Recently human–robot collaboration (HRC) has emerged as a promising paradigm for mass personalization in manufacturing owing to the potential to fully exploit the strength of human flexibility and robot precision. To achieve better collaboration, robots should be capable of holistically perceiving and parsing the information of a working scene in real-time to plan proactively and act accordingly. Although excessive attentions have been paid to human cognition in existing works of HRC, there is a lack of a holistic consideration of other crucial elements of a working scene, especially when taking a further step towards Proactive HRC. Aiming to fill the gap, this paper provides a systematic review of computer vision-based holistic scene understanding in HRC scenarios, which mainly takes into account the cognition of object, human, and environment along with visual reasoning to gather and compile visual information into semantic knowledge for subsequent robot decision-making and proactive collaboration. Finally, challenges and potential research directions that can be largely facilitated by enhanced holistic perception techniques are also discussed. 

Vision-based holistic scene understanding towards proactive human-robot collaboration

Deep learning-based object detection in augmented reality: A systematic review

As an emerging technology in the era of Industry 4.0, digital twin is gaining unprecedented attention because of its promise to further optimize process design, quality control, health monitoring, decision and policy making, and more, by comprehensively modeling the physical world as a group of interconnected digital models. In a two-part series of papers, we examine the fundamental role of different modeling techniques, twinning enabling technologies, and uncertainty quantification and optimization methods commonly used in digital twins. This first paper presents a thorough literature review of digital twin trends across many disciplines currently pursuing this area of research. Then, digital twin modeling and twinning enabling technologies are further analyzed by classifying them into two main categories: physical-to-virtual, and virtual-to-physical, based on the direction in which data flows. Finally, this paper provides perspectives on the trajectory of digital twin technology over the next decade, and introduces a few emerging areas of research which will likely be of great use in future digital twin research. In part two of this review, the role of uncertainty quantification and optimization are discussed, a battery digital twin is demonstrated, and more perspectives on the future of digital twin are shared. Code and preprocessed data for generating all the results and figures presented in the battery digital twin case study in part 2 of this review are available on Github . 

A comprehensive review of digital twin — part 1: modeling and twinning enabling technologies

Extended reality applications in industry 4.0. - A systematic literature review

Digital Twins: State of the art theory and practice, challenges, and open research questions

For human-robot collaboration (HRC), one of the most practical methods to ensure human safety with a vision-based system is establishing a minimum safe distance. This study proposes a novel integrated mixed reality (MR) system for safety-aware HRC using deep learning and digital twin generation. The proposed approach can accurately measure the minimum safe distance in real-time and provide MR-based task assistance to the human operator. The approach integrates MR with safety-related monitoring by tracking the shared workplace and providing user-centric visualization through smart MR glasses for safe and effective HRC. Two RGB-D sensors are used to reconstruct and track the working environment. One sensor scans one area of the physical environment through 3D point cloud data. The other also scans another area of the environment and tracks the user's 3D skeletal information. In addition, the two partially scanned environments are registered together by applying a fast global registration method to two sets of the 3D point cloud. Furthermore, deep learning-based instance segmentation is applied to the target object's 3D point cloud to increase the registration between the real robot and its virtual robot, the digital twin of the real robot. While only 3D point cloud data are widely used in previous studies, this study proposes a simple yet effective 3D offset-based safety distance calculation method based on the robot's digital twin and the human skeleton. The 3D offset-based method allows for real-time applicability without sacrificing the accuracy of safety distance calculation for HRI. In addition, two comparative evaluations were conducted to confirm the originality and advantage of the proposed MR-based HRC.

Dong Hyeon Roh

Papers

An integrated mixed reality system for safety-aware human-robot collaboration using deep learning and digital twin generation