Figure A. Table A. Fuzzy control is emerging as a technology that can enhance the capabilities of industrial automation, and is suitable for control level tasks generally performed in Programmable Controllers PC. Fuzzy control is based upon practical application knowledge represented by so-called linguistic rule bases, rather than by analytical either empirical or theoretical models. Fuzzy control can be used when there is an expertise that can be expressed in its formalism.
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The object of this part of IEC is to offer the manufacturers and the users a well-defined common understanding of the basic means to integrate fuzzy control applications in the Programmable Controller languages according to IEC , as well as the possibility to exchange portable fuzzy control programs among different programming systems. To achieve this, annex A gives a short introduction to the theory of fuzzy control and fuzzy logic as far as it is necessary for the understanding of this part of IEC It may be helpful for readers of this part of IEC who are not familiar with fuzzy control theory to read annex A first.
Introduction The theory of fuzzy logic in the application of control is named fuzzy control. Fuzzy control is emerging as a technology that can enhance the capabilities of industrial automation, and is suitable for control level tasks generally performed in Programmable Controllers PC. Fuzzy Control is based upon practical application knowledge represented by so-called linguistic rule bases, rather than by analytical either empirical or theoretical models.
Fuzzy control can be used when there is an expertise that can be expressed in its formalism. Fuzzy control can also in a straightforward way be combined with classical control methods. The application of fuzzy control can be of advantage in such cases where there is no explicit process model available, or in which the analytical model is too difficult to evaluate or when the model is too complicated to evaluate in real time.
Another advantageous feature is that human experience can be incorporated in a straightforward way. Also it is not necessary to model the whole controller with fuzzy control: sometimes fuzzy control just interpolates between a series of locally linear models, or dynamically adapts the parameters of a "linear controller", thereby rendering it non-linear, or alternatively just "zoom in" onto a certain feature of an existing controller that needs to be improved.
Fuzzy control is a multi-valued control, no longer restricting the values of a control proposition to "true" or "false". This makes it particularly useful to model empirical expertise, stating, which control actions have to be taken under a given set of inputs. The existing theory and systems already realized in the area of fuzzy control differ widely in terms of terminology definitions , features functionalities and implementation tools.
Fuzzy control is used from small and simple applications up to highly sophisticated and complex projects. To cover all kinds of usage by this part of IEC , the features of a compliant fuzzy control system are mapped into defined conformance classes. The basic class defines a minimum set of features which has to be achieved by all compliant systems.
This facilitates the exchange of fuzzy control programs.
Since IEC holds the copyright, there are no downloadable versions of the standard available. The International Standard IEC provides a complete collection of standards on programmable controllers and their associated peripherals. It consists of the following parts: IEC General information Contains the definitions and identifies the principal characteristics relevant to the selection and application of programmable controllers and their associated peripherals. Current edition is 2. Current edition is 4. It harmonizes the way people design and operate industrial controls by standardizing the programming interface.