ComputerAided_Design_Engineering_amp_Manufactur.pdf

• Provision for support functions and methodologies for design critiquing, recording of design
rationale, and planning and execution of design changes
• Facilitation of group interaction between different groups of designers and software systems used
for product development activities
• Facilitation of synchronization between different product design tasks
• Mechanisms for resolving conflicts among competing multiple product design perspectives
• Provision for infrastructural support for the integration of the different product design modules
• Development of a suitably structured product model for every stage of the product design process
• Algorithms for mapping functional requirements of the component into appropriate types and
associated values of product specifications (e.g., tolerances, surface finishes, geometry specifications,
etc.).
Which of the above tasks an IPD system ought to do and how it should go about doing them have
been the subject of continued debate. 2–4 As a first step toward realization of IPD systems, researchers
have focused their attention on the use of Intelligent Computer-Aided Design (ICAD) techniques for the
development of IPD systems. The domain of ICAD techniques among other things includes the organization,
integration, information management and transfer, and control of knowledge bases, expert
systems, and data bases within the framework of the IPD system.
A conventional CAD system with drafting, solid modeling, and design analysis capabilities often forms
the basis on which an IPD system is built. Knowledge-based expert systems and data bases are the other
key elements of an IPD system. In the past, the role of ICAD techniques was limited to the task of enabling
interoperability between different CAD systems and design analysis tasks. 5–8 However, the issue of an
effective integration of all product design tasks has still not been solved even with the introduction of
such knowledge engineering systems. The issues that need to be addressed are mainly from the standpoint
of a generic framework for design data representation, effective integration and coordination of design
tasks, information processing, retrieval of similar designs, and design modification.
The objective of this chapter is to report on the application of ICAD techniques for the implementation
of IPD systems for various tasks associated with product design, such as design analysis, process planning,
and tolerance assignment. Several case studies are presented to demonstrate the salient features of the
application of ICAD techniques for product design activities.
1.2 Elements of IPD Systems: ICAD Techniques
Expert System/Knowledge Base
As outlined in the previous section, one of the most useful functions of an IPD system is to embody the
knowledge available for a given design task. Currently, this task is performed by a technical specialist
who uses various high-level intelligent functions such as intuition, creativity, association, induction,
recognition, and deduction, as well as low-level functions such as computation and information retrieval.
Among the above list of functions, only a few low-level functions involving computation and search have
been analyzed and algorithms have been devised for automatically performing these tasks. To facilitate
higher levels of knowledge processing in an IPD system, the design artifact needs to be defined completely
along with its full functional description. However, there are two obstacles in embedding such knowledge
into an IPD system. First, the expert knowledge is characteristic of an individual or an organization based
on the past experiences and design practices and is often difficult to encapsulate in appropriate design
rules and guidelines; furthermore, this knowledge is extremely context sensitive and cannot be generalized.
Additionally, when several such sources of knowledge are available within an organization, there is
no algorithmic procedure or guideline to resolve the conflicting suggestions. In spite of these difficulties,
expert system shells, together with knowledge bases, can be used for various types of inferencing tasks
such as exploration of the space of all design solutions, generation of design alternatives, etc.
© 2001 by CRC Press LLC