Fault diagnosis for nonlinear systems using a bank of neural estimators

  • Authors:
  • A. Alessandri

  • Affiliations:
  • ISSIA-CNR Institute of Intelligent Systems for Automation, National Research Council of Italy, Via De Marini 6, 16149 Genova, Italy

  • Venue:
  • Computers in Industry - Special issue: Soft computing in industrial applications
  • Year:
  • 2003

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Abstract

A model-based method to detect faults in nonlinear systems is proposed. Fault diagnosis is accomplished by means of a bank of estimators, which provide estimates of parameters that describe actuator, plant, and sensor faults. These estimators perform according to a receding-horizon strategy and are designed using models of the failures. The problem of designing such estimators for general nonlinear systems is solved by searching for optimal estimation functions. These functions are approximated by feedforward neural networks and the problem is reduced to find the optimal neural weights. The learning can be split into two phases. In the first one, any possible "a priori" knowledge on the statistics of the random variables is used to initialize the neural estimation functions off line. In the second one, the optimization (or training) continues on line. Both off and on line learning rely on stochastic approximation. The performances obtained in the estimation of the fault parameters by the proposed neural estimators and by the extended Kalman filters are compared by means of simulations with an application to underwater robotics.