Abstract
When designers with an ergonomic background want to minimize the number of users that will be excluded from their design, they need interactive insight into the distribution of users throughout the design process of the size system for their product. For this purpose a software tool ‘Ellipse’ was developed.
The type of problems, which can be solved with Ellipse, can easy be illustrated by taking the size system of shoes where the distribution of foot length and the foot breadth, and their interrelation would be the key issues for the program Ellipse.
Ellipse needs the raw data, or mean values, standard deviations and correlation coefficients of both variables. The program Ellipse creates an ellipse for a chosen percentage of users to fit. Within the program the designer can choose if he wants to breakdown the bivariate (normal) distribution into one size of shoes for all, or in for example 10 length and 4 breadth sizes (10 stones). Then the production cost could be studied and compared with another size system of 8 times 3, for example. Both concept size systems can easy be analyzed and modified. For every stone the size of the included sample is displayed and also the amount of users that will be excluded from the concept size system. For economic reasons mostly the minimum number of sizes is preferred, however from the ergonomically viewpoint the comfort of fit makes the designer to take care of an acceptable roominess between the product and the human.
This paper will describe the working of Ellipse more in detail.
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