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:

2006 (Volume 16)
Number 1
1. Optimization of vibration acceleration in a quarter car suspension model
2. Lipschitz continuity of fuzzy controller
3. Predictive feedback approach to structural vibration suppression
4. Bounding approach to parameter estimation without prior knowledge on modeling error and application to quality modeling  in drinking water distribution systems
5. On sliding mode based non linear PID design for position control of permanent magnet synchronous machine with unknown load torque
6. The steering of the ship motion: a μ-synthesis approach
7. Hierarchical stochastic control in a large scale linear system


Optimization of vibration acceleration in a quarter car suspension modelDownload full PDF article
Andrzej Turnau, Maciej Rosół
(Department of Automatics, AGH University of Science and Technology, Kraków, Poland)

The main goal of the paper is to examine and optimize the parameters of a closed loop controller for a quarter car suspension model equipped with a semi-active magnetorheological damper. An oscillating vehicle model excited by perturbations of the ground and driving maneuvers is investigated. A quadratic quality criterion is assumed and minimized for an appropriately chosen sequence of the parameter values. In this way a trade-off between driving comfort and road holding capability is achieved. To emphasize advantages of the optimized LQR controller the car model behaviors under two different controllers: passive and hybrid are compared.

keywords: active suspensions, optimal control, LQR

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Lipschitz continuity of fuzzy controllerDownload full PDF article
Darina Bártová, Jaromir Kukal, Dana Majerová
(ICT Prague, Department of Computing and Control Engineering, Czech)

Any traditional fuzzy controller performs a sequence of three processes: fuzzification, control algorithm and defuzzification. It is useful when the controller exhibits continuous behavior with constrained output and sensitivity. After the normalization of controller inputs and outputs into the interval [0;1], we designed the fuzzy controller to be Lipschitz continuous, which implies the constrained sensitivity of the controller. Łukasiewicz algebra enriched by ŁAsqrt was used for the realization of the proposed fuzzy controller. The realization of fuzzification and control algorithm is trivial. The only problem is in the defuzzification. Neither Mamdani nor Larsen approaches are continuous in general. Both MOM and COG techniques generate discontinuous output behaviour. That is why we developed a new defuzzification method based on Łukasiewicz algebra. Thus, the proposed technique of defuzzification is based on propositional logic and it helps to realize a class of Lipschitz continuous fuzzy controllers. The controllers were realized in the Matlab environment.

keywords: ?ukasiewicz algebra, square root, Lipschitz continuity, Matlab, fuzzy control

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Predictive feedback approach to structural vibration suppressionDownload full PDF article
Ryszard Leniowski
(Rzeszów University of Technology, Rzeszów, Poland)
Lucyna Leniowska
(University of Rzeszów, Rzeszów, Poland)

The problem of active vibration control of a plate has been vastly researched and described in recent years. Theoretical and experimental results demonstrate the effectiveness of the designed controllers and indicate the potential of control techniques for reducing transient and steady state dynamics in structural acoustic systems. The examples from the computational studies, confirmed that vibration levels could be effectively reduced, however, the implementation procedures are not yet ideal, still exists the gap between experimental and simulations findings. To overcome this problem, authors propose extension for the Fuzzy-PID controller, with an on-line identification technique coupled with a control scheme, for a plate vibration suppression. It is assumed, that the system to be regulated is unknown, the control schemes presented in this work have the ability to identify and suppress a plate vibrations with only an initial estimate of the system order. A prediction method implemented was designed using a neural network (NN) identification algorithm, based on the well-known Runge-Kutta methods. This algorithm is similar to described by Wang and Lin [14], but it uses a computation structure of Runge-Kutta-3/8, with radial cosine basis neural network.

keywords: active vibration control, plate vibrations, clamped boundary condition, predictive methods, computer simulation, Runge-Kutta neural network

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Bounding approach to parameter estimation without prior knowledge on modeling error and application to quality modeling  in drinking water distribution systemsDownload full PDF article
Kazimierz Duzinkiewicz
(Department of Control Engineering, Faculty of Electrical Engineering and Automatic Control, Gdańsk University of Technology, Poland )

Parameter estimation of an autoregressive with moving average and exogenous variable (ARMAX) model is discussed in this paper by using bounding approach. Bounds on the model structure error are assumed unknown, or known but too conservative. To reduce this conservatism, a point-parametric model concept is proposed, where there exist a set of model parameters and modeling error corresponding to each input. Feasible parameter sets are defined for point-parametric model. Bounded values on the model parameters and modeling error can then be computed jointly by tightening the feasible set using observations under deliberately designed input excitations. Finally, a constantly bounded parameter model is established, which can be used for robust output prediction and control.

keywords: modeling errors, bounding method, parameter estimation, uncertain dynamic systems, robust control

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On sliding mode based non linear PID design for position control of permanent magnet synchronous machine with unknown load torqueDownload full PDF article
L. Nezli, M. Tadjine, M.S. Boucherit
(Process Control Laboratory, Electrical Engineering Departement Ecole Nationale Polytechnique, Algers, Algeria)

This paper presents a new control design procedure for permanent magnet synchronous machine (PMSM) motion drive in the case of unknown load torque. The control law is based on the combination of sliding mode, non linear proportional integral derivative (PID) regulators, and the backstepping approaches. More precisely, we determine the controllers imposing the current-position tracking in three recursive steps and by using appropriate sliding mode / PID gains that are non linear functions of the system state. Moreover, a comparative study between the proposed sliding mode PID/Backstepping approach and the feedback linearizing control is made by realistic simulation including load torque change, parametric variations and measurement noise. The results of current-position tracking show the effectiveness of the proposed method in presence of strong disturbances.

keywords: non linear PID control, sliding mode, backstepping, PMS machine, robustness, current-position tracking, feedback linearizing control

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The steering of the ship motion: a μ-synthesis approachDownload full PDF article
Witold Gierusz
(Gdynia Maritime University, Gdynia, Poland)

The main goal of this task was the synthesis of the multivariable regulator for precise steering of the real, training ship. However such object is strongly nonlinear and its characteristics depends on current work conditions. Therefore one of possible ways to build a proper ship's controller can be the robust control theory approach. It enables the introduction of the effects of the modeling errors, unknown nonlinearities, unawareness of the particular object phenomena into the controller synthesis process. First part of the paper describes the meaning of the weighting functions in the system, the conditions for computing of the H controller and the parametric and nonparametric uncertainties. The next part presents the requirements which should be fulfilled by regulator to be the robust one and it describes the way how to calculate the multivariable robust controller via D-K iteration. In the last part of the paper exemplary results of the steering process from simulation and the real-time trials illustrates the control quality of the obtained closed-loop system.

keywords: training ship, multivariable system, robust control, structured singular value, real-time steering

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Hierarchical stochastic control in a large scale linear systemDownload full PDF article
Zdzisław Duda
(Institute of Automatic Control, Silesian University of Technology, Gliwice, Poland)

In the paper a synthesis of suboptimal control laws for a large scale stochastic system composed of interacting linear  subsystems is presented. A two-level hierarchical control structure with a coordinator and local controllers having access to different information is assumed. The possibility of partially decomposed calculations is shown as well as realization of decentralized local control. An illustrative example is presented.

keywords: large scale systems, hierarchical control structure, decentralized stochastic control

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