STEP for Multi-Disciplinary Model Management: “Intelligent PDM” NASA’s Intelligent Synthesis Environment (ISE) initiative and its Collaborative Engineering Environment (CEE) will require sophisticated capabilities for the sharing and configuration management of engineering models. Engineers using these advanced environments will have state-of-the-art tools for Computer-Aided Design, Analysis, Simulation, Systems Engineering, Software Engineering, and other engineering disciplines. Each of these discipline’s tools focuses on a view that is in some ways unique and separate from other engineering disciplines, and yet the design of a particular item often requires a collaboration between two or more disciplines -- for example, a printed circuit assembly must be designed and analyzed from the mechanical as well as the electrical point of view in order to meet all system requirements. The engineering models on which the tools of different disciplines operate are unique in important ways, but if tools from different disciplines are brought to bear on a single product, it is important for data integrity that all tools work to a common underlying structure. This common underlying structure is contained in the STEP standard (ISO 10303), “STandard for the Exchange of Product model data”. This presentation will discuss how STEP can be used to provide a common structure to which all engineering discipline models refer, so that data integrity and configuration management are maintained. Stephen C. Waterbury NASA/Goddard Space Flight Center Presentation for the ESA/NASA Video/Teleconference “STEP for Aerospace Applications” July 16, 1999

The Product Master Model The Product Master Model is a integrated global model of the totality of information contained in all engineering discipline view-models of the product: Mechanical design (MCAD) Electronic design (ECAD) Analysis (CAE) -- all types Systems (requirements, behavior, function, rules) Simulation Visualization STEP Application Protocols provide the basis for a Product Master Model

Without PDM, CAx Models are “Islands” Models Are Isolated Within Disciplines Mechanical (MCAD) Analysis (CAE) Electronic (ECAD) Systems Engineering Tools Discipline- Specific Model Databases Item X MCAD Item X CAE Item X ECAD Item X SE CAD tools typically either save their data to files or to a vendor-specific database, which is also usually specific to a particular engineering discipline, such as mechanical design. There are some vendor-specific solutions to sharing data between two disciplines, such as mechanical design and finite-element analysis, for example, but these solutions are not open, extensible architectures. In a collaborative engineering environment in which many engineering disciplines are involved, the most valuable resources are the engineers themselves. The engineers should therefore be provided with the “best-of-breed” tools with which they will be most comfortable, capable, and efficient. Although it is sometimes desirable to select a single tool vendor as an enterprise-wide solution in a single engineering discipline (e.g., mechanical CAD), no single vendor can provide a tool suite that contains the best solution for *every* engineering discipline, Therefore, particularly in large enterprises like NASA, the engineering environment includes a wide variety of disciplines, tools, and vendors. The challenge of sharing and managing the data in this type of environment is precisely the motivation for the development of the STEP standard, which is designed to enable multi-tool and multi-discipline data exchange. Item Y MCAD Item Y CAE Item Y ECAD Item Y SE

Current Product Data Management (PDM): Models Can Be Associated But Not Integrated Mechanical (MCAD) Analysis (CAE) Electronic (ECAD) Systems Engineering Tools PDM System Item X MCAD Item X CAE Item X ECAD Item X SE Item X Models Product Data Management, or “PDM”, systems were developed in answer to the requirements of managing large and diverse sets of CAD files, data, and documents in a product development environment. Current state-of-the-art PDM systems provide sophisticated configuration management, versioning, association, product structure representation, viewing, and reporting capabilities. They offer a high-level product-oriented view (vs. a “file-oriented” view) of engineering models and data, grouping together all files and documents associated with a particular product version and configuration, In this diagram, a PDM system is tracking the two products “Item X” and “Item Y”, and it has grouped the various model files associated with them so that they can be managed as sets. The PDM system can then be programmed to recognize the event of one of the files being updated (for example the Item X MCAD file), and can then execute an appropriate business rule, which might be to automatically create a new version of that file and to notify the users of the other discipline files for Item X that a new version of their files may be needed (e.g., an analysis on the new Item X version, a new layout of Item X’s circuit board, etc.). However, the PDM system will not be able to generate the new views of Item X required for the other discipline models, since PDM systems do not understand the internal semantics of the models. (Note: some of the more advanced commercial PDM systems are implementing the capability to extract assembly structure information from STEP files.) Item Y MCAD Item Y CAE Item Y ECAD Item Y SE Item Y Models

“Intelligent PDM” (IPDM): Master Models Integrate Discipline Models Mechanical (MCAD) Analysis (CAE) Electronic (ECAD) Systems Engineering Tools Models (Discipline Views) AP 203 AP 209 AP 210 AP 233 STEP AP's This diagram illustrates the concept of “Intelligent PDM”. The essential ingredients for Intelligent PDM are: (1) a set of discipline-specific information models (the examples shown are the STEP Application Protocols 203 [MCAD], 209 [Finite-Element Analysis], 210 [ECAD], and 232 [Systems Engineering]); (2) STEP translators for the discipline tools: since Intelligent PDM is based on STEP, each tool to participate in this environment must have a STEP import/export capability; (3) a Product Master Model, which incorporates the STEP AP’s as subsets and represents each common object once. For example, the geometry of the product is a subset of the Product Master Model, and is “reflected” in the MCAD, ECAD, and Analysis models, in which it may have different projections (e.g., 2-D or “2.5”-D in an ECAD model) or transformations to lower fidelity. The Product Master Model could be thought of as a “union” or “superset” of all the discipline models of the product. (4) mappings between the discipline-specific views of the product (the STEP AP’s) and the Product Master Model. These mappings are being developed using the EXPRESS-X mapping language, a new part of the STEP standard. The diagram depicts the discipline tools feeding their models through the STEP AP’s and mappings into the Master Models for Spacecraft X and Instrument Y. The Intelligent PDM system can then generate, through the reverse mappings, the changed versions of the other discipline models. NASA Discipline View Mappings STEP Testbed Integrated Master Models Instrument Y Master Model Spacecraft X Master Model

Plug-and-Play IPDM: CORBA PDM Enablers Object Interfaces Mechanical (MCAD) Analysis (CAE) Electronic (ECAD) Systems Engineering CORBA- Enabled Tool IIOP AP 203 AP 209 AP 210 AP 233 Instrument Y Object This diagram illustrates the concept of “Intelligent PDM”. The essential ingredients for Intelligent PDM are: (1) a set of discipline-specific information models (the examples shown are the STEP Application Protocols 203 [MCAD], 209 [Finite-Element Analysis], 210 [ECAD], and 232 [Systems Engineering]); (2) STEP translators for the discipline tools: since Intelligent PDM is based on STEP, each tool to participate in this environment must have a STEP import/export capability; (3) a Product Master Model, which incorporates the STEP AP’s as subsets and represents each common object once. For example, the geometry of the product is a subset of the Product Master Model, and is “reflected” in the MCAD, ECAD, and Analysis models, in which it may have different projections (e.g., 2-D or “2.5”-D in an ECAD model) or transformations to lower fidelity. The Product Master Model could be thought of as a “union” or “superset” of all the discipline models of the product. (4) mappings between the discipline-specific views of the product (the STEP AP’s) and the Product Master Model. These mappings are being developed using the EXPRESS-X mapping language, a new part of the STEP standard. The diagram depicts the discipline tools feeding their models through the STEP AP’s and mappings into the Master Models for Spacecraft X and Instrument Y. The Intelligent PDM system can then generate, through the reverse mappings, the changed versions of the other discipline models. Discipline Model Mappings Integrated Master Models Spacecraft X Master Model Instrument Y Master Model NASA STEP Testbed

Preliminary Components Interface Control Docs The Product Master Model: Progressive Population of Model Over the Mission Life Cycle Pre-Phase A Requirements Functional Model Mission Parameters Preliminary Components Integrated Mission Proposal Phase A/B Prototyping and Analysis Requirements Functional Design Behavioral Model Mission Parameters Physical Model Phase C/D Requirements Functional Design Behavioral Design Physical Design/Arch. Interface Control Docs Mission Parameters Detailed Design, Build, and Test Another benefit of the Intelligent PDM approach is that it provides continuity of the product’s definition as it evolves through the various phases of its development life cycle. Imagine the Product Master Model’s framework as a large set of “shelves” or labeled compartments for the various aspects of a comprehensive product model. In the early conceptual definition of the product (corresponding to Pre-Phase A studies for a NASA mission), only a few of the shelves or compartments are populated, and that data may not be complete in the early stages. Still, it is important to propagate that high-level data, containing requirements and mission parameters, to the later phases of development and to allocate it to the various aspects of system design that it defines and constrains. These allocation relationships are supported in the Product Master Model, and can be viewed by the systems engineer at any point by extracting the systems engineering view of the evolving Master Model. In the early phases, the model may be populated just enough to enable low-fidelity simulations, for example. Another benefit of the Product Master Model is the capability to identify what additional data is needed in order to generate particular types of analysis or simulation models. As the Product Master Model becomes fully populated, more detailed views and simulation models can be generated, until finally the design model can be used to generate detailed drawings and fabrication models.

Product Master Model-Enabled Capabilities “Intelligent Product Data Management” Features: Integration of heterogeneous, multi-disciplinary models into a progressively and continuously defined Master Model Algorithmic generation of discipline-specific view-models (where possible) on demand Interdisciplinary tool “object services” (e.g., live linkage of design features between CAD and analysis models) Integration & persistence of global product model knowledge Integrated Model-based Systems Engineering Master Model explicitly identifies and maintains discipline model interdependencies Can provide immediate feedback on change impacts Supports cross-disciplinary view of requirements, function allocation, and behavior

Initial IPDM Capabilities: NASA STEP Testbed FY99 Plans Initial PDM Enablers (PDME) interfaces (CORBA/IIOP access) Check-in/out via PDME (or via file upload thru Web browser) of STEP models/files User-specified project/system/subsystem hierarchy Standardization of a NASA Systems Engineering Information Model Harmonization of Mission Design Parameters among NASA’s Integrated Design Centers Mapping of harmonized parameters to STEP AP 233 (Systems Engineering) Prototyping of MCAD/ECAD/CAE model integration and sharing The NASA STEP Testbed is collaborating with Boeing, IBM, and Delco-Delphi in the PDES, Inc. Electromechanical Pilot* * The PDES, Inc. Electromechanical Pilot Project is implementing MCAD/ECAD model exchange using STEP AP 203 and AP 210. The FY99 Plan for the NASA STEP Testbed includes the following features. The first 2 are basic PDM functions, which will be implemented using the STEP model for PDM. The second 2 items represent the initial phase of development of the multi-disciplinary Product Master Model: * File check-in/check-out (via Web interface) -- this will be the initial user interface for input to the system. The Object Management Group’s “PDM Enablers” interface will also be implemented (using CORBA and/or Java), and as more tool vendors implement that interface, a more transparent connection between CAx tools and the system will become available. * Input and reporting of project system/subsystem hierarchy. This can include “Work-Breakdown”-style structuring and/or product assembly structuring. * The standardization of a NASA Systems Engineering Information Model will be coordinated with NASA’s various Integrated Design Centers, which are often the first activities to populate the Product Master Model. * As a contribution to the PDES, Inc. Electromechanical Pilot, the NASA STEP Testbed will develop the capability to “split” and “merge” MCAD (AP 203) models and ECAD (AP 210) models. This will be the first increment in the implementation of the Product Master Model, integrating the mechanical and electrical views of an electromechanical product.

For More Info: STEP/OMG URL’s! STEP On-Line Information Service (SOLIS) -- http://www.nist.gov/sc4 Expresso for 95/NT (free download) -- http://www.nist.gov/expresso Note: if interested in the server (Unix) version of Expresso, contact Steve Waterbury STEP On A Page (a capsule summary and current status of STEP) -- http://pdesinc.aticorp.org/step_on_a_page.ppt PDES, Inc.: a government-industry consortium implementing STEP -- http://pdesinc.scra.org USPRO (U.S. Product Data Association), distributor for STEP documents -- http://www.uspro.org NASA STEP Central: the main NASA site for STEP information -- http://misspiggy.gsfc.nasa.gov/step The NASA STEP Testbed: STEP/OMG infrastructure pilot project -- http://misspiggy.gsfc.nasa.gov/step/step.html The OMG Manufacturing Domain Task Force (MfgDTF): PDM Enablers, etc. -- http://www.omg.org/homepages/mfg

AP 203: Configuration Controlled 3D Designs of Mechanical Parts and Assemblies Configuration Management Authorization Control(Version/Revision) Effectivity Release Status Security Classification Supplier Geometric Shapes Advanced BREP Solids Faceted BREP Solids Manifold Surfaces with Topology Wireframe with Topology Surfaces and Wireframe without Topology Specifications Surface Finish Material Design Process CAD Filename Product Structure Assemblies Bill of Materials Part Substitute Part Alternate Part

AP 209: Composite & Metallic Analysis & Related Design Configuration Control, Approvals Part, product definitions Finite element analysis model, controls, and results Analysis Discipline Product Definitions Finite Element Analysis Model (Nodes, Elements, Properties,...) Controls (Loads, Boundary Constraints,...) Results (Displacements, Stresses,...) Analysis Report Design Discipline Product Definition Shape Representations Assemblies Information Shared Between Analysis & Design 3D Shape Representations Composite Constituents Material Specifications & Properties Part Definitions Ply Boundaries, Surfaces Laminate Stacking Tables Reinforcement Orientation Composites Homogeneous (metallics) 3D Shape Representation AP202/203 Commonality Plus Composite Specific 3D Shapes Advanced B-Representation Facetted B-Representation Manifold Surfaces With Topology Wireframe & Surface without Topology Wireframe Geometry with Topology Composite Constituent Shape Representation

AP 210: Electronic Assembly, Interconnect, and Packaging Design Part Functionality Termination Shape 2D, 3D Single Level Decomposition Material Product Characteristics Product Structure/ Connectivity Functional Packaged Physical Component Placement Bare Board Geometry Layout items Layers non-planar, conductive & non-conductive Material product Configuration Mgmt Identification Authority Effectivity Control Requirement Traceability Analytical Model Document References Geometry Geometrically Bounded 2-D Shape Wireframe with Topology Advanced BREP Solids Constructive Solid Geometry Requirements Design Allocation Constraints Interface Technology Fabrication Design Rules Product Design Rules