US 4,965,743 A · Discrete event simulation tool for analysis of qualitative models of continuous processing system

Abstract

An artificial intelligence design and qualitative modelling tool is disclosed for creating computer models and simulating therein continuous activities, functions and/or behavior using developed discrete event techniquers. Conveniently, the tool is organized in four modules: library design module, model construction module, simulation module, and experimentation and analysis. The library design module supports the building of library knowledge including component classes and elements pertinent to a particular domain of continuous activities, functions and behavior being modelled. The continuous behavior is defined discretely with respect to invocation statements, effect statements and time delays. The functionality of the components is defined in terms of variable cluster instances, independent processes and modes, further defined in terms of mode transition processes and mode dependent processes. Model construction utilizes the hierarchy of libraries and connects them with appropriate relations. The simulation executes a specialized initialization routine and executes events in a manner that includes selective inherency of characteristics through the library hierarchy and runs the events through a time and event schema until the event queue in the simulator is emptied. The experimentation and analysis module supports analysis through the generation of appropriate log files and graphics developments and includes the ability of log file comparisons.

Claims25

Dependent claims

A method for off-line experiments and analyses of an application specific system of components using qualitative modeling and discrete event simulation to analyze dynamic system effects of changes in components with continuous behavior, including malfunction, comprising the steps of:

providing a library knowledge base of domain specific modeling elements which includes components with modes, mode transition, variables, and behavior descriptions, a qualitative algebra for defining and combining component variables, and relations to link the components, constructed relative to the application specific system,
providing a model knowledge base for the application specific system, which includes component instances, each with a current mode, linked by relation instances,
providing change control mechanisms, independent and distinct from the domain specific modeling elements, to select and control effects of changes within the model knowledge base, to control a time-ordered simulation,
inputting data, which may include malfunction data, to effect changes in the component instances within the model knowledge base, either by changing a variable value of a component instance or by changing the current mode of a component instance,
updating variable values and the current mode of component instances, and propagating changes through the model knowledge base in a time-ordered fashion in response to the input data and resulting changes, under control of the change control mechanisms,
and outputting information in response to the changes in variable values and the current mode of component instances and to the propagation of changes through the model knowledge base, to support analysis of effects of changes which may include malfunctions, on modes of component instances, and to support analysis of diagnostic experiments in which effects of malfunctions on the system are compared.

3 more elements

A simulation and analysis tool for off-line experiments and analyses of an application specific system of components using qualitative modeling and discrete event simulation to analyze dynamic system effects of changes in components with continuous behavior, including malfunctions, comprising:

a library knowledge base of domain specific modeling elements which includes components with modes, mode transitions, variables, and behavior descriptions, a qualitative algebra for defining and combining component variables, and relations to link the components, constructed relative to the application specific system,
a model knowledge base for the application specific system which includes component instances, each with a current mode and linked by relation instances,
means for inputting data to effect changes of component instances within the model knowledge base, either by changing a variable value of a component instance or by changing the current mode of a component instance,
change control mechanisms, independent and distinct from the domain specific modeling elements, to select the control effects of changes within the model knowledge base, by updating variable values and the current mode of the component instances, and by propagating changes in the model knowledge base in a time-ordered fashion in response to input data and the resulting changes, under control of the change control mechanisms,
means for applying the change control mechanisms to select and control changes in the component instance variables and the current mode of the component instances,
a discrete event simulator including an event queue containing an ordered list of simulation events, a clock containing the simulation time, and the simulation events, independent and distinct from the domain specific modeling elements, that are created under control of the change control mechanisms,
means for running the discrete event simulator,
and means for outputting information in response to changes of variable values and the current mode of component instances, and to the propagation of changes through the model knowledge base.

5 more elements

Dependencies are inferred from the claim text.

Discrete event simulation tool for analysis of qualitative models of continuous processing system

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Discrete event simulation tool for analysis of qualitative models of continuous processing system

Life of this patent

Abstract

Claims25