Research on SDG-Based Qualitative Reasoning in Conceptual Design

Abstract EN

Conceptual design is the initial stage throughout the product life cycle, whose main purposes include function creation, function decomposition, and function and subfunction designs.

At this stage, the information about product function and structure has the characteristics of imprecision, incompleteness, being qualitative, and so forth, which will affect the validity of conceptual design.

In this paper, the signed directed graph is used to reveal the inherent causal relationship and interactions among the variables and find qualitative interactions between design variables and design purpose with the help of causal sequence analysis and constraint propagation.

In the case of incomplete information, qualitative reasoning, which has the function of qualitative behavior prediction, can improve conceptual design level aided by the computer.

To some extent, qualitative reasoning plays a supplementary role in evaluating scheme and predicting function.

At last, with the problem of planar four-bar mechanism design, a qualitative reasoning flowchart based on the Signed Directed Graph is introduced, and an analysis is made of how to adjust design parameters to make the trajectory of a moving point reach to the predetermined position so as to meet the design requirements and achieve the effect that aided designers expect in conceptual design.