Estimation of parity equations in nonlinear systems

Many processes with nonlinear behaviour are difficult to model. Consequently model based approaches to fault detection can not be applied. For a certain class of these processes with mainly constant input signals a combination of parameter estimation techniques and the parity space approach allows online fault detection with small signal models. Only few knowledge of the process is required: An idea about the dynamic model order and the static nonlinear characteristic curve. Using the proposed method fault detection is performed at a flowrate control with a pneumatic driven valve.<>