15th Triennial World Congress of the International Federation of Automatic Control
  Barcelona, 21–26 July 2002 
ON MULTI-OBJECTIVE IDENTIFICATION OF TAKAGI-SUGENO FUZZY MODEL PARAMETERS
Tor A. Johansen* and Robert Babuška**
* Department of Engineering Cybernetics, Norwegian University of
Science and Technology, 7491 Trondheim, Norway.
Email: Tor.Arne.Johansen@itk.ntnu.no
** Systems and Control Engineering Group, Delft University of
Technology, P.O. Box 5031, 2600 GA Delft, The Netherlands.
Email: R.Babuska@its.tudelft.nl

The problem of identifying the parameters of the constituent local linear models of Takagi-Sugeno fuzzy models is considered. In order to address the tradeoff between global model accuracy and interpretability of the local models as linearizations of a nonlinear system, two multi-objective identification algorithms are studied. Particular attention is paid to the analysis of conflicts between objectives, and we show that such information can be easily computed from the solution of the multi-objective optimization. This information is useful to diagnose the model and tune the weighting and priorities of the multi-objective optimization. Moreover, the result of the conflict analysis can be used as a constructive tool to modify the fuzzy model structure (including membership functions) in order to meet the multiple objectives. The methods are illustrated on an experimental lungs respiration application.
Keywords: Fuzzy Modelling, Identification, Multi-objective Optimization, Sensitivity Analysis, Parameter Optimization.
Session slot T-Mo-A04: Fuzzy system analysis/Area code 3e : Fuzzy and Neural Systems