Interactive worker assistance: comparing the effects of in-situ projection, head-mounted displays, tablet, and paper instructions.

With increasing complexity of assembly tasks and an increasing number of product variants, instruction systems providing cognitive support at the workplace are becoming more important. Different instruction systems for the workplace provide instructions on phones, tablets, and head-mounted displays (HMDs). Recently, many systems using in-situ projection for providing assembly instructions at the workplace have been proposed and became commercially available. Although comprehensive studies comparing HMD and tablet-based systems have been presented, in-situ projection has not been scientifically compared against state-of-the-art approaches yet. In this paper, we aim to close this gap by comparing HMD instructions, tablet instructions, and baseline paper instructions to in-situ projected instructions using an abstract Lego Duplo assembly task. Our results show that assembling parts is significantly faster using in-situ projection and locating positions is significantly slower using HMDs. Further, participants make less errors and have less perceived cognitive load using in-situ instructions compared to HMD instructions.