Guided Heuristics in Engineering Design

Abstract

In Chapter 6, the desired function and constraints are mapped to the artifact description using an evolutionary process that can be visualized as a feedback loop of analysis, synthesis and evaluation. In this chapter, we define “basic synthesis” as the complete description of ‘primitive’ components and their relations so as to meet a set of specifications of satisfactory performance. To determine if “basic synthesis” could scale up to large problems, it is appropriate to analyze the computational complexity of the “basic synthesis” task — an issue which has often been ignored by the design research community. A special case of the “basic synthesis” activity, called the Basic Synthesis Problem (BSP), is addressed. The BSP is shown to be NP-Complete, generally applicable over all design domains, which suggests that the combinatorial complexity would be exponential, hence intractable within most modern computing environments. Such a theoretical mathematical analysis ignores critical domain-specific engineering knowledge. We show that by combining domain-specific mechanical engineering heuristics, which constrain the structure of potential artifacts, the BSP will be computationally tractable. In order to demonstrate the guided heuristics approach to specific domains, the heuristically guided combinatorial analysis will be presented for 2-D wireframe feature recognition systems which are predominant in industrial CAD systems.