Design for Manufacturability via Agent Interaction - PowerPoint PPT Presentation

1 / 35
About This Presentation
Title:

Design for Manufacturability via Agent Interaction

Description:

An approach for making the capability of manufacturing process manifest to ... As the designer browses through the human-readable documentation provided by the ... – PowerPoint PPT presentation

Number of Views:84
Avg rating:3.0/5.0
Slides: 36
Provided by: cadcamY
Category:

less

Transcript and Presenter's Notes

Title: Design for Manufacturability via Agent Interaction


1
Design for Manufacturability via Agent Interaction
  • ???
  • i-Design Lab.
  • Yonsei Univ.

2
Abstract
  • An approach for making the capability of
    manufacturing process manifest to designers
    starting with the earliest stage of geometry
    specification
  • The approach involves a dialogue among design and
    manufacturing agents over Internet.
  • The dialog focuses on the specification and
    exchange of process capability models for
    establishing design rules on-demand to ensure
    manufacturability.
  • The models include both declarative knowledge
    and, for those aspect of the process that are
    difficult to represent declaratively,
    platform-independent procedural code which is
    automatically loaded onto the designers
    machines.
  • The approach is being implemented using agent,
    written in Java language, which exchange
    feature-based capability models.
  • The approach is being tested initially on
    machining and shape-deposition processes.

3
FIGURE 1. Part of an agent dialog for
transmitting process capabilities into the design
environment. In this case, a KQML message is sent
from the design agent to obtain a list of
standard features that the process can
accommodate. The message content is in Express
and refer to ontologies (formal agreements on
terms and definitions Gruber 1993) of features
and constraints which, in turn, refer to the
PDES/STEP standard STEP 1992 EXPRESS 1992.
4
Introduction (1)
A CE Environment, supports DFM
A mechanism to evaluate the manufacturability
according to design rules and evaluating
procedures
The process capability models is provided
on-demand to designers by mfg. services in a
machine-readable, platform-independent format
An Architecture
designers
Mfg. Services
Agents
Agents
Formal comm. Interface (Internet)
Process design inf.
Process design inf.
Designers
Mfg. Services
Agents
Agents
  • Motivation
  • novel prototyping such as layered shape
    deposition, laser sintering
  • Not familiar, not be in the CADs DFM modules
  • exploration utilization of these processes
    requires capability models remotely loaded from
    the service provider integrated into the design
    env.

5
Introduction (2) More than HTML
  • Today, a number of services on the internet
  • PC board fabrication, cable harness assembly,
    stereolithography etc.
  • Use HTML forms-based interface to acquire
    information from designers and customize
    displayed data to match designer preferences
  • To make designers confident about using novel
    manufacturing processes, a more intimate dialogue
    between design manufacturing is required. We
    would like to make all aspect of the mfg. process
    accessible.
  • Ex.1) Before submitting designs to mfg. services,
    designers should able to run process simulation
    obtain manufacturability rules and guideline
    load processing constraints have them checked
    and enforced
  • gt designers can quickly become familiar with
    mfg. process as there desire.
  • Ex.2) When essential to minimize mfg. costs / to
    meet stringent demands / tolerances or materials
    properties,
  • gt the designer will want detailed access to
    process characteristics, constraints and costs
    as they apply to his or her design.

6
Introduction (3) A mechanism req.
  • The MOSIS project for VLSI design and
    prototyping, the ability to submit designs with
    confidence their specifications the adoption of
    conservative design rules to specify features
    with confidence their manufacturability.
  • variety of mechanical processes and facilities,
    more over variety of CAD tools, -gt necessary to
    establish a standard mechanism to obtain process
    capability models from disparate processes
    on-demand load them into their preferred CAD
    env.
  • The mechanism should designers enable to locate
    candidate services, evaluate the processes and
    acquire capability models to compute the
    manufacturability (include the ease of
    fabrication process planning) with accuracy to
    meet the design requirements.
  • The communication mechanism also allow
    unsolicited information (such as updates on
    process capabilities) to be transmitted from mfg.
    facilities to designers.

7
Introduction (4) Issues
  • Issues to enable such a dialog
  • How is process capability represented?
  • How are capability models locate and acquired by
    designer?
  • How are capability models mapped into the design
    space?
  • How is the information contained in these models
    applied during design?
  • Particular contributions
  • An architecture for information exchange between
    designers and manufacturing services which
    includes
  • An object-oriented agent template, with
    specializations for design, service and service
    agents (wrapping CAD process planning software)
  • A mechanism for knowledge representation (to
    exchange declarative, procedural and human
    readable inf.)
  • A negotiation protocol which outline the sequence
    of communications between designers and
    manufacturing services.
  • This approach build upon recent developments in
    the application of agent-based software including
    communication protocols representation language
    to exchange information via the Internet.

8
Introduction (5) contents remain
  • Assumptions about mfg design process,
  • A model of process capability
  • The agent architecture used for information
    exchange.
  • agent and technology for sharing objects among
    divers applications.
  • focused on the process of layered shape
    deposition and CNC machining services as examples
    of two very different mfg processes.
  • Appendix A provides details on capability model
    representation
  • Appendix B discusses the agent structure and
    class libraries developed along with pointers to
    down-loadable code for Java Agent Template

9
Layers produced by automatic decomposer for
slider crank mechanism
Gray steel, brown copper support material
10
Robot Leg compacts
The output of the software is a sequence of 3D
shapes and toolpaths.
Embedded components
Part
Support
11
2. Representing Manufacturing capabilities2.1
Design and Manufacturing feature
  • Assumption1 doing feature-based design using 3D
    CADs to represent the solid geom.
  • To match different design and mfg features,
  • Generalized cylinders
  • Efforts for mapping from design features to
    manufacturing features and of extracting features
    (holes, custom) from general three dimensional
    geometries, STEP Tools, Inc online service
  • geometric primitive that can be specialized to
    include common design and manufacturing features
    including those used by machining and layered
    shape deposition.
  • a useful neutral representation for mapping
    manufacturing features lt-gt design space.
  • The parameters can be translated into STEP,
    Part42, entities represented according to AP203
    facilitate in multiple CAD systems (see
    Appendix A).

12
Fig. 2. Generalized cylinders are a useful
geometric representation that can be sepecialized
to match different design and manufacturing
features and facilitate the mapping between them.
Corresponding STEP entities are labeled.
13
2.1 Design and Manufacturing feature (cont.)
  • Assumption 2 Manufacturing process can be
    represented in geometric terms as sequences of
    operations (add, modify, remove geometry
    features) from an initial stock part (may be
    null in the material deposition process)
  • Process may have additional effects (surface
    finish, material hardness, stress state, ).
  • For machining process, mapping between design and
    manufacturing features is fairly close (ex. holes
    pockets produced by drill end-mill)
  • For shape-deposition process, rarely any direct
    relation material layer of compacts to the
    design.

14
2.2 Process Capability Model
  • Represents mfg. services and the processes, using
    Hierarchical taxonomy of manufacturing objects
    (Fig. 3), similar to OO Process.
  • Each mfg object lt attributes lt other mfg objects,
  • Top mfg service lt mfg process lt materials.
  • Process materials lt capability models
    (declarative design rules constraints, process
    simulation procedures, document, )

15
Design rules and constraints
  • Declarative representation of process-derived
    constraints provide a way of assuring
    manufacturability on separating representation of
    the design and process
  • The neutral descriptions of these constraints
    also allow to them be used by constraint
    propagation systems or other reasoning systems
  • Multi-level designers process capabilities
  • Conservative set of rules ensure easy
    manufacturability.
  • Increasingly sophisticated analysis and
    simulation used for designs can not confirm to
    the easy rule.
  • Few exception flagging to save time.

16
Design rules and constraints (cont.)
  • Constraints associated with manufacturing
    features are often easier to express.
  • Machining layered shape deposition design rules
    can be express in terms of the specializations of
    generalized cylinders
  • Machining, feature constraints for easy
    machining
  • maximum length/diameter ratios for holes or
    depth/corner-radius ratios for efficient
    machining with standard drilled and end-mills.
  • Maximum envelope of a part and general
    specifications on tolerances and surface finish,
    refined in terms of part size and overall
    geometry.
  • -gt Appendix A table 1.

17
Design rules and constraints (cont.)
  • Layered shape deposition constraints for easy
    shape deposition -gt Appendix A table 2.
  • Whether the geometry of the design can
    efficiently be decomposed into layers.
    Decomposition function of surface profiles,
    desired surface finish
  • If both undercut non-undercut features are
    contained within the same horizontal band, the
    band must be split into a set of compacts.
  • This complication can be avoided by building the
    design from primives that taper monotonically in
    the direction of layering.

18
Simulation functions
  • Declarative representations of process-related
    constraints or characteristics are impractical,
    Provide functions
  • to simulate the effects of processing on the
    design
  • to analyze elements of the design from the
    standpoint of manufacturability
  • Ex. When machining a part with thin wall section,
    simulate the actions of milling the part using a
    dynamic milling model.
  • can help the designer to understand of the
    process and encourage DFM.
  • Portability problem with procedural code against
    declarative expressions -gt in neutral format (ex.
    STEP)
  • what if questions in batch mode -gt use machine
    independent Java language

19
3. Information Architecture
  • Agent architecture
  • A mechanism for encapsulating and exchanging
    distributed knowledge and functionality.
  • Scalable, modular system with well-defined
    interfaces. engineering agents interface
    agents
  • Autonomous
  • Encapsulate functionality
  • Use an agent communication language
  • Templates
  • Communicates asynchronously with other agents
    distributed over internet using KQML as comm.
    Language
  • Java Agent Template http//cdr.stanford.edu/ABR

20
3. Information Architecture (cont.)
  • functional Community level 3 classes
  • Service agent
  • engineering service on the internet.
  • Standalone app. Integrated with legacy s/w
    local database
  • Broker agent
  • Standalone process, A consortium of service
    agents and function
  • a central directory for agent names, addresses
    and descriptions.
  • Simple type ANS (Agent Name Server)
  • Client agent
  • Potentially transient processes, Java Applet
    loaded via WWW
  • Use brokers to discover specific service
    functionality directly communicate to access.

21
3. Information Architecture (cont.)
  • Because of the diversity of Mfg process design
    env., needs specialized graphical interfaces
    communication infrastructures.
  • functional Individual level 4 classes
  • Agent-context
  • separate the both agent and communication code
    from the execution environment user interface.
  • Same agent to be implemented as a stand-alone
    app., applet, daemon process, not directly depend
    on the presence of GUI.
  • communication interface
  • message output
  • Interface between an agent its contexts
  • the agent it self
  • Synchronously Accepts outputs messages (in
    KQML) via communication interface
  • Resources knowledge and functionality
    (addresses, classes, languages, ontologies)

22
3.1 Agents, distributed objects, CORBA and Java
  • design paradigm (Agents and distributed object)
    an agent-based system built on a distributed
    object substrate.
  • Agent
  • use formal message structure protocol (KQML)
  • maintain state infomation.
  • A level of abstraction above distributed objects
  • implementation (Java and CORBA)
  • Java provide a robust mechanism, minimal
    overhead, object-oriented, platform-independent,
    can dynamically import new code.
  • There are no barrier to integrating Java Template
    with CORBA objects

23
3.1 Agents, distributed objects, CORBA and Java
(cont.)
  • Example scenario
  • Pro/Engineer CAD platform
  • Shape deposition, CNC machining mfg process
  • -gt http//cdr.standford.edu/RVPP/
  • Cax tools ? design agents,Mfg service ? service
    agent
  • Comm. Is facilitated by service broker.

24
Sequence of designers actions
  • 1. Locate potential service/process combination.
  • 2. Evaluate a specific manufacturing service.
  • 3. Evaluate a process.
  • Acquire process capability model
  • 4. Use the process capability model to constrain
    the design process.
  • Feature constraint -gtprocess simulation
  • 5. Submit the design for fabrication.

25
4. Implementation status and future work
  • An approach enabling s/w agent to
  • Locate each other
  • exchange messages
  • automatically load resources
  • declarative(constaints) procedural(process
    simulations)
  • Implemented with Java Agent Template
  • Next step
  • Experiment with agent dialogues among design and
    manufacturing services to evaluate the
    effectiveness and limitations of this approach.
  • An object class hierarchy for process
    descriptions and capabilities has been
    established.
  • The generalized cylinder has been adopted as
    initial generic feature type.
  • Initial experiments will be conducted in
    collaboration with prototyping services.

26
Appendix A Generalized cylinder representation
and constraints
  • Generalized cylinder feature
  • Nominal geometry is defined by the following sets
    of constraints
  • Axis Constraints parameterized axis function
    x(s), y(s), z(s) and their derivatives (the
    curvature and torsion of the axis)
  • Cross-sectional surface constraints closed curve
    defining the edge of the surface.
  • Sweeping transformation constraints properties
    of the transformation (dependency on axis arc
    length)
  • The CGS operation to combine into more complex
    solids
  • Operator constraints subset of union,
    difference
  • Operand constraints coordinate transformation
    matrix

27
Appendix A. Table 1, 2
28
Appendix B details on the Java Agent Template
  • Agent Life Cycle
  • Execute of the Agent Context create itself,
    associated communication interface, message
    output and GUI components.
  • Initialization file is retrieved and
    processed(contains a set of KQML messages, one
    of which has been the address of ANS)
  • Connect to the internet and registration with the
    ANS
  • Transformation address invalidation message is
    sent to the ANS
  • Addressing every agent possesses a unique name
    and address. Address consist of a host name and a
    port. An ANS maintain an archive of all agent
    names and address (and enforces unique naming)

29
Appendix B details on the Java Agent Template
(cont.)
  • Message Interpretation
  • The message is parsed, at the top level,
    according the KQML syntax.
  • The ontology field for the message is checked
    against the agents local ontologies resource. If
    the specified ontology subclass is not present,
    the agent retrieves it before continuing with
    the message processing.
  • If the specified Ontology is successfully
    obtained, the interpretMessage() method of this
    ontology object is called to process the present
    message. This method first checks the Language
    field, fi the language is not locally known, it
    is retrieved before further processing if the
    language is supported and can be obtained, the
    content field of the message is parsed according
    to that language.
  • The action to be taken on the message content is
    encoded with the ontology class.

30
3.1 Agents, distributed objects, CORBA and Java
(cont.)
  • Service broker represent a group of service agent
    and can provide high level filtering for
    designers.
  • Information concerning process capabilities and
    design characteristics will be exchange between
    agents

31
Sequence of actions taken by the designer
  • 3.2 Locate potential service/process
    combinations.
  • The designer execute design agent (via WWW applet
    from service broker site / by execute a
    stand-alone agent
  • The agent is initialized with location of one or
    more service broker agents (representing groups
    of manufacturing services)
  • The designer will submit to the selected service
    broker (via design agent) information about the
    design requirements which can be used for
    high-level filtering of potential service/process
    combinations.
  • This filter has not implemented but important in
    overall process and should be based on the
    following general categories of design
    constraints
  • Purchasing/scheduling constraints ( maximum
    /hour for machining time, minimum lot size,
    maximum lead time)
  • Physical constraints material properties,
    geometry (required stock size / general volume,
    symmetries, solid features, surface types,
    tolerances)

32
Sequence of actions taken by the designer (cont.)
  • 3.3 Evaluate a specific manufacturing service.
  • Once a list of potential mfg services has been
    obtained, the designer will undertake a detailed
    evaluation of the characteristics and
    capabilities of each.
  • Each services is modeled by a hierarchy of
    manufacturing objects. Communication between the
    design agent and service agent will enable the
    designer to search this processes/material
    combinations. As the designer browses through the
    human-readable documentation provided by the
    service, the design agent builds an object model
    of the manufacturing service and its process.

33
Sequence of actions taken by the designer (cont.)
  • 3.4 Evaluate a process.
  • The next step is to acquire process capability
    models.
  • Declarative components of the capability model
    will be exchanged using KQML messages,Procedural
    elements will be loaded as Java classes.
  • In the present implementation, the capability
    model provides information for evaluating the
    manufacturability of a designs nominal geometry.
    Design rules consist of constraints on the
    geometry of generalized cylinder features and on
    the CGS operations used to combine those features
    into more complex solid.
  • Constrains (Appendix A) are represented
    declaratively using the Express languages.
  • Each capabiliry model will also include process
    simulation procedures which take design meeting
    the constraints and return, if the simulation is
    successful, trees of processing feature used to
    realize the design.

34
Sequence of actions taken by the designer (cont.)
  • 3.5 Use the process capability model to constrain
    the design process.
  • Acquired capability models will be mapped into a
    format suitable for integration with the
    designers preferred CAD system(STEP AP 203).
  • Feature constraints will be applied against all
    feature instantiations and CGS operations
    attempted by the designer.
  • Process simulations will be configured to accept
    input from the CAD system and return output which
    can be mapped from the CAD system can use.
  • These simulation procedures may be entirely
    represented by local java code or can be
    implemented as a Java interface (locally
    executed) which communicates to analysis code
    running on a remote machine.

35
Sequence of actions taken by the designer (cont.)
  • 3.6 Submit the design for fablication.
  • Completed designs will be submitted to the
    service agent which provided the process
    capability model. The manufacturing service
    represented by this agent can be then conduct
    process planning and quote generation in light of
    the applied costraints.
Write a Comment
User Comments (0)
About PowerShow.com