Larry A. Stauffer

A model of the mechanical design process based on empirical data

This paper describes the task/episode accumulation model (TEA model) of non-routine mechanical design, which was developed after detailed analysis of the audio and video protocols of five mechanical designers. The model is able to explain the behavior of designers at a much finer level of detail than previous models. The key features of the model are (a) the design is constructed by incrementally refining and patching an initial conceptual design, (b) design alternatives are not considered outside the boundaries of design episodes (which are short stretches of problem solving aimed at specific goals), (c) the design process is controlled locally, primarily at the level of individual episodes. Among the implications of the model are the following: (a) CAD tools should be extended to represent the state of the design at more abstract levels, (b) CAD tools should help the designer manage constraints, and (c) CAD tools should be designed to give cognitive support to the designer.

A Taxonomy for Design Requirements from Corporate Customers

Abstract:We have developed a taxonomy that classifies those needs of a corporation that impact product design. We call these needs corporate requirements. In contrast to the consumer or end-user requirements, corporate requirements come from internal sources such as marketing, finance, manufacturing, and service. This taxonomy allows for an organized method of gathering, managing, and retrieving the requirements. The taxonomy also helps to facilitate a broader, clearer form of Quality Function Deployment. Generic in nature, this taxonomy provides a template with which to create taxonomies for a given product within a given company or industry. We include an industrial case study to demonstrate this concept.

Fundamental Processes of Mechanical Designers Based on Empirical Data

SUMMARY The fundamental processes of problem solving during the mechanical design activity are presented based on a study of human designers. The designers in this study solve problems by applying 10 specialized actions, called operators, which are grouped into the categories of ‘generate’, ‘evaluate’ and ‘decide’. These operators are applied in unique sequences of which 95% constitute the following four local methods: ‘generate and test’ (23%), ‘generate and improve’ (8%), ‘deductive thinking’ (33%) and ‘means end analysis’ (36%). Furthermore, cognitive activity is reduced to a hierarchical architecture of tasks and episodes which reflect the goal structure of the designer. These descriptions demonstrate the abilities and limitations of the human designers problem-solving performance, yielding an insight into how the man-machine interaction of design automation can be improved.

An Experimental Evaluation of Design Information Reuse During Conceptual Design

SUMMARY This paper presents the results of an experimental case study conducted to evaluate the reuse of design information during the conceptual design phase. The goal of this study was to determine the usefulness of design history information and to establish the sneed for providing the conceptual level design information for future use. Five design engineers were given a task of product redesign to satisfy new customer requirements. The scope of the redesign was limited to generating new concept( S) using the old design information. We found that about 50% of the queries made by the subjects were related to the conceptual stage information from the past design effort. We also found that about 70% of the old design information was useful during redesign.

A comparison of the results of empirical studies into the mechanical design process

Abstract Six investigations are compared in which the mechanical design process was evaluated by studying human designers. These studies are summarized on the basis of their purpose and evidence followed by a brief discussion. The conclusions reached in all six studies are then compared to show areas of agreemtnt or disagreement and potential for further research needed to gain a better understanding of the mechanical design process.

Eliciting and Analysing Subjective Data about Engineering Design

SUMMARY Techniques for eliciting and analysing subjective data about the engineering design process are presented. The elicitation techniques are categorized as observations, questions, retrospective protocols, real-time protocols, and psychometric scales. The analysis techniques are categorized as unstructured observations, structured observations, content analysis, and statistical analysis. Advantages and disadvantages of each method are presented as well as their applications. The verification of the resulting data is also discussed.

Assessing the Usefulness of a Taxonomy of Design Requirements for Manufacturing

An assessment of the usefulness of a taxonomy of design requirements for manufacture is presented. The taxonomy describes the various issues that manufacturing imposes on the design of a product. The requirements themselves can be entered into this taxonomy at the appropriate level. The usefulness of this taxonomy is shown experimentally to determine whether the benefits of using it are worth the work it necessitates. The three-level taxonomy is relatively complete, perceptually orthogonal, and consistent in its level of abstractness. All of these factors constitute a sound taxonomy. Use of the taxonomy led to a greater number of requirements which were, overall, much more useful to the development of a quality product.

A design taxonomy for eliciting customer requirements

Abstract The concept design phase of the new product development process represents a high cost of delay in achieving time-to-market. This article introduces an improved method for eliciting customer requirements through the use of a design taxonomy.

Developing an Assessment Tool for Two Organizations Using Six Sigma Principles

Abstract: This article describes the development of a single assessment tool that is applicable to two organizations to reduce redundancy of operations. It is based on a case study of the application of Six Sigma tools and methods to develop an assessment tool for meeting the needs and procedures for the Office of Environmental Health and Engineering of the Albuquerque Area, Indian Health Service, and Region 6 of the Environmental Protection Agency, which had traditionally conducted independent surveys of water sewer and solid waste facilities of Indian tribal organizations in the same region. These efforts were focused on meeting the needs of tribal customers and the staff of both federal agencies following Six Sigmas Design Measure Analyze Improve and Control roadmap. Deliverables of the project included new survey forms, procedures, and training. The project resulted in the elimination of redundant services which in turn has allowed these organizations to be more cost effective in providing additional services to the tribal customers. This effort is resulting in similar adoptions in other regions of the country.

A Representation for Design Information During the Product Definition Process

An experiment was conducted to determine how to best represent the information that is used by designers during the product defini tion process—the first step in the product realization process A real-time protocol session between a design engineer and a customer was re corded while they developed product requirements for a new bass-drum pedal From this session, a base-line representation was developed Three additional protocol sessions were recorded to test the base-line representation during which three other engineers designed products where the definition information was presented according to the base-line representation Results from this testing yielded a slightly changed rep resentation scheme which is presented in this paper The categories of information within the representation were also arranged based on the priorities of use from the three sessions, and a case example for the new representation is also presented This representation has become the model upon which we are developing a computer environment which serves as a common database for product definition during concurrent development of products