The Application Of Qualitative Reasoning In Conceptual Design

Conceptual design is considered as an important part of product innovation and hasbeen more and more attention. Conceptual design is at initial stage throughout the lifeof product design. At this stage, some information which we have obtained about thestructure of the system is inaccurate, incomplete and qualitative. And the informationcannot be translated into quantitative information at this time. Then we cannot or evendo not need establish quantitative system model. Thence, it is not analyzed and solvedby numerical methods. Some behaviors which meet Human thinking habit can beefficiently introduced by qualitative reasoning according to this vague information, soit is an important significance to apply qualitative to the conceptual design.The process of the conceptual design of the product is further understood from theabstract point of view in this article. The importance of which qualitative reasoning isapplied in the conceptual design is emphasized. Having researched the commonly usedmethod of qualitative reasoning, qualitative reasoning based on SDG is emphaticallyintroduced. It is an important branch of qualitative reasoning and an important methodof qualitative reasoning. On the basis of summarizing the literatures of fault diagnosisbased on SDG method, qualitative reasoning based on SDG is presented to apply in thearea of conceptual design. Qualitative reasoning based on SDG is systematicallystudied. The character of SDG model, the process of the establishment of thequalitative model and reasoning based on this model are detailed. The process of theestablishment of the qualitative model is talked about taking certain type of tutoringsystem for example using the thought of qualitative reasoning in view of SDG. Thecorresponding SDG model is set up adopting the method due to the experiencedknowledge. Derive inference rules using SDG compatible pathway and carry on theconstraint propagation. Design the appropriate knowledge representation and constructthe algorithm of constraint propagation and backward reasoning and forwardverification in order to achieve reasoning. At last, taking the four-bar linkage as anobject of the study, establish the corresponding SDG model applying the integratedmeans based on the empirical knowledge and mathematica l models and the process ofbackward reasoning and forward verification is discussed in-depth.