Modeling and Control of a Magnetic Levitation System

T. Meressi and M.C. Kao (USA)


Modelling, simulation, Fuzzy Logic, Gain Scheduling


The objective of this study is to design and test a feedback controlled magnetic levitation system. Experimental data is first used to model the designed system by estimating system parameters and the resulting model is used to design linear and nonlinear controllers. The system considered is non-linear and open loop unstable. A linear controller is first designed by linearizing the nonlinear open loop system around a desired equilibrium point. While the linear controller worked well when the system is close to its equilibrium point, experiments revealed that the region of attraction around the equilibrium point is very small and a slight perturbation was enough to push the object away from the desired position. To expand the region of attraction to a practically reasonably value, a nonlinear controller is designed to deal with the case when the initial condition of the system is out of the small neighborhood of the desired equilibrium point. In this paper a nonlinear fuzzy scheduled controller is used. The performance of the nonlinear controller is analyzed using numerical simulations. Experimental verification of the simulation results is being done.

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