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§ Detailed specifications for the mechanical area.


§ Supplementary information about the data structures and concepts employed.

§ Provided rules and recommendations concerning specifications to ensure coherence in future developments

[16].

Association GOSET is an organization established by industry and government in France to support continued

development, maintenance, and implementation testing of SET. GOSET representatives are also active contributors

to developing STEP and testing services to conformance test ISO 10303 [17].

2.3.4 CAD*I

In 1984, the European Commission funded an ESPRIT project called CAD Interfaces (CAD*I), with twelve

participating organizations from six European countries. The project worked mainly in product model data

exchange and on data exchange for finite element analysis. As in STEP, the transfer of data was based on the use of

schemas defined formally using a data modeling language. In 1987, this project achieved the first ever transfer of

boundary-representation solid models between different CAD systems. CAD*I participants were involved in the

development of STEP from the beginning of the work of ISO TC184/SC4, and some of them are still active today.

Much of the shape modeling capability of STEP is based on CAD*I work [18], and the project also had a significant

influence on STEP developments in the finite element area.

2.3.5 Why Not Adopt IGES Worldwide?

The following realities became drivers for a common international standard:

· Global commerce and increased outsourcing making data exchange more critical.

· More complex products which require coordinating among multiple engineering disciplines.

· Multi-use software, e.g., design or engineering systems that apply to multiple industries and applications.

· Reliance on suppliers at all phases of product development.


· Need for lifecycle support.

Moreover, these are the generalities. As cited

earlier, IGES as a world contender for

international standardization, also had many

technical flaws.

2.4 THE PDES INITIATION

EFFORT

By 1984, many of these efforts had produced

enough results to be compared, and an

international community was preparing to

form a committee in hopes of creating a

common solution to CAD data exchange. In

May of 1984, a late night meeting of the IGES

Organization Edit Committee was held. The

outcome: Kal Brauner, the Boeing

representative was tasked to write a paper on

what the next generation of IGES might look

Larry O’Connell (then of Sandia Laboratories) recalls… I

remember the IGES quarterly meeting aboard the

landlocked Queen Mary liner near Long Beach, CA. Most of

us slept in staterooms aboard the elegant vessel and strolled

to the daily plenary session after power walking around the

ship and having breakfast on board. Much of the paneling

in the less pricey staterooms was bird's eye maple. At least

one of the plenary sessions was held in the grand ballroom

under massive crystal chandeliers. Many representatives

from across the Atlantic and some from across the Pacific

attended to give the conference a truly international flavor.

Brad Smith outlined his notion of what should be done to

expand the scope and vision of the next version of "the

standard." In the months that followed, a select few (guided

by Kal Brauner of Boeing) began defining the requirements

of what is now known as ISO 10303. In early 1985, the


Queen Mary was a fitting setting for the launch of such a

gigantic venture.

16

like without the IGES constraint to provide upward compatibility for processors. This informal request was in

response to pressure from PDDI results and European efforts. The first Product Data Exchange Specification

(PDES) report was issued in July of 1984, and was followed by a second report in November of 1984. These reports

laid the groundwork for the PDES Initiation Effort, which, similar to PDDI, was considered a theoretical exercise at

building a standard based on a broader automation goal and the discipline of information modeling. The PDES

Initiation Effort used a simple machined part as its focus for both the “logical” information being captured and the

“physical” mechanisms of data exchange. It also included an Electrical Schematic Application model. The

Initiation task validated, through modeling, the concept that electrical connectivity and mechanical “joining” both

shared a common topological model structure.

Those individuals involved originally assumed that this next-generation standard would be IGES Version 3. Instead,

the work spawned a separate U.S. national effort known as PDES. PDES was eventually the specification for the

international effort led by ISO TC184/SC4 responsible for developing and standardizing STEP. Chapter 3 provides

more detail on PDES impact and this initiation effort.

2.5 HOW DID ELECTRICAL CONTENT FIND ITS WAY INTO STEP?

One might wonder how electrical content ended up in an ISO, rather than an International Electrotechnical

Commission (IEC) standard. As with STEP, the roots trace back to IGES. The original vision for IGES included

easy access to all machine-readable product data from any CAD tool, including data about electrical and electronic


products. It was not until the second version of IGES that a very preliminary attempt was made to accommodate

electrical connectivity information. Under the leadership of the IGES Organization Electrical Applications

Subcommittee7, developers began using information modeling in 1983 to improve the quality of electrical constructs

in later versions of IGES.

Aside from the quality of the constructs, the EAC was concerned about overlap and duplication with other

standardization efforts. In late 1983, the EAC met with the Institute for Interconnecting and Packaging Electronic

Circuits (IPC) in an attempt to coordinate efforts. It was decided then that IPC would continue to focus on the

CAD-to-CAM interface and the IGES EAC would focus on the modeling and CAD to CAD issues. Members of the

EAC also heard of attempts by the silicon foundry to develop an interchange format for integrated circuit designs,

and many wondered if that effort would duplicate, complement, or conflict with what was being developed for

IGES.

2.5.1 Harmonization Activities

In April of 1984, The Institute of Electrical and Electronics Engineers (IEEE) Standards Coordinating Committee

called a meeting that further drew the IGES Organization into a dialog with other standards efforts. Of particular

interest was closer coordination between IGES and the relatively new Electronic Design Information Format (EDIF)

effort. The EDIF representative at this meeting declined an offer of joint participation, for fear that standardization

activities might delay the EDIF development schedule— a factor that has continued to impede, from both the IGES

and EDIF sides, true coordination among related standards efforts. Other electrical standards represented included

the IEEE Very High Speed Integrated Circuit (VHSIC) Hardware Description Language (VHDL) authorized by


IEEE Project Authorization Request (PAR) P1076, the Abbreviated Test Language for All Systems (ATLAS), and

the Tester Independent Support Software System (TISSS).

At about the same time, a representative from Westinghouse began reaching out to other related standardization

efforts across the Atlantic Ocean, and authored several related papers that were published by CAM-I. He developed

contacts that led to discussions between the IGES Organization EAC and the IEC TC3, Documentation and

Graphical Symbols. In particular, NBS along with other IGES officers attended a meeting of TC3 subcommittee

7 Later known as the Electrical Applications Committee (EAC).

17

Howard Bloom recalls… When I was asked

by the CALS program manager to lead the

harmonization effort, I had no realization of

the sensitivity of each of the standards

development organizations. I had to be

extremely careful at the early meetings with

the words that I used. One phrase that

might favor one specific standard sent the

consensus building activity “two steps

back.” It took hard work, keen listening

and great diplomacy to drive the activity

towards accepting HPS-100. I don’t think it

would have been possible if I had been from

any other organization other than NIST.

SC3B in Los Angeles. This later facilitated the involvement of TC3 in the ISO/IEC Joint Working Group within ISO

TC184/SC4.

Many organizations, including ANSI, and numerous individuals tried to find ways to increase the awareness and

cooperation among related electrical standardization efforts with little measurable success. Each group working on

some aspect(s) of the standardization for electrical and electronic product data had a set of volunteers, their

sponsors, and a clientele to whom they felt they owed their scheduled deliverables. For the most part, no two efforts

were initiated with the same goal, but rather were extended into overlapping territory in response to the needs of

their users. Furthermore, some of the sanctioning standards bodies depended in some part for revenue from the sale

of standards documents. A certain amount of jealousy about a perceived hierarchy of organizations also hampered

some of the willingness of people at the working level to share results and efforts. The resulting array of conflicting

and overlapping standards prevented the market from supporting any cohesive standard interchange methodology,

and left much of the burden of data exchange on the shoulders of manufacturers who used electrical CAD systems.

In February of 1988, ANSI/ASME Y14.26 (the same committee that standardized IGES) raised the concern to ANSI

management in a letter which stated:

“… we are concerned that there are concurrent overlapping standards activities that are not

coordinated. Of particular concern are the Initial Graphics Exchange Specification (IGES)

Electrical Application subset, the Electronic Design Interchange Format (EDIF), the Institute for

Interconnecting and Packaging Electronic Circuits (IPC) 35X series of specifications and the

VHSIC Hardware Description Language (VHDL)… ”

While the standards cited were not the only efforts of concern, they were specifications which

ANSI itself had authorized and which the government called out in CALS military standards.

This letter led to a “Harmonization” meeting at EIA Headquarters in May, 1988. CAM-I’s

Electronics Automation Program (CAM-I EAP) Manager followed by offering to champion the


effort. Participants included Boeing, McDonnell Douglas, Allied Signal, Eastman Kodak,

Hewlett-Packard, Northrop, The Plessey Company, Westinghouse, and NIST. In February of

1989, the EIA issued results of an Evaluation Report entitled “Harmonizing CALS Product Data

Description Standards.”

The CALS/EIA Report found “… far more overlap

than… anticipated… EDIF overlaps one or more other

standards 78 times.” The Report offered a matrix showing

which lifecycle steps were captured by which of the four

ANSI standards, carved out a scope for each standard based

on this matrix, and declared harmonization effectively

accomplished. This proposed solution was rejected by

industry, as noted in CAM-I EAP R-90-EAP-01 which

criticized the Report’s conclusions. Milton Piatok of Boeing

summed up industry’s viewpoint in a letter to ANSI in 1989:

“An electronics company which performs all the

steps in the design process… using heterogeneous

computer systems, work stations, and factory NC

[numerical control] machinery and robots would

have to support all four standards… At worst, this

could mean not only having to implement the software to support each standard, but also having

translators between each pair. … Such an approach (if it were feasible) would be cumbersome,

error-prone, time-consuming, and costly.”

In November 1989, NIST accepted the leadership of the Harmonization effort, which was later formalized as the

Harmonization of Product Data Standards (HPS) organization under the Industrial Automation Planning Panel

18

(IAPP) of ANSI. The HPS established three councils, to which NIST continued to serve as the Secretariat: Business

Needs and Planning, Standards Development and Coordination, and Tools and Technology. Barbara Goldstein from


McDonnell Douglas (now from NIST), led the Tools and Technology Council.

The major accomplishments of the HPS organization were to propose a methodology and a process for harmonizing

the four ANSI standards, and to publish the first version of a coordinated information model as ANSI/HPS-100

“HPS Information Federated Model Descriptions.”

Figure 2-4: The Operative Means to Harmonization

The HPS proposed the following process to guide harmonization, which reflects the group’s early belief that the four

standards would eventually be completely represented within STEP:

Process Guidance for Harmonization

Gather Models Gather verified conceptual models for the subject area of current focus from each of the

relevant standards organizations.

Federate Every element is added to federated model in data dictionary. Elements are classified.

Unique, identical, and conflicting coverage is identified. Conflicts are resolved by

creating generic elements that each conflicting element can be mapped to. Federated

model contains each conflicting element as well as resolving elements.

Test Define mapping between standards through the generic portion of the federated model.

Create test vehicles (test cases) for the subject area of interest in the original standards.

Run test:

Sending Ö Federated Ö Generic Ö Federated Ö Receiving

Standard Model Portion of Model Standard

Format Federated Model Format

Compare before & after files of test vehicles document mappings.

Harmonize Derive harmonized model from tested, generic portion of federated model.

Submit for

Standardization

Submit portions of harmonized model as candidate application reference models

(ARMs) in STEP as they are ready. The harmonized model may also be submitted for


national standardization. Hold public review.

Integrate with STEP The portions of the harmonized model submitted for standardization within STEP will

19

Process Guidance for Harmonization

be integrated with STEP resource models in accordance with STEP procedure.

Develop APs, CDIMs Develop application protocol (AP) and context-driven information model (CDIM) for

subject area of interest. The AP will reference the mappings between the harmonized

model and each standard. Identify information voids that none of the standards cover.

Table 2-1: The Harmonization Process (V1.1)

Both the information model and the guidelines for harmonization, later referred to as the “federation” to reflect the

individual organizations’ priority of autonomy, aided the groundwork for continuing international collaboration.

The HPS was moved under the CIM Standards Board of ANSI and then deactivated as leadership in the area was

transferred to the international arena under IEC Technical Committee (TC) 93. Through its working groups, IEC

TC93 continues to develop a federated model to aid the interoperability of electrical information exchange

standards. NIST representatives continue to play an active leadership role within IEC TC93 to build supporting

electrical and electronic standards.

2.5.2 IGES Electrical Transition to STEP

To help interested manufacturers prepare their people for Computer Integrated Manufacturing using STEP, the EAC

released the Layered Electrical Product Application Protocol (LEP AP), which was referenced in IGES Version 5.3.

Initial EAC leadership to accomplish this release was from the Department of Energy Sandia Laboratories, and later

from NIST by Curt Parks. The model resulted from a decade of development by scores of volunteers working under


the IGES banner, plus many more working under various other banners. People working for and with the ANSI HPS

mentioned above provided significant contributions to the model. A notable monetary and morale boost for this

model came from the U.S. Naval Command, Control & Ocean Surveillance Center, Research Development Test &

Evaluation Division which contracted for developing the IGES Hybrid Microcircuit Application Protocol [19]. This

IGES AP was the most immediate predecessor of the LEP STEP AP.

2.6 LEGACY TO STEP

Even before the ANSI/HPS-100 model emerged, the early efforts of the IGES EAC provided some valuable general

lessons learned about information modeling in a standard’s setting:



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