Qualitative monitoring of time-varying physical systems

The authors present an approach to monitoring physical systems which combines quantitative and qualitative techniques. A description of how the technique works is presented, and a prototype software system to perform this monitoring function is described. The qualitative modeling method used relies on the notion of landmark points, which are certain specific values of the system´s variables: landmark points are selected in such a way that they delimit regions of qualitatively different behaviors of the system. A qualitative monitoring approach using critical hypersurfaces is described. An example of deriving a critical hypersurface from the knowledge of one landmark point is shown. The monitoring algorithm presented is implemented as a module called Model Selector in the software system COPER/IC