Using Head-Mounted Displays and In-Situ Projection for Assistive Systems: A Comparison

The increasing demand to customize products affects production workers in many industries, as assembly tasks become more complex due to higher product variety. Assistive systems providing instructions at the workplace have been proposed to overcome increasing cognitive demand during assembly tasks. Commercially available assistive systems provide spatially registered instructions, either by using in-situ projections or head-mounted displays (HMDs). As there is little empirical knowledge about the individual advantages and disadvantages of both approaches, we are interested in comparing both types of systems. Through a user study at a manual assembly workplace, we compare both approaches to a paper baseline. Our results reveal that both in-situ instructions and paper instructions lead to significantly faster task completion times and significantly fewer errors than HMDs. Using additional questionnaires and interviews, we are able to identify the shortcomings of HMD-based instructions and discuss the possibilities of using flexible in-situ instructions for worker assistance.