Katja Hölttä-Otto

Degree of Modularity in Engineering Systems and Products with Technical and Business Constraints

There is consensus that modularity has many benefits from cost savings due to increased commonality to enabling a higher variety of products. Full modularity is, however, not always achievable. How engineering systems and products whose design is heavily influenced by technical constraints, such as weight or size limitations, tend to exhibit rather integral architectures is shown in this study. For this, two metrics are defined on the basis of a binary design structure matrix (DSM) representation of a system or product. The non-zero fraction (NZF) captures the sparsity of the interrelationships between components between zero and one, while the singular value modularity index (SMI) captures the degree of internal coupling, also between zero and one. These metrics are first developed using idealized canonical architectures and are then applied to two different product pairs that are functionally equivalent, but different in terms of technical constraints. Empirical evidence is presented that the lightweight variant of the same product tends to be more integral, presumably to achieve higher mass efficiency. These observations are strengthened by comparing the results to another, previously published, modularity metric as well as by comparing sparsity and modularity of a set of 15 products against a control population of randomly generated architectures of equivalent size and density. The results suggest that, indeed, some products are inherently less modular than others due to technological factors. The main advantage of SMI is that it enables analysis of the degree of modularity of any architecture independent of subjective module choices.

PLATFORM-BASED DESIGN AND DEVELOPMENT: CURRENT TRENDS AND NEEDS IN INDUSTRY

Many companies constantly struggle to find cost-effective solutions to satisfy the diverse demands of their customers. In this paper, we report on two recent industry-focused conferences that emphasized platform design, development, and deployment as a means to increase variety, shorten lead-times, and reduce development and production costs. The first conference, Platform Management for Continued Growth, was held November-December 2004 in Atlanta, Georgia, and the second, 2005 Innovations in Product Development Conference - Product Families and Platforms: From Strategic Innovation to Implementation, was held in November 2005 in Cambridge, Massachusetts. The two conferences featured presentations from academia and more than 20 companies who shared their successes and frustrations with platform design and deployment, platform-based product development, and product family planning. Our intent is to provide a summary of the common themes that we observed in these two conferences. Based on this discussion, we extrapolate upon industry’s needs in platform design, development, and deployment to stimulate and catalyze future work in this important area of research.

The characteristics of innovative, mechanical products

Many new products fail upon introduction to the marketplace, but a few products are exceptionally successful, earning innovation awards and other benchmarks of success. To better understand the features of those innovative products, 197 award-winning products are analyzed to identify the characteristics that distinguish those products from the competition. For the analysis, a set of product-level characteristics is identified and organized into categories, which include functionality, architecture, external interactions, user interactions, and cost. Based on their innovation award citations, the products are analyzed with respect to the set of characteristics, and results are tabulated. Several award-winning products are also compared with competitive products on the shelves of major retail stores. On average, award-winning products display multiple characteristics of innovation. Overall, a vast majority (more than two-thirds) of the award-winning products exhibit enhanced user interactions, with a similar percentage displaying enhanced external interactions, compared with approximately one-third of products offering an additional function and approximately half displaying innovative architectures. The award-winning products also exhibit an average of approximately two more characteristics than their competitors on retail shelves, along with significantly higher rates of innovative architecture, external interactions, and user interactions. The analysis concludes with a discussion of the implications of these findings for engineering design methods.

Level of modularity and different levels of system granularity

All complex system development projects involve analysis of the system architecture. Thus far it has been assumed that there is some correct system decomposition that can be used in the architectural analysis without consideration of the sensitivity of the results to the chosen level of decomposition. We represent 88 idealized system architectures and a real complex system as a design structure matrix at two different levels of decomposition. We analyze these architectures for their degree of modularity. We find that the degree of modularity can vary for the same system when the system is represented at the two different levels of granularity. For example, the printing system used in the case study is considered slightly integral at a higher level of decomposition and quite modular at a lower level of decomposition. We further find that even though the overall results can be different depending on the level of decomposition, the direction of change toward more modular or more integral can be calculated the same regardless of the level of decomposition. We conclude that the level of decomposition can distort the results of architectural analysis and care must be taken in defining the system decomposition for any analysis.

Identifying Customer Needs: Disabled Persons as Lead Users

In product development it is essential to understand what users need. But as current users are functionally fixed, they are not able to provide information that would help develop breakthrough products. Lead users — users that currently experience needs still unknown to the public — are better able to identify and communicate their needs, but identifying lead users is difficult. We show through a case study on mobile phones that extraordinary users, disabled persons in this example, can be seen as lead users. We show how these extraordinary users do experience similar needs as the ordinary users and, in addition, the extraordinary users experience, and are able to communicate, needs that the ordinary users do not yet have, and thus extraordinary users are a valuable resource in customer need identification.Copyright

Comparative analysis of coupling modularity metrics

Modular design has become a widely accepted developmental strategy to create products and systems that can be easily manufactured, upgraded and maintained. In order to achieve these benefits through improvement of a systems modularity, it must be measured. An ideal measure ought to capture modularity while being independent of other architectural factors such as size, system coupling density or the number of modules. In this work, we review past research on modularity measures. Eight modularity measures are selected for a detailed analysis. We use a design of experiments approach to analyse which metrics best measure the degree of modularity independent of other irrelevant factors. To do this, we conduct a factorial analysis of 24 canonical architectures with idealised modularity, including precisely integral, modular and bus architectures. We find that most measures produce inconsistent results, especially if the system architecture contains a bus or modules with loose internal coupling. We identify the metrics that are able to capture the degree of modularity in the most consistent manner.

Study of existing metrics used in measurement of ideation effectiveness

In recent years, many new idea generation methods have been developed to generate innovative concepts. The effectiveness of those methods is evaluated by applying a set of metrics to the resulting concepts. Several metrics have been proposed for this purpose, including quality, novelty, and variety metrics, but the inter-rater reliability of those metrics has not been investigated extensively. In this paper, the inter-rater reliability of three existing metrics is analyzed by applying them to the results of a representative idea generation study. The effects on inter-rater agreement of analyzing concepts at the overall concept level versus the feature level are investigated, along with the impacts of alternative scales for specific metrics. In general, the inter-rater reliability of the metrics is found to be relatively low, with the most reliable results obtained at the feature level. The use of different scales also affects inter-rater reliability, but the effect is less significant. In addition to their low levels of repeatability, the metrics differ in how novelty is appraised.Copyright

A multi-criteria assessment tool for screening preliminary product platform concepts

Platform concept evaluation is a more challenging task than evaluating a single product concept since a platform must effectively support multiple product variants over a prolonged period of time. Existing platform methods develop specific criteria in depth, yet an evaluation of alternative platforms should be based on a broad set of criteria. Based on expert interviews, personal experience, and a literature search we propose a platform assessment tool consisting of 19 criteria for platform evaluation. The criteria are group into six categories: customer satisfaction, variety, after-sale, organization, flexibility, and complexity. The tool is focused on the early platform architecture phase, before proof-of-concept prototyping. However, it can also be used subsequently for platform refinement when more data becomes available. We demonstrate our platform assessment tool through an example with a cordless drill platform.

An Experimental Investigation of the Effectiveness of Empathic Experience Design for Innovative Concept Generation

An important part of designing successful products is building empathy for the people for whom the product is intended. Despite recent interest in empathic design techniques, they remain confined primarily to customer needs analysis and design problem definition activities, and much of the evidence for their impact on engineering designs is anecdotal. In this paper, empathic design techniques are formally integrated into the conceptual design process, and their effectiveness is investigated with a controlled idea generation experiment. Empathic experience design (EED) is a structured conceptual design method focused on stimulating creative, user-centered concept generation by engaging designers in empathic experiences as part of concept generation. Empathic experiences are demanding product interaction tasks that are intended to help a design engineer empathize with customers who use a product under a variety of sometimes challenging conditions. Empathic experiences can represent either actual disabilities or situational disabilities, which are experienced by lead users who push a product to its extremes and experience needs prior to the general population. In some cases, these empathic experiences amplify the situational disability as a means of highlighting the challenges of interacting with a particular product or system. A representative example is the use of thick gloves to limit a designers dexterity and thereby highlight the challenges associated with either actual disabilities, such as arthritis, or situational disabilities, such as extreme cold or fatigue that make it difficult to move ones fingers freely. The EED method precedes concept generation activities with a series of these empathic experiences involving a baseline product to be redesigned. Many professional designers incorporate empathy and empathic experiences into their design practices, but evidence of their impact on resulting designs has been largely anecdotal. In this paper, their effectiveness is investigated formally with strategically designed experiments. The research hypothesis is that empathic experiences, when coupled with concept generation activities, lead to designs that are more original, especially with respect to features that enhance product-user interactions. To test this hypothesis, experiments were conducted on two example problems in which participants were asked to develop concepts for a next-generation product. Experimental groups completed a controlled concept generation task after engaging in empathic experiences with a prototype product to be redesigned. Control groups completed an identical concept generation task after interacting with the prototype products freely. Resulting concepts were analyzed for their originality, technical feasibility, and embodiment of a specific set of innovation characteristics. Results indicate that the experimental participants who were exposed to empathic experiences prior to concept generation produced concepts with significantly higher rates of original product-user interaction features without any sacrifice in technical feasibility. The overall originality of the concepts is also higher for redesign problems with an abundance of existing solutions, indicating that the EED method also helps alleviate design fixation.

Improved clustering algorithm for design structure matrix

For clustering a large Design Structure Matrix (DSM), computerized algorithms are necessary. A common algorithm by Thebeau uses stochastic hill-climbing to avoid local optima. The output of the alg ...