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MAGNETIC SUSPENSION OF IRON SPHERE BY FUZZY LOGIC CONTROL SYSTEM

Osman GÜRDAL* Zeki ERDEM**
GAZİ UNIVERSITY
Technical Education Faculty
*Electrical Education Department
**Computer/Control Education Department
Beşevler / ANKARA / TURKEY

Abstract
Magnetic suspension system of iron sphere shows a visual demonstration of principles in educational programs, e.g., electromagnetic design, compensation of a unstable control system and power amplifier design. This study is a sample application of magnetic suspension system used in a wide area as speed trains, wind tunnels, conveyor systems and magnetic ball bearings, etc. The prototype consists of a vertical electromagnet and a 12.5 mm diameter iron sphere to be suspended against earth gravity. Several works like implementing the control a proportional to derivative (PD) compensation and optimum electromagnetic design for a given sphere have been done on this subject before. The purpose of this study, to keep the gap between electromagnet and iron sphere in fixed position by fuzzy logic control system.
The control system of magnetic suspension system has been done as PD compensation in several works by using one optical transducers. In this study, fuzzy control system has a set of 3 optical transducers consisting of infrared diode and photo-transistor. Firstly, the control of the system is achieved by PD control compensation to get the rules of fuzzy logic control system. The position data obtained from 3 infrared photo-transistor is then sent to a PC which controls the gap of iron sphere by fuzzy logic control system. The fuzzy logic control system an advantage over PD controller. Observations has shown that, when a deviation of iron sphere from its original fixed position by external effects occurs, fuzzy logic control brings the iron sphere to its original position quicker than PD controller.

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