Design Process Planning by Multi-Objective Optimization of Technical Performance and Product Integrity

Abstract

The importance of flexible and optimal planning of engineering design process for ensuring business success is increasingly recognized in today’s competitive environment. Because a product consists of a lot of subsystems each of which has technical functionalities, an engineering design process consists of two different activities, i.e., an activity to enhance the technical performance level of each subsystem, and an activity to enhance the integrity among the subsystems. When considering the limitation of resources that a manufacturer possesses, there is a trade-off between the achievement probabilities of those activities, although they correlate with each other. This paper proposes a new optimization method of design process planning that aims at a Pareto-optimal achievement of individual technical performances and total product integrity in order to support decision makings of a project manager. A planning of design process is a very complicated optimization problem including a number of various design variables and various evaluation indices. Some of those are discrete factors, while the others are continuous. In order to solve such a complicated problem with a reasonable computation cost, this research separates the optimization problem into two sub problems, i.e., (i) defining of process architecture and organization structure, that is, definition of activities, their sequences, and task groups and (ii) scheduling of resource allocation into activities. A growth curve model with a fuzzy number, which we have been developing, is used to formulate objective functions that evaluate the achievement probability of technical performance and its total integrity. The same model is adopted for objective functions of both sub problems so as to keep consistency between their optimization results. Neighborhood Cultivation GA (NCGA) is adopted in order to effectively solve the multi-objective optimization problem. This paper demonstrates its application to a student design project in order to show the ability of the method. A proposed optimization method facilitates a project manager to explore various process plans, to assess their risks, and decide a temporary plan.

Planning method of creative and collaborative design process with prediction model of technical performance and product integrity

“…A potential area of the proposed model is to use an optimization technique to obtain optimal process plans. We have been developing an optimization algorithm of design process planning that aims at a Pareto optimal achievement of individual TPs and total product integrity (Nomaguchi et al, 2011) based on the mathematical model proposed in this article. Its details will be reported in our future article.…”