COMPUTER INTEGRATED TECHNOLOGIES AND KNOWLEDGE MANAGEMENT:ARCHITECTURES

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ARCHITECTURES

General Explanations

Product modeling creates product model data and is seen as a decisive constituent of the computer- supported product development activities. Product creation includes all the tasks or steps of product development, from the initial concept to the tested prototypes. During product modeling, a product model database is created and must support all relevant data throughout the product’s life cycle.

Product modeling is made up of interconnected parts: the product model and the process chain. The product model is related to the product database and the management and access algorithms. The process chain, besides usually being related to the operational sequence of the product devel- opment, is in this context all the necessary product modeling processes required to turn the initial idea into a finished product. The product modeling processes consist of technical and management- related functions. The product model data are the most important factor determined from the devel- opment and planning activities.

The term product model can be logically interpreted to mean the accumulation of all product- related information within the product life cycle. This information is stored in the form of digitalized product model data and is provided with access and management functions. Modeling systems serve for the processing and handling of the product model data.

As with many other systems, the underlying architecture for CAD systems is important for ex- tensibility and adaptability to special tasks and other systems. Compatibility with other systems, not just other CAD systems, is extremely important for profitable application. Product data should be

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made universally employable throughout the product development process because bridges between media and format changes are error-prone and not often automated.

Enhancements of existing CAD systems, in the form of general and specialty application modules, are important in order to allow customer-specific adaptations to already-provided functionality.

The various classes of CAD systems, which may appear in combination with one another (Figure 23), include the basic system, general and specialty application software, and open and shared sys- tems.

A basic CAD system is made up of a computer internal representation (CIR) of the product model, a core modeler with functionality for management and processing of the CIR, and a user interface for visualization of the CIR and interaction with the user (Figure 24).

Integration of Application Modules and Core Modeler

Many companies require not only a modeler for geometrical elements but also application modules to integrate into their product development process and for computer internal imaging of the pro- cesses. Calculation modules and simulation software belong in this category. Such application mod- ules must integrate with the modeler to form a functional entity (Figure 25).

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The application modules can be subdivided, according to their area of employment, into general and specialty modules. General application modules for widespread tasks, such as FEM modules or interfaces to widely used program systems, are commercially marketed by the supplier of the CAD system or by a system supplier of complementary software. Specially adapted extensions, on the other hand, are usually either created by the user or outsourced.

A thoroughly structured and functionally complete application programming interface (API) is a particular requirement due to the inability of the user to look deeper into the system.

Honda implemented a CAD system with around 200 application software packages (Krause and Pa¨tzold 1992), but the user was presented with a Honda interface as a uniform medium for accessing the new plethora of programs. This enabled relative autonomy from the underlying software in that as the user, switching between systems, always dealt with the same user interface.

A further step towards autonomy, stemming from the basic system in use, is met only when application modules use an interface already provided. If this does not occur, the conversion to another base system is costly and time consuming. Sometimes it is even cheaper to install a new application module.

Often special application modules are required that cannot be integrated seamlessly into the CAD system. Therefore, various automobile manufacturers, such as Ford, General Motors, Nissan, VW, Audi, and Skoda, have implemented special surface modelers besides their standard CAD systems to enable free-form surface designs to be carried out.

Shared System Architectures

The scope and time restrictions of most design projects demand the collaboration of many designers. The implementation of shared CAD systems significantly simplifies this teamwork. Here it is possible for several designers to work on the same CIR (computer internal representation). It is not necessary to copy the CIR to various computers in order to work on it and then manually integrate the changes afterwards. The management of this process is taken over by the CAD system. These tasks, however, remain widely concealed from the user. Before this work is begun, only the design area of the respective designer must be defined in order to avoid overlapping.

Such shared CAD systems use a common database. This is usually accessible from the individual CAD stations through a client–server architecture (Figure 26). Usually an Engineering Data Man- agement System (EDMS), implemented in conjunction with a CAD system, is used.

This technique is often found applied in local area networks (LANs), but new problems emerge when a changeover is made to wide area networks (WANs):

• The bandwidth available in a WAN is significantly lower than in a LAN and is often too small for existing shared systems.

• The data security must be absolutely ensured. Therefore, six aspects must be considered:

• Access control: exclusive retrieval of data by authorized personnel

• Confidentiality: prevention of data interception during transmission

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• Authentication: the origin of the data transferred can be reliably identified

• Integrity: data cannot be modified during transmission

• Nonrepudiation: the sending of data cannot be refused or denied

• Availability: the data must always be available to authorized users Newer implementations of shared systems rely on software architectures for the exchange of objects. Here, not only data is exchanged but, according to the object, also the data methods.

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