced-order anisotropic controller with LQG and H ones on the base of closed-loop system simulation are presented.

keywords: flight control, windshear, stochastic disturbances, anisotropy, induced norm, order reduction

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Dynamical analysis of the free-free damped transverse vibratory beam in transportationDownload full PDF article
S³awomir ¯ó³kiewski
(Silesian University of Technology, Gliwice, Poland)

One of the most popular method of vibrating systems analysis is dynamical flexibility method. This method makes possible the assignment of stability bands. The thesis is applied to the free-free damped beam systems analysis. The beam is loaded by transversal unitary force in accordance with a dynamical flexibility definition. In a mathematical model Coriolis forces, centrifugal forces and damping forces were took into the consideration. The damping forces enable active vibration control and can change dynamical characteristics of the system.

keywords: vibrations, dynamical analysis, free-free beam, damping, transportation, dynamical flexibility

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Design of a path following controller for an underactuated AUVDownload full PDF article
Bidyadhar Subudhi, Debabrata Atta
(National Institute of Technology Rourkela, Rourkela, India)

This paper describes a tracking control strategy for an underactuated autonomous underwater vehicle (AUV) on a two dimensional plane (R2). Based on a  smooth, inertial, 2D reference trajectory curve, the proposed algorithm uses vehicle dynamics to generate the reference orientation and body-fixed velocities. Following these, required error dynamics are developed. Error dynamics are then stabilized using inverse dynamics control strategy, forcing the tracking error to an arbitrarily small neighborhood of zero. Circular path, as a constant velocity reference trajectory, has been chosen for simulation studies. Simulation results are included to demonstrate the tracking performance of the controller.

keywords: kinematics, reference path, tracking control, inverse dynamics control

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A note on model matching for nonrealizable nonlinear systemsDownload full PDF article
Miroslav Halás
(Slovak University of Technology, Bratislava, Slovakia)
Ülle Kotta
(Tallinn University of Technology, Tallinn, Estonia)

In this technical note the model matching problem for nonlinear systems not admitting the state space realization is discussed. Both continuous- and discrete-time cases are addressed. It is demonstrated, by using a transfer function formalism, that even in case of nonrealizable systems it is sometimes still possible to find realizable compensators.

keywords: nonlinear systems, model matching, transfer functions, realizability

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Research and development of seat suspensions for working machines
Igor Maciejewski, Tomasz Kiczkowiak, Tomasz Krzy¿yñski
(Koszalin University of Technology, Koszalin, Poland)


The paper contains physical and mathematical model of passive and active control of working machine's seat suspension. Seat with a viscous-elastic passive suspension, which vibro-isolation properties became improved by modification of the air-spring and shock absorber forces and also by active control are the objects of simulation. As the results of computer simulation, power spectral density of acceleration for a seat have been presented in comparison with sample excitation on the working machine's cabin floor. Transmissibility functions for a passive suspension and corresponding active suspension also have been presented.

keywords: seat suspension, vibrations, passive and active systems

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