Design Methodology for Human Symbiotic Machines Based on the Description of User’s Mental Model

Abstract

This research establishes a methodology for designing human symbiotic machines. In our proposal, the mental model of a user is described by a user model diagram as an extended version of the well-known System Modeling Language (SysML). The user model diagram originated in the state machine diagram and the activity diagram of SysML. Concretely, the behavior of a machine observed by a user (user model), is drawn as a parallel to the actual behavior of a machine (system model). The user model diagram can visualize the physical processes required to use the machine and can reveal any inconsistencies between user and system models. We have selected a non-industrial stacker crane, which stores and retrieves containers through human manual operation, as an application target of the proposed design methodology. To make the stacker crane interface more user-friendly, several design plans are proposed and discussed together with descriptions of user model diagrams. To evaluate the relationship between diagrams and actual performance, prototypes of interfaces are developed, and usability tests are conducted. Results of usability tests indicate that the user model diagram is a good design tool for estimating the basic usability of a human symbiotic machine.