Estratégias de estimação de falhas em atuadores e sensores em processos não lineares com incertezas

Abstract

Over the years, control processes have become more complex, containing a large number of components that work in an integrated manner. Any of these components is subject to defects or malfunctions. All these factors are defined as faults, which are unexpected variations of the properties of a given component with respect to its nominal operating condition. The consequences of failures may cause economic losses and risk the life of the workers in the enclosure. A fault tolerant control system is able to keep the control process running with proper performance even in the presence of failures. In its active approach, the nominal control strategy is reconfigured so that the effect of the fault is accommodated. This reconfiguration is usually based on the estimate of the fault, which can be obtained by means of an observer. Generally the effectiveness of an observer is related to the degree of knowledge about the process by the designer. An unforeseen change in system parameters or the presence of uncertainties may adversely affect the performance of the observer. This work proposes two state observer design techniques which are able to perform the simultaneous estimation of states and faults in actuators and sensors in nonlinear systems in discrete time with uncertainties. The operation of this method is verified by means of computational simulations based on case studies involving liquid level processes and control of a flexible articulated robotic manipulator.