Building models for qualitative prediction of system dynamic behavior

The authors present a method of automatically constructing a model or a set of constraints from domain principles for solving the dynamic behavior of a mechanical system through qualitative simulation. The following issues are emphasized: (1) the extraction of a necessary and sufficient set of system constraints which provides the minimum uncertainty associated with qualitative simulation, and (2) the modification of system constraints through time by detecting and identifying ´system discontinuities´. The first is accomplished by describing a mechanical system by a collection of object and inter-connection primitives, which allows selection of the final set of constraints having the minimum complexity and uncertainty, based on the A* algorithm with heuristics providing the problem solving expertise. The second is accomplished by monitoring whether the states of any individual subsystems evolve to system discontinuities represented by intra/inter subsystem critical states