2015 年 17 巻 4 号 p. 411-420
It is very important for designers to ensure safety and usability of products. In this paper, a gap model between designers and users is first proposed as a framework to detect problems in safety and usability and to analyze the causes. Then methods to describe operations on a product, simulate its behavior as state transitions, and detect unsafe and invalid gaps based on temporal intervals and their qualitative relationships are proposed. The proposed methods are implemented in a gap analysis program (GAP), which is used to analyze the operations of a tractor by six general participants and two employees of a tractor-manufacturer. As the result, potential safety and effectiveness gaps are correctly detected.