A survey on HoloLens AR in support of human-centric intelligent manufacturing

Augmented Reality (AR) has attracted unprecedented attention in industrial activities, especially after the emergence of HoloLens in 2016, which is considered as the state-of-the-art head-mounted-display AR glass that has been widely applied in human-centric intelligent manufacturing (HCIM) by enabling workers to access intuitive work instructions directly. Nevertheless, to the best of the authors' knowledge, there has not been a holistic perspective on HoloLens in HCIM from the underlying techniques associated with its on-site deployments, preventing workers from being adequately aware of its pros and cons when deploying it in manufacturing activities. To this end, this article aims to provide a systematic overview of HoloLens AR in HCIM that was published from 2016 to 2022. We analyze the underlying techniques of HoloLens primarily, mainly including tracking and registration, scene perception, multimodal interaction and display, which are significant for its actual deployments in HCIM. Followed by detailed discussions on the various human-centric manufacturing activities that benefit from HoloLens, as well as a summary of challenges and opportunities of HoloLens AR in HCIM. We find that, although the feasibility of HoloLens in various industrial scenarios has been shown, on-going improvements in the areas of tracking accuracy, reliable interaction, and usability are still necessary to promote the HoloLens applications. Besides, this review is also meaningful to the awareness on the current technical and practical situations of AR devices in HCIM, providing insights to facilitate on-site industrial AR applications or perform further academic research.