Incorporating the Qualitative Variable Comfort into the Design of a Wearable Body Sensor System

Abstract

The design of mechatronic devices commonly includes qualitative design objectives that can play a significant role in the consumer appeal and the success of the product. This article presents an approach to incorporate the qualitative design objective comfort into the design process of a wearable device by determining the most suitable locations to mount such hardware. The objective is modeled through multiple criteria to represent comfort. The model is formulated through the theory of fuzzy measures and the Choquet integral. The fuzzy measures are determined through two different and new methods. One method uses a least squares algorithm and the other determines fuzzy measures using a preference ranking of alternatives. In this approach, the preference rankings are locations, ordered from the most comfortable to the least comfortable. This order of locations can be replicated with the determined fuzzy measures and Choquet integral, to build the comfort model. An error that quantifies the inaccuracy in the order of preferred to nonpreferred alternatives is introduced. The comfort model that is established in this article is validated using a training set and a test set. A comparison between the two methods that determine the fuzzy measures is presented.