1DATLab Research Overview

Creating Design Machines for Machine Design

Linda C. SchmidtMechanical Engineering Department

Institute for Systems ResearchUniversity of Maryland

December 1, 2000

2DATLab Research Overview

THE DATLab

Mission The Designer Assistance Tool Laboratory at the University of Maryland provides state-of-the-art fundamental research and implementation strategies to improve the quality of design processes and outcomes.

Vision Our current research emphasis focuses applying grammar-based generative design strategies to design tasks, from concept generation to optimization of detailed designs.

Values DATLab researchers operate with enthusiasm, professionalism, and a spirit of innovation.

3DATLab Research Overview

Generative Designer Assistance Tools: Automated Function to Form Design Generation

Accomplishment– We seek a unified grammar-

based approach to generating alternatives from functional descriptions of designs.

– Prior work demonstrates the Assembler

– Current work explores the HTN planning approach

Significance / Impact

Designers can benefit from techniques and tools that generate feasible design solutions.

Key People InvolvedLinda C. Schmidt and Hai Shi

ReferencesSchmidt, L., Shi, H. and Sameer, K., “The “Generation Gap”: A CSP Approach Linking Function to Form Grammar Generation”, To appear in Journal of Mechanical Design, 2000.Shi, H. and Schmidt, L., “Comparing HTN Planning Method with Grammar-Based Approach in Generative Design”, Submitted to Design Automation Conference, 2000

t3,2

t3,1

t1,3 t2,3

t1,2t2,2

t15,1

t3,1t3,1

t17,1

4DATLab Research Overview

Results of the Assembler

Result 1

Result 2

Result 3

Result 4 Result 5

Result 6 Result 7

5DATLab Research Overview

Modeling Generative Design As HTN Planning Problem

Top task

Methods (Refine Rules)

Subtask A Subtask B Subtask C

Primitive task a Primitive task b Primitive task c Primitive task d Primitive task e

In a certain order to fulfil the top task

Overall functionality

Basic functions and final concepts

Sub-functions

Func

tion

dec

ompo

siti

on

2. Count Wheels 1. Mount a Wheel 1. Mount a Piece 2. Count Surface

Create Cart

1. Create Rolling 2. Provide Surface

Mount Wheels Mount Pieces

Add a Subassembly

2. Choose a Subassembly

3. Check joints available

4. Assemble the Subassembly

3. Mount Wheels 3. Mount Pieces

Add a Piece

1. Choose a Piece

2. Check joints available

3. Assemble the Piece

1. Add a Piece

1. Choose a Piece

2. Check joints available

3. Assemble the Piece

Non-primitive task (non-basic function or concept)

Primitive task (basic function or concept)

Total ordered method

Sub-function

Function

Form

•The task set consists of the hierarchical functions that include basic functions (primitive tasks) and non-basic functions (non-primitive tasks)-A primitive task is a final solution concept of a basic function in the different levels that can be accomplished directly-A non-primitive task is a function that can not be accomplished directly and need to be decomposed into lower level sub-functions

•Methods (refining rules) are design principles and special field knowledge from experienced designers. They tell the HTN planner how to decompose functions, which means how a function (task) can be accomplished by a certain set of lower level sub-functions (task network)

6DATLab Research Overview

Grammar-based Designer Assistance Tool

For Epicyclic Gear Trains: An OverviewAccomplishment

– grammar-based graph generation engine

– other is the functional schematic sketching module.

Significance / Impact– This designer assistance tool

helps designers to generate concepts of EGT structure during the conceptual design phase

– an initial exploration of using grammar-based design to build a practical designer assistance tool

Key People Involved

Linda C. Schmidt and Xin Li

References

–Li, X., Schmidt, L., "Grammar-based Designer Assistance Tool for Epicyclic Gear Train", Presented at DETC 2000, Baltimore, MD.

–Chang, E., Li, X, Schmidt, L. MS Thesis, December 2000

DAT for EGT

Grammar-based Generation Engine

Functional Schematic Sketching Module

EGT Designer

Design Specifications

Recommended Concept

Interface

Labeled graph

2

4

1 3

a

a

b

Functional Schematic

Concept Selection Module

7DATLab Research Overview

Sub-task and Procedures

• Structural Synthesis based on graph-grammar

• Functional Schematic Sketching

• Concept selection

• Three dimensional drawing

• Behavior Model Proxy

1

3 2

4

1 3

2

4

1 3

Rule 1

2

4

1 3

a

a

b Labeling

Rule 1 Format Rule 5 Format

Rule 5 1,p 1,q 1,q 1,p

Rule 1 1, p

1, 2

1, p + 1 1, q + 1 1, q

Graph label: [ 3,3]

Graph label: [ 4,5]

Graph label: [ 4,5]

a

b 1

2

3

4

Grammar-based Designer Assistance Tool

For Epicyclic Gear Trains

8DATLab Research Overview

One-degree-of-freedom EGT up to 6 links can be generated by this system

Area 1: Design specification area

Area 4: User controls for viewing alternatives

Area 2: Function schematic display area

Area 2: System status window

Grammar-based Designer Assistance Tool

For Epicyclic Gear Trains: Interface and Results

Area 1- User inputs design requirementsArea 2- Functional schematic is sketched automaticallyArea 3- Text output will appearArea 4- User can select and view different design

9DATLab Research Overview

The Need for Behavior-based Representation Systems in

Design

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Detailed Form Model

Response to Stimuli Set X

Under Use Condition Y

AVOID: Behavior 1 Behavior 2 ENHANCE:

Behavior 1 Behavior 2

Form Model Proxy

Behavior Model Proxy

Detailed Function Model

(Intended Behavior)

Feedback to Designer Constraint

Set

Set

Analysis Models

Conceptual Design

Detail Design

Detailed Form Model

Form Model Proxy

Detailed Function Model

(Intended Behavior)

Feedback to Designer Reduced

Constraint Set

General Behavior

Model Intermediate Behavior

Model Detailed Behavior

Model

Diagram of the design process emphasizing the role of form,

function, and behavior

Modified Design Process