1. Ontology Reuse In MBSE Henson Graves Abstract January 2011
The promise of Model-based systems engineering (MBSE) is to reduce traditional problems of complexity management and allow for design evaluation before implementation. The promise has been difficult to realize. The promise requires the ability to share models without the necessity of the model being accompanied by a subject matter expert to explain what the model means and what assumptions are made. An ontological foundation, or formal foundation, for a modeling language enables model sharing between humans and computers as the meaning of the model is in a form that is independent of subject matter experts. An ontological foundation not only provides the ability to share models, but also provides the justification for inference.
SysML does not currently have an ontological foundation. However, it can be retrofitted with one. The retrofit is outlined using a SysML model as an example. The formal foundation uses intuitionistic type theory. the semantics of type theory accords well with the informal semantics. An intuitionistic type theory is generated from axioms expressed in the language of a multi-sorted signature of types, properties, and operations.
Henson Graves
January 2011

2. Outline
Examples of reuse of existing ontologies
Potential reuse Opportunities
What are the benefits
Approaches to ontology reuse
Some observations on reuse
Next steps

3. Ontology Reuse In MBSE
Examples
Units and measures
Physical interactions (laws)
Material classification and properties
Enterprise concepts
Levels of rigor in ontologies
Vocabulary
Informal textual semantics of vocabulary
Formal (axiomatic) semantics

4. Potential Reuse Opportunities
Ontology for events
Ontology for computational methods
Ontology for experimental setups
Ontology for system engineering artifacts
Ontology for product structure and attributes
Ontology for measurement value spaces

5. Ontologies may be Organized into hierarchies
Foundation Ontologies
Base, Mission, Project,
Quantities-Units-Dimensions-Values, Analysis, Artifact, Architecture Description
Discipline Ontologies
Mechanical, Electrical, Physics, Thermal, Propulsion, Attitude Control, Navigation, …
Application Ontologies
Star Tracker, Sun Sensor, Reaction Wheel, Thruster,..
2-axis vs. 3-axis S/C; Radio vs. optical comm; …
use
Fundamental terms use in all projects, disciplines, and applications
Discipline-specific terms specified and owned by discipline experts
Kinds of items that are modeled in a project; specified and owned by application experts
Focus is integration and interoperation
Focus is reuse

6. What Are The Benefits
Leveraging reusable knowledge to jump start engineering
Basis for model integration and large scale collaboration
Standardization of engineering work products

7. Approaches To Achieving Reuse
Opportunistic Reuse: identify candidate ontologies, acquire and refurbish and make available
Designed Reuse: establish modeling principles and start over, making use of lessons learned

8. Opportunistic Reuse
Identify candidate ontologies, acquire and refurbish and make available
Opportunistic reuse has only had limited success in
Hardware component design
Software design
Reuse only worked well when the right units of modularization were understood, e.g. ASICS, Patterns

9. Designed Reuse Process
Collect any reuse ontology candidates
Document modeling principles to be used in redo
Chose a foundation (upper) ontology, e.g., DOLCE in accord with design principles
Modify if needed, based on experience
Create specializations of subsets of the upper ontology, e.g.,
For physical laws, enterprise concepts
Repeat as needed

10. Upper Ontology Concepts That Might Be Useful
Classes
Properties

11. Example From Upper Ontologies That Is Particularly Useful: Qualities
Physical Object
hasQuality
Quality
Type
Car
hasMeasuredWeight
Measured
Weight
inPounds
1D Space
With units
The DUL class hierarchy includes classes for Physical Object, Quality, Event, and Region. These classes capture many concepts needed for systems engineering. Physical objects exist in time and have qualities such as weight, shape, color that are observed or measured. DUL differentiates between individual qualities (e.g., the weight of a specific material item), quality types (weight and color), quality spaces, and quality positions (locations in quality spaces). These together with Regions (measure spaces) which is used as the value space for a quality of an entity.
DOLCE differentiates between individual qualities (e.g., the weight of a specific material item), quality types (weight and color) quality spaces, and quality positions (locations in quality spaces) these, together with measure spaces (which coordinitize the quality spaces). Quality – used to classify entities that are perceived or measured, have values, about some other entity. Examples of qualities are color, length, mass, and shape, Region – used to classify the actual value of qualities associated with particular entities.
Empty 1969 VW
<Vw,mwt>
Weight object
<mwt, 18k>
18K pounds

12. Next Steps For Ontology Reuse Development
Get a working group established for this purpose
Collect any reuse ontology candidates
Document modeling principles to be used