System design and user evaluation of Co-Star: An immersive stereoscopic system for cable harness design

The system design and results of a user evaluation of Co-Star an immersive design system for cable harness design is described. The system used a stereoscopic head mounted graphical display, user motion tracking and hand-gesture controlled interface to enable cable harnesses to be designed using direct 3D user interaction with a product model. In order to determine how such a system interface would be used by a designer and to obtain user feedback on its main features a practical user evaluation was undertaken involving ten participants each completing three cable harness design tasks with the system. All user interactions with the system were recorded in a time stamped log file during each of the tasks, which were also followed by questionnaire (5 point scale) and interview sessions with each participant. The recorded interaction data for the third task was analysed using functional decomposition techniques and used to construct a single activity profile for the task based on the mean results obtained from the participant group. The goal was to identify in general terms the relative distribution of user activity between specific purposes during practical system operation, and it was found that in this task Navigation accounted for 41%, Design 27%, System Operation 23% and looking at Task Instructions 9% of all user activity. The scored questionnaire data collected immediately after the completion of each task was used to rank the major features of the system according to user opinion. This was further enhanced by also collecting real interview comments from the user group about these same features. The combination of both quantitative performance analysis and subjective user opinion data obtained during a practical design exercise has enabled an in depth evaluation of the system, leading to a much greater understanding of many of the key user and interface requirements that should be considered during the development of immersive interfaces and systems for practical engineering applications.