Constraint-handling techniques for generative product design systems in the mass customization context

Generative product design systems used in the context of mass customization are required to generate diverse solutions quickly and reliably without necessitating modification or tuning during use. When such systems are employed to allow for the mass customization of product form, they must be able to handle mass production and engineering constraints that can be time-consuming to evaluate and difficult to fulfill. These issues are related to how the constraints are handled in the generative design system. This article evaluates two promising sequential constraint-handling techniques and the often used weighted sum technique with regard to convergence time, convergence rate, and diversity of the design solutions. The application used for this purpose was a design system aimed at generating a table with an advanced form: a Voronoi diagram based structure. The design problem was constrained in terms of production as well as stability, requiring a timeconsuming finite element evaluation. Regarding convergence time and rate, one of the sequential constraint-handling techniques performed significantly better than the weighted sum technique. Nevertheless, the weighted sum technique presented respectable results and therefore remains a relevant technique. Regarding diversity, none of the techniques could generate diverse solutions in a single search run. In contrast, the solutions from different searches were always diverse. Solution diversity is thus gained at the cost of more runs, but no evaluation of the diversity of the solutions is needed. This result is important, because a diversity evaluation function would otherwise have to be developed for every new type of design. Efficient handling of complex constraints is an important step toward mass customization of nontrivial product forms

Restart Strategies for Constraint-Handling in Generative Design Systems

Product alternatives suggested by a generative design system often need to be evaluated on qualitative criteria. This evaluation necessitates that several feasible solutions which fulfill all technical constraints can be proposed to the user of the system. Also, as concept development is an iterative process, it is important that these solutions are generated quickly; i.e., the system must have a low convergence time. A problem, however, is that stochastic constraint-handling techniques can have highly unpredictable convergence times, spanning several orders of magnitude, and might sometimes not converge at all. A possible solution to avoid the lengthy runs is to restart the search after a certain time, with the hope that a new starting point will lead to a lower overall convergence time, but selecting an optimal restart-time is not trivial. In this paper, two strategies are investigated for such selection, and their performance is evaluated on two constraint-handling techniques for a product design problem. The results show that both restart strategies can greatly reduce the overall convergence time. Moreover, it is shown that one of the restart strategies can be applied to a wide range of constraint-handling techniques and problems, without requiring any fine-tuning of problem-specific parameters

Sistema de customização de mobiliário paramétrico aplicado ao contexto maker

O conceito de customização em massa foi introduzido nas décadas de 1970 e 1980, como resposta a mudanças culturais dos consumidores. Embora presente em diferentes segmentos industriais, como o mobiliário, apenas recentemente o conceito pôde ser aplicado de forma mais abrangente, viabilizado pela popularização de tecnologias como a fabricação digital e projetos auxiliados por computador. Valendo-se de transformações no comportamento do consumidor se identificou o uso destas tecnologias pelo movimento maker, que se caracteriza entre outros aspectos pela disseminação de projetos digitais, pela produção customizada e/ou distribuída, bem como pelo uso de espaços capacitados para a produção digital de objetos, como o mobiliário. Propõe-se o desenvolvimento de artefatos que compõe um sistema para implementação de ferramentas de projeto paramétrico como facilitador na concepção e produção destes objetos, visto que apresentam novos paradigmas de projeto e execução. Sendo esta pesquisa de caráter qualitativo e prescritivo, como metodologia utiliza-se a design science research a partir de uma implementação dos artefatos propostos em contexto real, de empresa de pequeno porte de produção de mobiliários com características maker na cidade de Porto Alegre/RS, tendo como produto avaliado um mobiliário tipo mesa de trabalho de projeto flexível e fabricação digital, com interação do consumidor a partir de configurador online. A análise do sistema desenvolvido ocorreu através da análise qualitativa dos resultados alcançados, vantagens e desvantagens em relação aos processos padronizados e nível de customização alcançado. Como resultado, observou-se grande eficácia no que diz respeito à adaptação de projetos e fabricação de mobiliários customizados, com flexibilidade e controle dos limites de projeto. Por fim, foi possível verificar a viabilidade de implementação de processos paramétricos e configuradores como facilitadores na customização de mobiliários no contexto de pequenas empresas e produção de característica maker.The concept of mass customization was introduced in the 1970s and 1980s in response to consumer cultural changes. Although present in different industrial segments, such as furniture, only recently the concept could be applied in a more comprehensive way, it was made possible by the popularization of technologies such as digital manufacturing and computer-aided projects. Using transformations in consumer behavior, the use of these technologies was identified by the maker movement, which is characterized among other things, by the dissemination of digital projects, by customized and/or distributed production, and by the use of spaces enabled for digital production of objects such as furniture. It is proposed the development of artifacts that make up a system for implementing parametric design tools as a facilitator in the design and production of these objects, as they present new design and execution paradigms. As this research is qualitative and prescriptive, design science research is used as a methodology for an implementation of the proposed artifacts in a real context, of a small furniture production company with maker characteristics in the city of Porto Alegre/RS, having as evaluated product a worktable type furniture with flexible design and digital fabrication with consumer interaction through an online configurator. The analysis of the developed system took place through the qualitative analysis of the results achieved, advantages and disadvantages in relation to the standardized processes and the level of customization reached. As a result, it was observed great effectiveness regarding the adaptation of projects and manufacture of customized furniture, with flexibility and control of project limits. Finally, it was possible to verify the feasibility of implementing parametric processes and configure them as facilitators of automated customization in the context of small companies with maker characteristics