The Potential of Fuzzy Logic Applications in Industry

Abstract

In this paper an overview is given of the various ways fuzzy logic can be used in industry. The application of fuzzy logic in control is illustrated by four case studies. The first example shows how fuzzy logic, incorporated in the hardware of an industrial controller, helps to improve a classical linear PID controller by reducing its overshoot. In the second example the overshoot of a PID controller is drastically reduced by scheduling of the set-point by means of fuzzy logic. A third study describes how fuzzy logic may be used to fine-tune a PID controller, without the operator having any a priori knowledge of the system to be controlled. The last example in the field of control is from process industry. Here, fuzzy logic supervisory control is implemented in software and enhances the operation of a sintering oven through a subtle combination of priority management and deviation-controlled timing. Finally the key areas of research in fuzzy logic control are discussed. First the paper discusses how fuzzy logic control can be combined with other methods. By properly separating the a priori model knowledge of the process under control, a hierarchy of non-linear control methods is established. After a short discussion of how to optimise an intuitive fuzzy rule base, we show that it is possible to derive conditions for asymptotic stability and robustness for fuzzy logic controllers, using classical non-linear analysis. Next, a completely different application area of fuzzy logic is discussed: sensor fusion. After a short overview on the various types of sensor fusion methods two case studies in this field are treated: the fuzzy human body detector and the earth quake detector. The review of the main industrial application fields of fuzzy logic is concluded with a case study on a fuzzy Health Management expert systems.