Kansei Engineering has been applied to product development for customer sat
isfaction based on ergonomic technology. The system is composed of three pa
rts such as Kansei analysis, inference mechanism, and presentation technolo
gies. The inference mechanism by which human Kansei is translated into desi
gn elements plays an important role in Kansei Engineering. The reasoning lo
gic in the system must satisfy several conditions. First, the whole aspects
of design elements must be considered in the reasoning processes. Second,
the reasoning logic can make the discrimination between Kansei words select
ed by customers and other words. Third, the reasoned results must have reli
ability high enough to reduce the difference between customer's image and r
easoned design elements.
In this paper, we propose a rule-based inference model which will cover the
above-mentioned conditions. The rule-based inference model is composed of
five rules and two inference approaches. Each of these rules reasons the de
sign elements for selected Kansei words with the decision variables from re
gression analysis in terms of forward inference. These results are evaluate
d by means of backward inference. By comparing the evaluation results, the
inference model decides on product design elements which are closer to the
customer's feeling and emotion. Finally, simulation results are tested stat
istically in order to ascertain the validity of the model.