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Design and Application of Industrial Fuzzy Logic Controllers

Professor Snejana Yordanova, Technical University of Sofia, Bulgaria; e-mail:;

Thursday 20 May 2010, 1300-1400
C60 InfoLab21

The fuzzy logic controllers (FLCs) mark a considerable progress in controlling complex, non-linear, time-varying processes satisfying the high system performance demands

Since their emergence in the area of process control the FLCs design is constantly being improved laying it out on theoretical grounds and making it more general and simple.

Different structures of model-free and T-S model-based FLCs and approaches have been suggested for treating together fuzzy system stability and uncertainty for the purposes not only of analysis but also of design.

The aim of this lecture is to present some results from the research of the author and her team on development and implementation of various types PI-like model-free process FLCs for robust control of complex industrial plants with time delay.

An effort has been made to treat together in the frequency domain the stability and the performance of a fuzzy control system of a plant with time delay and model uncertainties, provoked by plant complexity and shift of the operating point along the smooth non-linear plant characteristics due to disturbances, changes in the operating mode and time-varying plant properties.

Another research goal is to offer a simple and transparent both FLCs and FLCs design in order to make controllers and their design feasible and easy to complete in industrial PLCs.

Robust stability and robust performance criteria are derived by extending the Popov stability criterion for the case of a fuzzy control system and combining it with Morari robustness considerations, employing experts estimates of simple nominal plant model with time delay and plant uncertainties model.

These criteria lay the theoretical foundations for the developed simple and objective FLC design and parameter tuning procedure. The design starts with a single input - the signed distance, fuzzy controller (SI FC), making use of its crucial advantages for application of the Popov and Morari techniques - 1-D uniquely determined rule base, a sector bounded non-linear control curve and a reduced number of tuning parameters. Then it is extended to other sole and two-input FLCs. A model of the procedure is derived using LSM and feedforward ANNs to automate the PLC implementation of the design.

The design procedure is assessed by applying it for the control of the inside temperature of a laboratory-scale dryer using MATLAB real-time and Siemens SIMATIC PLC. A comparison of the fuzzy closed loop system performance with the performance of a designed ordinary PI controller system underlines the advantages of the fuzzy system. An extension to the case of multivariable FLCs is suggested which is tested for the control of an aerodynamic plant (laboratory-scale helicopter).

Brief biography of the speaker:

Snejana Yordanova - MEng in Electrical Engineering (Automatic Control) and Ph.D. holder from the Technical University of Sofia (TUS), a full-time Associate Professor with the Department of Process Control, Faculty of Automation, TUS; TUS ECTS expert

Member of the Union of Automatics and Informatics in Bulgaria and the World Scientific and Engineering Academy and Society (WSEAS)

Teaching activity - process control, fuzzy control, control systems, elements of industrial automation, modelling and simulation, MATLAB

Scientific and research interests - application of the robust, fuzzy logic and neural network approaches to system modelling, simulation and control under uncertainties in the areas of oil refining, milk processing, wastewater treatment; measurement systems; thermal power plants


papers - over 120 (in journals Int. Sc. J. of Computing, WSEAS Trans. on Systems, WSEAS Trans. on Circuits and Systems, J. of Electrical and Electronic Engineering, Australia, IEEE Trans. Instrum. and Measurement, Transactions of the Institute of Meas. and Control, Journal of Intelligent & Fuzzy Systems, Int. J. of Automation and Control, Advances in Physics, Electronics and Signal Processing Applications, Chemical & Biochemical Engineering Quarterly, Bioprocess Engineering, Problems of Eng. Cybernetics and Robotics, Automatica & Informatics, Proceedings of the Technical University of Sofia, Technical Review, Electrical Engineering and Electronics, etc.);

textbooks 8 and manuals 4,

Research and education projects 18;

Coordinator and guest lecturer in 8 Erasmus-Socrates projects (Spain, Italy, Sweden, UK, Portugal).

Supervisor of 2 Ph.D. students

Member of organising and international scientific committees of conferences (WSEAS, IDAACS, IFAC, UIEEE, "Challenges in Research and Education of 21-st century"- Bulgaria, etc.); co-editor of proceedings; reviewer for journals (WSEAS, Automatica, IEEE, etc.).