THE SUPPORTING ROLE OF ONTOLOGY IN A SIMULATION SYSTEM FOR COUNTERMEASURE EVALUATION Nelia Lombard DPSS, CSIR

Ontologies and Simulations What are the possible advantages that an ontology might have in the simulation environment? Can an ontology provide solutions to some of the challenges to be dealt with in the countermeasure simulation system? Introduction

Contents What is an Ontology The Countermeasure Simulation System Possible Role of Ontology in the Simulation System Constructing the Ontology Lessons Learned Conclusions and Future Development

What is Ontology? Study the meaning of being How an object relates to the world and to itself Describes the world Not a taxonomy Taxonomy: Oryx->Helicopter->Aircraft- >Transport Ontology: Oryx has countermeasures Oryx can hover

Ontology in Information Systems and Computing The artifact present, in a formal way, the knowledge of a domain as a set of concepts and relationships between the concepts, for the purpose of reasoning.

Use of Ontologies Share a common understanding of the structure of information and the concepts A common vocabulary Enable reuse of the domain knowledge For example, time ontology Make domain assumptions explicit Separate domain knowledge from the operational knowledge Analysis of domain knowledge

The Countermeasure Simulation System Purpose: Evaluate countermeasure design Determine aircraft vulnerability Simulate the interaction between models as results of specific events Use realistic models

The Countermeasure Simulation System The Simulation Scenario Type of aircraft: e.g. Oryx Flight plan: How will the Oryx fly? Type of missile threat Type of countermeasure and the dispensing logic Atmospheric conditions: e.g. clear skies or fog Terrain model

The Countermeasure Simulation System Extensible Markup Language (XML) is a set of rules for encoding documents in machine-readable format Model parameters are set up in XML files Simulation output written to XML files Name=”TestPoint1” FileName =”Oryx.xml” Type=”DPSSORYX” /> FileName=”ThreatType1.xml” Type=”BaseMissile” /> FileName=”Atmo.xml” />

The Countermeasure Simulation System Simulation results processed to show effectiveness of countermeasure against threat Results: 3D Viewer Videos

Possible Role of Ontology in the Countermeasure Simulation System To know what is available in the system Guideline for new models High-level description Verify and validation of scenarios Reverse engineer previous simulations

Constructing the Ontology Where will it be used? How can it add benefit? Purpose To capture concepts in a simulation scenario Scope A Simulation Scenario

Creating the Ontology (1) Identify the classes Scenario, Target, Threat, Atmosphere, Countermeasure Define object properties Relationships between classes Target has countermeasure Scenario has target Define data properties Position, Velocity

Creating the Ontology (2) Create individuals Specific objects used in the simulation Target: Oryx Atmosphere: Fog Countermeasure: Flare Scenario: ScenarioFlareLeftOryx200ft30kn

Classes in the Ontology

Object Properties

Data Properties

Ontology: Lessons Learned Naming of classes Consistency Agreement Classes versus instances Match the real world Modeling roles as classes Classes can loose their roles over time

Conclusions Clear, common understanding of what is in the domain High-level description Capture the meaning of objects Future functionality: Use ontology to set up scenario and to reason about validity of scenario

Commentary Questions?Suggestions Input