Quantificação de não-linearidades em malhas de controle oscilantes via método da função descritiva

The presence of friction and other non-linearities is a cause of oscillations in control loops, with negative effects on quality and cost of goods. The method of describing function is traditionally used to predict the period and amplitude of cycles limit control loops. This method is used in this article for detection and quantification of nonlinearities, using for this usual process data and an approximate model. The effect of uncertainty on the model and the presence of multiple frequencies of oscillation are analyzed. The potential for nonlinearities detection and quantification of the method is evidenced by its successful application to different situations.