AGRADECIMENTOSAgradeço ao meu orientador, professor doutor Claudio Garcia, por toda a orientação e apoio, que começou desde a graduação e vem colhendo ótimos frutos até hoje.Aos professores doutores Fuad Kassab Junior e Ricardo Paulino Marques, pela oportunidade de trabalhar nos projetos do Laboratório de Automação e Controle, o que me propiciou condições e experiências importantes para o desenvolvimento deste trabalho.Aos meus pais, Regina e Francisco, e à minha irmã, Lívia, por toda a ajuda e ensinamentos que me levaram até aqui.Aos amigos e colegas, por todos os conselhos, auxílios e bons momentos vividos.
ABSTRACTThe control valves are the final elements of most of the control loops in industry.Besides, the friction can cause variability in the process, which is an undesirable situation.Furthermore, about 20% to 30% of the oscillations in control loops are caused by friction or hysteresis. Another relevant fact is that much times it is not possible to make the maintenance of the valve that is under a considerable variability, because it is not desirable nor possible to stop the process to make the maintenance of the control valve.Thereby, studying friction compensation methods is necessary as a way to improve the control loop performance in this situation until the industrial plant maintenance is made.This dissertation presents controllers with friction compensation and analyzes its performances compared with other known and widely used compensators through experiments made at the Flow Pilot
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