Proposal: CMS-0116877 PI: Iris Tommelein Institution: University of California at Berkeley Date: July 22, 2001
Abstract: Improving Design Fitness by Applying Tolerance Analysis, Methods Knowledge, and Set-Based Design AEC practitioners as well as academics lack a vocabulary and conceptualization to describe tolerances. Tolerances--used broadly to denote any variation from the point solution that was designed and planned--significantly affect industry performance. This lack is reflected in AEC practices, teachings, and software tools, including those for 4D CAD modeling, which are inadequate in terms of reflecting alternative futures. To alleviate this problem, this research is investigating how performance risk due to tolerances can be reduced through the application of new principles combined with software solutions. Some of these principles have already been applied in manufacturing. They involve the application of distributed set-based design for improving design fitness throughout the project life cycle and analysis of the allocation of tolerances based on production method capabilities. In contrast to contractual approaches that are commonly used in the AEC industry to allocate risk, this research is investigating means for making designs and schedules more robust, so they will withstand impact better. Design in this context broadly refers to the development of the product itself (i.e., design in the narrow sense) but also to the development of processes for production (manufacturing, fabrication, and construction), operations, maintenance, and decommissioning. Fitness denotes the ability of a design and a schedule (product and process) to withstand the impact of tolerances and the corresponding changes while adhering to project goals. The research tasks are to identify and classify various kinds of tolerances affecting AEC product/process development. Case studies will illustrate and help assess how they impede system performance. For each tolerance, the key research question is "Which project stakeholder(s) is (are) in the best position to manage that tolerance?" The objective of the research is to develop a system for tolerance allocation. A method is needed to decide where and when in the product/process development effort the tolerance has an impact, and correspondingly, to decide how this situation is best managed. Research outputs also include: a review of existing software tools and their expressiveness with respect to modeling tolerances; if appropriate, development of guidelines for new software capabilities; a methodology for capturing product and process decisions that allow for alternative futures; and a decision support system to trade off multiple objectives between project stakeholders in order to gauge design fitness.