Quality management is a responding activity when a company
faces its customers'' requirements. From a product life cycle
point of view, the design quality in a product research stage
has a key inference on the product final quality robustness.
However, a design quality is determined according to customer''s
product quality requirements. These requirements should be
inferred, interpreted and translated into some engineer
requirements to achieve quality superiority. Usually, Quality
Function Development (QFD) method is used to improve the requirement
understanding, and the researcher communication in each research
stage.
However, customer (or technical) requirements are translated
to some pre-defined values (the Wasserman method) that can not
reflect the characteristic of linguistic variables. To solve such
problem, this research proposes a RQDS model that combines both
enhanced QFD method and the Taguchi Method to quantify the
customer''s linguistic expression by assigning each linguistic
requirement a fuzzy number. Firstly, we use a fuzzy analytic
hierarchical process (FAHP) to decide the weight of customer
requirements (WVOC) in HOQ. Secondly, some fuzzy contribution
functions are applied to evaluate the weight of technical
requirements (IVOE) in a fuzzy house of quality (FHOQ).
Thirdly, we use a quality table to analyze the relative design
parameters, and to experiment with Taguchi method of the weight
of technical requirements. Finally, we select a new product
manufacturing case to examine the efficiency of the proposed
algorithm.
In traditional QFD, the contributions of product technical
improvement to customer requirements are represented by fixed
values. However, these contributions are usually expressed by
linguistic variables, which are nature of ambiguity and
multiplicity of meaning. To solve this problem, this research
uses a set of fuzzy functions to represent these contributions.
The benefit of this is that it suits the practical application.
In addition, we find that determining the weight of technical
requirements not only the relationship matrix Cij between
customer requirement and design requirement should be considered,
but also the co-relationship matrix (Rjk) among VOEs must take
into account. Comparing the weight of technical requirement (IVOE)
obtained using the Wasserman method with the proposed FHOQ
method, we find that the proposed method has smaller diversity
of IVOE than that of Wasserman method.