Diagnostic reasoning based on means-end models: experiences and future prospects

Multilevel flow models (MFM) are graphical models of goals and functions of technical systems. MFM was invented by Morten Lind at the Technical University of Denmark and several new algorithms and implementations have been contributed by the group headed by Jan Eric Larsson at Lund Institute of Technology. MFM has several properties which makes for a relatively easy knowledge engineering task, compared to mathematical models as used in classical control theory and compared to the rule bases used in standard expert systems. In addition, MFM allows for diagnostic algorithms with excellent real-time properties. This paper gives an overview of existing MFM algorithms, and different MFM projects which have been performed, or are currently in progress