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Feedback Linearization and Model Reference Adaptive Control of a Magnetic Levitation System

Luiz H. S. Torres, Leizer Schnitman, Carlos A. V. V. Júnior
Centro de Capacitação Tecnológica em Automação Industrial (CTAI), Universidade Federal da Bahia
Rua Aristides Novis, no 02, Escola Politécnica, 2o andar, 40.210-630,
Salvador, Bahia, Brasil

J. A. M. Felippe de Souza
Electromechanical Engineering Dept, University of Beira Interior
Covilhã, Portugal


The aim of this paper is to combine two techniques to control a nonlinear Magnetic Levitation System (MLS). Firstly, a feedback linearization technique (here, exact linearization with state feedback) is applied to obtain a linear system. Secondly, the linearization is made via direct cancellation of nonlinear functions, which represent the phenomenological model of the system. Finally, to deal with the presence of uncertainty in the system model, an adaptive controller is used. The controller is based on model reference adaptive control to estimate the functions that contain the nonlinearities of the system. The exact linearization and the adaptive controller were implemented in a simulated environment (Matlab Simulink ©). The linear adaptive controller structure guarantees the parameters adaptation and the overall stability of the system. The results show that the controller output signal tracks a reference input signal with a small error.


Adaptive Control; Direct Approach; Exact Linearization; Magnetic Levitation; Model Reference.

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CITE THIS PAPER AS: Luis H. S. TORRES, Leizer SCHNITMAN, Carlos A. V. V. JUNIOR, J. A. M. FELIPPE DE SOUZA, Feedback Linearization and Model Reference Adaptive Control of a Magnetic Levitation System, Studies in Informatics and Control, ISSN 1220-1766, vol. 21 (1), pp. 67-74, 2012.