Oliveira, Luiz Affonso Henderson Guedes deVenceslau, Allan Robson Silva2016-03-032016-03-032013-01-31VENCESLAU, Allan Robson Silva. Detecção e diagnostico de agarramento em válvulas posicionadoras. 2013. 42f. Dissertação (Mestrado em Engenharia Elétrica e de Computação) - Centro de Tecnologia, Universidade Federal do Rio Grande do Norte, Natal, 2013.https://repositorio.ufrn.br/jspui/handle/123456789/19934Valve stiction, or static friction, in control loops is a common problem in modern industrial processes. Recently, many studies have been developed to understand, reproduce and detect such problem, but quantification still remains a challenge. Since the valve position (mv) is normally unknown in an industrial process, the main challenge is to diagnose stiction knowing only the output signals of the process (pv) and the control signal (op). This paper presents an Artificial Neural Network approach in order to detect and quantify the amount of static friction using only the pv and op information. Different methods for preprocessing the training set of the neural network are presented. Those methods are based on the calculation of centroid and Fourier Transform. The proposal is validated using a simulated process and the results show a satisfactory measurement of stiction.porAcesso AbertoAgarramentoVálvulas posicionadorasDetectarQuantificarRedes neuraisCentroideTransformada de FouriermasterThesisCNPQ::ENGENHARIAS::ENGENHARIA ELETRICA