It is a paradox that today's automated systems for geometry-based engineering activities such as process planning are not able to use geometric information directly. While geometric models have been available for some time, it is not proving easy to link them to decision-making systems. The main hope for building this bridge is feature recognition, in which the geometry of an object is interpreted in terms of geometric elements of engineering significance. In this speculative paper, some of the problems of applying such a process to shape models are outlined, and some lines of advance are suggested. In particular, the possible use of the set-theoretic (constructive solid geometry (CSG)) solid model for feature recognition is discussed.

Some speculations on feature recognition

A major desirable function of CAD systems is for human designers to be given sufficient information about the state of the product being designd to assist them in making design decisions. Building automated-design systems for a class of well known products or systems is an important topic of interest for researchers in artificial intelligence. The paper describes a system that uses Al and CAD techniques to solve combined 3D component-placing and routing-design problems, using the design of a hydraulic manifold block as an example. With the current system, a design that takes a specialized human designer 2 h can be carried out in 10 min by the automated-design system. Work on developing the sustem further continues.

Automated AI-based mechanical design of hydraulic manifold blocks

Marine system design is concerned with planning and development of huge and complex systems. The paper discusses current problems in design and puts forward a set of requirements for CAD systems. It is pointed out that it is important to understand and exploit the capabilities of both the human and the computer. Expert Systems have been identified as an important method for future design systems. Two current projects on application of ES in design are discussed in the last part of the paper.

Concept Definition in Marine System Design

A Computer Aided Design (CAD) system is presented which supports the iterative process of design, the dimensional continuity between mating parts, and the hierarchical structure of the parts in their assembled configuration. Prolog, an interactive logic programming language, is used to represent and interpret the data base. The solid geometry representing the parts is defined in parameterized form using the swept volume method. The system is demonstrated with a design of a spring piston.

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A rule based computer aided design system

‘Carter’ is an expert system that designs crankcases without any intervention from the user (other than setting the problem by describing the mechanism to be encased). It uses several algorithmic black boxes (hamiltonian path in a graph, plate theory, finite elements etc.). To reduce the cost of these algorithms as much as possible, it relies mainly on the engineer's knowledge to infer solutions, or at least to set the boundary conditions and limit the search space. Such a knowledge base has been set up step by step with the help of an original PDIS dealing with productions written in natural language.

Jean-Marc Fouet

Papers

Automated design of crankcases: the Carter system