Design process rationale capture and support by abstraction of criteria

The re-use of previous design knowledge is a potentially important way to improve design efficiency. To do so, both the product under study (product data) and the argumentation leading to it (process data) must be stored throughout the engineering design process. CAD systems do the former very well; the latter has to be developed. The objective of the paper is to contribute to a system able to capture design process rationale and make it available for re-use in the current design project or in further projects. The approach involves extracting elements of argumentation and maintaining connections between arguments, proposed solutions and decision-making contexts. Criteria exchanged between design participants leading to the acceptance or refusal of solutions are key clues to understanding design rationale. A descriptive model of a design process is proposed, based on features capitalising on the rationale of design: a conjecture (an element of a solution proposed for validation), a criterion (an element of evaluation of the proposal) and the interactions between them. Conjectures capture alternatives; criteria provide access to the rationale behind the alternatives. The model was validated by laboratory-based experimentation. A computer-aided tool supporting and analysing criteria–conjecture interactions was developed, focusing on the context of decision-making and currently available information. It comprises a database storing the interactions and five modules to process the data for use in a design context. The raw data in the database are abstracted into knowledge according to the manner in which a design engineer wants to retrieve and use it. This structure is represented in the form of a data-processing prototype.