We introduce bichronous collaboration in an eXtended Reality (XR) remote collaboration workflow that seamlessly links asynchronous review with synchronous cooperation on physical tasks. The aim is to reduce the misunderstandings and errors that often arise during remote work. The system records a novice's actions and presents them with three spatiotemporal cues-2D, 3D Basic, and 3D Action. An expert can review and provide feedback asynchronously, and also guide the novice synchronously to fix the error. A user study showed that the 3D Action cue allowed experts to identify faults more quickly, enabled novices to resolve problems in less time with higher success rates than a conventional 2D timeline, without increasing cognitive workload or cybersickness. These findings highlight the value of coupling asynchronous insight with synchronous teamwork and position bichronous collaboration as a practical solution for remote troubleshooting, training, and inspection in XR environments.

Prior research has largely focused on AR or VR alone, but recent CR advances show the benefit of fluidly combining them. This article presents a novel cross-reality (CR) task guidance system designed to support asynchronous task guidance on spatial tasks. The system enables (1) recording and playback of user actions within large-scale workspaces and (2) seamless transitions between augmented reality (AR), world-in-miniature (WIM), and virtual reality (VR) interfaces. A user study demonstrated that the CR interface significantly improved task efficiency, reduced required physical activity, enhanced spatial memory recall, and lowered perceived task load. These findings highlight the system’s ability to bridge temporal and spatial gaps in asynchronous task guidance and suggest the broader potential of CR technologies for collaborative workflows. Limitations and design implications are also discussed to inform future research on CR interface development.

Previous studies have investigated which context-sharing interfaces are effective in improving task performance; however, consistent results have yet to be found. In this study, we developed a convenient remote collaboration system that provides multiple context-sharing interfaces in a single platform (2D video, 360° video, and 3D reconstruction view). All interfaces can reflect live updates of environmental changes, and we aimed to clarify the effect of the interface on the quality of remote collaboration. Thirty participants were recruited to perform a target-finding-and-placing scenario. Using both objective and subjective metrics, we compared the task performance among the three interface conditions. The results showed that participants completed the task faster and reported a better collaborative experience in the 3D interface condition. Moreover, we found a strong preference for the 3D view interface. These results suggest that providing 3D reconstructed spatial information can enable remote experts to instruct local workers more effectively.

When using Virtual Reality (VR) and Augmented Reality (AR) to support remote collaboration, effective communication between a remote expert in VR and a local worker in AR is important for guiding and following task instructions. This is especially crucial for assembly tasks, which require precise identification of parts and clear directions for their combination. Despite the increasing interest in efficient VR-AR communication methods, previous studies have been limited to complex hardware setups and simplified assembly tasks. In this research, we introduce a communication approach for remote collaboration in complex assembly tasks, utilizing simplified hardware configurations. We conducted a user study (n=30) and compared three interaction interfaces (hand gestures, 3D drawing, and virtual replicas) in task completion time, subjective questionnaires, and preference rank. The results showed that the use of virtual replicas not only enhances task efficiency but also receives strong preference by users. These findings indicate that virtual replicas can provide intuitive instructions to local workers, resulting in a clearer understanding of the expert’s guidance.

In virtual reality (VR), users can experience symptoms of motion sickness, which is referred to as VR sickness or cybersickness. The symptoms include but are not limited to eye fatigue, disorientation, and nausea, which can impair the VR experience of users. Though many studies have attempted to reduce the discomfort, they produced conflicting results with varying degrees of VR sickness. In particular, a visually improved VR does not necessarily result in decreased VR sickness. To understand these unexpected results, we surveyed the causes of VR sickness and measurement of symptoms. We reorganized the causes of the VR sickness into three major factors (hardware, content, and human factors) and investigated the sub-component of each factor. We then surveyed frequently used measures of VR sickness, both subjective and objective approaches. We also investigated emerging approaches for reducing VR sickness and proposed a multimodal fidelity hypothesis to give an insight into future studies.