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BY:K SHARATH KARANTHM.TECH CONTROL SYSTEMS

MIT MANIPAL

DIGITAL CONTROL OF MAGNETIC LEVITATION SYSTEM USING FUZZY

LOGIC CONTROLLER

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CONTENTSIntroductionModelling of magnetic levitation systemController design

a>PID controller b>Fuzzy logic controllerComparison of resultsConclusion

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INTRODUCTION

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Contd..Practical applications 1.Maglev trains 2.Maglev bearings

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Contd...Advantages of Maglev systems1.Very less friction2.Active vibration damping3.Undisturbed by non ferromagnetic materials

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MODELLING OF MAGNETIC LEVITATION SYSTEM

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Contd...Objective: To control the vertical position of the

sphere by adjusting the current through the coil

• Non linear system with i,x as nonlinear states • To present such a model as transfer function

it has to be linearized• Linearization techniques commonly used are 1.Taylor series method 2.Jacobian method

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Contd...

Where Fc=ki2/x2 and k is constant

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Contd...

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Contd...• Equilibrium point obtained is Xo=-1.5v Io=0.8A• Minimum and maximum distance of the

sphere from the coil is .5 cm and 2.5 cm• State model is given by

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Contd...

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CONTROLLER DESIGNPID CONTROL 1.Proportional control-increases gain 2.Integral control-reduces steady state error 3.Derivative control-improves transient

response

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Contd...• The parameters of PID controller are updated

using Zeigler Nichols technique

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Contd...FUZZY LOGIC CONTROL• Concept was introduced by Zadeh in 1965• Human knowledge with linguistic variables

are used to control a plant Advantages:• Good popularization• High fault tolerance• Applied to nonlinear systems

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Contd...• Parts of fuzzy logic system 1.Fuzzifier 2.Rules 3.Inference engine 4.Defuzzifier

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Contd...Fuzzy set operations 1.AUB:max(µA (x),µB (x))

2.A∩B:min(µA (x),µB (x))

3.A’:1-µA (x)• Fuzzy rules are expressed in the form of fuzzy

conditional statements Ri:if ‘x’ is small and/or ‘y’ is medium then ‘z’

is big

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Contd...FIS editor

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Contd...Inputs and output of the controller

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Contd...Fuzzy rule base

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COMPARISON OF RESULTSFor Kp=4, Kd=0.2, Ki=2

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Contd...Using fuzzy controller

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CONCLUSIONPID and Fuzzy logic controllers were

successfully designed to control the magnetic levitation system

Based on the experimental results it is recorded that the fuzzy controller can stabilize the system more efficiently than classical PID controller

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REFERENCESK. Ishaque, S.S Abdullah, S Ayub, Z Salman

”A simplified approach to design fuzy logic controller for an underwater vehicle”. Ocean engg Vol 38. No 271-284(2010)

K.H Ang, G chong, Y Li “PID control system analysis, Design and technology” IEEE trans on Control system technology Vol 13. No 559-576(2007)

Fuzzy logic toolbox for use with MATLAB, The mathworks Inc. Version 2, Natick, MA (2006)

www.wikipedia.org/maglev

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