1. Part 1. Constrained Objects
Enhancing engineering design and analysis interoperability,
Part 1. Constrained Objects
First M.I.T. Conference on Computational Fluid and Solid Mechanics
June, 2001
Miyako W. Wilson, Russell Peak, and Robert E. Fulton
Georgia Institute of Technology
Seamless communication between People, models, and tools
This topic has 3 papers.

2. Motivation
The need for a unified physical behavior modeling representation with the following characteristics
Has tailoring for design-analysis integration including supports for multi-fidelity idealization, product-specific analysis templates, and CAD-CAE tool interoperability.
Supports product information-driven analysis (I.e., supports plugging in detail design objects and idealizing them into a diversity of analysis models).
Has computer-processible lexical forms along with human-friendly graphical forms.
Represents relations in a non-casual matter (I.e., enables multi-directional combinations of model inputs/outputs).
Capture engineering knowledge in a modular reusable form
Constraint object take advantage of the followings techniques
So our approach for solving this problem is constrained object.

3. Constrained Object (COB) Overview - Techniques Leveraged
Object-oriented modeling [Lalonde & Pugh, et al.1990, Muller 1997]
class vs instance
inheritance
Constraint graph techniques [Borning, et al. 1990]
relations without fixed input/output direction
Declarative knowledge representation (non-casual)
Characterized by entities, attributes, and relations
Constraint object take advantage of the followings techniques

4. COB Representation Components
Users
Definition
Languages
Graphical
Representations
Definition
Languages
Graphical
Representations
COB
Meta
Information
Model
Protocol
Developers
Highlight about this technique
Meta
Information
Model
Protocol

5. Example COB Structure (COS) Spring Primitive
Figure
Relations
Traditional Form
Constraint Schematic-S
Spring L D F k 1 x 2
Subsystem View
(for reuse by other COBs)
COB spring ;
undeformed_length, L₀ : REAL;
spring_constant, k : REAL;
start, x₁ : REAL;
end, x₂ : REAL;
length, L : REAL;
total_elongation, ΔL : REAL;
force, F : REAL;
RELATIONS
r1 : "<length> == <end> - <start>";
r2 : "<total_elongation> == <length> - <undeformed_length>";
r3 : "<force> == <spring_constant> * <total_elongation>";
END_COB;
COS Language
7 attributes and 3 relations
How Traditional Spring example fits to COB.
Subsystem - encapsulate/ modular form
inside the subsystem contains constraint schematic above.

6. Example COB Instance (COI) Spring Primitive
Lexical COB Instance (COI)
Constraint Schematic-I
example 1, state 1.1
state 1.0 (unsolved):
INSTANCE_OF spring;
undeformed_length : 20.0;
spring_constant : 5.0;
total_elongation : ?;
force : 10.0;
END_INSTANCE;
state 1.1 (solved):
start : ?;
end : ?;
length : 22.0;
total_elongation : 2.0;
Basic Constraint Schematic-I Notation

7. Multi-Directional I/O (non-causal) Spring Primitive
Constraint Schematic-I
Lexical COB Instance (COI)
Design Verification
example 1, state 1.1
state 5.0 (unsolved):
INSTANCE_OF spring;
undeformed_length : 20.0;
spring_constant : ?;
start : 10.0;
length : 22.0;
force : 40.0;
END_INSTANCE;
state 5.1 (solved):
spring_constant : 20.0;
end : 32.0;
total_elongation : 2.0;
Design Synthesis
example 1, state 5.1

8. COB Representation Traditional Form: Spring System
System Figure
Free Body Diagrams
Variables and Relations
System-Level Relations
(Boundary Conditions)
The spring example shows how COB can be used as analysis template.
In this two spring system example shows
Taking traditional problem and capturing knowledge in object oriented form
Two springs connected in series, one end fixed to wall, other end has applied force.
In order to analyze the system in traditional way, first the free body diagrams ()
are created. Then, the relations similar to the one in are listed so that the next step is to assign values and solve any unknown values.
Spring 1
Spring 2

9. COB Representation Constraint Graph: Spring System
L10 k1
L1 L1
L20 k2
x21
x22 F2
L2 L2 F1
bc4
r12
r13
r22
r23
bc5
bc6
bc3
r11
r21
bc2
bc1
x11
x12 u1 u2 P
Spring 2
spring2
spring1
System level
This slide shows Constraint network
circle is variable
box represent relation
Blue areas shows spring1 and spring2 variable and relations
that is repeated for both springs
So opportunity to define modular reusable object
Constraint Graph-S

10. COB Representation Extended Constraint Graph-S: Two Spring System
One step is first attributes that belong to spring one and relations.
Grouping
Part of overall system
Groups objects & relations into parent objects
Object-oriented vs. flattened
partial
(BC relations not included)

11. COB Representation Constraint Schematic: Spring System
Constraint Graph-S
Constraint Schematic-S
bc1
bc3 P
bc4 F 1 k F 1 2 k 2
spring 1
r13
spring2
r23 x L
spring1
Spring
Elementary L D F k 1 x 2 11 1 x L D L 22 2
r11 D L 1
r21 2
r12
r22 x x 12 21
bc5 1 u L
bc6 L 10
bc5 20
bc1 u u 11 = x 1 2
bc2
This
Take use of the subsystem spring in the blue areas
Spring is template and reusing here
bc2
bc3
spring 2
Spring
Elementary L D F k 1 x 2
bc4 P
Encapsulated form (hides details)
Template re-usage 1 2 u L + D = 2 u
bc6

12. COB Representation Constraint Schematic-S: Spring System
Analysis Primitives
with Encapsulated Relations
spring 1
Spring
Elementary L D F k 1 x 2
System-Level Relations
(Boundary Conditions)
bc5 1 u
bc1 11 = x
bc2
bc3
spring 2
Spring
Elementary L D F k 1 x 2
bc4 P 1 2 u L + D = 2 u
bc6

13. COB Representation COS Language: Spring System
Constraint Schematic-S
COB spring_system ;
spring1 : spring;
spring2 : spring;
deformation1, u₁ : REAL;
deformation2, u₂ : REAL;
load, P : REAL;
RELATIONS
r1 : "<spring1.start> == 0.0";
r2 : "<spring1.end> == <spring2.start>";
r3 : "<spring1.force> == <spring2.force>";
r4 : "<spring2.force> == <load>";
r5 : "<deformation1> == <spring1.total_elongation>";
r6 : "<deformation2> == <spring2.total_elongation> + <deformation1>";
END_COB;
r1-r3 relations in spring COB is not needed included in spring_system COB.
R1-r6 relations in spring system COB are the boundary conditions

14. COB Representation COB Instance (COI): Spring System
COI Language
Constraint Schematic-I
state 1.0 (unsolved):
INSTANCE_OF spring_system;
spring1.undeformed_length : 8.0;
spring1.spring_constant : 5.5;
spring2.undeformed_length : 8.0;
spring2.spring_constant : 6.0;
load : 10.0;
deformation2 : ?;
END_INSTANCE;
state 1.1 (solved):
spring1.start : 0.0;
spring1.end : 9.818;
spring1.force : 10.0;
spring1.total_elongation : 1.818;
spring1.length : 9.818;
spring2.start : 9.818;
spring2.force : 10.0;
spring2.total_elongation : 1.667;
spring2.length : 9.667;
spring2.end : 19.48;
deformation1 : 1.818;
deformation2 : 3.485;

15. COB Representation Lexical and Graphical Views
COB Structure (COS)
COB Instance (COI)
Constraint Schematic-S
Subsystem -S view
COB Instance(COI)
Language
Extended Constraint Graphs-I
Constraint Schematic-I
STEP
Part 21
200
lbs
30e6
psi
100
20.2 in
R101
COB Structure (COS)
Language
I/O Tables
Object Relationship Diagram
Constraint Graphs-S
Purpose of different views
Each view enphasize different aspect to help human understanding
Text form enable computer processing
Extended Constraint Graphs-S
HTML
Express-G
STEP
Express
HTML
Constraint Graph = Constraint Network

16. COB Representation Components (see Wilson,2000)
Users
Definition
Languages
Graphical
Representations
Definition
Languages
Graphical
Representations
COB
Meta
Information
Model
Protocol
Developers
Highlight about this technique
Meta
Information
Model
Protocol

17. COB Meta Information Model & Protocol Generic Nature
Metadata
Meta Information
Model
Protocol
Generic
Data
COB
Structure
Definition
Data
COB
Instance
Definition
Data
COS
COI
Information model is higher level mode for COS and COI
allow to describe structure object and specific instance of objects
any COBs in general
The protocol operates on any cobs for manipulation
Specific
Structure
Data
Specific
Instance
Data
Definition Languages
10.0
20.0
5.0
22.0
2.0
32.0
Example: L k x 2 F D 1
Graphical Representations

18. XaiTools ™ X-Analysis Integration Toolkit
Java
COB Definition Files
Solvers
COB
Instances
Structures
Constraint Network
Constraint
Solver
Mathematica
FEA
ANSYS
COB Meta Information Model -> classes
COB Protocol -> methods (API)
API
COB based
Design/Analysis Tools
Generic
Viewer

19. Engineering Service Bureau
Using Internet/Intranet-based Analysis Solvers Thick Client Architecture
Users
Engineering Service Bureau
Client PCs
Host Machines
Thick Client
CORBA Daemon
XaiTools
Iona orbixdj
CORBA IIOP
CORBA Servers
Internet
XaiTools Ansys
Solver Server
XaiTools Ansys
Solver Server
XaiTools Math.
Solver Server
XaiTools Ansys
Solver Server
Part of implementation, solvers can be accessed through over internet using Middelware tech.
June’99-Present:
EIS Lab
- Regular internal use
U-Engineer.com
- Demo usage:
- US
- Japan
Nov.’00-Present:
Electronics Co.
- Began production usage
(dept. Intranet)
Future:
Company Intranet
and/or
(commercial)
- Other solvers
FEA Solvers
Ansys
Internet/Intranet
...
Math Solvers
Mathematica

20. XaiTools ™ COB Browser Spring System
Functionality:
View
Change value
Change I/O
Activate/Disactivate relations
This show
Like oo spread sheet.
This shows one of tool which has the functionality as shown.
Look at detail in later

21. Constrained Object (COB) Representation
Capabilities & features:
Various forms: computable lexical forms, graphical forms
Sub/supertypes, basic aggregates, multi-fidelity objects
Multi-directionality (I/O change)
Wrapping external programs as white box relations
Analysis module/template applications (XAI):
Product model idealizations
Explicit associativity relations with design models & other analyses
White box reuse of existing tools (e.g., FEA, in-house codes)
Reusable, adaptable analysis building blocks
Synthesis (sizing) and verification (analysis)
General information modeling capability
Apply to Analysis integration
Part2 talk more

22. Constrained Objects (cont
Constrained Objects (cont.) Representation Characteristics & Advantages
Overall characteristics
Declarative knowledge representation (non-causal)
Combining object & constraint graph techniques
COBs = (STEP EXPRESS subset) (constraint graph concepts & views)
Advantages over traditional analysis representations
Greater solution control
Richer semantics (e.g., equations wrapped in engineering context)
Unified view of diverse capabilities
Capture of reusable knowledge
Enhanced development of complex analysis models