Development of an Integrated Strategy for Customer Requirement Oriented Product Design

• Main Authors: Chen-Cheng Wang, 王振琤
• Other Authors: Ming-Chyuan Lin
• Format: Others
• Language: en_US
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/41106845112435770819

博士 === 國立成功大學 === 工業設計學系碩博士班 === 96 === This study work aims to develop an integrated strategy for customer requirement oriented product design. A well-designed product must depend on the ultimate judgment of customers and should satisfy customers’ practical or emotional requirements. Based on the market-pull concept trend, it is a critical issue to design customer-driven products to maximize customer satisfaction. However, current solutions cannot effectively address the dynamics in customer requirement oriented product design. Thus, an integrated strategy needs to be developed to help designers effectively engage in design activities. The research methodologies used in this study are based on the transformation mechanism for customer requirements from the product functional design and affective design aspects. The proposed integrated strategy defines two levels of customer requirements. First, the functional requirements based on the practical demanding attributes can be mapped into product design characteristics using Quality Function Deployment (QFD). Second, the affective requirements based on the emotional attributes can be transformed into product form design elements using Kansei Engineering (KE). The proposed integrated strategy also introduces several algorithms to conduct product functional design and affective design. For the affective design, this study applied Quantification Theory Type I (QTTI) to investigate the relationships between design elements and product images. For the functional design, this study applied an adapted Analytic Hierarchy Process (AHP) approach to assess the weighting functions of customer requirements and employed a normalized relationship matrix approach to determine the relative importance degree of customer requirements and design characteristics. Furthermore, a competitive benchmarking design was performed for a multiple criteria decision-making process of design alternatives by the Technique for Order Preference by Similarity to the Ideal Solution (TOPSIS). Finally, a structural relational map of customer requirements was analyzed using Interpretive Structural Modeling (ISM) technique to help designers obtain keen insight into interdependent relationships among systematic elements. The personal digital assistant (PDA) was used as an illustrated example to demonstrate the effectiveness of the proposed integrated strategy and design support information systems. To assist designer in choosing an appropriate integrated design strategy, three types of product category consisting of technology-driven products, user-driven products, and technology-and-user-driven products were identified according to the design goal of achieving technological performance or designing the exterior. Based upon the assessing the quality of industrial design for a finished product, four strategic dimensions were defined as SD1: ‘quality of functional interface’, SD2: ‘appropriate use of resources’, SD3: ‘emotional appeal’, and SD4: ‘product differentiation’. The strategic dimensions can be used to evaluate product category, to identify the characteristics of a specific product, and thus to find out an appropriate integrated strategy for that product. The analytical results of a validation test indicate that the integrated strategy for the PDA design should first conduct product affective design for its high demands on emotional appeal. In the affective design process, a image evaluation experiment was conducted to measure 32 samples with nine design elements and 32 categories against six image word pairs, i.e. ‘Convenient-Difficult’, ‘Leisure-Formal’, ‘Noble-Vulgar’, ‘Special-Usual’, ‘Kindly-Indifferent’, and ‘Simple-Complex’ from various aspect. The image prediction models were obtained using the analysis of QTTI. The partial correlation coefficients were used to rank the design elements and category scores used to indicate the impact degree of categories on a product image. The multiple correlation coefficients of each image prediction model were also identified as 0.903 (‘C-D’), 0.728 (‘L-F’), 0.829 (‘N-V’), 0.889 (‘S-U’), 0.929 (‘K-I’), and 0.826 (‘S-C’). The results of a paired-samples t-test indicate that all the paired differences are not significant and therefore the models can be regarded as valid. The principles of PDA form design were characterized according to the category scores of design elements. Therefore, six optimal combinations of design elements for the corresponding six image word pairs were obtained and validated by an image degree test. Furthermore, a Kansei Design Support Information System (KDSIS) was developed to assist designers in analyzing embodied design suggestions and establish image prediction models for a particular product design features or form elements by providing some required design parameters. In the functional design process for the PDA, 10 customer requirements and nine design characteristics and their associated alternative values were extracted from a variety of sources. The normalized relationship matrix, correlation matrix, and planning matrix were also constructed to evaluate the importance degree of design characteristic, and the results can indicate the impact of that design characteristic on customer satisfaction level. The relative overall relationships of customer requirements to all design characteristics were establish to help designers to clarify the influence of a specific customer requirement on all design characteristics. Moreover, a prototyping system for the generation of conceptual design alternatives based on the identified design criteria was created. A TOPSIS procedure for competitive benchmarking analysis of five PDA design alternatives including DA1~DA4 and a competitor DA5 was performed. The results showed that the design alternative DA3 has the shortest distance (0.574) to the positive ideal solution and thus is selected for further detailed design. This benchmarking analysis can improve the sensitivity of design alternatives to customer requirements, and therefore leads designers to continuously improve design characteristics to achieve a better design solution. Finally, the ISM technique as an extension of QFD is used to tackle the interdependency of customer requirements so as to clarify their structural relationships. The adjacency matrix and reachability matrix of customer requirements were constructed to determine the structural map that helps designers to identify design entries (R12, R14 and R25), design exits (R11, R21, R22, R23, R24 and R31), and also the independent objective (R13). A level partitioning is also conducted in order to classify the elements into different levels of a hierarchical structure. This study also categorizes customer requirements into four clusters based on their driver power and dependence power attributes. The analytical results indicate that an element with strong dependence power but weak driver power might have higher level and become a design exit. An element with strong driver power but weak dependence might have lower level and become a design entry. However, an autonomous or independent element usually possesses weak dependence and weak driver power. Finally, a validation test in terms of strategic dimensions was performed for the integrated strategy. The results indicate that the PDA design should consider the dominant product affective design, and the following sub-dominant product functional design. Although this study uses the PDA for illustration and validation purposes, the proposed integrated strategy is also applicable to other products with various design elements and customer requirements.