  Virtual reality (VR) technology is commonly used in entertainment
applications; however, it has also been deployed in practical applications in
more serious aspects of our lives, such as safety. To support people working in
dangerous industries, VR can ensure operators manipulate standardized tasks and
work collaboratively to deal with potential risks. Surprisingly, little
research has focused on how people can collaboratively work in VR environments.
Few studies have paid attention to the cognitive load of operators in their
collaborative tasks. Once task demands become complex, many researchers focus
on optimizing the design of the interaction interfaces to reduce the cognitive
load on the operator. That approach could be of merit; however, it can actually
subject operators to a more significant cognitive load and potentially more
errors and a failure of collaboration. In this paper, we propose a new
collaborative VR system to support two teleoperators working in the VR
environment to remote control an uncrewed ground vehicle. We use a compared
experiment to evaluate the collaborative VR systems, focusing on the time spent
on tasks and the total number of operations. Our results show that the total
number of processes and the cognitive load during operations were significantly
lower in the two-person group than in the single-person group. Our study sheds
light on designing VR systems to support collaborative work with respect to the
flow of work of teleoperators instead of simply optimizing the design outcomes.
