Superior performance of switched fuzzy control systems: An overview and simulation experiments

Dimirovski, Georgi M. (Dogus Author)This article gives a brief overview of the basic notions of switched fuzzy systems, their model construction and stability analysis, followed by the proposed concepts for building simulation algorithms for this type of systems. Using these concepts we have shown the whole process of modelling, stability analysis and design of stabilizing switching fuzzy logic controllers for the hovercraftvehicle as a typical nonholonomic system. MATLAB Simulator (Simulink model) and special MATLAB functions for the switching fuzzy controller of the hovercraft vehicle, along with the numerous simulation results, verify the correctness of the proposed concepts. Using this typical nonholonomic system we have also explored the good performance of switched fuzzy systems in comparison to the ordinary T-S fuzzy systems

Recent advances in analysis and control design for switched fuzzy systems: A review

Dimirovski, Georgi M. (Dogus Author) -- Conference full title: 2012 6th IEEE International Conference Intelligent Systems, Sofia, Bulgaria, September 6-8.This paper overviews recent advances in the field of switched fuzzy systems, switched systems whose subsystems are fuzzy systems, followed by the comparative study for this kind of systems. Starting with the basic ideas of switched fuzzy systems, the comparative study is aimed in introducing the diverse approaches in their model construction, as well as the challenges related with the stability analysis and stabilization of such systems. The last includes the issue of stability analysis and finding conditions for existence of switched fuzzy controllers which will stabilize the nonlinear system.The Ss Cyril and Methodius Universit

Fuzzy linear programming: foreign exchange market

Dimirovski, Georgi M. (Dogus Author) -- Conference full title: 13th International Conference on Rough Sets, Fuzzy Sets and Granular Computing, RSFDGrC 2011; Moscow; Russia; 25 Jun 2011 through 27 Jun 2011.Strategic asset management is concerned with a complex process that usually involves a variety decision making situations. But managers, decision makers, and experts dealing with optimization problems often have a lack of information on the exact values of some parameters and in the same time are unable to put into the model important aspects that couldn't be defined as crisp. To deal with this kind of imprecise data, Fuzzy Sets provide a powerful tool to model and solve these problems. A method for solving Fuzzy Linear Programming problems is provided, and this method is applied to a concrete real problem for foreign exchange market. With proposed fuzzy model in this work, asset managers obtain a tool for making better decisions for FX transactions when exchange rates are not known

Fuzzy matrix game perspective for problems of cooperation, non-cooperation, and conflicts

Dimirovski, Georgi M. (Dogus Author) -- This article belongs to a special issue-12th IFAC Workshop on Supplementary Ways for Improving International StabilityIn societal applications of systems science where competition under conflicting interests is pertinent to, the decision making faces situations in which one must decide whether to cooperate or not with a competitor or opponent. Each of the opponents (‘players’) has as well as carries own missions within the society out. At least two if not more parties need to make decisions under fully or partially conflicting objectives when involved in a dispute or open conflict. By and large decisions must be made under risk, uncertainty, and incomplete or fuzzy information implying large amounts of linguistic and probabilistic information. For cases of two opponents, the synergy of fuzzy control approach and matrix games seems rather effective to represent and find solutions for such multi-criteria conflicting situations. The fuzzy procedure is used to take into account some of the subjective attitudes of the decision makers that are difficult to model using classical game theory

Uticaj podele prostora stanja na regıone prilikom projektovanja prebacivačkih fazi kontrolera

Dimirovski, Georgi M. (Dogus Author)In this paper we explore the influence of the state-space partitioning into specific regions, when designing switched fuzzy controllers, to the stability performance of the system. For examination purposes we have designed switched fuzzy model and appropriate switched fuzzy controller for a hovercraft vehicle, as a typical nonholonomic system. The design is made for four different ways of state-space partitioning. The simulation results verify the influence of the different partitioning of the state space to the control performance of the system.U ovom radu istražuje se uticaj podele prostora stanja u određenim regionima, prilikom projektovanja prebacivačkih fazi upravljača, na performanse stabilnosti sistema. Za svrhe ispitivanja projektovali smo prebacivački fazi model i odgovarajući prebacivački fazi upravljač za hovercraft vozila, kao tipični neholonomni sistem. Dizajn je napravljen za četiri različita načina podele prostora stanja. Rezultati simulacije verifikuju uticaj različitih podela prostora stanja na performanse upravljanja sistema

Robust discrete-time sliding mode control algorithm for TCP Networks congestion control

Dimirovski, Georgi M. (Dogus Author) -- Conference full title: TELSIKS 2007: 2007 8th International Conference on Telecommunications in Modern Satellite, Cable and Broadcasting Services, Nis, Serbia & Montenegro, 26-28 September 2007For solving the problem of congestion control in transmission control protocol (TCP) networks, we propose a new active queue management (AQM) algorithm based on discrete- time sliding mode control (DSMC) theory. We use a discrete- time system model with uncertainties to decipt the time-varying TCP networks. Based on the model, an asymptotically stable sliding surface is designed by linear matrix inequality (LMI). The design of sliding surface compensates for the disadvantageous effect of uncertainties. Therefore, the robustness of the algorithm is good. The proposed controller can guarantee the controlled object, namely, the queue length in router to converge to the desired value quickly and constrain oscillation of the queue length effectively. The simulation results certify the validity of the algorithm

New synthesis design of adaptive back-stepping controller for static SVC

Dimirovski, Georgi M. (Dogus Author) -- Conference full title: 2007 9th European Control Conference, ECC 2007; Kos International Convention Center (KICC)Kos; Greece; 2 July 2007 through 5 July 2007A new synthesis design for nonlinear adaptive control of Static VAR Compensator for a single-machine infinite-bus system with SVC is derived and proved. The proposed method differs from the 'traditional' adaptive back-stepping in both ways how the parameter estimator is constructed and the nonlinear gains are assigned. In comparison with the existing traditional adaptive back-stepping controller, the proposed approach does not follow the classical certainty-equivalence philosophy for the first time, thus yielding the novel parameter estimator and feedback controller dynamics in dealing with unknown parameters. Computer simulation experiments demonstrated that the proposed approach is considerably superior to the control synthesis based on 'classical' adaptive back-stepping in terms of the properties of stability and parameter estimation. Results show that the proposed design almost completely recovers the performance of the 'full-information' controller

A quadratic stability solution for switched singular linear systems

Dimirovski, Georgi M. (Dogus Author) -- Conference full title: European Control Conference, ECC '09: Budapest, Hungary, 23-26 August 2009.Quadratic stability for a class of switched singular linear systems is investigated. The convex combination technique of standard switched linear systems is extended to switched singular systems and a sufficient condition for quadratic stability derived. A stabilizing switching law is also designed. For a switched singular system with two subsystems this appears a necessary and sufficient condition for quadratic stability. Also, the switching law realization is discussed relative to avoiding zeno behavior. An illustrative example is given to demonstrate the validity of these new results

Systems approaches to sustainable advancement of developing countries: Recent contributions

Dimirovski, Georgi M. (Dogus Author) -- Conference full title: 17th World Congress, International Federation of Automatic Control, IFAC; Seoul; South Korea; 6 July 2008 through 11 July 2008.Advanced information technologies resulting from automation of control and decision expertise and their respective scientific disciplines have essential impacts on the development of national economies within the more and more globalized economy hence a decisive role in ameliorating current socioeconomic problems in developing countries. Recent developments have put new emphasis on the IFAC activities dedicated to help improving the technological background of developing countries so as to assists their sustainable but accelerated developments. It is important to keep the focus should be on innovative systems approaches to combined knowledge and technology transfer to developing countries that may remedy their current state of the matters

UKF based nonlinear filtering for parameter estimation in Linear Systems with correlated noise

Dimirovski, Georgi M. (Dogus Author) -- Conference full title: 17th World Congress, International Federation of Automatic Control, IFAC; Seoul; South Korea; 6 July 2008 through 11 July 2008.Based on the Unscented Kalman Filter (UKF), the nonlinear filter is presented for parameter estimation in linear system with correlated noise where the unknown parameters are estimated as a part of an enlarged state vector. To avoid the computational burden in determining the state estimates when only the parameter estimates are required, a new form of UKF, where the state consists only of the parameters to be estimated, is proposed. The algorithm is based on the inclusion of the computed residuals in the observation matrix of a state representation of the system. Convergence properties of the proposed algorithm are analyzed and ensured. The algorithm is verified by using Matlab simulations on the vehicle navigation systems with aided GPS