Fuzzy logic

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Fuzzy logic is an outcome of merging the techniques of traditional rule based expert system, set theory and control theory, which is essentially based on mathematical models of the controlled process.

The concept of this paper is to control the illumination of a light source by using the fuzzy logic.

Here the error and error rate are input parameters and the voltage is the output. Theses are all normalized in the form of intersecting triangular membership functions with seven linguals each. The rules are formed by the knowledge.

At a time four rules are fired, and the maximum of their output is taken. The value is defuzzified by the method named center of the area or center of gravity.

The defuzzified voltage is denormalised and made as a pulse to be given to a power control circuit using phase control method.

The pulse produced proportionally to give the power to the circuit, the illumination is again sensed and given to the controlling unit

1. INTRODUCTION

1.1. An Overview of the Paper : -

In some situations in industries and also for some research processes, constant illumination is to be maintained. For example , to study the photosynthetic process constant illumination is to be maintained throughout twenty four hours. But the sun, the natural source for photosynthetic process, does not give light for twenty four hours. so we have to use an artificial supplementary light source.

Depending upon the changes in the illumination intensity of the sun light, due to reasons beyond control, the artificial light source acts as an automatically adjusted supplementary light source acts with the natural sun light, the resultant light intensity is maintained constant.

While there are so many techniques available, to have an automatic controller, the system adopts the fuzzy logic technique, the emerging technique being adopted for industry appliances, to control the artificial light source.

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